Dihalides cycloalkanes

The procedure described here provides a simple and general method for the construction of optically active trans-cycloalkane-1,2-dicarboxylic acids. The reaction has been applied successfully to a series of dihalides and ditosylates (Table). 

Treatment of primary a,u)-haloalkanes with r-butyllithium at low temperature leads to efficient production of cycloalkanes, provided at least one of the halides is an iodide. - This method provides very good yields of three-, four- and five-membered rings, but produces only minor amounts of cyclic products for 1,6-dihalides. Examples of this approach are given in equations (41) and (42). 

---