St. Petersburg State University, Institute of Chemistry, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
J Org Chem. 2022 Jul 1;87(13):8835-8840. doi: 10.1021/acs.joc.2c00977. Epub 2022 Jun 22.
A novel strategy for the synthesis of 1-pyrrolines based on formal [4 + 1] annulation of 2-alkyl-2-azirines with diazocarbonyl compounds has been developed. This one-pot approach includes the Rh(II)-catalyzed formation of 4-alkyl-2-azabuta-1,3-dienes, followed by the DBU-promoted cyclization, and features a good substrate tolerance. The 1-pyrrolines containing an ester group at the C3 were prepared in a three-step one-pot procedure starting from 5-alkoxyisoxazoles. The cyclization of 2-azabutadienes to 1-pyrrolines most likely proceeds via the 6π electrocyclization of a conjugated NH-azomethine ylide.
开发了一种基于 2-烷基-2-氮丙啶与重氮甲酮的形式[4+1]环化反应合成 1-吡咯啉的新策略。这种一锅法包括 Rh(II)催化形成 4-烷基-2-氮杂丁-1,3-二烯，然后是 DBU 促进的环化，具有良好的底物耐受性。从 5-烷氧基异恶唑出发，通过三步一锅法制备了在 C3 位含有酯基的 1-吡咯啉。2-氮杂丁二烯环化生成 1-吡咯啉可能是通过共轭 NH-亚甲胺叶立德的 6π电环化进行的。
