| Abstract
| - Citrinadin A (2) is a pentacyclic indolinone alkaloid isolated from the cultured broth of a fungus,Penicillium citrinum, which was separated from a marine red alga. The absolute stereochemistryof the pentacyclic core in 2 and its new congener, citrinadin B (1), was elucidated by analysis ofthe ROESY spectrum for the chlorohydrin derivative (3) of 1 as well as comparison of the electroniccircular dichroism (ECD) spectra for 1 and 2 with those of known spirooxiindole alkaloids. On theother hand, the absolute configuration at C-21 bearing an epoxide ring was assigned as S bycomparison of the vibrational circular dichroism (VCD) spectra of 1 with those of model compounds2S- and 2R-2,3-epoxy-3,3-dimethyl-1-phenylpropan-1-one (4a and 4b, respectively).
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