α‐Chloroalkyl and α‐Alkenyl Isothiocyanates

The Chemistry of Thiophosgene

“…Reaction with imines The reaction of thiophosgene with ketimines (191) having an a-hydrogen atom proceeds with initial formation of an intermediate a-chloroalkyl isothiocyanate (192) which undergoes elimination of hydrogen chloride to give the corresponding a-alkenyl isothiocyanate (193) The ketimines (194), having no a-hydrogen atoms, also react with thiophosgene when heated at 100-130 oc to form a-chloroalkyl isothiocyanates (195). 375 194 195 (40-80%) A number of fused 2H-1,3-oxazine-2-thiones (197,199) (200) with thiophosgene leads to the convenient formation of N-(a-substituted benzyl)-N-arylaminothiocarbonyl chlorides (201) which may be used to prepare various trisubstituted 5-thioxo-1,2, 4-triazolidines (202) by reaction with N,N'-disubstituted hydrazines 379 (Scheme 56). (206).…”