6,19-carbon-bridged steroids. Synthesis of 6,19-methanoprogesterone.
6,19-Methanoprogesterone (4) was synthesized in nine steps from the readily available 3 beta,20 beta-diacetyloxy-5 alpha-bromo-6,19-oxidopregnane (5) in 14% overall yield. The additional carbon atom was introduced by reaction of a C-19 aldehyde with Ph3PCHOCH3 under salt free conditions and subsequent hydrolysis to give the homologous aldehyde. Intramolecular addition of the newly incorporated carbonyl (C-19a) to the olefinic C-6 in ring B was achieved by means of a Prins reaction with TiCl4 as Lewis acid.
Joselevich
María
M
Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EGA Buenos Aires, Argentina.
Ghini
Alberto A
AA
Burton
Gerardo
G
D008956:Models, Chemical; D015394:Molecular Structure; D011374:Progesterone / Q000031:analogs & derivatives / Q000138:chemical synthesis*; D013256:Steroids / Q000138:chemical synthesis*
C485198:6,19-methanoprogesterone; D013256:Steroids; D011374:Progesterone