Abstract
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] photocycloaddition. Product control by employing co-crystallization of solvent molecules and an extremely 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.
