Vibronic spectra of 9H-adenine, 9-acetyladenine and several alkyladenines have been recorded by resonant two-photon ionization spectroscopy of the laser-desorbed molecules, entrained in a molecular beam. While adenine and the alkyladenines exhibit similar electronic spectra, 9-acetyladenine behaves considerably different. Theoretical absorption spectra of 9H-adenine and 9-acetyladenine were calculated using the combined density functional theory/multi-reference configuration interaction approach and using second order coupled cluster theory, in order to explain striking differences in the experimental spectra. The major differences between the 9H-adenine and the 9-acetyladenine absorption spectra can be traced back to the different configurations, which contribute to the excitations, both of the lowest ππ* and the nπ* states. While the excitations in 9H-adenine are localized in the chromophore, they show considerable charge transfer character from the chromophore to the acetyl group in the case of 9-acetyladenine.

Aryl-substituted 5-(3-indolyl)oxazoles are readily synthesized in a novel one-pot three-component synthesis consisting of a microwave assisted sequence of Sonogashira coupling, an acid-catalyzed cycloisomerization, and a concluding Fischer indole synthesis. All title compounds are intensely blue-luminescent with large Stokes shifts upon UV-irradiation. The experimental absorption spectra are rationalized by ZINDO-CI computations based upon DFT geometry optimization.

Blue-Luminescent 5-(3-Indolyl)oxazoles via Microwave-Assisted Three-Component Coupling-Cycloisomerization-Fischer Indole Synthesis. -The novel microwave-assisted one-pot three-step synthesis of title indolyloxazoles consists of Sonogashira coupling of propargylic amides (I) with acyl chlorides (II), followed by acid-catalyzed cycloisomerization of the so obtained ynones to oxazoles and Fischer indole formation with aromatic hydrazines (III). -(GROTKOPP, O.; AHMAD, A.; FRANK, W.; MUELLER*, T. J. J.; Org. Biomol. Chem. 9 (2011) 23, 8130-8140, http://dx.doi.org/10.1039/c1ob06153d ; Inst. Org. Chem. Makromol. Chem., Heinrich-Heine-Univ., D-40225 Duesseldorf, Germany; Eng.) -Mischke 18-136

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Oxazole derivatives R 0220 2-Oxazol-5-ylethanones by Consecutive Three-Component Amidation-Coupling-Cycloisomerization (ACCI) Sequence. -(MERKUL, E.; GROTKOPP, O.; MUELLER*, T. J. J.; Synthesis 2009, 3, 502-507; Inst. Org. Chem. Makromol. Chem., Heinrich-Heine-Univ., D-40225 Duesseldorf, Germany; Eng.) -Mais 24-121