Skip to main content
NCBI home page
ACS Omega logoLink to ACS Omega
. 2020 Apr 1;5(15):8912–8918. doi: 10.1021/acsomega.0c00562

Hydroamination of Aromatic Alkynes to Imines Catalyzed by Pd(II)–Anthraphos Complexes

Christina Erken †,‡, Carsten Hindemith †,§, Thomas Weyhermüller †, Markus Hölscher ‡, Christophe Werlé †,§,*, Walter Leitner †,‡,*
PMCID: PMC7178791  PMID: 32337454

Abstract

graphic file with name ao0c00562_0002.jpg

Herein, we report the synthesis, characterization, and catalytic performance of cationic Pd(II)–Anthraphos complexes in the intermolecular hydroamination of aromatic alkynes with aromatic amines. The reaction proceeds with 0.18 mol % of catalyst loading, at 90 °C for 4 h under neat conditions. Good to excellent yields could be obtained for a broad range of amines and alkynes.

Introduction

Nitrogen-based functionalities such as amines, enamines, and imines are ubiquitous structural motifs in biologically active molecules, fine chemicals, pharmaceuticals, or the agriculture industry.1 Accordingly, substantial efforts were allocated to develop synthetic methods capable of introducing these functional groups. Among those protocols, the hydroamination reaction constitutes an (atom-)efficient technology, allowing the direct formation of C–N bonds through the addition of amines to unsaturated C–C bonds.2−6 It is in 1936 that Kozlov et al. reported the first homogeneously catalyzed hydroamination of alkynes using a mercury catalyst.7 Although the stability, activity, and carbophilicity plead for mercury, its toxicity was detrimental. Consequently, alternatives have been sought and discovered among early transition metals (i.e., zirconium and titanium) and lanthanides.8−11 However, because of their high sensitivity toward moisture and air, they showed severe limitations for oxygen-containing substrates. Then, late-transition metals started to attract attention because of their reduced oxophilicity. As expected, they were found to be more tolerant.10,12−14 Since then, many catalytic systems based on late-transition metals capable of performing the hydroamination reaction under mild conditions have been developed.2,8−11,15−32 Palladium, as a metal, has attracted much attention for the reaction of alkyl or aryl amines with a large variety of unsaturated substrates (e.g., alkynes,19,33−38 alkenes,20,39−47 allenes,48,49 enynes,50 and 1,3-dienes51).

In 2006, mechanistic studies by Hartwig et al. investigated structure–activity relationships for bidentate phosphine ligands on the nucleophilic attack of aniline to the metal-activated alkene. They concluded that an increase in the bite angle of the phosphine ligand from 102° to 108° enhanced the reaction rate by an order of magnitude.20 While the two phosphorus donor atoms reside in a cis arrangement for bidentate ligands, pincer-type ligands force them into a trans arrangement. However, to the best of our knowledge, palladium pincer complexes have not been reported for the intermolecular hydroamination of alkynes. A prototypical tridentate example is the Anthraphos ligand, resulting in a large P–Pd–P angle of 166.2 (1)°.52,53 Moreover, the palladium(II) Anthraphos system has demonstrated high efficiency for a broad range of reactions such as the formation of C=C double bonds in allylation, electrophilic substitution, or dehydrogenation reactions.53−60 However, they have yet to be studied for hydroamination reactions. The present study aims at fulfilling this gap and discloses the synthesis and catalytic activity of palladium(II) complexes supported by Anthraphos ligands. We found that the selected complexes, in their cationic form, were able to catalyze the intermolecular hydroamination of alkynes with primary aromatic amines, forming Markovnikov (imines) products. Good to excellent yields could be obtained for a broad range of amines and alkynes, in favorable cases, with a catalyst loading as low as 0.18 mol %, at 90 °C within 4 h under neat conditions.

Results and Discussion

Palladium complexes [Pd(AnthraphosPh)Cl] (4, Ph = phenyl) and [Pd(AnthraphosXyl)Cl] (5, Xyl = 3,5-dimethylphenyl) were prepared by following modified reported procedures in the individual steps, as described in Scheme 1.52,57,61,62

Scheme 1. Reagents and Conditions: (a) nBuLi, −78 °C, R2PCl (R = Ph or Xyl), THF, 2 h, 80 °C; (b) PdCl2(NCC6H5)2, 2-Methoxyethanol, Reflux, Overnight; (c) AgSbF6, THF/CH3CN, 2 h, r.t.

