Self-assembly of a (benzothiazolyl)ethenylbenzocrown ether into a sandwich complex and stereoselective [2+2] photocycloaddition

• In the presence of Ba2+ ions, (benzothiazolyl)ethenylbenzocrown ether forms the stable sandwich complex 2L center dot Ba2+ with an unusual structure, in which the benzothiazole fragments are arranged one above the other. Irradiation of the sandwich complex with visible light induces stereoselective [2+2] cycloaddition giving rise to two "head-to-head" isomers of biscrown-cyclobutane. The addition of dibasic dicarboxylic acids that additionally stabilize the sandwich complex in a favorable conformation affects the isomer ratio of the cyclobutanes formed. The conformational equilibria for the sandwich complex and cyclobutanes were studied by H-1 N MR spectroscopy.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

hetarylphenylethylenes

(benzothiazolyl)ethenylbenzocrown ether

complexation

barium

sandwich complexes

cycloaddition

cyclobutanes

dicarboxylic acids

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