[Studies on the synthesis and antitumor activities of howiinol A and its analogues].

Howiinol A(1), one of the active antitumor constituents from the root and stem bark of Goniothamus howii Meer. (Annonaceae) has been synthesized in nine steps from alpha-D-glucoheptonic gamma-lactone with an over all yield of 13.3%. It shows that all data of the synthetic product are identical to those of the natural howiinol A, thus the absolute configuration of natural howiinol A is further confirmed as 1. In the search for new antitumor compounds with high potency, 26 analogues have been synthesized. In pharmacological tests most of them showed antitumor activities in vitro, some of them are significant.