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. Author manuscript; available in PMC: 2017 Sep 14.
Published in final edited form as: Org Lett. 2016 Oct 25;18(21):5532–5535. doi: 10.1021/acs.orglett.6b02778

Table 1.

Identification of Optimal Reagent for Cycloguanidylationa

graphic file with name nihms903037u2.jpg
entry reaction conditions conversion (%) yield (%)
1 10 mol % Pd(OAc)2, CuI, K2CO3, DMF, 23 °C, 24 h 0 0
2 25 mol % Pd(OAc)2, PhI(OAc)2, CH2Cl2, 23 °C, 24 h 15 0
3 5 mol % Pd(OAc)2, PhI(OAc)2, NMe4Cl, NaOAc, CH2Cl2, 23 °C, 24 h 30 0
4 10 mol % NiCl2, PhI(OAc)2, NaOAc, DMF, 23 °C, 24 h 0 0
5 10 mol % CuI, K2CO3, 10 mol % 2,2′-bipyridine, O2, DMF, 60 °C, 24 h 0 0
6 3 equiv of t-BuOCl, CH2Cl2, 0 °C, 20 min 100b 0
7 Py2IBF4, toluene, 23 °C or reflux, 24 h 65 0
8 2.1 equiv of I2, NaHCO3, CH2Cl2, 23 °C, 6 h 15 0
9 2.1 equiv of NIS, NaHCO3, CH2Cl2, 23 °C, 1 h 100 62
10 2.1 equiv of NIS, NaHCO3, CH3CN, 0 °C, 5 h 100 84
a

See Supporting Information for additional details; isolated yields of 5a after tosylation are reported. Conversion measured by 1H NMR analysis of a crude mixture of products.

b

Dichloroguanidine is isolated.