Collect. Czech. Chem. Commun. 2004, 69, 261-266

Formation of Ring A in the Biosynthesis of Hopanoids from Squalene. A Density Functional Study

B. Andes Hess, Jr.

Department of Chemistry, Vanderbilt University, Nashville, TN 37235, U.S.A.


Density functional calculations were carried out on the ring closure of the 2,6-dimethyloct-6-en-2-yl cation to a chair conformer of the 1,2,3,3-tetramethylcyclohexyl cation as a model for the first step in the biosynthetic cyclization of squalene to the triterpene hopanoids. The concerted reaction was found to have an activation energy of 4.6 kcal/mol and to be exothermic by 11.5 kcal/mol.

Keywords: Triterpenes; Steroids; Biosynthesis; Squalene; Cyclizations; Reaction mechanism; DTF calculations; Ab initio calculations.

References: 14 live references.