[8-[Bis(carboxymethyl)aminomethyl]-6-bromo-7-hydroxycoumarin-4-yl]methyl Moieties as Photoremovable Protecting Groups for Compounds with COOH, NH₂, OH, and C═O Functions

Abstract

We introduce a variant of coumarin-based photoactivatable protecting groups and use it exemplarily for caging of a carboxylic acid, an amine, a phenol, and a carbonyl compound. The caged compounds are efficiently photolyzed at long-wavelength UV/vis irradiation. Compared to the corresponding (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) derivatives, the novel coumarin-type caged compounds are distinguished by (i) dramatically increased solubilities in aqueous buffers, (ii) lower pK(a) values of the C7 hydroxyl of the coumarin chromophore, thus permitting efficient photorelease at lower pH, and (iii) higher photolysis quantum yields in the case of photoprotected carbonyl compounds. The primary step of the photocleavages occurs with rate constants of about 10(9) s(-1).

What Goes around Comes around-A Comparative Study of the Influence of Chemical Modifications on the Antimicrobial Properties of Small Cyclic Peptides

“…Components for peptide synthesis were purchased/prepared as follows: Fmoc-Arg(Pbf)-OH, Fmoc-Lys(Boc)-OH, Fmoc-Trp(Boc)-OH (GL Biochem, Shanghai Ltd., Shanghai, China), Fmoc-L-Dap(Dde)-OH (Iris Biotech, Marktredwitz, Germany), 4-Chloro-7-nitro-1,2,3-benzoxadiazole, (NBD-Cl, Sigma-Aldrich, St. Louis, MO, USA), 6-bromo-7-hydroxycoumarin-4-yl [12]. Chemical components for buffer preparation were purchased from Fluka (Taufkirchen, Germany).…”

Ethyl substituted coumarin-4-yl derivatives as photoremovable protecting groups for amino acids with improved stability for SPPS

“…Coumarin-4-yl methyl derivatives [12,15,16] meet these requirements and, in addition, they display decent two-photon excitation cross-sections allowing two-photon activation [17]. Coumarin-4-yl methyl photolabile groups have been successfully applied to cage phosphate and carboxylic groups in cAMP [12], ATP [11], GABA [10] and glutamic acid [18].…”

Optopharmacological control of TRPC channels by coumarin-caged lipids is associated with a phototoxic membrane effect

“…In an attempt to make the previously reported preparation protocol (Hagen et al, 2010;Hess et al, 2007;Kim et al, 2011;Nadler et al, 2013;Tsien et al, 2000) more efficient, we have performed the initial two synthetic steps using sealed vessel controlled microwave heating. For the initial condensation step an increased reaction temperature of 80°C delivered 6-bromo-4-(chloromethyl)-7-hydroxy-2H-chromen-2-one in only 10 min.…”