Scheme 1

Open in a new tab

The two ligand frameworks AnthraphosPh and AnthraphosXyl were synthesized, starting from commercially available 1,8-dibromoanthracene (1, molecular structure from X-ray diffraction in the Supporting Information).63,64 The addition of chlorodiphenylphosphine or bis(3,5-dimethylphenyl)chlorophosphine to the lithiated organic backbone 1 in THF led to AnthraphosPh (2) in 87% yield and AnthraphosXyl (3) in 76% yield. A subsequent overnight reaction under reflux conditions of ligands 2 and 3 with bis(benzonitrile)palladium(II) chloride in 2-methoxyethanol led to precatalysts [Pd(AnthraphosPh)Cl] (4, in 80% yield) or [Pd(AnthraphosXyl)Cl] (5, in 75% yield). Finally, the cationic versions of complexes 4 and 5 were obtained by chloride abstraction using silver hexafluoroantimonate in a mixture of THF/CH3CN at r.t. for 2 h, leading to [Pd(AnthraphosPh)CH3CN]SbF6 (6) in 67% yield and [Pd(AnthraphosXyl)CH3CN]SbF6 (7) in 63% yield (Scheme 1).

The formation and structural identity of the molecular complexes were confirmed by spectroscopic methods in solution and by single-crystal X-ray analysis. Solid-state molecular structures of 5 and 6 in single crystals of 5·THF and 6·2THF were obtained by diffusion of n-pentane into their concentrated THF solutions (Figure 1). The crystallographic data of the compounds are shown in the Supporting Information (see Table S1).65 The molecular structures of 5 and 6 are shown with thermal ellipsoids drawn at the 60% probability level. For clarity reasons, the solvent molecules (THF), the SbF6 anion, and the hydrogen atoms were omitted (Figure 1). As described in Table S1, complexes 5 and 6 crystallize in the triclinic space group P-1. The palladium center in 5 and 6 adopts a square-planar coordination environment with the coplanar Anthraphos ligand in the tridentate coordination mode to the metal center. In the neutral complex 5, the Cl ligand fills the fourth coordination site, while this is occupied with acetonitrile in cationic complex 6, which prevails in the coordination sphere, despite the presence of large excess of THF as a solvent. Selected bond lengths and bond angles are reported in Figure 1. The bond length between the anthracene carbon C14 and the palladium center in 5 (C14–Pd1, 2.007 (2) Å) is consistent with its analogue [Pd(AnthraphosPh)Cl] (2.010 (5) Å) reported in the literature52 and consistent more generally for Caryl–Pd σ-bonds (Figure 1).52,66 Similar interatomic distances are observed for complex 6. Finally, the molecular structure confirms the expected large P–Pd–P angle for complexes 5 (167.08 (2)°) and 6 (164.527 (11)°).

Figure 1.

Figure 1

Open in a new tab

Molecular structure of (a) 1,8-bis-((3,5-dimethylphenyl)phosphino)-9-anthrylpalladium(II) chloride ([Pd-AnthraphosXyl-Cl]) (5) and (b) 1,8-bis-(diphenylphosphino)-9-anthrylpalladium(II) acetonitrile hexafluoroantimonate ([Pd-AnthraphosPh-CH3CN]SbF6) (6). Selected interatomic distances (Å) and angles (°) for 5: C14–Pd1, 2.007 (2); Pd1–P16, 2.2714 (7); Pd1–P1, 2.2818 (7); P16–Pd–P1, 167.08 (2); C15–C2–P1, 111.81 (17); C13–C12–P16, 111.83 (18); C2–P1–Pd1, 102.66 (8); C12–P16–Pd1, 103.05 (8). Selected interatomic distances (Å) and angles (°) for 6: C14–Pd1, 2.0149 (10); Pd1–P16, 2.3035 (3); Pd1–P1, 2.3001 (3); P16–Pd–P1, 164.527 (11).

The catalytic activity of complexes 4–7 was evaluated for the hydroamination of phenylacetylene (8a) with aniline (9a) by using 2.8 mol % palladium(II) in THF at 70 °C for 20 h as standard conditions (Figure 2). While the neutral complexes 4 and 5 showed only low activity, the cationic complexes 6 and 7 proved to be highly active and selective with the exclusive formation of the Markovnikov product 10a. Hence, quantitative conversion and 94% yield could be achieved with complex 6, whereas only 2% conversion and 2% yield were obtained with the analogous neutral complex 4. Similar differences were observed for 5 and 7. The aryl substituents at the phosphorous donor atom had only a minor influence on the reactivity, with somewhat lower yields for the sterically more encumbered cationic complex 7 as compared to 6.

Figure 2.

Figure 2

Open in a new tab

Hydroamination of phenylacetylene: investigation of the palladium precursors. Yields were determined by GC analysis using tetradecane as an internal standard. Reaction conditions: 8a (1 mmol), 4–7 (2.8 mol %), and 9a (1.3 mmol) in THF (2 mL) at 70 °C for 20 h.

