A strategy for generating alkyl radicals from aliphatic esters and lactones via sequential hydrolysis and photoinduced decarboxylation

Formation and Reaction Kinetics of Biradicals and Triplet States in a Series of Carboxylated 1,4,5,8-Naphthalene Diimides

“…The solvent was removed under vacuum rotary evaporation and the solid product was recrystallized from methanol. The structures were confirmed by 1 H and mass spectrometry. The synthesis of N,N′-bis(carboxymethyl)-1,8:,4,5-bis(dicarboxyamide) (NDI-1), N,N′-bis(2-carboxyethyl)naphthalene-1,8:4,5-bis-(dicarboxamide) (NDI-2), N,N′-bis(3-carboxypropyl)naphthalene-1,8:4,5-bis(dicarboxamide) (NDI-3), N,N′-bis(4carboxybutyl)naphthalene-1,8:4,5-bis(dicarboxamide) (NDI-4), and N,N′-bis[2-(N-pyridinium)ethyl]-1,8:4,5-bis-(dicarboxyamide) (NDI-Pyr) have been previously published.…”

“…UV (10 mM phosphate buffer pH 7.0) λ max (ε): 382 nm (24 700 ± 100 M −1 cm −1 ), 360 nm (19 800 ± 150 M −1 cm −1 ), 310 nm (3990 ± 80 M −1 cm −1 ), 234 nm (29 500 ± 100 M −1 cm −1 ). 1 H NMR (DMSO-d 6 ): δ 8.5 (s, 4H, naphth), 3.47 (t, J = 8.0 Hz, 4H, CH 2 ), 2.53 (t, J = 7.6 Hz, 4H, CH 2 ). MS m/z 410.3 amu; Found: 410.2 amu.…”

“…UV (10 mM pH 7.0 phosphate buffer) λ max (ε): 382 nm (25 000 ± 100 M −1 cm −1 ), 360 nm (18 800 ± 200 M −1 cm −1 ), 310 nm (7100 ± 100 M −1 cm −1 ), 234 nm (32 100 ± 200 M −1 cm −1 ). 1 20 Ethanolamine (10 mL, 0.16 mol) and 1,4,5,8-napthalenetetracarboxylic dianhydride (5 g, 18 mmol) were suspended in 40 mL of DMF and heated at 95 °C for 2.5 h. The solvent was removed under vacuum by rotary evaporation, and the remaining red crystals were washed with acetone to yield 4.6 g. The hydroxyethyl product (4.6 g, 3 mmol), p-toluenesulfonyl chloride (7.6 g, 40 mmol), and anhydrous pyridine (60 mL, 0.7 mol) were dissolved in 10 mL of DMF and stirred for 24 h at room temperature. After cooling the solution, yellow crystals were collected and recrystallized from methanol.…”

Recent Advances in Photoredox Catalysis Enabled Functionalization of α-Amino Acids and Peptides: Concepts, Strategies and Mechanisms

“…The phenanthryl radical cation is a powerful oxidant and subsequently oxidizes, for example, the peptide carboxylate, resulting in extrusion of CO 2 to furnish the corresponding alkyl radical, which can engage in a variety of ensuing radical manifolds. [139][140][141][142][143][144][145][146][147][148][149][150][151][152] The visible-light-mediated direct decarboxylative conjugate addition previously developed by the MacMillan group (see Scheme 10) was also instrumental in their discovery that this reactivity is not limited to simple -amino acids and dipeptides, but can also be exploited for site-and chemoselective functionalization of peptides and proteins (Scheme 36). 153 Initial evaluations on achieving selective Cterminal decarboxylative functionalization of tetrapeptides using photocatalyst 2; however, this proved to be less than fruitful.…”

Metal-Free Photoinduced Decarboxylative Radical Polymerization Using Carboxylic Acids as Benign Radical Initiators: Introduction of Complex Molecules into Polymer Chain Ends

“…In the first step, photoinduced polymerization of 10 having both a carboxylic acid and methyl ester with t -butyl acrylate led to the formation of polymer 11 ( M n = 27300). After evaporation to eliminate t -butyl acrylate, the resulting polymer 11 having an ester moiety was hydrolyzed by NaOH (100 mM) in aqueous acetonitrile at 50 °C for 3 h to form the corresponding carboxylate ion as reported previously, followed by the second photoinduced polymerization with N -isopropylacrylamide to obtain polymer 12 with a higher molecular weight ( M n = 41300) having different segments (GPC and 1 H NMR are shown in Figure S11 of the Supporting Information). Similarly, the sequential photoinduced radical polymerization of 11 with t -butyl acrylate and styrene took place to obtain the corresponding polymer 13 .…”