Synthesis of Homopropargyl Alcohols via Zinc Iodide Mediated Three‐Component Reaction of Propargyl Carbamates With Organoboranes and Aldehydes

Homopropargyl alcohols are versatile building blocks in a wide range of synthetic transformations; consequently, the development of efficient and practical methods for their preparation remains an important objective in organic synthesis. This study presents a novel and practical zinc iodide mediated three‐component reaction of terminal alkyne‐bearing propargyl carbamates, trialkylboranes, and aldehydes for the synthesis of homopropargyl alcohols. A variety of α , γ ‐substituted allenylboranes are formed in situ through a 1,2‐metallate shift of alkynylborates to the sp carbon atom, which subsequently react with aldehydes to afford the corresponding homopropargyl alcohols. In contrast to conventional methods for the generation of alkynylborates, the present system requires only a catalytic amount of lithium diisopropylamide as the base.