The lithiation of 2-(2,2-dimethyl-1,3-dioxolan-4-yl)ethyl diisopropylcarbamate (1) is achieved freely by sec-butyllithium in diethylether with high lk-diastereoselectivity: the bicyclic chelate complexes 3a and 3b are reacted with electrophiles to form optically active precursors 4a and 4b with >95% diastereoselectivity. In addition, tertiary diamines can undergo an external complexation in contest
Asymmetric Synthesis of α-Substituted Allyl Boranes and Their Application in the Synthesis of Iso-agatharesinol
作者:Guang Yu Fang、Varinder K. Aggarwal
DOI:10.1002/anie.200603659
日期:2007.1.8
Application of the Lithiation−Borylation Reaction to the Preparation of Enantioenriched Allylic Boron Reagents and Subsequent in Situ Conversion into 1,2,4-Trisubstituted Homoallylic Alcohols with Complete Control over All Elements of Stereochemistry
作者:Martin Althaus、Adeem Mahmood、José Ramón Suárez、Stephen P. Thomas、Varinder K. Aggarwal