Synthesis 2007(8): 1179-1184  
DOI: 10.1055/s-2007-965981
PAPER
© Georg Thieme Verlag Stuttgart · New York

Stereoselective Synthesis of 3,4-trans-Disubstituted γ-Lactams by Cerium(IV) Ammonium Nitrate Mediated Radical Cyclization of Cinnamamides

Vijay Nair*, Kishor Mohanan, Tachapully D. Suja, Akkattu T. Biju
Organic Chemistry Section, Regional Research Laboratory (CSIR), Trivandrum 695019, India
Fax: +91(471)2491712; e-Mail: vijaynair_2001@yahoo.com;
Further Information

Publication History

Received 9 January 2007
Publication Date:
12 March 2007 (online)

Abstract

A facile synthesis of 3,4-trans-disubstituted γ-lactams was developed, consisting of the radical cyclization of cinnam­amides mediated by cerium(IV) ammonium nitrate. The single-electron-transfer (SET) reaction of the methoxystyrenyl moiety mediated by cerium(IV) ammonium nitrate gives rise to a cation radical, whose cyclization followed by reaction with oxygen and methanol generates 3,4-trans-disubstituted γ-lactams.

10

The difference between the coupling constants for the benzylic protons in 2a (4.2 Hz) and 2a′ (2.4 Hz) indicates that the isomeric pair 2a and 2a′ differs only in the relative stereochemistry of the methoxy group at the benzylic position.