The influence of the reaction conditions was studied for the most promising catalyst 6 (Table 1). No conversion was observed in the absence of the complex (entry s). Catalyst loading of the leading catalyst 6 was varied in the range of 2.8 to 0.18 mol % (entries a–e). At 0.3 mol % of catalyst loading still, full conversion and high yields (88%, entry d) were achieved; further reducing the catalyst loading to 0.18 mol % decreased both conversion (89%) and yields (84%) only slightly (entry e). Next, different solvents were considered (entries g–k). When the reaction was performed in nonpolar solvents such as toluene or benzene, full conversion and high yields (80% for toluene and 86% for benzene) were obtained (entries h and j). In contrast, polar aprotic solvents such as dichloromethane (DCM) or acetonitrile produced lower yields (e.g., 73% for DCM and 55% for CH3CN; entries g and i).67 This may reflect competing for coordination of the solvents with the substrates, as suggested by the crystallographic analysis. Notably, the best results were obtained under neat conditions with quantitative yields (entry k). Reducing the reaction time (entries k–o) showed that 4 h was sufficient to achieve high conversions (>99%) and high yields (95%). Further reducing the reaction times decreased yields to 77% (2 h) and 75% (1 h). Decreasing the temperature below 70 °C (entries p and r) lowered the conversions (e.g., 81% conversion at 50 °C and 25% conversion at 25 °C). As a result of this systematic variations, the optimum performance of catalyst 6 was achieved when carrying out the reaction with a catalyst loading of only 0.18 mol % under neat conditions at 90 °C for 4 h where quantitative yield could be obtained (entry q). This corresponds to a turnover number of 555 and an average turnover frequency of 139 h–1 as the lower limit.

Table 1. Hydroamination of Phenylacetylene: Investigation of the Palladium Precursors and Variation of the Reaction Conditionsa.

graphic file with name ao0c00562_0003.jpg

entry cat. cat. loading solvent T (°C) t (h) conv. 8a (%) yield 10a (%)
a 6 1.6 mol % THF 70 20 100 90
b 6 1.2 mol % THF 70 20 100 89
c 6 0.6 mol % THF 70 20 100 89
d 6 0.3 mol % THF 70 20 100 88
e 6 0.18 mol % THF 70 20 89 84
f 7 0.18 mol % THF 70 20 81 66
g 6 0.18 mol % acetonitrile 70 20 69 55
h 6 0.18 mol % benzene 70 20 100 86
i 6 0.18 mol % DCM 70 20 91 73
j 6 0.18 mol % toluene 70 20 100 80
k 6 0.18 mol % neat 70 20 100 >99
l 6 0.18 mol % neat 70 8 100 >99
m 6 0.18 mol % neat 70 4 >99 95
n 6 0.18 mol % neat 70 2 98 77
o 6 0.18 mol % neat 70 1 96 75
p 6 0.18 mol % neat 50 4 81 81
q 6 0.18 mol % neat 90 4 100 >99
r 6 0.18 mol % neat 25 1 25 25
s   no cat. neat 90 1 0 0
Open in a new tab
a

Yields were determined by GC analysis using tetradecane as an internal standard. Reaction conditions: 8a (1 mmol), 6 and 7 (0.18–1.6 mol %), and 9a (1.3 mmol) in solvent (2 mL) at r.t. to 90 °C for 1–20 h.

Based on the optimized set of reaction conditions (0.18 mol % 6, neat conditions, 90 °C, 4 h), we examined the substrate scope of the reaction. These results are summarized in Scheme 2. In all cases, the Markovnikov product was obtained exclusively. The only exception was the sterically most encumbered 2,6-diisopropylaniline 9j for which 10% of the anti-Markovnikov product was formed as a side product. These findings were confirmed by several methods (GC, GC–MS analysis, and NMR spectroscopy) and are consistent with previous observations.9,68 The fluorine substituent in the para-position still provided high yields (10c, 92%). However, when introducing strong electron-donating (−OMe) or electron-withdrawing (−CF3) groups in the para-position, the yields of the reaction decreased to 75% (10b) and 56% (10d), respectively. Introducing the −CF3 group in the meta-position was found to be less deactivating (10e, 68%). Strong electron-withdrawing groups such as halides or nitro groups in the ortho-position deactivated the substrates almost completely, and only marginal yields were observed within 4 h of reaction time (24% of 10g, 7% of 10h, and 0% of 10i). Low yields were observed initially also for the methoxy group in the ortho-position, but these results could be improved for 10f (79%) with a prolonged reaction time (8 h) under otherwise identical conditions. In general, electron-donation in the ortho-position was tolerated well despite the increased steric bulk. When ortho-diisopropyl-substituted substrates were tested (10j), high yields (79% Markovnikov and 10% anti-Markovnikov) could be obtained. Even the sterically highly congested 2,4,6-trimethylaniline was hydroaminated, providing 10k in high yield (84%).

Scheme 2. Hydroamination of Phenylacetylene: Investigation of the Amines Using Pd Complex 6 as the Catalyst.

Scheme 2

Open in a new tab

Yields were determined by GC analysis using tetradecane as an internal standard. The results are given in conversion (left) and yield (right). Reaction conditions: 8a (1 mmol), 6 (0.18 mol %), and 9a–9k (1.3 mmol) at 90 °C for 4 h.

For 8 h of reaction time.

