Abstract
The role of in situ generated fluorinated sulfur intermediates, formed through the interaction of the electrophilic fluorine source Selectfluor with sulfur-containing reagents, in the chemoselective transformations of benzhydrols was investigated from a mechanistic perspective. The 1,2-dimethyldisulfide–Selectfluor combination enabled the selective self-etherification of benzhydrols, and this transformation was shown to proceed via benzhydrol-centered reactive intermediates activated by fluorinated sulfur species. Upon increasing the reaction temperature and 1,2-dimethyldisulfide was replaced with carbon disulfide, the reaction pathway was altered, leading to the selective oxidation of benzhydrols to the corresponding benzophenones. Under the same conditions, when nitromethane was employed as the solvent, Ritter-type amidation was achieved via the solvolytic activation of the benzhydrols. Based on control experiments and the effects of reaction parameters, plausible mechanisms for these condition-dependent chemoselective transformations are proposed and discussed.
Introduction
Selectfluor, a strong “N–F”-type electrophilic fluorinating reagent and oxidizing agent, has been extensively employed in the functionalization of organic molecules as its high reactivity allows the formation of key reactive intermediates under mild conditions, together with its safety, low toxicity, and ease of handling. It is well-known that sulfides rapidly react with Selectfluor to form fluorosulfonium salts. Similarly, the sulfur atoms in disulfides readily interact with the electrophilic fluorine provided by Selectfluor, leading to the formation of sulfur radicals or nucleophilically susceptible cationic sulfur centers as dictated by the reaction conditions. It has been reported that the reactions of aromatic and benzylic disulfides with Selectfluor in aqueous media result in the formation of thiosulfonates, whereas increasing the Selectfluor loading and elevating the reaction temperature lead to the formation of sulfonyl fluorides (Scheme a). The reaction of an aryl disulfide–Selectfluor combination with primary, secondary, and tertiary aliphatic alcohols has been shown to result in the formation of sulfinic esters via sulfination of the alcohols (Scheme b). Sulfinamides have been reported to be obtained in moderate yields from the reaction of the same combination with amines (Scheme c). In our previous study, we achieved the deoxygenation of N-heterocyclic N-oxides by employing Selectfluor in combination with disulfides (Scheme d). In all of the aforementioned studies, the reaction mechanisms are observed to be initiated by the transfer of fluorine from Selectfluor to the sulfur atom of the disulfide. In addition to the experience gained from deoxygenation and our other previous studies on Selectfluor and sulfide chemistry, the fact that benzhydrol derivatives provide mechanistically suitable models due to their sensitivity to carbocationic and radical processes motivated us to investigate the reactions of the reactive intermediates generated by the Selectfluor–sulfide combination with these compounds. In our initial experiments, we observed evidence for the formation of a Ritter-type amide arising from the involvement of acetonitrile in the reaction alongside benzhydrol ether and the oxidation product benzophenone. By validating our hypothesis that reactive intermediates bearing a fluorinated sulfur unit can be generated from a Selectfluor–carbon disulfide combination, and by leveraging the benefits of elevated temperature and judicious solvent selection, we uncovered highly chemoselective and unprecedented strategies for the selective self-etherification, oxidation, and Ritter-type amidation of benzhydrols (Scheme e) (see Table ).
