FONKEN AND MILES
2432
VOL.
28
Steroid B-Ring Lactones and Derivatives of 5,6-Seco Steroids G. J. FONKEN ASD H . M. MILES Department of Chemistry, Cniversify of Texas, Austin, Texas Received February 15, 156s The preparation of lactones from cholestan-6-one and 3~-hydroxycholestan-6-oneby the Baeyer-Villiger reaction is described. A number of 5,6-seco derivatives of the cholestane nucleus have been prepared, and structural and stereochemical assignments of these materials have been put forth.
The synthetic modification of steroids has been a major chemical endeavor in the past several decades. Among the numerous modes of modification one finds skeletal modifications involving the introduction of heteroatoms a t various sites in the steroid nucleus.' The introduction of such atoms has been based largely on processes involving the preparation of suitable ringopened intermediates and subsequent recyclization of a derivative containing a suitable heteroatom. 1-4 Among the various seco steroids which have been prepared for such purposes one finds the 5,6-seco derivatives which have been described by a number of in~estigators.5-~" Some of the derivatives of these 5,6-seco sterols have been shown to possess cytotoxic behavior5 and are thus of possible interest as antitumor agents. In the present investigation we have developed a new route to derivatives of 5,6-seco sterols based on the Baeyer-Villiger oxidation of 6-keto sterols to B-ring lactones. Further elaboration of these materials has led to a proof of stereochemistry of the cytotoxic substance described by Lettre and Hotz5 and to the preparation of other substances of possible physiological interest. The Baeyer-Villiger oxidation of steroid ketones and similar substances has been shown t o be a stereospecific process7b leading to lactones in a number of By analogy one would anticipate the peracid reaction with a 6-keto sterol to yield a derivative of a 5,6-seco steroid 5~3-hydroxy-6-oic acid lactone. Accordingly, we have assigned structures IIa and IIb, respectively, to the lactones thus derived from 3/3-acetoxycholestan6-one (Ia) and cholestan-6-one (Ib). Support of these assignments of structure arid stereochemistry is gained from the chemical conversions described. When Ia was allowed to react with perbenzoic acid the lactone IIa was obtained in good yield. Hydrolysis of IIa gave the dihydroxy acid IIIa, or the hydroxy lactone IIc, depending on the care with which the hydrolysis reaction mixture was worked up. The dihydroxy acid IIIa readily lactonizes to IIc and acetylation of IIc leads again to IIa. Reduction of either IIa, IIc or IIIa afforded a triol to which we have assigned the structure 5,6-secocholestane-3P,5P,A-triol (1) .\ brief review of s u c h niotiifications is contained in a n article by
T.
L. Jacobs and R. B. Brownfield, J . A m . Chem. Sac.. 82, 4033 (1900). ( 2 ) N. ,J. Doorenbos and h1. T.!Vu, J . O r g . Chem., 2 6 , 4550 (1961). (3) G . R. Pettit and T. R . Iiasturi, ? h i d . , 26, 4557 (1961). ( 4 ) H. Lettre and L. Knof. Chem. Ber., 93,2800 (1960). ( 3 ) H. L e t t r e a n d D. Hotz, A n n . , 620, (3(1959). ( A ) 11. Lettre and A . .Iahn. bid., 6 0 8 , 43 (1957). (7a) L. Iinof. ?hid.,6 4 1 , . i 3 (1901); (b) T. F. Gallagher and T. H. Kritchevsky. J . d m . C h r m . Sor., 72, 882 (1950). (8) R . B. Turner, i h i d . , 72, 878 (1950). (9) S . L. n'endlrr, I). Taub. an
