Title of article
A new synthetic approach to 5-dethia-4-methyl-5-oxacephems
Author/Authors
Zbigniew Ka?u?a، نويسنده , , Arkadiusz Kazimierski، نويسنده , , Krzysztof Lewandowski، نويسنده , , Kinga Suwinska، نويسنده , , Beata Szcz?sna، نويسنده , , Marek Chmielewski، نويسنده ,
Issue Information
هفته نامه با شماره پیاپی سال 2003
Pages
11
From page
5893
To page
5903
Abstract
Starting from (l)-ethyl lactate and 4-vinyloxy-azetidin-2-one the diastereomeric (4S,6R)- and (4S,6S)-4-methyl-5-oxa-3-methylene and 3-oxo-cephams were obtained. The formation of the cepham skeleton proceeds with a diastereomeric excess up to 80%, depending on catalyst and reaction conditions. For comparison, the corresponding racemic cephams lacking a methyl at C-4 or with a gem-dimethyl group at C-4 were synthesized.
Keywords
iminium cation stereoselective cyclization , 5-oxacephams
Journal title
Tetrahedron
Serial Year
2003
Journal title
Tetrahedron
Record number
1088071
Link To Document