title: Controlled rearrangement of lactam-tethered allenols with brominating reagents: a combined experimental and theoretical study on α- versus β-keto lactam formation.
abstract: N-Bromosuccinimide (NBS) smoothly promotes the ring expansion of lactam-tethered allenols to efficiently afford cyclic α- or β-ketoamides with good yields and high chemo-, regio-, and diastereoselectivity, through controlled C-C bond cleavage of the β- or γ-lactam nucleus. Interestingly, in contrast to the rearrangement reactions of 2-azetidinone-tethered allenols, which lead to the corresponding tetramic acid derivatives (β-keto lactam adducts) as the sole products, the reactions of 2-indolinone-tethered allenols under similar conditions give quinoline-2,3-diones (α-keto lactam adducts) as the exclusive or major products. To rationalize the experimental observations, theoretical studies have been performed.
authors: Grupo de Lactamas y Heterociclos Bioactivos, Departamento de Química Orgánica I, Unidad Asociada al CSIC, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain. alcaideb@quim.ucm.es
authors: Benito
authors: B
authors: Alcaide
authors: Pedro
authors: P
authors: Almendros
authors: Amparo
authors: A
authors: Luna
authors: Sara
authors: S
authors: Cembellín
authors: Manuel
authors: M
authors: Arnó
authors: Luis R
authors: LR
authors: Domingo
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D001974:Bromosuccinimide / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry*; D007769:Lactams / Q000737:chemistry*; D008962:Models, Theoretical; D015394:Molecular Structure; D013237:Stereoisomerism; D047090:beta-Lactams / Q000737:chemistry*
chemical_list: D000466:Alkadienes; D007202:Indicators and Reagents; D007769:Lactams; D047090:beta-Lactams; C025947:propadiene; D001974:Bromosuccinimide