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Base‐Promoted Cycloisomerization for the Synthesis of Indolizines and Related Heterocycles
Author(s) -
Xiao Ke,
Zhu Congjun,
Lin Maohua,
Song Chuanjun,
Chang Junbiao
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201802620
Subject(s) - indolizine , cycloisomerization , chemistry , isomerization , deprotonation , base (topology) , combinatorial chemistry , medicinal chemistry , double bond , catalysis , organic chemistry , ion , mathematical analysis , mathematics
The base‐mediated 5‐exo‐dig type cyclization reaction of homopropargyl pyridines for the construction of indolizines has been reported for the first time. A variety of indolizine derivatives could be obtained in moderate to excellent isolated yields by treatment of homopropargyl pryidines with cesium carbonate in DMSO at 100 °C. This strategy could also be adapted to the synthesis of pyrrolo[1,2‐ a ]quinolines and pyrrolo[1,2‐ a ]pyrimidines from the corresponding homopropargylquinolines and homopropargylpyrimidines, respectively. The mechanism involves α C−H deprotonation, 5‐exo‐dig cyclization, and isomerization of the exocyclic double bond to provide the heteroaromatic system. The transformation reported herein does not require the aid of transition metal catalysts or halogens, and is thus environmentally friendly.