General synthesis of methyl- and dimethyl -cyclobutanes from simple 1,3-diols by phase transfer catalysis

A general method is described for the preparation of methyl- and dimethyl-cyclobutanes from simple 1,3-diols. The key steps of the procedure are a phase transfer catalysed ring closure and the transformation of a carboxyl group to a methyl group. Phase transfer catalysis provides good yields in the synthesis of the cyclobutane skeleton.