Strategies To Assemble Catenanes with Multiple Interlocked Macrocycles

As a major class of mechanically interlocked molecules, not only are catenanes topologically intriguing targets that challenge the chemical synthesis to the efficient formation of mechanical bonds, but also the mechanical properties arising from the topology offer unique and attractive features for the development of novel functional molecular materials. Despite advancements in templated methods for different types of interlocked architectures, [<i>n</i>]­catenane possessing multiple numbers of interlocked macrocycles still remains a difficult synthetic target with very few reported examples. If the unique mechanical properties of catenanes are to be fully exploited, reliable, controllable, and efficient strategies for accessing [<i>n</i>]­catenanes will be necessary. In this Viewpoint, challenges, considerations, and strategies to [<i>n</i>]­catenanes are discussed

Enantioselective Synthesis of <i>trans</i>-Dihydrobenzofurans via Primary Amine-Thiourea Organocatalyzed Intramolecular Michael Addition

A primary amine-thiourea organocatalyzed intramolecular Michael addition access was developed for the synthesis of <i>trans</i>-dihydrobenzofurans. Under the catalysis of an (<i>R</i>,<i>R</i>)-1,2-diphenylethylamine derived primary amine-thiourea bearing a glucosyl scaffold, the corresponding <i>trans</i>-dihydrobenzofurans were obtained in high yields with excellent level of enantioselectivities (94 to >99% ee). Moreover, an in situ isomerization occurring at high temperature gave good to excellent <i>trans</i>/<i>cis</i> ratios as well (<i>trans</i>/<i>cis</i>: 84/16–96/4)