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Alkynyl N ‐Nosylhydrazones: Easy Decomposition to Alknynl Diazomethanes and Application in Allene Synthesis
Author(s) -
Yang Yang,
Liu Zhaohong,
Porta Alessio,
Zai Giuseppe,
Bi Xihe
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701462
Subject(s) - allene , chemistry , propargyl , decomposition , intramolecular force , combinatorial chemistry , boric acid , medicinal chemistry , organic chemistry , catalysis
The decomposition of N ‐tosylhydrazones is a safe and convenient method for the generation of donor carbenes. However, alkynyl carbenes cannot be isolated by this route because they readily undergo intramolecular cyclization to pyrazoles as soon as formed from alkynyl N ‐tosylhydrazones. Here, the use of alkynyl N ‐nosylhydrazones for the in situ generation of alkynyl carbenes and their coupling reaction with boronic acids under metal‐free conditions is reported, giving rise to a wide array of di‐ and trisubstituted allenes. Preliminary mechanistic investigations demonstrated that γ‐protodeboration of propargyl boric acid was responsible for the initial allene formation. This methodology based on the nosyl group allows for novel transformations that involve an alkynylcarbene transient species.