Tadashi Takeuchi

Identification of (3Z,6Z)-1,3,6-9,10-epoxyheneicosatriene and (3Z,6Z)-1,3,6-9,10-epoxyeicosatriene in the sex pheromone of hyphantria cunea

(3Z,6Z)-1,3,6–9,10-Epoxyheneicosatriene and (3Z,6Z)-1,3,6–9,10-epoxyeicosatriene were identified in the sex pheromone gland of the arctiid moth, Hyphantria cunea. Of the synthesized enantiomers, the (9S,10R)trienes were biologically active while the (9R,10S) forms were inactive.

Synthesis of punaglandin 4 by means of enzymatic resolution of the key chlorocyclopentene derivative

Abstract Punaglandin 4, a chlorinated marine prostanoid, was synthesized starting from two chiral building blocks, (+)-tartaric acid and (1 S ,4 R )-(-)-4- t -butyldimethyl-silyloxy-3-chloro-2-cyclopenten-1-ol, which was prepared by asymmetric hydrolysis of the corresponding (±)-acetate with pig pancreatic lipase.

Structural Revision of the Acetal Intermediates in Brassinolide Synthesis

Acetalization of a steroidal ketone possessing an isopropylidenedioxy moiety in the other part of the molecule by acetal exchange with 2-ethyl-2-methyl-l,3-dioxolane was found to give an acetal with a sec-butylidenedioxy moiety. By this additional exchange reaction, a new chiral center was generated in the sec-butylidenedioxy moiety, and hence an unnecessary stereochemical complexity was added. To circumvent the problem, 2,2-dimethyl-l,3-dioxolane was employed for the acetalization. By adopting this procedure, several intermediates in Mori’s brassinolide synthesis could be obtained in pure and crystalline states. The present improved synthesis furnished 30 g of brassinolide in a 7.0% overall yield from stigmasterol, in contrast to 3.0% by the original procedure.