Scope and Stereochemical Course of the Addition of (Trimethylsilyl)allenes to Ketones and Aldehydes. A Regiocontrolled Synthesis of Homopropargylic Alcohols

Article abstract of DOI:10.1021/jo00370a023

The reaction of (trimethylsilyl)allenes with aldehydes and ketones in the presence of titanium tetrachloride provides a regiocontrolled route to homopropargylic alcohols of a variety of substitution types.The addition of 1-alkyl-substituted (trimethylsilyl)allenes to carbonyl compounds furnishes the desired acetylenes directly, while reactions involving allenylsilanes 6,7, and 9 initially produce mixtures of acetylenes and (trimethylsilyl)vinyl chloride derivatives.Exposure of these mixtures to the action of potassium fluoride in dimethyl sulfoxide then generates the desired homopropargylic alcohols.The addition of the chiral allenylsilane 9 to achiral aldehydes has been found to proceed with modest (3-4:1) diastereoselectivity to produce mainly syn (erythro) homopropargylic alcohols.