An α-diaminoboryl carbanion-mediated one-pot olefination directly converts an acetonitrile or the homologous nitrile into a series of α,β-disubstituted acrylonitriles in a stereoselective manner. The protocol involves the formation of an α-substituted α-diaminoboryl acetonitrile and subsequent olefination with an aldehyde. The use of an aryl or conjugated aldehyde preferentially leads to a (Z)-acrylonitrile, while an aliphatic aldehyde gave an (E)-isomer as a major product. Two complementary approaches, a linear method and a divergent method, are developed.

Two efficient methods are reported: the use of aromatic and conjugated aldehydes predominantly leads to (Z)‐isomers, whereas with aliphatic aldehydes the (E)‐isomers are mainly formed.

Styrene oxides react with an equimolar mixture of BuLi and lithioacetonitrile, which is generated in situ from BuLi and acetonitrile, to give one‐carbon homologated allylic alcohols in a highly regioselective manner.

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Significance: Herein, the synthesis of conjugated allyl alcohols by conversion of various aryl epoxides with a 1:1 mixture of n-BuLi and lithioacetonitrile is reported, furnishing the resulting homologated allyl alcohols in good yields. This protocol shows an unusual regioselectivity, leading to the opposite regioisomers than the strategy reported by Falck (Tetrahedron Lett. 1994, 35, 5449). Comment: Because, besides one equivalent of lithioacetonitrile, one equivalent of n-BuLi is necessary to make the protocol reproducible, and because deprotonation of styrene oxide often shows carbene-like reactivities of the latter, it is assumed that the reaction proceeds via a carbenoid path rather than through an anionic mechanism. CH 3 CN 1. n-BuLi (1.95 equiv) THF, -78 °C 2. (0.95 equiv) -78 to 20 °C, overnight CH 2 OH up to 80% yield R 1 = Me, t-Bu, Ph, Naph, Cl, OMe, dioxolane derivative R 2 = H, Me R 3 = H, Me