Oxyoxazolidinone as an auxiliary for heterocyclic synthesis. Enantioselective formation of N-unprotected 2-pyrrolidones from selenocarboxylate and allylamines via radical cyclization |
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Authors: | Akio Kamimura Yoji OmataKeiichi Tanaka Masashi Shirai |
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Affiliation: | a Department of Applied Chemistry, Faculty of Engineering, Yamaguchi University, Ube 755-8611 Japan b Ube Laboratory, Ube Industries Ltd., Ube 755-8633 Japan |
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Abstract: | Optically 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. |
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Keywords: | radical cyclization orthoesters stereoselection pyrrolidines |
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