Photoinduced molecular rearrangements. The photochemistry of 1,2,4-oxadiazoles in the presence of sulphur nucleophiles. Synthesis of 1,2,4-thiadiazoles
The photochemistry of some 1,2,4-oxadiazoles in the presence of sulphur nucleophiles has been investigated. Irradiation of the 5-amino-3-phenyl- and 3,5-diphenyl-1,2,4-oxadiazole at γ = 254 nm in methanol in the presence of sodium hydrogensulphide or thiols gave a photo-induced redox reaction at the ring ON bond, leading to the corresponding N-substituted benzamidines. By contrast, irradiation of
Concomitant Desulfurization and Transesterification of Alkyl Thionocarbamates
作者:Uday M. Joshi、Laxmikant N. Patkar、Srinivasachari Rajappa
DOI:10.1081/scc-120027235
日期:2004.12.31
Abstract Alkyl carbamate (such as 1) reacts with triphosgene at the nitrogen atom, whereas the analogous thionocarbamates (5) react at the sulfur. Subsequent treatment with various phenols or alcohols leads to the corresponding aryl carbamates or alkyl carbamates (6) respectively. The process thus involves both desulfurization and transesterification.
作者:Sagun K. Tandel、Srinivasachari Rajappa、Sunil V. Pansare
DOI:10.1016/s0040-4020(01)87224-0
日期:1993.8
Treatment of methyl N-methylthionocarbamate (2a) with a catalytic amount of iodine or conc. H2SO4 results in the unexpected formation of the isomer, methyl N-methylthiolcarbamate (3a) in 90% yield. This has subsequently been transformed into methyl N-methylcarbamate (4a), by sodium methoxide. A curious transformation of methyl N-methyldithiocarbamate (1a) to (4a) on prolonged treatment with sodium