Issue 8, 2014

Titanium-mediated cross-coupling reactions of 1,3-butadiynes with α-iminonitriles to 3-aminopyrroles: observation of an imino aza-Nazarov cyclization

Abstract

Ti(OiPr)4/2 nBuLi-mediated highly efficient cross-coupling reactions of 1,3-butadiynes with α-iminonitriles are described. The method provides convenient access to functionalized 3-aminopyrroles with a wide diversity of substituents in a highly regioselective manner. When optically pure α-iminonitrile is employed in this reaction, a chiral pyrrole derivative is obtained without loss of enantiopurity. Mechanistic study indicates that the 3-aminopyrroles are formed upon treatment of the crude hydrolysis products with silica gel or Lewis acid. A novel imino aza-Nazarov cyclization reaction is proposed to account for the formation of the pyrrole products. Employing the titanium-monoyne complex in this reaction resulted in the homo-coupling of α-iminonitriles, leading to the formation of 1,2-diimines.

Graphical abstract: Titanium-mediated cross-coupling reactions of 1,3-butadiynes with α-iminonitriles to 3-aminopyrroles: observation of an imino aza-Nazarov cyclization

Supplementary files

Article information

Article type
Research Article
Submitted
28 May 2014
Accepted
15 Jul 2014
First published
16 Jul 2014

Org. Chem. Front., 2014,1, 940-946

Author version available

Titanium-mediated cross-coupling reactions of 1,3-butadiynes with α-iminonitriles to 3-aminopyrroles: observation of an imino aza-Nazarov cyclization

X. You, X. Xie, R. Sun, H. Chen, S. Li and Y. Liu, Org. Chem. Front., 2014, 1, 940 DOI: 10.1039/C4QO00159A

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