Enantioselective Lactonization of 3,3,6-Trimethyl-4(E)-heptenoic Acid Esters

Scheme 1

(i) (a) SOCl₂, C₆H₆, reflux and (b) ROH, Et₃N, DMAP, Et₂O, rt; (ii) NXS, THF/H₂O.