KALEIDOSCOPIC PHOTOCHEMICAL BEHAVIOR OF UNSYMMETRIC DIOLEFIN CRYSTALS

Various types of topochemical [2+2] photocycloaddition behaviors are described focusing on the recent results of a series of alkyl pyridylethenylcinnamate derivatives. Highly stereoregular polymerization and “absolute” asymmetric synthesis were achieved by using crystal-lattice controlled [2+2] photocyclo-additions. Product control by employing co-crystallization of solvent molecules and a low temperature photoirradiation technique is demonstrated in the topochemical photoreactions of diolefin molecules. A methodology for the synthesis of highly strained compounds, [2.2]paracyclophane derivatives, in the crystalline state is also described. © 1992, Taylor & Francis Group, LLC. All rights reserved.