Regioselective allenylation of carbonyl compounds with propargylic organometallics

TLDR: In this paper, the ambient anions, propargylic and allenic alcohols, may be equilibrated in solution, therefore in the condensation with aldehydes or ketones, two products can be formed.

Abstract: Regioselective synthesis of a-hydroxyallenes has great synthetic value, because they are used for the extention of carbon chain and the conversion of functionality (Patai, 1980; Okamura et al., 1982; Zweifel, 1983; Marshall, 1990; Cha., 1992; Mayers et al., 1993). Also, natural products such as antibiotics and pheromones have allenic linkage (Landor et al., 1971). Their utility in organic synthesis has been limited due to the difficulties in controlling the regioselectivity of the reactions. The ambient anions, propargylic and allenic anions, may be equilibrated in solution (Patai, 1978), therefore in the condensation with aldehydes or ketones, two products, propargylic and allenic alcohols, can be formed (Scheme 1).