5a, 8a-Androstane

To a stirred solution consisting of 5 g (9.45 mmoles) 3, 17) -dibenzoyloxy-5a-androst-7-en-6a-ol in a mixture of 150 ml of dry ether and 150 ml of glyme is added lOg (0.16 moles) of zinc-copper couple and 26.7 (8 ml, 0.1 moles) methylene iodide. The mixture is heated under reflux for 4 hr, cooled to room temperature, diluted with 200 ml of ether and filtered. The filtrate is washed with a saturated solution of sodium chloride and water, and dried over anhydrous sodium sulfate. The ether is removed under reduced pressure and the residue is crystallized from acetone-hexane to yield 4.4 g (86%) of 3, 17 -dibenzoyloxy-7a,8a-methylen-5a,8a-androstan-6a-ol mp 166-167° [ ]d -62° (CHCI3). 

Dibenzoy loxy-7 a, 8a-methylen-5a,8a-androstan-6a-ol, 113 Dibromocarbene, 366, 367, 372 1,4-Dichloro-2-butyne, 68 Dichlorocarbene, 364 9a,l 1 -Dichloroandrosta-1,4-diene-3,17-dione, 150... 

Altering the stereochemistry at any of the ring-juncture with a heavy-dark line (see general steroid formula s Fig. 23.1) changes immensely the prevailing shape of the steroid , as may be observed in the above cited examples of S -androstane and 5a, 8a-androstane. 

The structures of the 9-methyl-5a,9j8,10a-oestran-3-one (1) and its 2a- and 2/8-bromo-derivatives have been studied by X-ray crystallography. Ring A in the 2/8-bromo-compound is forced into a twist-boat conformation by steric compression (2/8-Br/9/3-Me), but the other two compounds are only slightly deformed from the chair conformation. These findings are compatible with the properties (c.d. and n.m.r.) of the same compounds in solution. 3a-Acetoxy-4a,8a,14/8-trimethyl-18-nor-5a,9/3,13a-androstan-17-one (2), another steroid of unusual configuration, derived from fusidic acid, has a twisted boat conformation of ring B. ... 

C(3)-carbonyl group. A close approach to ideal boat geometry is observed in ring B of 3-methoxy-7a,8a-methyleneoestra-l,3,5(10)-trien-17)8-yl bromoacetate. Crystal and molecular structures are also reported for 16/8,17)8-dibromo-5a-androstane, 2a-bromo-17a-methyl-5a,14/S-androstan-3a-ol, esters of 3a,5a-cyclocholestan-6/3-ol, 4a,6,7a-trichloro-17a,21-dihydroxypregn-5-ene-3,l 1,20-trione 21 -acetate," 6a-bromo-17/8-hydroxy-17a-methyl-4-oxa-5a-androstan-3-... 

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