Subsequently, various alkynes were tested for their amination with aniline under the standard set of reaction conditions (Scheme 3). Aromatic alkyne derivatives with the electron-withdrawing fluorine substituent 10l and the electron-donating methoxy group 10m in the para-position provided high isolated yields of 79% or 81%, respectively. When the strong electron-withdrawing group (−CF3) 10n was introduced in the para-position, a good isolated yield of 52% was obtained. Considerable side reactions such as the dimerization of the alkyne or the hydrolysis of the imine product to the aldehyde were not observed.

Scheme 3. Intermolecular Hydroamination of Alkynes: Investigation of the Alkynes Using Pd Complex 6 as the Catalyst.

Scheme 3

Open in a new tab

Yields were determined by GC analysis using tetradecane as an internal standard. The results are given in conversion (left) and yield (right). Reaction conditions: 8a–8d (1 mmol), 6 (0.18 mol %), and 9a (1.3 mmol) at 90 °C for 4 h.

Conclusions

In conclusion, we have reported the synthesis of neutral and cationic palladium(II) complexes bearing the conformationally rigid Anthraphos ligand framework. The cationic variants provide good catalytic efficiency in the hydroamination reaction. The best catalytic performance was obtained, with complex 6 giving quantitative yield for the benchmark reaction of phenylacetylene and aniline at a low catalyst loading of 0.18 mol % at 90 °C in a short reaction time of 4 h under neat conditions. A broad class of alkynes was selectively converted with primary aromatic amines into valuable imines as the Markovnikov product was formed exclusively in most cases.

Experimental Section

Synthesis of Ligands and Complexes

A detailed description of the preparation of ligands and metal complexes is available in the Supporting Information.

General Procedure for the Hydroamination Reaction

A mixture of Pd(II) catalyst 6 (0.18 mol %), selected alkyne (1.0 mmol), and selected amine (1.3 mmol) was stirred at 90 °C for 4 h. Subsequently, the reaction mixture was cooled down to room temperature and was subjected to gas chromatography with a flame ionization detector. Therefore, the sample was weighed and dissolved in tetrahydrofuran (1.0 mL), and tetradecane (40 mg, 0.2 mmol) was added as an internal standard. For the isolated yields, the expected compounds were obtained after crystallization from dry methanol.

Acknowledgments

We gratefully acknowledge the basic support by the Max Planck Society, the RWTH Aachen University, and the Ruhr University Bochum. We thank the involved analytic departments for their excellent support. This work is supported by the research network SusChemSys, funded by the State Government of North Rhine-Westphalia. W.L. thanks Prof. Dr. Matthias Haenel for useful discussion about the Anthraphos and Acriphos ligand families. Open Access funding was provided by the Max Planck Society.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.0c00562.

  • General considerations, experimental methods, and synthetic details, copies of NMR and IR spectra, and X-ray data (PDF)

  • Crystallographic data of CCDC-1972782 (1) (CIF)

  • Crystallographic data of CCDC-1972783 (5) (CIF)

  • Crystallographic data of CCDC-1972784 (6) (CIF)

The authors declare no competing financial interest.

Supplementary Material

ao0c00562_si_001.pdf (1.9MB, pdf)
ao0c00562_si_002.cif (585.7KB, cif)
ao0c00562_si_003.cif (1.9MB, cif)
ao0c00562_si_004.cif (3.7MB, cif)

