1.2- Diacetoxy hexane

Beim 2,4,6-Trioxo-l,l,3,3,5,5-hexamethyl-cyclohexan in Gegenwart von Acetanhy-drid/Acetonitril reagieren zwei Oxo-Gruppen zum 1,5-Diacetoxy-3-oxo-2,2,4,4,6,6-he-xamethyl-bicycla[3.1.0]hexan (71% d.Th.)1 ... 

To a solution of2 (340 mg, 0.9 mmol) in THF (30 mL) cooled to —78°C K-Selectride (1.34 mL of a 1 -M solution in THF) was slowly added (1 h) under nitrogen atmosphere. The reaction mixture was stirred for an additional 1 h, quenched with an aqueous saturated solution of NaHC03 (20 mL) and allowed to attain room temperature. The product was extracted with ethyl acetate (4 x 20 mL), the combined extracts were dried (MgS04) and concentrated to dryness. The residue was dissolved in dichloromethane (30 mL), then triethylamine (500 p,L, 3.6 mmol), acetic anhydride (250 p.L, 2.6 mmol), and a crystal of AJA-dimethylaminopyridine (DMAP) were added, and the mixture was left under nitrogen at room temperature. After 24 h the solution was concentrated to dryness and the residue was chromatographed on a silica gel column with hexane-ethyl acetate (3 1) to give 25,35,4/ ,6/ -3,4-diacetoxy-2-(l-menthyloxy)-6-(2-furyl)-tetrahydropyran 4 (290 mg, 79%) mp 127°-129°C, [a]D - 5.3° (c 0.8, CHC13). 

Hexane 1,2-Diacetoxy-nonafluoro-1-phenylthio-1H,2H- E10b2, 192 (Ar —SO —CH2 —CHRF —OH + Ac20)... 

Free-radical epimerisation of unactivated tertiary carbon atoms by irradiation in cyclohexane containing 1 equivalent of mercuric bromide has been demonstrated in both cyclo-pentanes and -hexanes. Thus, 5/S-androstane gives 95 % 5, 14 -androstane after irradiation for 12 hours. Irradiation for longer periods gives up to 70% of the 5a,14jS-androstane. Similarly, irradiation of 3, 11 P-diacetoxy-4 -methyl-5a-androstane led to quantitative epimerisation and the formation of the 4a-methyl-14 -isomer. ... 

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