NOVEL SOLID-STATE SYNTHESIS OF POLYFUNCTIONALIZED 3,9-DIAZATETRAASTERANES

Upon irradiation, crystalline 4-methoxyphenyl-1,4-dihydropyridines 1 u ndergo nearly quantitative [2+2]cycloaddition to form, via the ring-op en intermediates 2, the centrosymmetric, polyfunctionalized 3,9-diazat etraasteranes 3. The centrosymmetric character of 3 was confirmed by H -1 NMR spectral data as well as by X-ray crystal structure analysis. T he dimerization reactions prove to be topochemically controlled by the nearest distance between potentially reacting double bonds, as well a s by the conformationally determined packing restraints. This latter f actor is shown by the X-ray crystal structure analysis of one dimerizi ng and one photostable derivative of the monomers 1.