Vinyl carbanions. Part 4. Use of vinyl carbanions derived from ββ-diphenylacrylonitrile as nucleophiles

Abstract

Vinyl carbanions of the type Ph₂C·CN (1a) were formed by treating ββ-diphenylacrylonitrile (1) with BuLi in tetrahydrofuran, at –78 °C. These vinyl carbanions were applied as nucleophiles in addition and S_N-type reactions with the following electrophiles: ββ-diphenylacrylonitrile, benzophenone, trans-α-cyanostilbene, carbon dioxide, and alkyl iodides. The addition of (1a) to (1) took place at C(α) and afforded the addition product 1,1,4,4-tetraphenyl-2,3-dicyanobut-1-ene, and the addition–elimination products 1,1,4,4-tetraphenyl-2-cyanobutadiene and 1,1,4,4-tetraphenyl-2-butyl-3-cyanobut-1-ene. With trans-α-cyanostilbene, the Michael addition product was formed. A common by-product in all reactions was 1,1-diphenylhex-1-ene.