Photochemistry of 7-azide-1-ethyl-3-carboxylate-6,8-difluoroquinolone: a novel reagent for photoaffinity labeling

Copper(I)‐Catalyzed Azide‐Alkyne Cycloaddition Microwave‐Assisted: Preparation of 7‐(4‐Substituted‐1H‐1,2,3‐Triazol‐1‐yl)‐Fluoroquinolones

“…The Cu(I) species may either be introduced as performed complexes, but these conditions did not generate favorable results, even when a variety of solvents (MeOH, CH 3 CN, DMSO, DMF, H 2 O/acetone, H 2 O/CH 3 CN) were used in combination with other bases as DIPEA or TEA, or when the temperature was increased to 140 °C . It is possible that the poor stability of Cu I and its rapid oxidation to Cu II does not allow catalyzed the cycloaddition reaction, which led to the fluoroquinolone azide being easily broken with the irreversible loss of N 2 , producing singlet nitrene that generated secondary products by selective O−H or N−H insertion with CH 3 OH or DEA respectively or proton abstraction . However, triazole ring was obtained when the catalyst CuI was exchanged for a mixture of CuSO 4 and sodium ascorbate in solid form, obtaining low yields (Table , entry 2); but when catalyst was used in a solution system, CuSO 4 (1 M) and sodium ascorbate (7.5%),‐ the yields increased to 80% with 5 days of reaction (Table , entry 3).…”

“…[28,29] The Cu(I) species may either be introduced as performed complexes, but [ [26] It is possible that the poor stability of Cu I and its rapid oxidation to Cu II does not allow catalyzed the cycloaddition reaction, [30,31] which led to the fluoroquinolone azide being easily broken with the irreversible loss of N 2 , producing singlet nitrene that generated secondary products by selective OÀ H or NÀ H insertion with CH 3 OH or DEA respectively or proton abstraction. [32] However, triazole ring was obtained when the catalyst CuI was exchanged for a mixture of CuSO 4 and sodium ascorbate in solid form, obtaining low yields (Table 1, entry 2); but when catalyst was used in a solution system, CuSO 4 (1 M) and sodium ascorbate (7.5%), [33][34][35] the yields increased to 80% with 5 days of reaction (Table 1, entry 3). On the other hand, temperatures below 50°C did not proceed, temperatures above it were not made to prevent the formation of nitrene group in the quinolone ring by thermolysis.…”

Recent Advances in Target Characterization and Identification by Photoaffinity Probes

“…The activation of an aryl azide generates the desired singlet nitrene (Scheme 3) which can generate a triplet nitrene via intersystem crossing. Moreover, at a certain temperature, the singlet nitrene rearranges into a bicyclic benzazirine, which generates 1,2-azacycloheptatetraene that can interact with remote nucleophiles thereby decreasing the photolabeling yields and inducing non-specific labeling [1,9,10].…”

Photochemistry of 2,6‐di(4′‐azidobenzylidene)‐methylcyclohexanone in polymer matrices

“…The rapid response of aryl azides to the UV light and their rich photochemistry guarantee their constant importance in industrial and research—development areas. The known high reactivity of the arylnitrene radicals is now very efficiently exploited in modern and on‐the‐edge applications such as functionalization of polymer surfaces for biomedical applications, as DNA cleaving agents, for chemically modification of carbonaceous materials, for obtaining hybrid materials based on noble metal nanoparticles, as photoaffinity probes, as photoactivatable metal complexes used in photochemotherapy, or basically in organic synthesis, for example, in obtaining azepin‐4‐one …”