Novel carbonyl bromoallylation/Heck reaction sequence. Stereocontrolled access to bicyclic beta-lactams.
[reaction: see text] The reaction of 2,3-dibromopropene with racemic as well as enantiopure 4-oxoazetidine-2-carbaldehydes 1 in aqueous media was promoted by tin in the presence of several additives to afford the corresponding bromohomoallyl alcohols 2 in high diastereoselectivities. However, indium or zinc were unable to promote the bromoallylation reaction of aldehydes 1 under similar Barbier-type conditions. Vinyl bromides 2 bearing an extra alkene tether were used for the preparation of differently sized, fused bicyclic beta-lactams of nonconventional structure via Heck cyclization.
Alcaide
Benito
B
Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain. alcaideb@quim.ucm.es
Almendros
Pedro
P
Rodríguez-Acebes
Raquel
R
D009682:Magnetic Resonance Spectroscopy; D013055:Spectrophotometry, Infrared; D047090:beta-Lactams / Q000737:chemistry*
D047090:beta-Lactams