Ah. Schmidt et al., OXOCARBONS AND RELATED-COMPOUNDS .20. BY THIOPHENOLS MEDIATED CONVERSION OF SEMISQUARIC HYDRAZIDES TO SQUARIC-1,2-DIAMIDES, Journal fur praktische Chemie, Chemiker-Zeitung, 336(3), 1994, pp. 211-217
In the presence of thiophenols semisquaric hydrazides (4) are converte
d into squaric-1,2-diamides (6) upon heating in alcoholic solution. Pr
oof is given that thiosquaric-S-ester-amides (8) are intermediates in
this process.