1. Representative Examples Demonstrating the Reactivity of Selectfluor–Disulfide Mixtures.
1. Optimization Study.
| entry | Selectfluor | additive | solvent | time (h) | temperature |
,
yield (%) |
||
|---|---|---|---|---|---|---|---|---|
| 2a | 3a | 4a | ||||||
| 1 | 2.0 eq | 1,2-dimethyldisulfane (2 equiv) | MeCN | 17 | rt | 85 | trace | trace |
| 2 | 2.0 eq | dimethylsulfane (2 equiv) | MeCN | 17 | rt | 44 | 14 | trace |
| 3 | 2.0 eq | carbon disulfide (2 equiv) | MeCN | 17 | rt | 45 | 32 | trace |
| 4 | 2.0 eq | 1,2-dimethyldisulfane (1 equiv) | MeCN | 17 | rt | 86 | trace | trace |
| 5 | 1.0 eq | 1,2-dimethyldisulfane (1 equiv) | MeCN | 17 | rt | 93 | - | - |
| 6 | 1.0 eq | 1,2-dimethyldisulfane (0.5 equiv) | MeCN | 17 | rt | 93 | - | - |
| 7 | 0.55 eq | 1,2-dimethyldisulfane (0.55 equiv) | MeCN | 17 | rt | 94 | - | - |
| 8 | 2.0 eq | carbon disulfide (2 equiv) | MeCN | 18 | 60 °C | 20 | 50 | 25 |
| 9 | 2.0 eq | carbon disulfide (2 equiv) | MeCN | 18 | 80 °C | - | 61 | 35 |
| 10 | 2.0 eq | carbon disulfide (2 equiv) | MeCN | 18 | 100 °C | - | 81 | trace |
| 11 | 2.0 eq | carbon disulfide (2 equiv) | CH3NO2 | 18 | 100 °C | - | 45 | - |
| 12 | 2.0 eq | carbon disulfide (2 equiv) | HFIP | 18 | 100 °C | - | 43 | - |
| 13 | 1.0 eq | carbon disulfide (2 equiv) | MeCN | 18 | 100 °C | - | 82 | trace |
| 14 | 2.0 eq | carbon disulfide (1 equiv) | MeCN | 18 | 100 °C | - | 82 | trace |
| 15 | 2.0 eq | carbon disulfide (0.5 equiv) | MeCN | 18 | 100 °C | - | 94 | trace |
| 16 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN | 18 | 100 °C | - | 94 | - |
| 17 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/MeNO2 (1:4) | 17 | 60 °C | 43 | trace | 45 |
| 18 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/MeNO2 (1:4) | 17 | 100 °C | - | 52 | 44 |
| 19 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/MeNO2 (1:1) | 17 | 100 °C | - | 50 | 46 |
| 20 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/MeNO2 (4:1) | 17 | 100 °C | - | trace | 71 |
| 21 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/HFIP (4:1) | 17 | 100 °C | - | trace | 68 |
| 22 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/DMF (4:1) | 17 | 100 °C | 27 | 15 | 12 |
| 23 | 1.0 eq | carbon disulfide (0.5 equiv) | MeCN/DMSO (4:1) | 17 | 100 °C | 50 | trace | 36 |
| 24 | 0.5 eq | carbon disulfide (0.5 equiv) | MeCN/MeNO2 (4:1) | 17 | 100 °C | - | 52 | 49 |
| 25 | 0.25 eq | carbon disulfide (0.25 equiv) | MeCN/MeNO2 (4:1) | 17 | 100 °C | - | trace | 72 |
| 26 | 0.25 eq | carbon disulfide (1 equiv) | MeCN/MeNO 2 (4:1) | 17 | 100 °C | - | trace | 93 |
Standart conditions: 1a (0.4 mmol), solvent (5 mL), 17–18 h (determined by TLC).
Determined by 1H NMR based on 1a.
In the literature, the etherification, Ritter-type amidation, and oxidation of benzhydrols have been investigated separately using strong Brønsted and Lewis acids, metal salts, transition-metal complexes, heterogeneous catalysts, and various oxidative systems. Benzhydrol ethers are typically synthesized under metal-mediated or strongly acidic conditions employing ZnCl2, TiF4, and Fe(OTf)3, or in the presence of specialized transition-metal catalysts such as (Ph 2NNN)RuCl2(CO), whereas Ritter-type amidation reactions generally require superacids or high-temperature nitrile-containing media. In contrast, the oxidation of benzhydrols has been achieved using SO2F2, peroxides, P2O5-based systems, or costly and specialized heteropolyacid catalysts such as H6P2W18O62. However, the chemoselective differentiation of these three transformations and their rational control within a single reactive platform have not yet been addressed in a general and practical manner.
