Indium-copper and indium-silver mediated Barbier-Grignard-type alkylation reaction of aldehydes using unactivated alkyl halides in water

(Chemical Equation Presented) An efficient method has been developed for the Barbier-Grignard-type alkylation reaction of aldehydes (including aliphatic version) using unactivated alkyl halides in water in the presence of an In/CuI/I₂ or In/AgI/I₂ system. The reactions proceeded more efficiently in water than in organic solvent. In, CuI or AgI, and I ₂ were all essential for the efficient progress of the reactions. A radical-type reaction mechanism was studied and proposed by using 4-pentenal as substrate.