Synthetic Utility of Organometallic Reagents Derived from Group IV Metal Tetrachlorides and CH3Li. A Direct Synthesis of 2-(2-Keto-1-alkylidene)tetrahydropyrroles from 4-Alkynylamines and Acyl Cyanides

The non-Cp-bearing titanium alkyls (CH 3 ) 2 TiCl 2 ·L 2 ( 1a ) and (CH 3 ) 2 Ti(OTFE)Cl·L 2 ( 1b ) and their Zr(IV) analogues have been shown to mediate efficient aminoalkyne cyclizations to provide azatitanium intermediates that undergo facial C-acylation in the presence of acyl cyanides.