A-Carboxy-y-lactones

Knoevenagel condensation a-methylene-y-lactones. A new synthesis of these lactones is based on the Knoevenagel condensation by the procedure of Lehnert (4, 507-508). Condensation of 1 with Meldrum s acid (2) gives 3, which is hydrolyzed by acid mainly to an a-carboxy-y-lactone (5). Lactones of this type have been converted into a-methylene-y-lactones (6). The lactones 5 and 6 have the CIS ring junction. 

---