Results an Discussion
Owing to its low cost, facile removal from the reaction mixture after completion, and the good reactivity demonstrated in our previous study, 1,2-dimethyldisulfane was selected and used in combination with Selectfluor to react with diphenylmethanol in acetonitrile at room temperature. Under these conditions, we unexpectedly discovered the formation of (oxybis(methanetriyl))tetrabenzene (2a) along with trace amounts of benzophenone (3a) and N-benzhydrylacetamide (4a) (entry 1). In light of this result, we focused on the chemoselective synthesis of these three products (2a, 3a, and 4a). First, we changed the sulfide reagent and observed a pronounced increase in the proportion of the oxidation product (3a), particularly when carbon disulfide was employed (entries 2 and 3). Meanwhile, the equivalent amounts of Selectfluor and 1,2-dimethyldisulfane used in the synthesis of the ether (2a) were optimized (entries 4–7); in the reaction carried out in acetonitrile at room temperature, the use of 0.55 equiv of Selectfluor and 0.55 equiv of 1,2-dimethyldisulfane was identified as the optimal conditions for ether synthesis (entry 7). Subsequently, we focused on the chemoselective synthesis of the oxidation and Ritter products (3a and 4a), and we tested the carbon disulfide-containing reactions, which were found to be more prone to oxidation product (3a) formation (Entry 3), at 60, 80, and 100 °C, respectively (entries 8–10). Further, by optimizing the reaction solvent and the equivalent amounts of Selectfluor and carbon disulfide (entries 11–16), we determined that the optimal conditions for the synthesis of 3a involved the use of 1 equiv of Selectfluor and 0.5 equiv of carbon disulfide in acetonitrile at 100 °C (entry 16). We hypothesized that the Ritter product (4a) is formed via a diphenylmethylium carbocation and considered that the addition of polar solvents to the reaction, together with acetonitrile, could enhance the yield of the amidation products (4a). In line with this hypothesis, the effect of adding various polar solvents to acetonitrile was examined in carbon-disulfide-containing systems (entries 17–26). MeCN/MeNO2 mixtures preferentially promoted the formation of the Ritter product (4a), while both the solvent ratio and reagent equivalents exerted a pronounced influence on chemoselectivity. At lower Selectfluor and higher carbon disulfide loadings, the amidation product (4a) became dominant, and the highest yield of 4a was achieved in a MeCN/MeNO2 (4:1) medium using 0.25 equiv of Selectfluor and 1 equiv of carbon disulfide (entry 26).
Under the optimized conditions, we investigated the functional group tolerance and substrate scope of the self-etherification, oxidation, and Ritter-type amidation of benzhydrols. As shown in Scheme , in addition to benzhydrol derivatives bearing electron-donating or electron-withdrawing substituents at the ortho, meta, or para positions, the reactivity of di(thiophen-2-yl)methanol, di(furan-2-yl)methanol, 10,11-dihydro-5H-dibenzo[a,d][7]annulen-5-ol, and 5H-dibenzo[a,d][7]annulen-5-ol toward self-etherification, oxidation, and Ritter-type amidation reactions was systematically investigated. Symmetric and asymmetric benzhydrol derivatives bearing electron-donating or -withdrawing substituents at the ortho, meta, or para positions were generally found to undergo all three transformations in good to high yields. In particular, para-substituted benzhydrols were well tolerated across all reaction manifolds, whereas strongly electron-donating methoxy groups led to a pronounced decrease in reactivity in certain cases (Scheme ). In the self-etherification reaction, a majority of benzhydrol derivatives bearing substituents with diverse electronic properties at the para position were efficiently converted into the corresponding ether products in high yields. In contrast, benzhydrols substituted at the ortho or meta positions were found to be unreactive under these conditions. Heteroaromatic substrates such as di(thiophen-2-yl)methanol and di(furan-2-yl)methanol were not completely inert; however, they preferentially led to the formation of nonetheric, polymeric-type products rather than the desired ether derivatives. The etherification reactions of methyl 4-(hydroxy(p-tolyl)methyl)benzoate and (4-nitrophenyl)(phenyl)methanol proceeded in low yields at room temperature, whereas a marked improvement in the etherification efficiency was observed upon increasing the reaction temperature to 80 °C. Nevertheless, as a side effect of the elevated temperature, the amidation product 4g was obtained as a side product during the synthesis of ether 2g under these conditions. Substrates with extended π-conjugation, namely, 10,11-dihydro-5H-dibenzo[a,d][7]annulen-5-ol and 5H-dibenzo[a,d][7]annulen-5-ol, underwent a smooth self-etherification process, enabling the selective formation of products containing either single or double bonds. However, under prolonged reaction conditions, the initially formed ether products (2r and 2s) derived from these substrates underwent subsequent