Alkynyl N-Nosylhydrazones: Easy Decomposition to Alknynl Diazomethanes and Application in Allene Synthesis

Yang Yang; Zhaohong Liu; Alessio Porta; Giuseppe Zanoni; Xihe Bi

doi:10.1002/chem.201701462

Alkynyl N-Nosylhydrazones: Easy Decomposition to Alknynl Diazomethanes and Application in Allene Synthesis

Chemistry. 2017 Jul 6;23(38):9009-9013. doi: 10.1002/chem.201701462. Epub 2017 Jun 27.

Authors

Yang Yang¹, Zhaohong Liu¹, Alessio Porta², Giuseppe Zanoni², Xihe Bi^{1

3}

Affiliations

¹ Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of Chemistry, Northeast Normal University, Changchun, 130024, P. R. China.
² Department of Chemistry, University of Pavia, Viale Taramelli, 10-27100, Pavia, Italy.
³ State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.

PMID: 28547785
DOI: 10.1002/chem.201701462

Abstract

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.

Keywords: acetylenic carbene; allene; boronic acid; coupling reaction; n-nosylhydrazone.