Asymmetric reaction using new chiral auxiliaries and catalysts synthesized from (S)-indoline-2-carboxylic acid

Abstract

New chiral auxiliaries and catalysts and have been synthesized from (S)-indoline-2-carboxylic acid and found to provide high stereoselectivities in various asymmetric reactions. New chiral acrylamides were prepared to examine 1,3-dipolar cycloaddition with nitrile oxides. The nitrile oxides cycloadditions to dipolarophiles gave chiral 2-isoxazolines with high diastereoselectivities (up to 95 : 5). Asymmetric Diels-Alder reactions of new chiral dienophiles with 1,3-dienes proceeded with high opposite diastereofacial selectivity in both endo-S and endo-R (up to 99 : 1ds, respectively) depending upon Lewis acids and the structures of chiral auxiliaries. Diastereoselective allylations of new chiral α-keto amides were examined by allylating reagents (allyl-silane and-stannane) in the presence of Lewis acids to result in extremely high diastereoselectivities (up to 99% de). Simmons-Smith cyclopropanation of cinnamyl alcohol with $Et_2Zn$ and $CH_2I_2$ in the presence of new chiral amino alcohols afforded high enantioselectivity (up to 82% ee). Stereoselective β-masked formylation of 1,3-dioxolan-2-yl radical to new chiral a,b-unsaturated amides using $(n-Bu_4N)_2S_2O_8$ showed fairly good levels of asymmetric inductions (up to 85 : 15). Enantioselective addition of lithium diethyl phosphite to imine in the presence of chiral ligands afforded modest enantioselectivities (up to 50% ee).