References

  1. Herrmann W. A.; Beller M.; Cornils B.; Paciello R.. Applied Homogeneous Catalysis with Organometallic Compounds, A Comprehensive Handbook in Four Volumes; Third Edition ed., Wiley-VCH: Weinheim, 2018. [Google Scholar]
  2. Müller T. E.; Hultzsch K. C.; Yus M.; Foubelo F.; Tada M. Hydroamination: direct addition of amines to alkenes and alkynes. Chem. Rev. 2008, 108, 3795–3892. 10.1021/cr0306788. [DOI] [PubMed] [Google Scholar]
  3. Wang Z.; Yang L.; Liu H.; Bao W.; Tan Y.; Wang M.; Tang Z.; He W. Selective Synthesis of Quaternary Carbon Propargylamines from Amines, Alkynes, and Alkynes under Neat Condition. Chin. J. Org. Chem. 2018, 38, 2639–2647. 10.6023/cjoc201805033. [DOI] [Google Scholar]
  4. Risi C.; Cini E.; Petricci E.; Saponaro S.; Taddei M. In water Markovnikov hydration and one-pot reductive hydroamination of terminal alkynes under Ruthenium nanoparticle catalysis. Eur. J. Inorg. Chem. 2020, 1000–1003. 10.1002/ejic.201901235. [DOI] [Google Scholar]
  5. Casnati A.; Voronov A.; Ferrari D. G.; Mancuso R.; Gabriele B.; Motti E.; Della Ca’ N. PdI2 as a Simple and Efficient Catalyst for the Hydroamination of Arylacetylenes with Anilines. Catalysts 2020, 10, 176. 10.3390/catal10020176. [DOI] [Google Scholar]
  6. Virant M.; Mihelač M.; Gazvoda M.; Cotman A. E.; Frantar A.; Pinter B.; Košmrlj J. Pyridine Wingtip in [Pd(Py-tzNHC)2]2+ Complex Is a Proton Shuttle in the Catalytic Hydroamination of Alkynes. Org. Lett. 2020, 2157. 10.1021/acs.orglett.0c00203. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Kozlov N. S.; Dinaburskaya B.; Rubina T. J. J. Gen. Chem. USSR 1936, 6, 1341. [Google Scholar]
  8. Pohlki F.; Doye S. The catalytic hydroamination of alkynes. Chem. Soc. Rev. 2003, 32, 104–114. 10.1039/b200386b. [DOI] [PubMed] [Google Scholar]
  9. Severin R.; Doye S. The catalytic hydroamination of alkynes. Chem. Soc. Rev. 2007, 36, 1407–1420. 10.1039/b600981f. [DOI] [PubMed] [Google Scholar]
  10. Huang L.; Arndt M.; Gooßen K.; Heydt H.; Gooßen L. J. Late transition metal-catalyzed hydroamination and hydroamidation. Chem. Rev. 2015, 115, 2596–2697. 10.1021/cr300389u. [DOI] [PubMed] [Google Scholar]
  11. Huo J.; He G.; Chen W.; Hu X.; Deng Q.; Chen D. A minireview of hydroamination catalysis: alkene and alkyne substrate selective, metal complex design. BMC Chem. 2019, 13, 89. 10.1186/s13065-019-0606-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Müller T. E.; Pleier A.-K. Intramolecular hydroamination of alkynes catalysed by late transition metals. J. Chem. Soc., Dalton Trans. 1999, 583. 10.1039/a808938h. [DOI] [Google Scholar]
  13. Tillack A.; Garcia Castro I.; Hartung C. G.; Beller M. Anti-markovnikov hydroamination of terminal alkynes. Angew. Chem., Int. Ed. 2002, 41, 2541–2543. . [DOI] [PubMed] [Google Scholar]
  14. Iali W.; La Paglia F.; Le Goff X. F.; Sredojevic D.; Pfeffer M.; Djukic J.-P. Room temperature tandem hydroamination and hydrosilation/protodesilation catalysis by a tricarbonylchromium-bound iridacycle. Chem. Commun. 2012, 48, 10310–10312. 10.1039/c2cc35520e. [DOI] [PubMed] [Google Scholar]
  15. Burling S.; Field L. D.; Messerle B. A. Hydroamination of Alkynes Catalyzed by a Cationic Rhodium(I) Complex. Organometallics 2000, 19, 87–90. 10.1021/om9902737. [DOI] [Google Scholar]
  16. Hartung C. G.; Tillack A.; Trauthwein H.; Beller M. A convenient rhodium-catalyzed intermolecular hydroamination procedure for terminal alkynes. J. Org. Chem. 2001, 66, 6339–6343. 10.1021/jo010444t. [DOI] [PubMed] [Google Scholar]
  17. Utsunomiya M.; Kuwano R.; Kawatsura M.; Hartwig J. F. Rhodium-catalyzed anti-Markovnikov hydroamination of vinylarenes. J. Am. Chem. Soc. 2003, 125, 5608–5609. 10.1021/ja0293608. [DOI] [PubMed] [Google Scholar]
  18. Utsunomiya M.; Hartwig J. F. Ruthenium-catalyzed anti-Markovnikov hydroamination of vinylarenes. J. Am. Chem. Soc. 2004, 126, 2702–2703. 10.1021/ja031542u. [DOI] [PubMed] [Google Scholar]
