Controlled photochemical reaction of 4-oxo(phenylacetyl) morpholine and 1-(phenylglyoxylyl)piperidine in solid supramolecular systems

Six inclusion compounds containing a photoreactive guest molecule, 4-oxo( phenylacetyl) morpholine or 1-(phenylglyoxylyl) piperidine, with different host molecules have been crystallized. The guest molecules underwent photochemical reaction upon irradiation. Examining their structures suggests that gamma-hydrogen abstraction by an oxygen, the first step in cyclization of alpha-oxoamides, should be possible in all cases. In four cases crystallinity was maintained during and at the end of the conversion process i.e. the process was a single-crystal to single-crystal transformation. The crystal structure of the product crystals revealed that in two of the inclusion compounds the product obtained is a result of enclosure to a four-membered ring while in the other two the product obtained results from enclosure to a five-membered ring. The morpholine molecules adopt two different conformations. The photochemical reaction may take different courses either as a result of the different conformation or as a result of the different shapes of the cavities provided by the host molecules.