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Photochemical Activation of Amino Acids: From the Synthesis of Enantiomerically Pure β,γ‐Unsaturated Amino Acids to Macrocyclic Ring Systems
Author(s) -
Griesbeck Axel G.
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619961202
Subject(s) - chemistry , homolysis , regioselectivity , singlet state , photochemistry , amino acid , excited state , alkyl , reactivity (psychology) , ring (chemistry) , chromophore , bond cleavage , isomerization , stereochemistry , medicinal chemistry , organic chemistry , catalysis , radical , medicine , biochemistry , physics , alternative medicine , pathology , nuclear physics
Amino acids whose amino groups are transformed into phthalimido chromophores are versatile substrates for photochemical transformations such as cyclization, isomerization, and β‐cleavage. These processes are initiated by homolytic or mesolytic CH activation and depend on the spin state of the excited substrate. Derivatives of α‐amino acids without strong electron‐donating substituents [Abu, Nva, Val, Leu, Ile, Tle, Phe, Met(SO)] react by initial homolytic CH activation and solely via their first excited singlet states, whereas substrates with strong electron‐donating substituents (Tyr, DOPA, Met, Glu, Asp) react by initial photoinduced electron transfer (PET) followed by mesolytic CH activation and solely via their first excited triplet states. The S ‐alkyl cysteine derivatives are the only ones which show competing singlet and triplet state reactivity with pronounced spin‐determined regioselective CH activation. The amino dicarboxylic acids Glu and Asp could be applied as the carboxylates in PET reactions, a strategy which also opened up a new synthetic approach to medium‐ and large‐ring systems.