| 摘要 |
<p>PURPOSE:To produce the titled compound useful for the remedy of hypercalcemia, etc., economically, by irradiating a novel 1alpha.3beta.25-trihydroxycholesta-5.7- diene-26.23-lactone with ultraviolet radiation, thermally isomerizing the product, and if necessary, removing the protecting group. CONSTITUTION:A novel 1alpha.3beta.25-trihydroxycholesta-5.7-diene-26.23-lactone of formula I (R1 and R2 are H or protecting group) is irradiated with ultraviolet rays of about 200-360nm wavelength, especially 260-310nm wavelength to effect the cleavage of the 9-10 bond and obtain a 1alpha.25-dihydroxyprevitamin D3- 26.23-lactone. The product is thermally isomerized at 20-120 deg.C, preferably 40- 100 deg.C, and if the product has an OH-protecting group, the protecting group is removed by conventional method to obtain the objective compound of formula IIeconomically in an industrial scale in high yield. The novel substance of formula I can be produced from the compound of formula III via the intermediates such as the compound of formula IV (R<3> is OH-protecting group), etc.</p> |
