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 N,N‐dimethylformamide (DMF) without any metal catalysis (neutral Lewis base activation of nucleophiles). The use of Hünig's base as an additive is beneficial in terms of chemical yields.