Asymmetric synthesis of double bond isomers of the structure proposed for pyrinodemin A and indication of its structural revision.

Asymmetric synthesis of double bond isomers (+)-2 (delta(15',16')) and (+)-3 (delta(14',15')) of the structure (1) (delta(16',17')) proposed for pyrinodemin A, a cytotoxic bis-pyridine alkaloid with a unique cis-cyclopent[c]isoxazolidine moiety from a marine sponge, has been accomplished. Pyrinodemin A was indicated to be a 1:1 racemic mixture of 2 from comparison of C(18 )and chiral HPLC analysis for pyrinodemin A and the synthetic compounds as well as ESIMS data of oxidative degradation products of pyrinodemin A.