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Updated: Aug 3, 2026

Metal-free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts
Published on: February 24, 2015
Titanium-catalyzed reductive umpolung reactions with a metal-free terminal reducing agent
Georg Frey1, J Niklas Hausmann, Jan Streuff
1Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg (Germany), Fax: (+49) 761-203-8715.
Abstract:
A new method for titanium-catalyzed reductive umpolung reactions is reported that overcomes the traditional requirement for a stoichiometric metallic reductant. With N,N'-disilylated tetramethyldihydropyrazine as a potent organic reducing agent, reductive carbonyl-nitrile, enone-acrylonitrile and pinacol coupling reactions can be achieved in good yields and stereoselectivities. [Cp2TiI2] is a superior catalyst to [Cp2TiCl2], which is rationalized by a faster generation of the active catalyst [Cp2TiI]. A mechanism is proposed that is in agreement with the experimental results.
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