Straightforward asymmetric entry to highly functionalized 3-substituted 3-hydroxy-beta-lactams via Baylis-Hillman or bromoallylation reactions.
The reaction of various activated vinyl systems, including 2-cyclopenten-1-one, with enantiopure azetidine-2,3-diones 1 was promoted by DABCO to afford the corresponding optically pure Baylis-Hillman adducts 2 without detectable epimerization. However, the reaction of alpha-keto lactams 1 with but-3-yn-2-one was not as successful, giving the corresponding beta-halo Baylis-Hillman adduct in low yield. Metal-mediated bromoallylation reaction between 2,3-dibromopropene and azetidine-2,3-diones 1 was investigated in aqueous media. Surprisingly, indium was unable to promote the bromoallylation reaction of alpha-keto lactams 1, but the Sn-Hf(4)Cl-promoted bromoallylation of ketones 1 proceeded efficiently to achieve bromohomoallyl alcohols 5 as single diastereomers. On this basis, simple and fast protocols for the asymmetric synthesis of the potentially bioactive 3-substituted 3-hydroxy-beta-lactam moiety were developed.
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
Aragoncillo
Cristina
C
Rodríguez-Acebes
Raquel
R
D000498:Allyl Compounds / Q000138:chemical synthesis*; D000900:Anti-Bacterial Agents / Q000737:chemistry; D001384:Azetidines / Q000138:chemical synthesis*; D006842:Hydrocarbons, Brominated / Q000737:chemistry*; D013237:Stereoisomerism; D047090:beta-Lactams / Q000737:chemistry*
D000498:Allyl Compounds; D000900:Anti-Bacterial Agents; D001384:Azetidines; D006842:Hydrocarbons, Brominated; D047090:beta-Lactams