Synthesis of spiro-cyclopropanne derivatives containing multiple chiral centers

Tandem asymmetric double Michael addition/internal nucleophilic substitution of the novel chiral source, 5-( l-menthyloxy)-3-bromo-2 (5H)-furanone with nucleophilic alcohol compounds has been investigated. The tandem asymmetric reaction can afford four new stereogenic centers with one reaction and give optically pure spiro-cyclopropane derivatives 5a-5d which are difficult to obtain by routine methods. The synthetic method for 5a-5d was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [alpha](20), IR,H-1 NMR, C-13 NMR,MS and elementary analysis. The absolute configuration of the sprio [5-l-menthyloxy-3-brumo-butyrolactocyclopropane-3 ", 3'(4'-methyloxy-5'-menthyloxybutyrolactone)] (5a) was established by X-ray crystallography. The wort can provide important synthetic strategy in synthesis of some new optically active spiro-cyclopropane analogues and some biologically active molecules with complex structure.