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Three‐Component Synthesis of Cryofluorescent 2,4‐Disubstituted 3 H ‐1,5‐Benzodiazepines – Conformational Control of Emission Properties
Author(s) -
Willy Benjamin,
Dallos Timea,
Rominger Frank,
Schönhaber Jan,
Müller Thomas J. J.
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200800619
Subject(s) - chemistry , sonogashira coupling , benzene , absorption (acoustics) , fluorescence , photochemistry , organic chemistry , palladium , catalysis , physics , quantum mechanics , acoustics
2,4‐Disubstituted benzodiazepines are readily synthesized in good yields from acyl chlorides, terminal alkynes, and benzene‐1,2‐diamines by a consecutive one‐pot, three‐component Sonogashira coupling/Michael addition/cyclocondensation sequence. These diazepines display intense solid‐state fluorescence, but only weak emission in solution at room temperature. The absorption and emission maxima can be controlled by the substitution pattern. Upon cooling, however, the phenomenon of cryofluorescence can be observed. X‐ray structure analysis and temperature‐dependent NMR indicate that freezing out of conformational interconversions is the source of the thermochromicity observed upon UV excitation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)