Ketenimines deprotonation

Let us first consider the reaction between vinylketene complexes and phosphoramidate anions.90,134 Deprotonation of the appropriate phos-phoramidate with Bu"Li affords the corresponding phosphoramidate anion (232.a-232.c), which undergoes a Wadsworth-Emmons type reaction on the ketene carbonyl to afford the ketenimine complexes 233. Ketenimine complexes may also be prepared by the thermolysis of the vinylketene complexes (221) with isonitriles (vide infra).69... 

In the benzo-fused series, synthetic efforts have given rise not only to new quinazolines, but also to new methods of preparing them. Quinazoline 34 has been obtained via deprotonation of A-phenyldiethylketenimine with excess strong base (LTMP/KOrBu) in rert-BuOMe followed by addition of another equivalent of the ketenimine and subsequent introduction of rBuCOCl [95T9031]. Semiempirical computational analyses were conducted to provide support for the... 

Another example in which a Grignard base generates a reactive intermediate by elimination is depicted in Eq. (32) [39]. a-Cyanoeneamines are deprotonated by MeMgl, giving the reactive trialkyl ketenimine. The ketenimine subsequently reacts with primary amines, yielding amidines. The critical step is cyanide elimination from the deprotonated eneamine. The keteneimines could be isolated either by careful distillation or could be directly reacted with amines. 

In contrast, C-3 deprotonation of quatemized isoxazolium salts causes fission of the 0-N bond with formation of acyl ketenimines ... 

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