Oligomeric Isoflavonoids. Part 4. Synthesis of the Daljanelin Class of Isoflavonoid-Neoflavonoid Dimers.

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.