  19. Shimada T.; Bajracharya G.; Yamamoto Y. Aquapalladium Complex: A Stable and Convenient Catalyst for the Intermolecular Hydroamination of Alkynes. Eur. J. Org. Chem. 2005, 2005, 59–62. 10.1002/ejoc.200400568. [DOI] [Google Scholar]
  20. Johns A. M.; Utsunomiya M.; Incarvito C. D.; Hartwig J. F. A highly active palladium catalyst for intermolecular hydroamination. Factors that control reactivity and additions of functionalized anilines to dienes and vinylarenes. J. Am. Chem. Soc. 2006, 128, 1828–1839. 10.1021/ja056003z. [DOI] [PubMed] [Google Scholar]
  21. Mizushima E.; Chatani N.; Kakiuchi F. Synthesis of [Ru(CO)2(PPh3)(SP)] and [Ru(CO)(PPh3)2(SP)] and their catalytic activities for the hydroamination of phenylacetylene. J. Organomet. Chem. 2006, 691, 5739–5745. 10.1016/j.jorganchem.2006.09.015. [DOI] [Google Scholar]
  22. Ackermann L.; Althammer A. One-Pot 2-Aryl/Vinylindole Synthesis Consisting of a Ruthenium-Catalyzed Hydroamination and a Palladium-Catalyzed Heck Reaction Using 2-Chloroaniline. Synlett 2006, 2006, 3125–3129. 10.1055/s-2006-950440. [DOI] [Google Scholar]
  23. Zhang Y.; Donahue J. P.; Li C.-J. Gold(III)-catalyzed double hydroamination of o-alkynylaniline with terminal alkynes leading to N-vinylindoles. Org. Lett. 2007, 9, 627–630. 10.1021/ol062918m. [DOI] [PubMed] [Google Scholar]
  24. Lai R.-Y.; Surekha K.; Hayashi A.; Ozawa F.; Liu Y.-H.; Peng S.-M.; Liu S.-T. Intra- and Intermolecular Hydroamination of Alkynes Catalyzed byortho-Metalated Iridium Complexes. Organometallics 2007, 26, 1062–1068. 10.1021/om060965c. [DOI] [Google Scholar]
  25. Dabb S. L.; Ho J. H. H.; Hodgson R.; Messerle B. A.; Wagler J. Weakly coordinating counter-ions for highly efficient catalysis of intramolecular hydroamination. Dalton Trans. 2009, 4, 634–642. 10.1039/B814168A. [DOI] [PubMed] [Google Scholar]
  26. Hesp K. D.; Stradiotto M. Rhodium- and Iridium-Catalyzed Hydroamination of Alkenes. ChemCatChem 2010, 2, 1192–1207. 10.1002/cctc.201000102. [DOI] [Google Scholar]
  27. Kumaran E.; Leong W. K. Rhodium(III)-Catalyzed Hydroamination of Aromatic Terminal Alkynes with Anilines. Organometallics 2012, 31, 1068–1072. 10.1021/om201134j. [DOI] [Google Scholar]
  28. Ickes A. R.; Ensign S. C.; Gupta A. K.; Hull K. L. Regio- and chemoselective intermolecular hydroamination of allyl imines for the synthesis of 1,2-diamines. J. Am. Chem. Soc. 2014, 136, 11256–11259. 10.1021/ja505794u. [DOI] [PubMed] [Google Scholar]
  29. Jahromi B. T.; Kharat A. N.; Amini M. M.; Khavasi H. Ruthenium diphosphine complexes as an efficient hydroamination catalyst. Appl. Petrochem. Res. 2015, 5, 105–112. 10.1007/s13203-014-0095-5. [DOI] [Google Scholar]
  30. Shi S.-L.; Buchwald S. L. Copper-catalysed selective hydroamination reactions of alkynes. Nat. Chem. 2015, 7, 38–44. 10.1038/nchem.2131. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Saint-Denis T. G.; Zhu R.-Y.; Chen G.; Wu Q.-F.; Yu J.-Q. Enantioselective C(sp3)-H bond activation by chiral transition metal catalysts. Science 2018, 359, eaao4798. 10.1126/science.aao4798. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Shen H.-C.; Zhang L.; Chen S.-S.; Feng J.; Zhang B.-W.; Zhang Y.; Zhang X.; Wu Y.-D.; Gong L.-Z. Enantioselective Addition of Cyclic Ketones to Unactivated Alkenes Enabled by Amine/Pd(II) Cooperative Catalysis. ACS Catal. 2019, 9, 791–797. 10.1021/acscatal.8b04654. [DOI] [Google Scholar]
  33. Kadota I.; Shibuya A.; Lutete L. M.; Yamamoto Y. Palladium/Benzoic Acid Catalyzed Hydroamination of Alkynes. J. Org. Chem. 1999, 64, 4570–4571. 10.1021/jo990498r. [DOI] [PubMed] [Google Scholar]
  34. Shimada T.; Yamamoto Y. Palladium-catalyzed intermolecular hydroamination of alkynes: a dramatic rate-enhancement effect of O-aminophenol. J. Am. Chem. Soc. 2002, 124, 12670–12671. 10.1021/ja027683y. [DOI] [PubMed] [Google Scholar]
