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3 H ‐Pyrroles, Alkylidene‐Pyrrolines and Functionalized Pyrrolidines by Radical Cyclization of β‐Allenyliminyl Radicals
Author(s) -
Depature Michaël,
Grimaldi Jacques,
Hatem Jacques
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200103)2001:5<941::aid-ejoc941>3.0.co;2-e
Subject(s) - chemistry , allene , radical , radical initiator , isomerization , moiety , tin , hydride , semicarbazide , radical cyclization , sulfur , tributyltin hydride , photochemistry , medicinal chemistry , organic chemistry , catalysis , metal , polymerization , polymer
In this work, we show that the tin hydride‐mediated reaction of allene‐tethered dithiosemicarbazides 4 is a convenient method for the preparation of five‐membered unsaturated nitrogen heterocycles. The sulfur‐directed intermolecular attack of the tin radical at the semicarbazide moiety leads to an allene‐tethered iminyl radical, which then undergoes a 5‐ exo ‐ dig cyclization leading to both the 3 H ‐pyrroles 5 and the alkylidene pyrrolines 6 ; thermal isomerization of 5 to 6 occurs in some cases.