Oxyoxazolidinone as an auxiliary for heterocyclic synthesis. Enantioselective formation of N-unprotected 2-pyrrolidones from selenocarboxylate and allylamines via radical cyclization
摘要:
Optic ally active N-unprotected 2-pyrrolidones were prepared in a highly stereoselective manner through radical cyclization reaction of oxyoxazolidinone. Asymmetric induction from the oxyoxazolidinone ring system was generally high and oxazabicyclo[3.3.0]-octanones were obtained in good yields. Treatment of the bicyclic compounds with TBAF resulted in the one-step cleavage of C-O and C-N bond. directly giving secondary 2-pyrrolidones in good yields along with recovery of chiral mandelic acid without loss of optical purity. The use of the present procedure gave optically active 4,5-disubstituted N-unprotected 2-pyrrolidone derivatives trans selectively. (C) 2003 Elsevier Ltd. All fights reserved.
Asymmetric synthesis of chiral amines by highly diastereoselective 1,2-additions of organometallic reagents to N-tert-butanesulfinyl imines
作者:Derek A. Cogan、Guangcheng Liu、Jonathan Ellman
DOI:10.1016/s0040-4020(99)00451-2
日期:1999.7
High yielding and highly diastereoselective methods for 1,2-additions of organometallic reagents to N-tert-butanesulfinyl aldimines (2) and N-tert-butanesulfinyl ketimines (3) are described. The additions of alkyl, aryl, alkenyl, and allyl carbanions to a diverse set of imines with different steric and electronic properties are demonstrated. Acidic methanolysis of the sulfinamide products (4 and 6)