Diastereoselective intramolecular [4+4] photocycloaddition reaction of N-(naphthylcarbonyl)anthracene-9-carboxamides: temperature effects and reversal of diastereoselectivity

Intramolecular diastereoselective [4 + 4] photocycloadditions of acyclic im ides 1a and 1b possessing anthracene and naphthalene moieties were carried out in the solid state and in solution. For 1a, novel reversal of diastereo selectivity was observed on changing the reaction phase. The diastereomeric excess was changed from -60% de in the solid state at 60 degreesC to 70% d e in acetone at -78 degreesC. Almost 100% de was observed for the solid-sta te photocycloaddition of 1b. The reactivity of 1a in the solid state was di scussed based on its single crystal X-ray analysis.