Utilization of CS₂ as a source of C₁ synthetic units for the preparation of bis(alkylthio)methanes and alkyl dithioformates

Abstract

Double insertion of CS₂ into two Ru−H bonds of [(dppm)₂Ru(H)₂] (dppm = Ph₂PCH₂PPh₂) affords the methanedithiolate complex [(dppm₂Ru(η²-S₂CH₂)]. The methanedithiolate moiety has been functionalized using 2 equiv of RX resulting in bis(alkylthio)methane derivatives [(dppm)₂Ru(RSCH₂SR)][X]₂. The bis(alkylthio)methane complex loses the bis(alkylthio)methane moiety under very mild conditions and in turn affords the [(dppm)₂RuX₂] complex from which the starting dihydride [(dppm)₂Ru(H)₂] has been regenerated via reaction with KOH/EtOH. On the other hand, insertion of CS₂ into one Ru−H bond of [(dppe)₂Ru(H)₂] (dppe = Ph₂PCH₂CH₂PPh₂) followed by functionalization using RX results in alkyl dithioformate complex trans-[(dppe)₂Ru(H)(SC(SR)H)][X]. In this case also, the alkyl dithioformate moiety gets eliminated under very mild conditions to afford the [(dppe)₂Ru(H)(X)] derivative from which the starting dihydride has been regenerated via reaction with NaBH₄. The reactions presented here constitute utilization of CS₂ as a C₁ synthetic source for the generation of useful organic compounds.