Oligomeric isoflavonoids. Part 4.† Synthesis of the daljanelin class of isoflavonoid–neoflavonoid dimers

Abstract

A protocol of introducing an electrophilic C₁ fragment to a pterocarpan nucleus, followed by anionic coupling of a C₆–C₂ benzofuranoid precursor and late introduction of the final C₆ fragment, permitted the syntheses of daljanelins B 3 and D 5. The feasibility of introducing the same electrophilic C₁ fragment to C-2 of the pterocarpan moiety to obtain a precursor to daljanelin A 2 was also demonstrated.