Toward a switchable molecular rotor. Unexpected dynamic behavior of functionalized overcrowded alkenes

摘要

in an approach toward a photochemically bistable molecular rotor the synthesis of cis-1a and trans- 1b isomers of 2-(2,6-dimethylphenyl)-9-(2',3'-dihydro-1'H-naphtho[2,1-b]thiopyran-1'-ylidene)-9H- thioxanthene (1), being sterically overcrowded alkenes functionalied with an o-xylyl group as a rotor, is described. The key steps in the synthesis are a Suzuki coupling to attach the xylyl moiety ana a diazo-thiodetone coupling with subsequent desulfurization to introduce the central olefinic bond in 1.