disproportionation to afford the corresponding ketone and diarylmethane, and therefore the reaction times were deliberately kept short. With respect to oxidation, the benzhydrol core exhibited broad functional group tolerance, and a wide range of substituted benzhydrols, as well as 10,11-dihydro-5H-dibenzo[a,d][7]annulen-5-ol, were cleanly converted into the corresponding ketones in high yields. Electron-withdrawing substituents were generally found to accelerate the oxidation process, whereas the presence of a sterically demanding substituent at the ortho position completely suppressed the reactivity under these conditions. Benzhydrol derivatives bearing heteroaromatic substituents were found to be incompatible with the oxidation conditions. Notably, oxidation of 5H-dibenzo[a,d][7]annulen-5-ol resulted in the formation of anthracene and anthracene-9-carbaldehyde (see Supporting Information S16 and S17). Under the optimized conditions, the formation of amidation products was occasionally observed alongside the desired oxidation products. To suppress this side reaction, the amounts of Selectfluor and carbon disulfide were increased, which led to a significant reduction in amidation byproduct formation. Nevertheless, trace amounts of amidation products were still detected in the synthesis of certain benzophenone derivatives. In particular, benzhydrol derivatives bearing electron-donating methyl or methoxy substituents (3e, 3f, and 3l) predominantly underwent amidation, with the corresponding amide products becoming the major species. Under Ritter-type amidation conditions, benzhydrols bearing aromatic rings with diverse electronic properties were found to participate in amide formation with high selectivity. In contrast, substrates containing heteroaromatic rings were not completely inert; instead, they led to the formation of complex product mixtures that could not be isolated rather than the corresponding amidation products. Notably, benzhydrol derivatives substituted at the ortho or meta positions, which were unreactive in the self-etherification and oxidation reactions, were fully compatible with amidation conditions. With respect to annulen derivatives, the outcome of the amidation reaction exhibited pronounced selectivity, depending on the degree of bond saturation. Moreover, during the synthesis of certain amidation products, oxidation products were also detected as minor byproducts in low yields. Overall, these results demonstrate that the Selectfluor-based system provides broad substrate scope and high chemoselectivity for benzhydrol derivatives while highlighting heteroaromatic frameworks and strongly electron-donating substituents as limiting factors for reactivity.
2. Substrate Scope.
a Reaction conditions: 1 (0.4 mmol), Selectfluor (0.22 mmol), 1,2-dimethyldisulfane (0.22 mmol), MeCN (5 mL), rt, 17 h,
b Reactions were carried out at 80 °C.
c 4g was obtained as a side product (32%).
d Reaction time was 6 h.
e Reaction time was 1 h.
f 1 (0.4 mmol), Selectfluor (0.4 mmol), carbon disulfide (0.2 mmol), MeCN (5 mL), 100 °C, 18 h.
g 1 (0.4 mmol), Selectfluor (1.2 mmol), carbon disulfide (0.6 mmol).
h 4d was obtained as a side product (26%).
j 4e was obtained as a side product (40%).
k 4f was the main product, l4g was obtained as a side product (19%).
m 4j was obtained as a side product (trace).
n Reactions were carried out at 110 °C.
o 4l was obtained as the main product (62%).
p 4s was obtained as a side product (trace).
r 1 (0.4 mmol), Selectfluor (0.1 mmol), carbon disulfide (0.4 mmol), MeCN/MeNO2 (5 mL, 4:1), 100 °C, 17 h.
s 3b was obtained as a side product (23%).
t 3d was obtained as a side product (trace).
v Reaction time was 14 h.
y 3g was obtained as a side product (trace).
z 3h was obtained as a side product (40%).
x 3j was obtained as a side product (15%).
w 3k was obtained as a side product (8%).
q 3m was obtained as a side product (20%), yields of isolated products are given.
The mechanistic studies presented in Scheme clearly demonstrate that the chemoselective transformations of benzhydrol derivatives observed under the Selectfluor–disulfide/CS2 system proceed through well-defined and distinguishable reactive intermediates. Initial control experiments (Scheme , a,d) revealed that benzhydrol does not undergo etherification, oxidation, or Ritter-type amidation in the presence of Selectfluor, carbon disulfide, or 1,2-dimethyldisulfane alone, even under conditions employing increased equivalents and elevated temperatures. These results indicate that the reaction is not driven by any single reagent individually; rather, a synergistic interaction between Selectfluor and the sulfur-containing components is essential for the reaction to occur. According to the proposed mechanism, in the initial stage Selectfluor interacts with 1,2-dimethyldisulfane or carbon disulfide, leading to the formation of an electrophilically activated sulfur species with cationic character (Scheme g,h). This interaction is directly supported by the 1H NMR spectra obtained from the control experiments shown in Scheme .
