ACYCLIC ISOPRENOID 1,3-DIENEAMINES IN THE DIELS-ALDER REACTION

Article abstract of DOI:10.1007/BF00961359

The dieneamines obtained from 3-methyl-2-butenal and citral (Ia) and (Ib, c) enter into <4 + 2>-cycloaddition with monoethyl citrylidenemalonate (II) and prenylidenemalonate (III), respectively, forming the esters of substituted 1,3-cyclohexadiene-1-carboxylic acids with side chains of the isoprenoid type.The same or analogous cyclohexadiene can be obtained from "citral dieneamine" (Ib, c) and typical dienophiles (methyl acrylate, diethyl fumarate, etc.) in a two-stage path, including the initial production of derivatives of 2-amino-3-cyclohexene-1-carboxylic acid in the Diels-Alder reaction and then elimination of the amino group from the cyclic adducts.The isomeric composition of the mixture of cyclic adducts formed in the reaction of (Ib + Ic) with diethyl fumarate under strictly aprotic conditions correlates with the ratio of the structural isomers with Δ³ and Δ³⁽⁹⁾ bond (Ib, c) in the "citral dieneamine".In the reaction of the dieneamine with the less reactive methyl acrylate the obtained mixture of cyclic adducts contains a significantly larger fraction of the isomer corresponding to the minor Δ³⁽⁹⁾ isomer of the dieneamine.