Highly Diastereo- and Enantioselective Vinylogous Mannich Reactions of Fluorinated Aldimines with Siloxyfurans
作者:Qian-Yi Zhao、Zhi-Liang Yuan、Min Shi
DOI:10.1002/adsc.201000843
日期:2011.3.7
A highly regio‐ and enantioselective asymmetric vinylogousMannichreaction of readily available fluorinatedaldimines bearing a chiral auxiliary [(S)‐1‐phenylethyl group] with siloxyfurans to afford chiral fluorine‐containing γ‐butenolide or γ‐lactone derivatives has been developed in the presence of silver acetate (10 mol%) and axially chiral phosphine‐oxazoline ligand L1 (11 mol%). In most cases
Axially chiral phosphine–oxazoline ligands in the silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran
作者:Qian-Yi Zhao、Zhi-Liang Yuan、Min Shi
DOI:10.1016/j.tetasy.2010.05.025
日期:2010.4
Axiallychiralphosphine–oxazolineligand L7, prepared from (S)-binol, was found to be a fairly effective chiralligand in the silver(I)-catalyzed asymmetricMannichreaction of fluorinated aldimines with trimethylsiloxyfuran to give the corresponding adducts in up to 99% yield, over 20:1 dr and 81% ee.
Difluoroacetaldehyde ethyl hemiacetal (1), prepared from ethyl difluoroacetate and lithium aluminum hydride in diethyl ether, was found to be a potential difluoroethylating reagent for the preparation of a wide variety of difluoromethylated compounds. Compound 1 shows promise for use in the synthesis of carbinols prepared by the reaction of 1 with metal reagents or enol silyl ethers, the synthesis of amino acid ketones and beta-lactams via the nucleophilic reaction of imines, and the synthesis of sugar analogues.