Making Crystals by Phase Transition

This enantioselective complexation in the solid state was proven by the following experiment. A mixture of finely powdered 4 c (1.2 g, 4.8 mmol) and roc-3 (1.2 g, 

4 mmol) was kept at room temperature for 1 day and then washed with hexane to give a complex of 4 c and (+)-3 (1.3 g) as crystals and hexane solution. From the complex, (+)-3 of 88 % ee (0.29 g, 24%) was obtained by distillation in vacuo. From the hexane solution, (-)-3 of 36% ee (0.6 g, 50%) was obtained. It is also clear that the Bayer-Villiger oxidation of 3 to 65 proceeds more slowly in the complex 5 than does the oxidation of 3 alone [5], 

1 Phase Transition from Photochemically Nonreactive Inclusion Complexes 

As a model reaction for DNA damage by photodimerization of its thymine component, which finally causes a skin cancer, photodimerization reactions of 2-pyridone derivatives are interesting. Photoirradiation of a 1 2 inclusion complex of 66 a and 66 b with the host 67 gives the corresponding rac-cis-anti dimer 68 a and 68 b, respectively [37, 38], Photoirradiations of 66 c and 66 b in their inclusion complexes with 67 and 69, respectively, gives rac-trans-anti dimer 70 c and meso-cis-syn dimer 71 b, respectively [38, 39]. X-ray analysis of these inclusion complexes showed that 2-pyridone molecules are ordered at adequate positions for the corresponding photodimerization reactions in all cases [37-39]. 

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