The preparation of (1alpha,3beta)-3-hydroxycholestane-4,6-diene- 1,25-diol diacetate from a 5,7-diene precursor: a new method for the synthesis of heteroannular dienes.
Starting from the 7alpha-bromide 5a, a regioselective synthesis of (1alpha,3beta)-3-hydroxycholestane-4,6-diene-1,25-diol diacetate (2) is described. The preparative removal of contaminating 5,7-diene 9 was accomplished by the formation of the corresponding Diels-Alder adduct 11. Acetylation of the diacetate 2 followed by acid-catalyzed elimination and rearrangement yielded styrene 13.
Van Arnum
Susan D
SD
Pharmaceutical Process Development, Hoffmann-La Roche, 340 Kingsland Avenue, Nutley, New Jersey 07110, USA. svanarnum@rcsb.rutgers.edu
Carpenter
Barry K
BK
Parrish
David R
DR
MacIntrye
Archibald
A