Considerable interest has recently been focused on the nucleophilic ringopening reaction of geminally activated cyclopropanes 2 and the reactions with thiols 3 or amines 4 were utilized as a crucial step for construction of complex molecules. In this paper, we wish to report the ring-opening reaction of 2oxobicyclo[3.l.O]hexane-1-carboxylate with cyanide anion 5 and an application of the reaction to the synthesis of methyl dl-jasmonate6 which is an essential constituent found in jasmine oi17. The starting methyl 2-oxobicyclo[3.l.O]hexane-1-carboxylate (1) was prepared from methyl 3-oxo-6-heptenoate through diazotization and then intramolecular carbenoid addition 3a . When 1 was treated with acetone cyanohydrin in methanol in the presence of triethylamine for 12 hrs at 100" in a sealed tube, there was obtained dimethyl 3-cyanomethyladipate (fl) [bp 130s135°/0.2 mmHg, v max 2240, 1740 cm-'; nmr (CC14) 61.43s2.70 (m, 9H), 3.62, 3.65 (s, 2x3H)] in almost quantitative yield.
This means that though the desired ring-opening of cyclopropane moiety in 1 occurs, the cleavage of cyclopentanone ring8 in the resulting product also proceeds under the reaction conditions.
After several trials, a suitable condition leading to the desired ring-opening product was found.
Thus the bicycle ester 1 was treated with 1.1 equivalent of sodium cyanide in dimethyl sulfoxide (DMSO) at 10~20' for 24 hrs and then the reaction mixture was quenched with acetic acid-water (1:l). Thin layer chromatography of the resulting mixture indicated the presence of single product. However, this product was found to be too soluble in aqueous layer. Thus, without wash-