A convenient approach to substituted 1-(1-alkenyl)cyclopropanols: a new preparation of 2,3-methanoamino acids

The diastereoselective titanium(IV)-mediated cyclopropanation of ethyl 3,3-diethoxypropionate by Grignard reagents, followed by modified Knoevenagel condensation with malonic acid under microwave irradiation, allow the preparation of (E)-1-(1-alkenyl)cyclopropanol derivatives, suitable precursors of π-1,1-dimethyleneallylmetal species. The azidation of such complexes, followed by a reduction–oxidation sequence led to pure (E)-2,3-methanoamino acids.