ChemInform Abstract: On the Cyclization Mechanism of Squalene: A Ring Expansion Process of the Five-Membered D-Ring Intermediate.

Site-directed mutagenesis experiments with W169F, W169H and W489F for the squalene-hopene cyclase, and the formation of 10 possessing the five-membered D-ring and a tetrahydrofuran moiety as the enzyme product of the analogue 8 with a hydroxy group, strongly suggest that a ring expansion reaction from the five- to the six-membered ring is responsible for the D-ring formation of hopene.