3. Mechanistic Studies and Proposed Mechanisms.
4. 1H NMR Spectra of Control Experiments.
Indeed, when Selectfluor was mixed separately with 1,2-dimethyldisulfane or CS2, the resulting spectra in both cases revealed the loss of the electrophilic fluorine atom from Selectfluor and the formation of the (chloromethyl)DABCO species. These observations strongly indicate that the fluorine atom is accepted by either CS2 or 1,2-dimethyldisulfane, and that the generation of the active sulfur species occurs at this stage. Although the fluorination of the sulfur atom in 1,2-dimethyldisulfane by Selectfluor has been mechanistically proposed in several studies, no direct experimental evidence supporting this assumption has been explicitly reported in the literature. Moreover, to the best of our knowledge, the interaction between Selectfluor and carbon disulfide as a trigger for reactivity is disclosed here for the first time. The resulting reactive sulfur intermediate subsequently interacts with the hydroxyl group of benzhydrol, leading to the formation of the corresponding intermediate species (Scheme g,h). This step constitutes a common entry point for both the etherification and oxidation pathways. Under disulfide-containing conditions, this intermediate is trapped by the nucleophilic attack of a second benzhydrol molecule, resulting in the formation of the symmetric benzhydrol ether (Scheme g). In contrast, in the presence of carbon disulfide, the elimination of HF and CS2 from the intermediate facilitated by elevated temperature leads to the formation of benzophenone (Scheme , h).
According to the proposed mechanism, the formation of S-methylmethanesulfinothioate is expected during the etherification process (Scheme , g). It has been reported in the literature that such species undergo further oxidation under Selectfluor/MeCN conditions to afford S-methylmethanesulfonothioate. In the present study, the detection of the methanesulfonothioate species in the crude 1H NMR spectrum of benzhydrol’s etherification reaction shown in Supporting Information 11 provides compelling experimental evidence in strong support of the proposed etherification mechanism (Scheme h). On the other hand, under CS2-containing conditions, it is proposed that a carbonodithioate-type complex is formed via the active sulfur species, assisted by the HF released during the oxidation process (Scheme g). Subsequent generation of the diphenylmethylium cation from this intermediate, followed by its reaction with acetonitrile, provides a mechanistically consistent pathway toward Ritter-type amidation (Scheme , (i). The formation of HF along this pathway and the isolation of the amide product after aqueous workup are fully consistent with the experimental observations. Indeed, a control experiment (Scheme , e) designed to probe the role of HF demonstrated that a catalytic amount of HF alone in a MeCN/MeNO2 medium is insufficient to initiate amide formation. In contrast, when CS2 was added under otherwise identical conditions (Scheme , f), the Ritter-type amide product was obtained in a high yield (85%). Beyond these control experiments, several observations from the substrate scope (Scheme ) further support the proposed mechanism. The formation of trace amounts of oxidation products under the amidation conditions in most cases suggests that the oxidation process is required for the release of catalytic amounts of HF. Moreover, the fact that (2-chlorophenyl)(phenyl)methanol, which does not undergo etherification or oxidation nevertheless affords the amide product in high yields, strongly argues against an SN2-type displacement pathway and instead supports the involvement of a carbocationic intermediate. In this context, although the ortho-chloro substituent imposes significant steric hindrance that disfavors SN2 processes, the corresponding (2-chlorophenyl)(phenyl)methylium carbocation remains theoretically well suited for Ritter-type amidation. Similarly, the preferential formation of 4s in high yields, accompanied by the absence of 4t (Scheme ), can be rationalized by the relative ease of formation of the 10,11-dihydro-5H-dibenzo[a,d][7]annulen-5-ylium carbocation compared to the more conformationally constrained and planar 5H-dibenzo[a,d][7]annulen-5-ylium carbocation. Collectively, these findings provide strong additional support for the proposed carbocation-mediated mechanistic pathway. In conclusion, when the control experiments (Scheme , a–f), product distributions (Scheme ), and spectroscopic findings (Scheme and Supporting Information 11) are considered collectively, it becomes evident that both the reaction pathway and the observed chemoselectivity are governed by the nature of the reactive sulfur species and the composition of the reaction medium. These results lead to the conclusion that Selectfluor functions in this system not merely as a fluorinating agent but as a key activator that triggers the formation of critical reactive intermediates.
