Unusual oxidative transformations of a steroidal 16alpha,17alpha,22-triol.
A number of unexpected reactions were observed during attempts to invert configuration at C16 in 16alpha,17alpha,22-triol 3a. The PDC oxidation of 3a produced the D-seco-aldehyde 4a. Analogous compound 4b was obtained by Swern oxidation of the 16alpha,17alpha-dihydroxy-22-O-TES-ether 3b in addition to the desired 16-ketone 7. The unprotected triol 3a yielded pentacyclic products 5 and 6 under similar conditions. The Mitsunobu reaction of the triol 3a afforded 16-ketone 8 with inverted configuration of the side chain. During heating of a solution of 3a in THF with NaH at reflux autoxidation to the 16-ketone cyclic hemiketal 5, identical to one of the Swern oxidation products, took place.
Institute of Chemistry, University of Białystok, al. Piłsudskiego 11/4, 15-443 Białystok, Poland. morzycki@uwb.edu.pl
Jacek W
JW
Morzycki
José Oscar H
JO
Pérez-Díaz
Rosa
R
Santillan
Agnieszka
A
Wojtkielewicz
D002783:Cholestenones / Q000138:chemical synthesis / Q000737:chemistry; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D008956:Models, Chemical; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012503:Saponins / Q000138:chemical synthesis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D013256:Steroids / Q000138:chemical synthesis* / Q000737:chemistry*
D002783:Cholestenones; D012503:Saponins; D013256:Steroids; C106408:OSW 1