Concomitant C-ring Expansion and D-ring formation in lanosterol biosynthesis from squalene without violation of Markovnikov's rule.
A mechanism is proposed for the formation of the C and D rings of lanosterol from squalene on the basis of density functional calculations of a model cyclopentylcarbinyl carbocation. The mechanism involves the ring expansion of the cyclopentylcarbinyl carbocation to the six-membered ring C in concert with the formation of the D ring. The mechanism does not involve a violation of Markovnikov's rule as the earlier proposed mechanism does for the formation of rings C and D.
Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA. hessba@ctrvax.vanderbilt.edu
B Andes
BA
Hess
D007810:Lanosterol / Q000096:biosynthesis* / Q000737:chemistry; D008958:Models, Molecular; D013185:Squalene / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics
D007810:Lanosterol; D013185:Squalene