Effects of Steroid Hormones in the Neonate

Photoinduced molecular transformations. Part 106. The formation of cyclic anhydrides via regioselective β-scission of alkoxyl radicals generated from 5-and 6-membered α-hydroxy cyclic ketones

“…Products of the Photoinduced Reactions of Cyclic a-Ketol Hypoiodites.-2a-Hydroxy-5a-cholestan-3-one (12), 17P-hydroxy-3~-methoxy-5a-androstan-16-one (18) and a mixture of 3-exo-and 3-endo-hydroxy camphors (24) and (25) were chosen as the model of a-ketols. The authentic 2a-hydroxy-5acholestan-3-one (12) for the present study was prepared without ketol rearrangements by an acidic hydrolysis of 3,3dimethoxy-5a-cholestan-2a-ol (1 1) which was prepared by an epoxidation of 3-methoxy-5a-cholest-2-ene (10) according to the procedure of Frimer as outlined in Scheme 2. The structure was proved by its independent synthesis by stereoselective hydrolysis of 2a-bromo-5a-cholestan-3-one and by the 'H NMR spectrum.…”

“…The residue was dissolved in diethyl ether and washed with 5% sodium thiosulphate solution, 5% sodium hydrogen carbonate solution, water and saturated brine successively and dried (Na,SO,). The usual work-up of the solution gave a crude 2a-01 (11) (12).-To 3,3-dimethoxy-5acholestan-2a-01 (11) (255 mg, 0.57 mmol) in THF (5 ml) 2M hydrochloric acid (0.5 ml) was added dropwise at 0°C. The solution was stirred for 6 h at room temperature and THF was evaporated under reduced pressure.…”

“…The remaining aqueous solution was extracted with diethyl ether. The organic layer was worked up by the usual method to give crystals which were recrystallized from acetone to yield ketone (12) Irradiation of the Hypoiodite of 2a-Hydroxy-5a-cholestan-3one (12) in the Presence of Mercury(I1) Oxide and Iodine.-The alcohol (12) (203 mg, 0.5 mmol) in dry benzene (35 ml) containing mercury(I1) oxide (328 mg, 1.5 mmol) in a Pyrex vessel was flushed with nitrogen and was irradiated with a 100-W high pressure Hg arc for 5 h. The solution was filtered and the filtrate was washed with 5% aqueous sodium thiosulphate and water successively and dried (Na,SO,). The solution was worked up as usual to yield crude anhydride (13) (237 mg) as an amorphous solid which was immediately subjected to reduction with sodium borohydride (Found: m/z 416.3260.…”