Ionic Liquid-Promoted Wagner-Meerwein Rearrangement of 16 alpha,17 alpha-Epoxyandrostanes and 16 alpha,17 alpha-Epoxyestranes

Ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmitn](+)[PF(6)](-)) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim](-)(+)[BF(4)](-)) were found to promote an unusual Wagner-Meerwein rearrangement of steroidal 16 alpha,17 alpha-epolddes leading to unnatural 13-epi-18-nor-16...

Full description

Saved in:
Bibliographic Details
Published inJournal of organic chemistry Vol. 76; no. 15; pp. 6048 - 6056
Main Authors Horvath, Anita, Szajli, Agota, Kiss, Robert, Koti, Janos, Maho, Sandor, Skoda-Foeldes, Rita
Format Journal Article
LanguageEnglish
Published WASHINGTON Amer Chemical Soc 05.08.2011
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
REAGENT
SYSTEM
EPOXIDES
ACID
C AROMATIC STEROIDS
HYDROXY
BUILDING-BLOCK
16,17-EPOXIDES
CLEAVAGE
SESTERTERPENES
Online AccessGet full text

Cover

More Information
Summary:Ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmitn](+)[PF(6)](-)) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim](-)(+)[BF(4)](-)) were found to promote an unusual Wagner-Meerwein rearrangement of steroidal 16 alpha,17 alpha-epolddes leading to unnatural 13-epi-18-nor-16-one derivatives as the main products. These compounds were isolated in good to excellent yields. 16 alpha-Hydroxy-Delta(13)-18-norsteroid5, the results of the usual rearrangement, were obtained as minor components of the reaction mixtures. The ionic liquid [bmim](+)[PF(6)](-) was shown to induce C-ring aromatization of 16 alpha,17 alpha-epoxyestranes due to the formation of HF, the hydrolysis product of [PF(6)](-). Increasing amounts of HF and [PO(2)F(2)](-) were detected by (19)F and (31)P NMR when the ionic liquid was reused. The structures of the steroidal products, 16-oxo-18-nor-13 alpha-steroid derivatives, 16 alpha-hydroxy-Delta(13)-18-norsteroids, and C-aromatic compounds were determined by two-dimensional NMR techniques and high-resolution mass spectrometry (HRMS). The ionic liquids were recirculated efficiently.
ISSN:0022-3263
DOI:10.1021/jo2006285