| 摘要 |
<p>NEW MATERIAL:A compound expressed by formula I (R<2> is H, OH or trifluoroacetoxy when R<1> is methyl; R<2> and R<3> together form pi bond; R<1> and R<2> together form methylene; R<3> is H; R<4> and R<5> are H or R<4> and R<5> together form pi bond; R<6> is H or OH-protecting group; R<7> is H or alkyl; St is steroid parent nucleus). EXAMPLE:(22R)-20,23-Dihydroxy-6beta-methoxy-3alpha,5-cyclo-5alpha-ergo st-23-eno-28,22- lactone. USE:A synthetic intermediate for brassinolide derivatives and epibrassinolide derivatives. PREPARATION:A steroid derivative expressed by formula IV is reacted with a tetronic acid derivative expressed by formula V and the resultant product is subjected to dehydration and then reduced to give a compound expressed by formula VI, which is then isomerized and reduced to afford the aimed compound expressed by formula VII.</p> |
