Z. Naturforsch. 2014, 69b, 1088 – 1096
Enantioselective Synthesis and Photoreactivity of a Diazirinyl-substituted (R)-β-Phenylalanine
Jan-Niklas Schäckermann and Thomas Lindel
Institute of Organic Chemistry, TU Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
Reprint requests to Prof. Dr. Thomas Lindel. E-mail: th.lindel@tu-bs.de
Received July 11, 2014 / published online December 19, 2014
Dedicated to Professor Hubert Schmidbaur on the occasion of his 80th birthday
The first enantioselective synthesis of a photoreactive (R)-β-phenylalanine is described. In the key step, m-diazirinyl-substituted benzaldehyde is converted to a chiral sulfinimine in a Ti(OEt)4-mediated reaction, followed by diastereoselective enolate addition. The absolute configuration of photo (R)-β-phenylalanine was confirmed by Mosher analysis. The photo amino acid proved to be thermally stable under standard laboratory conditions. Irradiation in toluene afforded cycloheptatriene/norcaradiene valence tautomers, together with carbene benzylation. Quantum-chemical calculations indicate a small triplet-singlet gap.
Key words: Amino Acids, Diazirines, Photochemistry, Carbenes, DFT Calculation
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