jo070458k_si_004.pdf (1.13 MB)
The Supertristeroids: Large, Chiral, Molecular Bowls Prepared by Trimerization of Pentacyclic Steroidal Ketones
journal contribution
posted on 2007-06-08, 00:00 authored by Qiuling Song, Douglas M. Ho, Robert A. PascalRobinson annulation of coprostanone (1) at the 2,3- and 3,4-positions gave two pentacyclic enones (7
and 10) that contain A/B-cis-fused ring junctions. Reduction of these enones gave the pentacyclic steroidal
ketones 2α,3β- (8) and 2α,3α-(3‘-oxocyclohexano)-5β-cholestane (9) and 4α,3β- (11) and 4α,3α-(3‘-oxocyclohexano)-5β-cholestane (12). The structures of compounds 8, 9, and 11 were unambiguously
established by X-ray analysis. TiCl4-promoted trimerization of compounds 8 and 11 gave the
“supertristeroids” 4 and 5, respectively: large (C93) chiral, hydrocarbon clefts with C3-symmetric pockets
approximately 12 Å in diameter.