| 摘要 |
<p>PURPOSE:To obtain the titled compound useful as a synthetic intermediate in high yield, by reacting a hydroxycholesterol with a special dialkyl tartrate with tert-butyl hydroperoxide and titanium tetraisopropoxide in the presence of a special dialkyl tartrate. CONSTITUTION:26-Hydroxy-DELTA<24>-cholesterol of formulaI(R is H or a protecting group), e.g. 3beta-tetrahydropyranyloxy-26-hydroxycholesta-25,24-diene, is reacted with tert-butyl hydroperoxide and titanium isopropoxide in the presence of a dialkyl D-(-)- or L-(+)-tartrate, e.g. ethyl D-(-)-tartrate, in an amount equimolar with the raw material compounds preferably in a reaction solvent, e.g. preferably dichloromethane, at -50-0 deg.C for 10-20hr to give the aimed compound of formula II. Preferably, the respective molar amounts of the tert-butyl hydroperoxide and titanium tetraisopropoxide are 2 times or more and equimolar amount based on the raw material compounds. sponding to its thickness. Thus an optical switch of the simple construction</p> |
