Hydrotalcite catalysed [4+2] cycloaddition reactions of nitroso- and azo-alkenes

The generation of nitroso- and azo-alkenes and their [4+2] cycloaddition reactions with furan and ethyl vinyl ether, producing dihydro-1,2-oxazines and tetrahydropyridazines, by the use of catalytic Mg:Al 3:1 hydrotalcite, is described. The absence of an organic solvent, the catalytic quantities of Ht required together with its regeneration and reuse, may be regarded as environmentally friendly, greener and economically advantageous over the usual methods.