SEQUENTIAL FUNCTIONALIZATION OF BIS-PROTECTED TETRATHIAFULVALENE-DITHIOLATES

The utilisation of the 2-cyanoethyl group as a versatile protecting gr oup for 2-thioxo-1,3-dithiole-4,5-dithiolates and tetrathiafulvalene-t hiolates is reported. Mono deprotection of bis-protected 2-thioxo-1,3- dithiole-4,5-dithiolate and of bis-protected tetrathiafulvalene-2,3-di thiolales [obtained by cross coupling of 4,5-bis(2-cyanoethylthio)-1,3 -dithio-2-one 5 and the 1,3-dithiole-2-thiones 2b-h and 2j in triethyl phosphite] was achieved in very high yields. The monothiolates were g enerated from the bis-protected starting materials by selective mono d eprotection in dimethylformamide solution using one equivalent of caes ium hydroxide monohydrate in methanol. Subsequent quenching with iodom ethane gave the resulting methylthio-substituted 1,3-dithiole-2-thione 2i and tetrathiafulvalenes 8 in near quantitative yield. The X-ray cr ystal structure of the air-stable caesium tetrathiafulvalene-thiolate 10 is reported. This is the first single crystal X-ray structure deter mination of a tetrathiafulvalene-thiolate.