Enantioselective diels-alder cycloadditions in the synthesis of two enantiomeric sets of chiral polyhydroxylated pipecolic acid derivatives

Abstract

(2E)-Penta-2,4-dien-1-ol was combined with electrophilic tert-butyl 2H-azirine-3-carboxylate by using a Lewis acid-catalyzed self-assembled Diels-Alder methodology with 1,1-binaphthalene-2,2-diol (BINOL) as a chiral inductor. By changing the chirality of the BINOL inductor, both enantiomeric forms of the resulting cycloadducts could be obtained with high enantioselectivities and yields. Simple chemical transformations of the cycloadducts gave two types of polyhydroxylated pipecolic acids. The synthetic strategy provides the first reported synthesis of chain-branched pipecolic acids.