Scope and stereochemical course of the addition of (trimethylsilyl)allenes to ketones and aldehydes. A regiocontrolled synthesis of homopropargylic alcohols
Reactions and characterization of allylic and related zirconium reagents (allenic and γ-alkoxyallylic zirconiums) generated by treatment of allylic and/or propargylic ethers with a zirconocene-butene complex (“Cp2Zr”) are described.
Various cerium allenyl reagents were generated by trans- metallation of allenyl Grignard compounds with CeCl3 and sub- sequent conversion into homopropargylic alcohols by addition to various aliphatic and aromatic aldehydes. The a-acetylenic alcohols were obtained with regioselectivities and diastereoselectivities up to 98% de in favor of the threo-diastereomers.