Conclusion
In summary, a Selectfluor-promoted strategy enabling highly chemoselective self-etherification, oxidation, and Ritter-type amidation of benzhydrols has been developed. The three divergent transformations proceed with excellent chemoselectivity under closely related conditions, allowing controlled access to distinct products from common substrates. Mechanistic studies, supported by control experiments and spectroscopic data, suggest that these reactions operate through related reactive intermediates whose reactivities are dictated by the reaction environment. The protocol exhibits a broad substrate scope and good functional group tolerance, and its synthetic practicality is demonstrated by gram-scale reactions for all three transformations (SI10–SI11). Collectively, this work highlights the versatility of Selectfluor in chemoselective benzhydrol functionalization and provides mechanistic insight into its role in promoting divergent reactivity.
Supplementary Material
Acknowledgments
We gratefully acknowledge the support provided by the Atatürk University.
The data underlying this study are available in the published article and the Supporting Information.
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.joc.6c00350.
General experimental details, general procedures, characterization for all products, scale-up experiments, control experiments, and copies of 1H and 13C{1H} spectra (PDF)
The authors declare no competing financial interest.
References
- Nyffeler P. T., Durón S. G., Burkart M. D., Vincent S. P., Wong C. H.. Selectfluor: mechanistic insight and applications. Angew. Chem., Int. Ed. 2005;44(2):192–212. doi: 10.1002/anie.200400648. [DOI] [PubMed] [Google Scholar]
- Lal G. S.. Site-selective fluorination of organic compounds using 1-alkyl-4-fluoro-1, 4-diazabicyclo [2.2. 2] octane salts (Selectfluor reagents) J. Org. Chem. 1993;58(10):2791–2796. doi: 10.1021/jo00062a023. [DOI] [Google Scholar]
- a Ying L., Song X., Tang J., Hu Z., Zhao Q., Song Z.. Metal-Free Radical [3+ 2] Annulation of Tetraalkylthiuram Disulfide with Alkynes/Alkenes: An Approach of Synthesizing 1, 3-Dithiole and 1, 3-Ditholane Derivatives. Org. Lett. 2024;26(15):3230–3234. doi: 10.1021/acs.orglett.4c00833. [DOI] [PubMed] [Google Scholar]; b Niu T., Zhang J., He Y., Hong M., Zhu L., Lan Y.. Chloride Induced S–C bond selective cleavage of disulfides to access unsymmetrical β-fluorodisulfides. Chem. Commun. 2024;60(87):12714–12717. doi: 10.1039/D4CC04065A. [DOI] [PubMed] [Google Scholar]; c Zhou P., Chen C., Li S.. Selectfluor-initiated cyanation of disulfides to thiocyanates. J. Chem. Res. 2020;44(7–8):376–380. doi: 10.1177/1747519820902670. [DOI] [Google Scholar]
- a Anjos T., Gutterres E. L., Barancelli D. A., Cargnelutti R., Godoi B., Barcellos T., Schumacher R. F.. Synthesis of chalcogen-functionalized 4 H-chromen-4-ones via cyclization/chalcogenation of alkynyl aryl ketones mediated by Selectfluor®. New J. Chem. 2023;47(3):1076–1080. doi: 10.1039/D2NJ05567H. [DOI] [Google Scholar]; b Yuan J. W., Huang G. C., Wang L. L., Wang X. Y., Yang L. R., Zhang S. R., Mao P., Xiao Y. M., Qu L. B.. Chalcogenative spirocyclization of N-aryl propiolamides with diselenides/disulfides promoted by Selectfluor. Z. Naturforsch., B: Chem. Sci. 2022;77(1):75–85. doi: 10.1515/znb-2021-0154. [DOI] [Google Scholar]
