Acid - catalyzed rearrangements of flavan 4 phlorogkinol derivatives

Acetic acid-catalyxed cleavage of proanthocyanidins in the preaeace of phloroglucinol gives a series of 2R procyanidlnand prodelphfnidin-phIoroglucino~ adducta together with a novel 2s skis derivative implicating cleavage of the pyran ring and subsequent imersion of stereochemistry at C&. These Bavan4-phloroglucinoi adducta also suffer dehydration to producb with novel fused dihydro&ozopyrandihydrohcnaofuran ringa. In addition, cleavage of the &wan C-10,4Xc bond followed by dehydration . . results In unique 3,2’aphwbi@ihyd&~ofurans~.