Antineoplastic agents. 565. Synthesis of combretastatin D-2 phosphate and dihydro-combretastatin D-2.

A modified synthetic route to combretastatin D-2 (5) was devised in order to further evaluate its biological activity, for its conversion to phosphate prodrugs (25-28), and as a route to obtaining dihydro-combretastatin D-2 (42). A parallel first total synthesis of dihydro-combretastatin D-2 was completed, proceeding from a saturated 3-phenylpropionic ester intermediate via the Ullmann biaryl ether reaction (39-41). In contrast to the cancer cell growth inhibitory activity exhibited by combretastatin D-2, relatively minor structural modifications (41, 42) caused elimination of those properties.