Ring opening ofaziridine with dithianes

To a solution of 2-tosylaminodithiane in acetone was added methyl iodide (typically a 10-fold excess) and the solution was heated under reflux for 1 h. A few drops of water were then added and heating was continued for 4h. The resulting mixture was partitioned between EtOAc and H20. The organic layer was washed with brine, dried and the solvent was removed in vacuo to yield crude 2-tosylaminocarbonyl compounds. Chromatographic purification of these compounds gave analytically pure 

2-tosylaminocarbonyl compounds in yields from 42 to 100% (eight examples). 

We have discussed previously (see Section 2.4) some aspects of the dithioacctalization step involved in this strategy. The presence of the sulfur atoms uffers another possibility as a methylene unit results from desulfurization by Raney nickel, dissolved metal or LiAlH4/ZnCl2 reduction [281]. 

Some non-cyclic thioacetals have been used sometimes, particularly those bearing phenylthio groups or some special feature such as an extra electron-withdrawing group. The corresponding carbanion can then be used for a 1,4 addition on an a,(3-unsaturated ketone as reported [282]. 

Treatment with mercuric chloride or methyl fluorosulfonate before the oxidation step initiated the migration of a second alkyl group from boron to carbon, and a synthesis of tertiary alcohols was thus at hand [284]. 

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