A new dibenzorocin derivative, named protosappanin B, C, 6H1606, white amorphous powder, [ a lb5 -11.4-(MeOH) was isolated from the heart-wood of Caesalpinia s a w L. (Leguminosae).It yielded a trimethyl ether ( 2 ) on methylation "" with diazomethane, a tetraacetate ( 5 ) and a pentaacetate (61 on "" ?I acetylation, and sappanin (41 on alkali fusion.Protosappanin B ly (kl was chemically correlated with trimethyl ether (3) of protoly sappanin A (7).On the basis of the chemical and spectroscopic l l i evidence, the chemical structure of was established as 3,7,10,11-tetrahydroxy-7,8-dihydr0-7(6~]-dibenzl~,@]oxocinmethan-01.The cd spectrum of 1 indicated that its biphenyl system ""
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Nagai et al. (1986) studied this question.