Total Synthesis of Mulberry Diels–Alder-Type Adducts Kuwanons G and H

Abstract

Mulberry Diels–Alder-type adducts (MDAAs) are a group of rare natural polyphenols biosynthetically derived from [4 + 2]-cycloaddition of chalcones and dehydroprenylphenols. In this study, kuwanons G (1) and H (2), two bioactive MDAAs with unique dehydroprenylflavonoid dienes, were totally synthesized for the first time in a biomimetic manner. The key features of the convergent route include the use of the Baker–Venkataraman rearrangement, alkylation of β-diketone, intramolecular cyclization, and Suzuki–Miyaura coupling to achieve the subunit diene.