Photoreaction of tropolone alkyl ether, cycloocta-2,4-dien-l-one and pyridone

1 Photoreaction of Tropolone Alkyl Ether, Cycloocta-2,4-dien-l-one and Pyridone 

Enantioselective intramolecular photocyclization reactions of enones as inclusion crystals with chiral host compounds proceeds very efficiently. Several examples of such reactions are described in this Chapter. 

Irradiation of the 1 2 inclusion complex of cycloocta-2,4-dien-l-one (108) with 10 for 48 h gave (-)-109 of 78% ee in 55% yield [65]. The mechanism of this enantioselective reaction has been studied by X-ray analysis of the inclusion complex [66]. 

Irradiation of the inclusion complex of iV-methylpyridine (110a) with 2a gave (+)-llla of 100% ee in 93% yield after 15% conversion [61]. Irradiations of inclusion complexes of 110b with the chiral host 10 or 2a gave (-)-lllb (100% ee, 97% yield) or (-t-)-lllb (72% ee, 99% yield), after 50 and 15% conversions, respectively, in the optical and chemical yields indicated [67]. Photoreaction of fifteen other derivatives of 110 as inclusion complexes has also been studied [68]. 

When the benzoyl group of 112 is substituted with alkyl or benzyl groups, the type of the photoreaction changes. Irradiation of 116a-h in the inclusion complexes with the chiral hosts shown in Table 15-22 gave (-)-117a-h, respectively, in the optical and chemical yields indicated [70J. 

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