Vinylidene isocyanide, reactions with

The alternative building scheme C2 + Q was used by Petasis and Hu [89], who reacted various aldehydes and ketones with alkenyltitanocene derivatives 172 to obtain the corresponding allenes 173 in high chemical yields (Scheme 2.54). The reaction probably proceeds via titanocene vinylidene complexes, which can also be trapped with alkynes and isocyanides to afford allenylketene imines [90],... 

Generation of 1-stannaallene 35 was suggested as an intermediate in the synthesis of the first stable distannirane 36, by Escudie et al. (Scheme 2.9.12). Because of the probable lability of the Sn—C double bond, 35 could behave as a stannylene-vinylidene carbene complex, as observed in the related 1-stannaketenimine 31, which behaves as a stannylene-isocyanide complex. Therefore, the generation of the final product of this reaction, 36, should be most likely interpreted in terms of the [2+ l]-cycloaddition of 35 with the stannylene 37, which should be generated in an equilibrium amount. 

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