- Kirihara M., Naito S., Ishizuka Y., Hanai H., Noguchi T.. Oxidation of disulfides with Selectfluor: concise syntheses of thiosulfonates and sulfonyl fluorides. Tetrahedron Lett. 2011;52(24):3086–3089. doi: 10.1016/j.tetlet.2011.03.132. [DOI] [Google Scholar]
- Liu A., Liu J., Mei H., Roeschenthaler G. V., Han J.. Selectfluor-Promoted Twofold Sulfination of Alcohols for the Synthesis of Sulfinic Ester from Diaryldisulfides. Chin. J. Org. Chem. 2020;40(7):1926. doi: 10.6023/cjoc202003004. [DOI] [Google Scholar]
- Mei H., Liu J., Pajkert R., Röschenthaler G. V., Han J.. A Selectfluor-promoted oxidative reaction of disulfides and amines: access to sulfinamides. Org. Biomol. Chem. 2020;18(19):3761–3766. doi: 10.1039/D0OB00720J. [DOI] [PubMed] [Google Scholar]
- Çelikoğlu M. H., Uçar S., Nişancı B.. Deoxygenation of N-heterocyclic N-oxides with Selectfluor and disulfane. J. Heterocycl. Chem. 2024;61(7):1029–1034. doi: 10.1002/jhet.4818. [DOI] [Google Scholar]
- a Dagalan Z., Kocak R., Dastan A., Nişancı B.. Selectfluor and TBAX (Cl, Br) Mediated Oxidative Chlorination and Bromination of Olefins. Org. Lett. 2022;24(45):8261–8264. doi: 10.1021/acs.orglett.2c02627. [DOI] [PMC free article] [PubMed] [Google Scholar]; b Dağalan Z., Çelikoğlu M. H., Çelik S., Koçak R., Nişancı B.. Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement. Beilstein J. Org. Chem. 2024;20(1):1462–1467. doi: 10.3762/bjoc.20.129. [DOI] [PMC free article] [PubMed] [Google Scholar]; c Ziyaei Halimehjani A., Dagalan Z., Marjani Z., Gunduz F., Dastan A., Nişancı B.. Catalyst/Metal/Solvent-Free Markovnikov Hydrothiolation of Unactivated Alkenes with Dithiocarbamic Acids. J. Org. Chem. 2024;89(8):5353–5362. doi: 10.1021/acs.joc.3c02722. [DOI] [PubMed] [Google Scholar]
- a Brahmachari G., Banerjee B.. Facile Synthesis of Symmetrical bis (benzhydryl) ethers using p-Toluenesulfonyl Chloride Under Solvent-Free Conditions. Org. Med. Chem. Lett. 2013;3(1):1. doi: 10.1186/2191-2858-3-1. [DOI] [PMC free article] [PubMed] [Google Scholar]; b Singh A. G., Alawaed A. A., Ramachandran P. V.. Titanium Tetrafluoride Catalysis for the Dehydrative Conversion of Diphenylmethanols to Symmetric and Unsymmetric Ethers. RSC Adv. 2024;14(33):24236–24239. doi: 10.1039/D4RA04712E. [DOI] [PMC free article] [PubMed] [Google Scholar]; c Wang H., Zhu X., Lu Y., Li Y., Gao X.. Sodium Bisulfite: An Efficient Catalyst for Ether Formation via Dehydration of Aromatic/Aliphatic Alcohol. Chin. J. Chem. 2011;29(6):1180–1184. doi: 10.1002/cjoc.201190220. [DOI] [Google Scholar]; d Tarlani A., Riahi A., Abedini M., Amini M. M., Muzart J.. Catalytic condensation process for the preparation of organic peroxides from tert-butyl hydroperoxide and benzylic alcohols. Appl. Catal., A. 2006;315:150–152. doi: 10.1016/j.apcata.2006.09.005. [DOI] [Google Scholar]; e Stavber S., Zupan M.. Room temperature reactions of XeF2 with phenyl substituted alcohols. Tetrahedron Lett. 1993;34(27):4355–4356. doi: 10.1016/S0040-4039(00)79350-6. [DOI] [Google Scholar]; f Johnson A. L.. New reaction of (diethylamino) sulfur trifluoride: bis (diphenylmethyl) ethers as dehydration products of (diethylamino) sulfur trifluoride and diarylcarbinols. J. Org. Chem. 1982;47(26):5220–5222. doi: 10.1021/jo00147a041. [DOI] [Google Scholar]; g Toda F., Takumi H., Akehi M.. Efficient solid-state reactions of alcohols: dehydration, rearrangement, and substitution. J. Chem. Soc., Chem. Commun. 