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.
Chemistry. 2011 Oct 4;17(41):11559-66. doi: 10.1002/chem.201101160. Epub 2011 Aug 31.
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.
N-溴代丁二酰亚胺（NBS）可平稳地促进连接内酰胺的烯丙醇的环扩张，通过β-或γ-内酰胺核的受控 C-C 键断裂，以高收率、高化学选择性、区域选择性和非对映选择性高效地得到环状α-或β-酮酰胺。有趣的是，与导致相应四氢酸衍生物（β-酮内酰胺加合物）作为唯一产物的 2-氮杂环丁酮连接的烯丙醇的重排反应相反，在类似条件下，2-吲哚啉酮连接的烯丙醇的反应以喹啉-2,3-二酮（α-酮内酰胺加合物）作为唯一或主要产物。为了合理化实验观察结果，已经进行了理论研究。