  35. Bajracharya G. B.; Huo Z.; Yamamoto Y. Intramolecular hydroamination of alkynes catalyzed by Pd(PPh3)4/triphenylphosphine under neutral conditions. J. Org. Chem. 2005, 70, 4883–4886. 10.1021/jo050412w. [DOI] [PubMed] [Google Scholar]
  36. Patil N. T.; Lutete L. M.; Wu H.; Pahadi N. K.; Gridnev I. D.; Yamamoto Y. Palladium-catalyzed intramolecular asymmetric hydroamination, hydroalkoxylation, and hydrocarbonation of alkynes. J. Org. Chem. 2006, 71, 4270–4279. 10.1021/jo0603835. [DOI] [PubMed] [Google Scholar]
  37. Chen Q.; Lv L.; Yu M.; Shi Y.; Li Y.; Pang G.; Cao C. Simple, efficient and reusable Pd–NHC catalysts for hydroamination. RSC Adv. 2013, 3, 18359. 10.1039/c3ra42990c. [DOI] [Google Scholar]
  38. Franco D.; Marchenko A.; Koidan G.; Hurieva A. N.; Kostyuk A.; Biffis A. Palladium(II) Complexes with N-Phosphanyl-N-heterocyclic Carbenes as Catalysts for Intermolecular Alkyne Hydroaminations. ACS Omega 2018, 3, 17888–17894. 10.1021/acsomega.8b02619. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Nakamura I.; Itagaki H.; Yamamoto Y. Ring Opening in the Hydroamination of Methylenecyclopropanes Catalyzed by Palladium. J. Org. Chem. 1998, 63, 6458–6459. 10.1021/jo981468b. [DOI] [Google Scholar]
  40. Müller T. E.; Beller M. Metal-Initiated Amination of Alkenes and Alkynes. Chem. Rev. 1998, 98, 675–704. 10.1021/cr960433d. [DOI] [PubMed] [Google Scholar]
  41. Kawatsura M.; Hartwig J. F. Palladium-Catalyzed Intermolecular Hydroamination of Vinylarenes Using Arylamines. J. Am. Chem. Soc. 2000, 122, 9546–9547. 10.1021/ja002284t. [DOI] [Google Scholar]
  42. Nakamura I.; Itagaki H.; Yamamoto Y. Palladium-catalyzed Inter- and Intramolecular Hydroamination of Methylenecyclopropanes with Amines. Chem. Heterocycl. Compd. 2001, 37, 1532–1540. 10.1023/A:1014513411239. [DOI] [Google Scholar]
  43. Nettekoven U.; Hartwig J. F. A new pathway for hydroamination. Mechanism of palladium-catalyzed addition of anilines to vinylarenes. J. Am. Chem. Soc. 2002, 124, 1166–1167. 10.1021/ja017521m. [DOI] [PubMed] [Google Scholar]
  44. Utsunomiya M.; Hartwig J. F. Intermolecular, markovnikov hydroamination of vinylarenes with alkylamines. J. Am. Chem. Soc. 2003, 125, 14286–14287. 10.1021/ja0375535. [DOI] [PubMed] [Google Scholar]
  45. Michael F. E.; Cochran B. M. Room temperature palladium-catalyzed intramolecular hydroamination of unactivated alkenes. J. Am. Chem. Soc. 2006, 128, 4246–4247. 10.1021/ja060126h. [DOI] [PubMed] [Google Scholar]
  46. Xu T.; Qiu S.; Liu G. Palladium-catalyzed inter- and intramolecular hydroamination of styrenes coupled with alcohol oxidation using N-fluorobenzenesulfonimide as the oxidant. J. Organomet. Chem. 2011, 696, 46–49. 10.1016/j.jorganchem.2010.07.015. [DOI] [Google Scholar]
  47. Kang O.-Y.; Kim B. E.; Park S. J.; Ryu D. H.; Lim H. J. Stable Palladium Hydride Catalyzed Intermolecular Hydroamination of Vinylarenes. Asian J. Org. Chem. 2018, 7, 451–457. 10.1002/ajoc.201700636. [DOI] [Google Scholar]
  48. Al-Masum M.; Meguro M.; Yamamoto Y. The two component palladium catalyst system for intermolecular hydroamination of allenes. Tetrahedron Lett. 1997, 38, 6071–6074. 10.1016/S0040-4039(97)01370-1. [DOI] [Google Scholar]
  49. Beck J. F.; Samblanet D. C.; Schmidt J. A. R. Palladium catalyzed intermolecular hydroamination of 1-substituted allenes: an atom-economical method for the synthesis of N-allylamines. RSC Adv. 2013, 3, 20708. 10.1039/c3ra43870h. [DOI] [Google Scholar]
  50. Radhakrishnan U.; Al-Masum M.; Yamamoto Y. Palladium catalyzed hydroamination of conjugated enynes. Tetrahedron Lett. 1998, 39, 1037–1040. 10.1016/S0040-4039(97)10697-9. [DOI] [Google Scholar]
  51. Löber O.; Kawatsura M.; Hartwig J. F. Palladium-catalyzed hydroamination of 1,3-dienes: a colorimetric assay and enantioselective additions. J. Am. Chem. Soc. 2001, 123, 4366–4367. 10.1021/ja005881o. [DOI] [PubMed] [Google Scholar]
  52. Haenel M. W.; Jakubik D.; Krüger C.; Betz P. 1,8-Bis(diphenylphosphino)anthracene and Metal Complexes1. Chem. Ber. 1991, 124, 333–336. 10.1002/cber.19911240214. [DOI] [Google Scholar]
