130762-72-0Relevant academic research and scientific papers
Tartrate-Derived Aryl Aldehyde Acetals in the Asymmetric Directed Metalation of Chromium Tricarbonyl Arene Complexes
Kondo, Yoshinori,Green, James R.,Ho, Jianwei
, p. 6182 - 6189 (1993)
A series of three chromium tricarbonyl benzaldehyde acetal complexes were prepared from benzaldehyde diethyl acetal and (+)-diethyl tartrate.These compounds were ortho-lithiated by a number of bases, and the diastereoselectivity of lithiation was determined by quenching of the resulting anions with Me3SiCl.Complexes 1 and 2 were found to give moderate levels of diastereoselection, while the combination of complex 3 and 2.4 equiv of n-BuLi under equilibrating conditions gave an 86percent de of silylated products.Other electrophiles gave slightly higher de's (88percent to >/= 94percent), and all products derived from 3 were separable by column chromatography.Hydrolysis of the ortho-methylated product to the corresponding benzaldehyde complex (-)-21 as well as X-ray structural analysis of the trimethylsilylated complex demonstrated that preferential pro-R deprotonation had occurred.
