The origins of the benzotriazole project, its versatility illustrated by a new --C = CHCH+OEt synthon, and novel syntheses of α,β-unsaturated aldehydes and ketones, furans, pyrroles and allyl ethers

Article abstract of DOI:10.1055/s-1995-4102

A historical introduction describes the discovery and progress of benzotriazole synthetic methodology. 3-(Benzotriazol-1-yl)-1-ethoxyprop-1-ene (6), readily prepared from 3-(benzotriazol-1-yl)-3-ethoxyprop-1-ene (4) via zinc bromide promoted allylic rearrangement, undergoes lithiation and regiospecific single or double 3-alkylation to give products which undergo (i) hydrolysis to afford α,β-unsaturated aldehydes, (ii) silica gel promoted reverse allylic rearrangement of the benzotriazolyl group, followed by further alkylation and subsequent hydrolysis to furnish α,β-unsaturated ketones, (iii) intramolecular cyclizations to construct pyrroles and furans, and (iv) intermolecular nucleophilic substitution with Grignard reagents to provide allyl ethers.