通过试剂控制2-吡啶基氮丙啶中C-N或C-C氮丙啶键的裂解实现吡唑并[1,5 -]吡啶和咪唑并[1,5 -]吡啶的发散合成

Divergent Synthesis of Pyrazolo[1,5-]pyridines and Imidazo[1,5-]pyridines via Reagent-Controlled Cleavage of the C-N or C-C Azirine Bond in 2-Pyridylazirines.

作者信息

Agafonova Anastasiya V, Golubev Artem A, Smetanin Ilia A, Khlebnikov Alexander F, Spiridonova Dar'ya V, Novikov Mikhail S

机构信息

Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia.

出版信息

Org Lett. 2023 Oct 6;25(39):7165-7169. doi: 10.1021/acs.orglett.3c02696. Epub 2023 Sep 22.

DOI:10.1021/acs.orglett.3c02696

PMID:37738046

Abstract

The three-membered ring in 2-(2-pyridyl)azirine-2-carboxylic esters and thioesters can undergo selective cleavage of either the N-C2 bond under copper(II) catalysis or the C-C bond under the action of HCl to provide isomeric azirine ring expansion products of pyrazolo[1,5-]pyridine or imidazo[1,5-]pyridine series, respectively. Mild catalytic reaction conditions for the formation of pyrazolopyridines make it possible to obtain them directly from 4-bromoisoxazoles by a one-pot, three-stage procedure without isolating the intermediate 2-bromoazirines and 2-(2-pyridyl)azirines.

摘要

2-(2-吡啶基)氮杂环丙烷-2-羧酸酯和硫酯中的三元环，在铜(II)催化下可发生N-C2键的选择性断裂，或在HCl作用下发生C-C键的断裂，分别得到吡唑并[1,5-]吡啶或咪唑并[1,5-]吡啶系列的异构氮杂环丙烷扩环产物。形成吡唑并吡啶的温和催化反应条件，使得直接通过一锅三阶段程序从4-溴异恶唑获得它们成为可能，而无需分离中间体2-溴氮杂环丙烷和2-(2-吡啶基)氮杂环丙烷。