The invention provides a process for preparing an enantiomerically enriched cis-6,6-dimethyl-3-oxa-bicyclo[3.1.0]hexan-2-one by reacting a sulphonic ester of &bgr;,&bgr;-dimethyl-&ggr;-(hydroxymethyl)-&ggr;-butyrolactone with a compound of formula M(C
1-6
alkoxide)
y
.
本发明提供了一种制备对映体富集的顺式-6,6-二甲基-3-氧杂双环[3.1.0]己-2-酮的工艺,其方法是将&bgr;,&bgr;-二甲基-&ggr;-(羟甲基)-&ggr;
-丁内酯的
磺酸酯与式 M(C)化合物反应。
1-6
烷氧基)
y
.