In Vitro Reactions of Alkaloids. 2. Selective Decarbalkoxylation of Geminal Diesters, β-Keto Esters, and δ-Keto-β,γ-unsaturated Esters

Article abstract of DOI:10.1021/jo00339a025

The reactivity of brucine, tropine, nicotine, reserpine, yohimbine hydrochloride, and quinidine has been demonstrated by the decarbalkoxylation of diethyl bis(3,4-dichlorobenzyl)malonate, ethyl β-(1-adamantyl)-β-oxopropionate, and 4-carbethoxy-3-methyl-2-cyclohexen-1-one.All reactions were conducted in dry o-xylene at 144-146 deg C for 24 h with equivalent ratios (8:1) of base to substrate.These conditions were chosen for the purpose of establishing maximum selectivity.Brucine, nicotine, and yohimbine hydrochloride were shown to be selective toward the β-keto ester system, whereas tropine, reserpine, and quinidine were more selective catalysts toward decarbalkoxylation of δ-keto-β,γ-unsaturated esters.Brucine gave higher yields with all esters decarbalkoxylated and thus is the most reactive.The ability of these alkaloids to decarbalkoxylate esters, with some selectivity, suggests that one of the roles of alkaloids in plants may be to catalyze certain decarboxylation reactions.