  53. Romero P. E.; Whited M. T.; Grubbs R. H. Multiple C–H Activations of Methyltert-Butyl Ether at Pincer Iridium Complexes: Synthesis and Thermolysis of Ir(I) Fischer Carbenes1. Organometallics 2008, 27, 3422–3429. 10.1021/om8003515. [DOI] [Google Scholar]
  54. Jensen C. M. Iridium PCP pincer complexes: highly active and robust catalysts for novel homogeneous aliphatic dehydrogenations. Chem. Commun. 1999, 24, 2443–2449. 10.1039/A903573G. [DOI] [Google Scholar]
  55. Haenel M. W.; Oevers S.; Angermund K.; Kaska W. C.; Fan H.-J.; Hall M. B. Thermally Stable Homogeneous Catalysts for Alkane Dehydrogenation. Angew. Chem., Int. Ed. 2001, 40, 3596–3600. . [DOI] [PubMed] [Google Scholar]
  56. Solin N.; Kjellgren J.; Szabó K. J. Palladium-catalyzed electrophilic substitution via monoallylpalladium intermediates. Angew. Chem., Int. Ed. 2003, 42, 3656–3658. 10.1002/anie.200351477. [DOI] [PubMed] [Google Scholar]
  57. Solin N.; Kjellgren J.; Szabó K. J. Pincer complex-catalyzed allylation of aldehyde and imine substrates via nucleophilic eta1-allyl palladium intermediates. J. Am. Chem. Soc. 2004, 126, 7026–7033. 10.1021/ja049357j. [DOI] [PubMed] [Google Scholar]
  58. Choi J.; Goldman A. S.. Ir-Catalyzed Functionalization of C–H Bonds. In Iridium Catalysis; Springer: Berlin, Heidelberg, 2011; Vol. 34, pp 139–167, 10.1007/978-3-642-15334-1_6. [DOI] [Google Scholar]
  59. Kundu S.; Lyons T. W.; Brookhart M. Synthesis of Piperylene and Toluene via Transfer Dehydrogenation of Pentane and Pentene. ACS Catal. 2013, 3, 1768–1773. 10.1021/cs400398w. [DOI] [Google Scholar]
  60. Lyons T. W.; Bézier D.; Brookhart M. Iridium Pincer-Catalyzed Dehydrogenation of Ethers Featuring Ethylene as the Hydrogen Acceptor. Organometallics 2015, 34, 4058–4062. 10.1021/acs.organomet.5b00501. [DOI] [Google Scholar]
  61. Azerraf C.; Shpruhman A.; Gelman D. Diels-Alder cycloaddition as a new approach toward stable PC(sp3)P-metalated compounds. Chem. Commun. 2009, 4, 466–468. 10.1039/B815051F. [DOI] [PubMed] [Google Scholar]
  62. Gelman D.; Azerraf C.. Synthesis of Stable C-(sp3)carbometalated Transition Metal Complexes. WO2,010,013,239, 2010.
  63. Desvergne J.-P.; Chekpo F.; Bouas-Laurent H. Dimerization stereochemistry and local order in organic crystal imperfections. Part 1. Photodimerization of some dichloroanthracenes in the solid state and in fluid solution. J. Chem. Soc., Perkin Trans. 2 1978, 84–87. 10.1039/p29780000084. [DOI] [Google Scholar]
  64. Nakanishi W.; Hitosugi S.; Piskareva A.; Isobe H. 1,8-Diiodo-anthracene. Acta Crystallogr., Sect. E 2010, 66, o2515. 10.1107/S1600536810035191. [DOI] [PMC free article] [PubMed] [Google Scholar]
  65. Hu J.; Xu H.; Nguyen M.-H.; Yip J. H. K. Photooxidation of a platinum-anthracene pincer complex: formation and structures of PtII-anthrone and -ketal complexes. Inorg. Chem. 2009, 48, 9684–9692. 10.1021/ic900479w. [DOI] [PubMed] [Google Scholar]
  66. Allen F. H.; Bellard S.; Brice M. D.; Cartwright B. A.; Doubleday A.; Higgs H.; Hummelink T.; Hummelink-Peters B. G.; Kennard O.; Motherwell W. D. S.; Rodgers J. R.; Watson D. G. The Cambridge Crystallographic Data Centre, Computer-based search, retrieval, analysis and display of information. Acta Crystallogr., Sect. B 1979, 35, 2331–2339. 10.1107/S0567740879009249. [DOI] [Google Scholar]
  67. Jessop P. G. Searching for green solvents. Green Chem. 2011, 13, 1391. 10.1039/c0gc00797h. [DOI] [Google Scholar]
  68. Greenberg S.; Stephan D. W. Hydroamination as a route to nitrogen-containing oligomers. Polym. Chem. 2010, 1, 1332. 10.1039/c0py00120a. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

ao0c00562_si_001.pdf (1.9MB, pdf)
ao0c00562_si_002.cif (585.7KB, cif)
ao0c00562_si_003.cif (1.9MB, cif)
ao0c00562_si_004.cif (3.7MB, cif)

Articles from ACS Omega are provided here courtesy of American Chemical Society

RESOURCES