Treatment of (−)-O-acyllactamides or mandelamides with TBSOTf in the presence of base gives opticallyactive 2-oxy-1,3-oxazolidin-4-ones stereoselectively, which serve as useful precursors for the preparation of opticallyactive secondary 2-pyrrolidones via radical cyclization and subsequent one-step removal of mandelic acid.
Oxyoxazolidinone as an auxiliary for heterocyclic synthesis. Enantioselective formation of N-unprotected 2-pyrrolidones from selenocarboxylate and allylamines via radical cyclization
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.
CYCLIC AMIDINO AGENTS USEFUL AS NITRIC OXIDE SYNTHASE INHIBITORS