Chiral Brønsted Acid-Promoted Enantioselective Desymmetrization in an Intramolecular Schmidt Reaction of Symmetric Azido 1,3-Hexanediones: Asymmetric Synthesis of Azaquaternary Pyrroloazepine Skeletons
The enantioselectivedesymmetrization of 2‐substituted‐2‐azidopropyl 1,3‐hexanediones through an asymmetric intramolecular Schmidt reaction using a chiral Brønsted acid has been developed for the first time. Synthetically interesting pyrroloazepine skeletons with an azaquaternary stereogenic center with up to 59 % ee are accessed effectively (see scheme; R=H, alkyl, or aryl).
首次开发了使用手性布朗斯台德酸通过不对称分子内Schmidt反应对2-取代2-叠氮丙基1,3-己二酮进行对映选择性脱对称。合成有趣的吡咯并ze庚因骨架,其氮杂季铵立体异构中心的ee高达59%(请参阅方案; R = H,烷基或芳基)。
Copper‐Nitrene‐Catalyzed Desymmetric Oxaziridination/1,2‐Alkyl Rearrangement of 1,3‐Diketones toward Bicyclic Lactams
oxaziridination reaction of cyclic diketones with alkyl azides and the subsequent rearrangement of the resulting highly active intermediate, which produces a synthetically challenging chiralbicycliclactam containing a quaternarycarbon center. This procedure not only enriches the copper-nitrene-catalyzed asymmetric reactions, but also provides an alternative strategy to address the inherent challenges of catalytic
Concise access to indolizidine and pyrroloazepine skeleta via intramolecular Schmidt reactions of azido 1,3-diketones
作者:Duanpen Lertpibulpanya、Stephen P. Marsden
DOI:10.1039/b608801e
日期:——
Readily prepared 2-alkyl-2-azidopropylcycloalkyl-1,3-diones undergo intramolecular Schmidt rearrangement with a range of hard Lewis acids, leading to indolizidinediones and pyrroloazepinediones. Chiral aluminium-based Lewis acids could also be used to mediate this symmetry-breaking transformation, but no significant asymmetric induction was observed.