Photochemical reactions of 5-fluorouracil and 5-fluoro-2′-deoxyuridine with Nα-acetyl-L-tryptophan N-ethylamide in aqueous solution

Characterisation of the interactions of aromatic amino acids with diacetyl phosphatidylcholine

“…1,2-Diacetyl-sn-glycero-3-phosphocholine 9 (DAPC, 1): CA 54672-38-7; N-acetyl-L-tyrosine ethylamide 10 (2): CA 49577-69-7; N-acetyl-L-tryptophan ethylamide 11 (3): CA 96384-15-5; N-acetyl-L-phenylalanine ethylamide 12 (4): CA 29744-08-9; N-acetyl-L-valine ethylamide 13 (5): CA 38075-78-4.…”

On the Route to the Photogeneration of Heteroaryl Cations. The Case of Halothiophenes

“…This leads indirectly to ion 3 14 + (Scheme , path g) , which is trapped by π-bond nucleophiles to give the arylated products (path h). The formation of aryl cations from an ET mechanism within a radical pair has been sparsely documented, providing that it takes place in a high polar medium (e.g., water). ,, Notice further that 5-uracyl and 5-citosyl cations have been invoked when investigating the reactivity of 5-fluorouracil and 5-bromocytosine, respectively, where the heteroaryl radical intermediate was oxidized by the radical cation of N α -acetyl- l -tryptophan N -ethylamide. , More relevant to the present case, the formation of the parent triplet phenyl cation from the corresponding aryl radical has been previously postulated in the photodechlorination of chlorobenzene . The formation of a small amount of trifluoroethoxythiophene ( 2e′ ) in TFE is best justified via ISC from triplet to singlet thienyl cation ( 1 14 + , Scheme , path i) .…”

“…The formation of a small amount of trifluoroethoxythiophene ( 2e′ ) in TFE is best justified via ISC from triplet to singlet thienyl cation ( 1 14 + , Scheme , path i) . Despite calculations supporting that triplet thienyl cations are slightly more stable than the corresponding singlets (by 8–10 kcal mol –1 , Figures S6–S10 in Supporting Information), such a small energy difference may be overestimated, as previously observed . Indeed, solvolysis to 2e′ took place as a minor process and is fully suppressed when a reactive π-bond trap is used, supporting that the singlet cation arises from the formerly generated 3 14 + .…”

Oxygen Uptake in the Vitamin B2‐sensitized Photo‐oxidation of Tyrosine and Tryptophan in the Presence of Uracil: Kinetics and Mechanism

“…Reactions between biologically significant compounds are being increasingly investigated in relation to relevant chemical/biochemical events in several fields, such as biology, pharmacology and medicine (1–3). This is the case of thermal and photochemical interactions between amino acids (AA) and nucleic bases, which strongly attracted scientific attention (4–6). The addition of AAs to uracil (ur), upon photoirradiation with ultraviolet light is known and has been investigated for several decades (4).…”

“…The relevance of these reactions was related to the mechanism by which DNA and proteins are cross‐linked in vivo , stimulated by ultraviolet light. Similarly, the formation of cross‐links between ur‐substituted nucleic acids and tryptophan‐containing (trp) proteins was detected and studied by the characteristic fluorescence of the ur‐trp fluorophore (5). In addition, energetic aspects of charge‐ and proton‐transfer reactions between nucleobases and AAs, that can produce DNA and RNA damage, have been recently studied by means of computational calculations for several nucleoside models including ur (6).…”