Centre of Biomedical Research, Sanjay Gandhi Post-Graduate Institute of Medical Sciences Campus, Raebareli Road, Lucknow 226014, India.
Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
J Org Chem. 2022 Jul 1;87(13):8656-8671. doi: 10.1021/acs.joc.2c00863. Epub 2022 Jun 22.
Brønsted acid- and/or Lewis acid-catalyzed selective C3-allylation and formal [3 + 2]-annulation of spiro-aziridine oxindoles with allylsilanes have been demonstrated to deliver direct access to 3-allyl-3-aminomethyl oxindoles and 5-silyl methyl spiro[pyrrolidine-3,3'-oxindoles], respectively. The acid-catalyzed methods do not provide any stereoselectivity when chiral spiroaziridines are used. However, the reaction of nonracemic sprioaziridines with allyl-Grignard reagent under catalyst-free conditions afforded 3-allyl-3-aminomethyl oxindoles with good stereoselectivity (ee up to 80%). The allylation protocol is utilized for the short synthesis of coerulescine and various 5'-substituted spiro[pyrrolidine-3,3'-oxindoles].
布朗斯特酸和/或路易斯酸催化的螺-氮丙啶氧吲哚与烯丙基硅烷的选择性 C3-烯丙基化和形式[3+2]-环加成反应分别提供了直接合成 3-烯丙基-3-氨甲基氧吲哚和 5-硅基甲基螺[吡咯烷-3,3'-氧吲哚]的方法。当使用手性螺氮丙啶时，酸催化方法没有提供任何立体选择性。然而，在无催化剂条件下，非外消旋螺氮丙啶与烯丙基格氏试剂反应可得到具有良好立体选择性的 3-烯丙基-3-氨甲基氧吲哚（ee 值高达 80%）。该烯丙基化方案被用于短程合成色胺和各种 5'-取代的螺[吡咯烷-3,3'-氧吲哚]。
