Enantioselective Photocyclization of N-Alkylfuran-2-carboxyanilides to trans-Dihydrofuran Derivatives in Inclusion Crystals with Optically Active Host Compounds Derived from Tartaric Acid.

The steric course of the photocyclization reaction of the title achiral compounds (1) to optically active trans-dihydrofuran derivatives (2) was controlled by carrying out the reaction in inclusion crystals (4) with optically active hosts (3) derived from tartaric acid. The mechanism of the enantioselective reaction of 1 in 4 was studied by X-ray structural analysis of 4. In some cases, the steric course of the photoreaction was different depending on whether 4 was prepared by recrystallization or by mixing of 1 and 3.