Highly selective preparation of allenic and homopropargylic hydrazides through regiospecific addition of propargyltrichlorosilane and allenyltrichlorosilane to various types of N-acylhydrazones

The highly selective preparation of various types of allenic and homopropargylic hydrazides through regiospecific allenylation and propargylation of the corresponding N-acylhydrazones is reported. These carbon-carbon bond-forming reactions employing in situ prepared propargyl- and allenyltrichlorosilanes proceed smoothly in NN-dimethylformamide (DMF) without any metal catalysis (neutral Lewis base activation of nucleophiles). The use of Hunig's base as an additive is beneficial in terms of chemical yields.