1990;(18):1270–1271. doi: 10.1039/c39900001270. [DOI] [Google Scholar]; h Sahoo P. K., Gawali S. S., Gunanathan C.. Iron-catalyzed selective etherification and transetherification reactions using alcohols. ACS Omega. 2018;3(1):124–136. doi: 10.1021/acsomega.7b01705. [DOI] [PMC free article] [PubMed] [Google Scholar]; i Kim S., Chung K. N., Yang S.. Direct synthesis of ethers via zinc chloride-mediated etherification of alcohols in dichloroethane. J. Org. Chem. 1987;52(17):3917–3919. doi: 10.1021/jo00226a036. [DOI] [Google Scholar]; j Li J., Zhang X., Shen H., Liu Q., Pan J., Hu W., Xiong Y., Chen C.. Boron Trifluoride· Diethyl Ether-Catalyzed Etherification of Alcohols: A Metal-Free Pathway to Diphenylmethyl Ethers. Adv. Synth. Catal. 2015;357(14–15):3115–3120. doi: 10.1002/adsc.201500663. [DOI] [Google Scholar]; k Das K., Yasmin E., Kumar A.. Pincer-Ruthenium Catalyzed Oxygen Mediated Dehydrative Etherification of Alcohols and Ortho-Alkylation of Phenols. Adv. Synth. Catal. 2022;364(22):3895–3909. doi: 10.1002/adsc.202200780. [DOI] [Google Scholar]
- a Sanz R., Martínez A., Guilarte V., Álvarez-Gutiérrez J. M., Rodríguez F.. The Ritter Reaction under Truly Catalytic Brønsted Acid Conditions. Eur. J. Org Chem. 2007;2007:4642–4645. doi: 10.1002/ejoc.200700562. [DOI] [Google Scholar]; b Barbero M., Bazzi S., Cadamuro S., Dughera S.. o-Benzenedisulfonimide as a Reusable Brønsted Acid Catalyst for Ritter-Type Reactions. Eur. J. Org Chem. 2009;2009:430–436. doi: 10.1002/ejoc.200800931. [DOI] [Google Scholar]; c Gullickson G. C., Lewis D. E.. Synthesis of N-benzhydrylamides from nitriles by Ritter reactions in formic acid. Synthesis. 2003;2003(05):0681–0684. doi: 10.1055/s-2003-38069. [DOI] [Google Scholar]
- a Zha G. F., Fang W. Y., Leng J., Qin H. L.. A simple, mild and general oxidation of alcohols to aldehydes or ketones by SO2F2/K2CO3 using DMSO as solvent and oxidant. Adv. Synth. Catal. 2019;361(10):2262–2267. doi: 10.1002/adsc.201900104. [DOI] [Google Scholar]; b Tarlani A., Riahi A., Abedini M., Amini M. M., Muzart J.. Wells–Dawson tungsten heteropolyacid-catalyzed reactions of benzylic alcohols, influence of the structure of the substrate. J. Mol. Catal. A: Chem. 2006;260(1–2):187–189. doi: 10.1016/j.molcata.2006.07.007. [DOI] [Google Scholar]; c Arterburn J. B., Liu M., Perry M. C.. Polystyrene-Supported (Catecholato) oxorhenium Complexes: Catalysts for Alcohol Oxidation with DMSO and for Deoxygenation of Epoxides to Alkenes with Triphenylphosphine. Helv. Chim. Acta. 2002;85(10):3225–3236. doi: 10.1002/1522-2675(200210)85:10<3225::AID-HLCA3225>3.0.CO;2-H. [DOI] [Google Scholar]; d Khazaei A., Rad M. N. S., Borazjani M. K., Saednia S., Borazjani M. K., Golbaghi M., Behrouz S.. Highly Efficient Etherification and Oxidation of Aromatic Alcohols Using Supported and Unsupported Phosphorus Pentoxide as a Heterogeneous Reagent. Synth. Commun. 2011;41(10):1544–1553. doi: 10.1080/00397911.2010.487982. [DOI] [Google Scholar]
- Jereb M., Vražič D.. Iodine-catalyzed disproportionation of aryl-substituted ethers under solvent-free reaction conditions. Org. Biomol. Chem. 2013;11(12):1978–1999. doi: 10.1039/c3ob27267b. [DOI] [PubMed] [Google Scholar]
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Data Availability Statement
The data underlying this study are available in the published article and the Supporting Information.