21002-96-0Relevant academic research and scientific papers
PHOTO-INDUCED MOLECULAR TRANSFORMATIONS.PART 87. REGIOSPECIFIC PHOTO-BECKMANN REARRANGEMENT OF STEROIDAL α,β-UNSATURATED KETONE OXIMES: SYNTHESIS OF SOME STEROIDAL ENAMINO LACTAMS
Suginome, Hiroshi,Kaji, Makoto,Yamada, Shinji
, p. 321 - 326 (2007/10/02)
While it is well known that the Beckmann rearrangement of steroidal cyclic α,β-unsaturated ketone oximes lead to the exclusive formation of enone-type lactams regardless of the initial geometry of their hydroxyimino group, the photolysis of three isomeric cholestenone oximes, (E)- and (Z)-cholest-4-en-3-one oximes, (E)-2,2-dimethylcholest-4-en-3-one oxime, and (E)-cholest-5-en-7-one oxime in protic solvents has shown that in each case an enamine-type lactam is the sole product (yield/=33 percent), no enone-type lactam being formed.This regiospecific photo-rearrangement may be of value for the preparation of these enamine-type lactams which cannot be achieved by the Beckmann rearrangement.
Resolution of conflicting migratory reports in ring expansion of 3-keto steroids to oxygen and nitrogen
Dave, Vinod,Stothers, J. B.,Warnhoff, E. W.
, p. 2666 - 2678 (2007/10/02)
The migration of C-2 and/or C-4 to O or N in the Beckmann, Schmidt, and Baeyer-Villiger reactions of 3-keto steroids has been studied with the aid of (13)Cmr spectroscopy.Authentic specimens of the eight possible lactone and lactam products from both 5α- and 5β-cholestan-3-one have been prepared; their physical properties and 13Cmr assignments are given.Seven ring expansion reactions reported to give only one product have been found to give both possible migration products.The much studied reactions of 5α-cholestan-3,6-dione and its derivatives have been reexamined.The results emphasize again the necessity of using 13C spectra both as an analytical tool and as the best criterion of purity in work with these molecules.
