Steroids CCC. Photochemical cycloadducts. Part I. Addition to 16-dehydro-20-keto steroids.

✍ Scribed by Paul Sunder-Plassmann; John Zderic; John H. Fried

• Book ID: 104235139
• Publisher: Elsevier Science
• Year: 1966
• Tongue: French
• Weight: 243 KB
• Volume: 7
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)82809-4

✦ Synopsis

The intermolecular photochemical cycloaddition of ethylenes to conjugated systems has recently attracted considerable attention .( 4) We now wish to report the preparation of the hitherto inaccessible steroid cyclobutanes, with examples in the progestational and corticoid series, by photochemical addition of ethylene and tetrafluoroethylene to 16-dehydro-20-keto steroids. irradiation(5) of 3@-acetoxypregna-5,16-dien-20-one (I) in a benzene solution saturated with ethylene (maintained by bubbling the gas through the solution) afforded 3B-acetoxy-16o,17aethylenepregn-5-en-20-one [IIa (52%); m.p. 186-187O; [a], +19'; v max 1695, 1730 cm-'; n.m.r. 35 (18-H), 62 (19-H) c.p.s. w.

Calcd. for C25H3603: C, 78.08; H, 9.44; 0, 12.48. Fpund: C, 78.01; H, 9.12; 0, 12.94]@) and the epimeric 3B-acetoxy-16@, 17@-ethylenepregn-5-en-20-one [IIb (7%); (a],, -84";

V max 1695, 1730 cm-'; n.m.r. 62 (19-H), 69.5 (18-H) c.p.s. u. Found: C, 78.16; H, 9.43; 0, 12.56].( 7)

The stereochemistry of addition follows from the n.m.r. frequency of the 18-protons which correlate well with the observed