title: Preparation of a functionalized tetracyclic intermediate for the synthesis of rhodexin A.
abstract: An efficient synthesis of the tetracyclic steroid core, 19, of rhodexin A and sarmentogenin is reported. An initial inverse-electron-demand Diels-Alder reaction of the acyldiene 6 with the silyl enol ether 7a gave the cycloadduct 8 with the required four contiguous stereocenters in a single step. This compound was then transformed into the methylated enedione 13 which afforded after a reductive alkylation and annulation sequence the tetracycle 19.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095, USA. jung@chem.ucla.edu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Jung
authors.forename: Hiufung V
authors.initials: HV
authors.lastname: Chu
mesh_terms: D000478:Alkylation; D018360:Crystallography, X-Ray; D003500:Cyclization; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D012502:Sapogenins / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D006027:Glycosides; D007783:Lactones; D012502:Sapogenins; C482684:rhodexin A