The supertristeroids: large, chiral, molecular bowls prepared by trimerization of pentacyclic steroidal ketones.
Robinson 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 2 alpha,3beta- (8) and 2 alpha,3 alpha-(3'-oxocyclohexano)-5 beta-cholestane (9) and 4 alpha,3beta- (11) and 4 alpha,3 alpha-(3'-oxocyclohexano)-5 beta-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 A in diameter.
Song
Qiuling
Q
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
Ho
Douglas M
DM
Pascal
Robert A
RA
D002776:Cholestanes / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure
D002776:Cholestanes; D007659:Ketones