18839-90-2

A method for the synthesis of 2-hydroxyestrone/estradiol, 4-hydroxyestrone/estradiol, 3′-hydroxydiethylstilbestrol, 3′-hydroxyhexestrol, and 3′-hydroxydienestrol is reported, in which 2-iodoxybenzoic acid (IBX) and the corresponding phenolic estrogen are reacted. Treatment of the natural estrogens, estrone/estradiol, with stoichiometric amounts of IBX in dimethylformamide initially yielded a mixture of estrone/estradiol-2,3- and -3,4-quinones, which were reduced in situ to the corresponding catechols by treatment with a 1 M aqueous solution of ascorbic acid. Chromatographic separation of the reaction products afforded 2- and 4-hydroxyestrone/estradiol in good overall yields (79%). In the case of the synthetic estrogens containing two identical phenolic rings, protection of one ring is a prerequisite for the synthesis of the monocatechol. Thus, diethylstilbestrol and dienestrol were protected at one phenol ring as their methyl ethers. The resulting monophenols were treated with stoichiometric amounts of IBX for 1 h, followed by treatment with 1 M aqueous ascorbic acid to obtain the corresponding catechols in more than 70% yield. Furthermore, the catechol of diethylstilbestrol, protected at one ring, was reduced by catalytic hydrogenation at the C3-C4 double bond to obtain 3′-hydroxyhexestrol in 90% yield. Removal of the protected methoxy groups of the synthetic estrogen catechols was carried out by treatment with a 1 M solution of boron tribromide in dichloromethane. This method is highly efficient for the preparative scale synthesis of catechols of both natural and synthetic estrogens.

Diethylstilbestrol oxide is a metabolic intermediate of diethylstilbestrol.In order to elucidate the effects of optically active diethylstilbestrol oxides on microtubule assembly and cell culture, we synthesized (+/-)-diethylstilbestrol oxide (2a).Since 2a was not stable under moderately acidic and basic conditions, the monomethyl ether (2c) of diethylstilbestrol oxide, which was more stable than 2a, was separated by high-pressure liquid chromatography using a chiral column.The mono (4-bromobenzoate) of (-)-2c was analyzed by X-ray crystallography and its absolute structure was determined as C (1R,1'R).Keywords: optical resolution; diethylstilbestrol oxide monomethyl ether; absolute structure; X-ray crystallography; pig liver esterase; diethylstilbestrol oxide