Iron-photocatalyzed double decarboxylative coupling reactions of alkynoic acids and alkyl carboxylic acids: access to alkylated alkynes

An efficient iron-photocatalyzed approach for the double decarboxylative coupling of alkynoic acids and alkyl carboxylic acids was developed to provide facile access to alkylated alkynes. When alkynoic and alkyl carboxylic acids were reacted in CH3CN at room temperature, the Fe(NO3)3 center dot 9H2O or FeCl2/TPA catalyst exhibited good activity in the presence of PhI(OAc)2 under blue light conditions. This iron-photocatalytic decarboxylative coupling system exhibited good functional-group tolerance and good activity toward primary, secondary, and tertiary alkyl carboxylic acids. Under an iron-photocatalytic system, the double decarboxylative coupling reaction between alkynoic acids and alkyl carboxylic acids produced alkylated alkynes in good yields.