A new and efficient route has been developed to four derivatives of (R)-4-h
ydroxycyclohex-2-enone (7-10) from one intermediate, 6. These derivatives a
re useful chiral building blocks in the synthesis of natural products and i
n asymmetric reactions. The key step is a stereoselective intramolecular en
e reaction with 4 Angstrom MS as the Lewis acid and catalyst.