Diastereoselective pinacol coupling of alkyl aryl ketones with rare earth metals in the presence of chlorosilanes

Article abstract of DOI:10.1016/S0040-4039(99)01504-X

Rare earth metals (Ln) are found to act as useful reducing agents for the pinacol coupling reaction of alkyl aryl ketones in the presence of chlorosilanes. Although the hitherto known pinacol coupling reaction using rare earth reducing agents generally exhibits very low diastereoselectivities, the present pinacol coupling by use of a Ln/R₃SiCl system usually indicates higher diastereoselectivities. In particular, a Yb/Me₃SiCl system attains the diastereoselective pinacol coupling of primary alkyl aryl ketones with the dl/meso ratio of 8/2~9/1.