Epoxide with phenylmagnesium bromide

To a mixture of 100 ml of THF and 0.10 mol of the epoxide (note 1) was added 0.5 g Of copper(I) bromide. A solution of phenylmagnesium bromide (prepared from 0.18 mol of bromobenzene, see Chapter II, Exp. 5) in 130 ml of THF was added drop-wise in 20 min at 20-30°C. After an additional 30 min the black reaction mixture was hydrolysed with a solution of 2 g of NaCN or KCN and 20 g of ammonium chloride in 150 ml of water. The aqueous layer was extracted three times with diethyl ether. The combined organic solutions were washed with water and dried over magnesium sulfate. The residue obtained after concentration of the solution in a water-pump vacuum was distilled through a short column, giving the allenic alcohol, b.p. 100°C/0.2 mmHg, n. 1.5705, in 75% yield. 

The preparation of other 6-aIkylated steroids has also been accomplished with 5,6-epoxides. Thus treatment of 3,3-ethylenedioxy-5a,6a-epoxy steroids (6) with acetylenedimagnesium bromide,propargylmagnesium bromide " or phenylmagnesium bromide, gives the corresponding 6 -ethynyl-, 6j5-propargyl- and 6/ -phenyl-3,3-ethylenedioxy-5a-ols. 

The reaction of epoxides and nucleophiles was introduced in Chapter 11 (Section 11.8.2). Grignard reagents and organolithium reagents react with epoxides at the less sterically hindered carbon atom. The reaction of phenylmagnesium bromide and epoxide 33, for example, generates alkoxide 34. An aqueous acid workup converts the alkoxide to the conjugate acid and final product, alcohol 35. 

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