由4-甲氧基-2-溴代丁烯内酯合成螺环-环丙烷类化合物的研究

以4-甲氧基-2-溴代丁烯内酯为合成子,在温和条件下与不同的亲核试剂通过串联的双Michael加成及分子内的亲核取代反应,得到螺环-环丙烷类化合物8a～8d.通过元素分析,IR,¹HNMR,¹³CNMR和MS对化合物进行了结构表征,其中化合物8d经单晶X射线衍射测定,确定了其立体化学结构.

An Efficient Approach to the Synthesis of Spiro-cyclopropane Derivatives Utilizing 4-Methoxy-2-bromobutyrolactone

Cyclopropane-containing natural products have received considerable attention as the synthetic targets due to their significant effects on bioactivities with concomitant medical and agricultural implications. We recently reported a valuable synthetic route to spiro-cyclopropane-butinolied derivatives containing multiple stereogenic centers, using 5-L-menthyloxy-3-bromo-2(5H)-furanone, and different nucleophiles by tandem double Michael addition/internal nucleophilic substitution. On the basis of the previous work, the synthesis of 4-methoxy-2-bromobutyrolactone (4) was conveniently achieved from 4-hydroxybutyrolactone (2) as a starting material through the acetalization of methanol. 2-Bromobutyrolactone (4) as a synthon reacts with various nucleophiles under mild conditions to form the diversely functionalized spiro-cyclopropane derivatives 8a—8d via tandem double Michael addition/intramolecular nucleophilic substitution. Spiro-cyclopropane compounds 8a—8d were identified on the basis of their elemental analysis and spectroscopic data, such as IR, 1H NMR, 13C NMR and MS. The stereochemistry and configuration of the spiro-cyclopropane compound 8d was measured by X-ray crystallography. This result provides an efficient synthetic route to the interesting functionalized target molecules 8 with 4-methoxy-2-bromobutyrolactone (4) as a cheap substrate. It could be furnished further an important synthetic strategy for some complex cyclic natural and nonnatural products.