Synthesis 2023; 55(02): 272-288
DOI: 10.1055/a-1868-8092
paper
Special Issue dedicated to Prof. Alain Krief

Radical Cyclization of Ynamides to Nitrogen Heterocycles

Chunyang Zhang
a   Laboratoire de Chimie Organique, Service de Chimie et PhysicoChimie Organiques, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, 1050 Brussels, Belgium
b   Université de Haute-Alsace, Université de Strasbourg, CNRS,LIMA, UMR 7042, 68000 Mulhouse, France
,
Nicolas Blanchard
b   Université de Haute-Alsace, Université de Strasbourg, CNRS,LIMA, UMR 7042, 68000 Mulhouse, France
,
a   Laboratoire de Chimie Organique, Service de Chimie et PhysicoChimie Organiques, Université libre de Bruxelles (ULB), Avenue F. D. Roosevelt 50, CP160/06, 1050 Brussels, Belgium
› Author Affiliations
Our work was supported by the Université libre de Bruxelles (ULB) and the Région de Bruxelles-Capitale - Innoviris (2019-BRIDGE-5 PhotoCop). C.Z. acknowledges the China Scholarship Council (CSC) for a graduate fellowship.


Dedicated to Prof. Alain Krief on the occasion of his 80th birthday

Abstract

An efficient radical cyclization of suitably functionalized ynamides to nitrogen-containing heterocycles is reported. Upon reaction with tributyltin hydride in the presence of catalytic amounts of AIBN in toluene at 80 °C, a range of ynamides bearing a N-iodopropyl chain could be smoothly cyclized, in a highly regio- and stereoselective manner, to the corresponding 2-arylidenepyrrolidines in good to excellent yields. The exocyclic double bond was in addition shown to be an excellent anchor for further chemical diversification and the generality of this radical cyclization could be highlighted by its extension to the synthesis of other nitrogen heterocycles including piperidines, azepanes, pyrazolidines and hexahydropyridazines.

Supporting Information



Publication History

Received: 04 May 2022

Accepted after revision: 03 June 2022

Accepted Manuscript online:
03 June 2022

Article published online:
12 July 2022

© 2022. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany