Synthesis of the chiral spiro-cyclopropane derivative and its crystal structure

The spiro[ 1-bromo-4-l-mentholoxy-5-oxo-6-oxabicyclo[3.1.0] hexane-2,3 '-(4 ' -ethoxy-5 ' -1-menthyloxybutyrolactone)] 4 was synthesized via the tande m double Michael addition/internal nucleophilic substitution of chiral synt hon 1, 5-1-menthyloxy- 3-bromo-2 (SH)-furanone, with nucleophilic ethanol. The two synthetic routes to compound 4 and its analytical data of structure are reported. The absolute configuration of 4 was determined by X-ray crys tallography. These results provide a valuable strategy for synthesizing som e biologically active molecules.