| Abstract
| - Irradiation of a benzene solution of 3-cyano-2,6-dimethoxypyridine in the presence of ethyl vinylether (EVE) gave 1:1 photoadducts, 3-cyano-5-ethoxy-2,8-dimethoxy-4,5-dihydroazocine, in goodyields, whose structure was established by X-ray single-crystal analysis. The photoadduct wasproduced via cycloaddition between the C3−C4 position of the pyridine derivatives and an alkenechromophore. On the other hand, 3-cyano-2,6-dimethoxy-4-methylpyridine cycloadds to EVE atthe C2−C3 position of the pyridine ring upon irradiation. The difference is explained on the basisof the steric effect.
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