Straightforward asymmetric entry to highly functionalized medium-sized rings fused to β-lactams via chemo- and stereocontrolled divergent radical cyclization of Baylis-Hillman adducts derived from 4-oxoazetidine-2-carbaldehydes

被引:76
作者
Alcaide, B [1 ]
Almendros, P [1 ]
Aragoncillo, C [1 ]
机构
[1] Univ Complutense Madrid, Fac Quim, Dept Quim Organ 1, E-28040 Madrid, Spain
关键词
D O I
10.1021/jo005715z
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
DABCO promoted reactions of various activated vinyl systems with optically pure 4-oxoazetidine-2-carbaldehydes 1 gave rise to Baylis-Hillman adducts 3 With excellent syn stereoselectivities, without detectable racemization. Products 3 are used. for the asymmetric preparation of unusual 2-azetidinones fused to medium-sized rings via chemo- and Stereocontrolled divergent radical cyclization. The formation of bicyclic beta -lactams 4-6 could be rationalized through a tandem radical Michael addition/endo cyclization or a tandem radical addition/Michael addition, depending pn the electronic nature of the radical promoter.
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页码:1612 / 1620
页数:9
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