Abstract: Aryl diazonium salts are ubiquitous building blocks in chem., as they are useful radical precursors in organic synthesis as well as for the functionalization of solid materials. They can be reduced electrochem. or through a photo-induced electron transfer reaction. Here, we provide a detailed picture of the ground- and excited-state reactivity of a series of nine rare and earth-abundant photosensitizers with 13 aryl diazonium salts, which also included three macrocyclic calix[4]arene tetradiazonium salts. Nanosecond transient absorption spectroscopy confirmed the occurrence of excited-state electron transfer and was used to quantify cage-escape yields (i.e., the efficiency with which the formed radicals sep. and escape the solvent cage). Cage-escape yields were large; they increased when the driving force for photo-induced electron transfer increased and also tracked with the C-N+2 bond cleavage propensity, among others. A photo-induced borylation reaction was then investigated with all the photosensitizers and proceeded with yields between 9% and 74%.
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Example 147 Ethyl N-[5-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)methyl-2-acetoxybenzoyl]-4-aminobenzoate Ethyl 4-aminobenzoate (-0.265 g, 1.604 mmol), triethylamine (0.162 g, 1.604 mmol) and <strong>[37091-73-9]2-chloro-1,3-dimethylimidazolinium chloride</strong> (0.271 g, 1.604 mmol) were added to a methylene chloride solution (50 ml) of 5-(5,6-dimethoxy-3-methyl-1,4-benzoquinon-2-yl)methyl-2-acetoxybenzoic acid (0.200 g, 0.535 mmol) and the resulting solution was stirred at room temperature for 12 hours. The reaction solution was poured into ice water and then extracted with methylene chloride. The extract was washed with water and then dried, and the solvent was removed by distillation. The obtained residue was purified by preparative thin-layer chromatography (hexane: ethyl acetate = 1:1) and then recrystallized from ether to obtain the titled compound (0.165 g, 0.316 mmol, 59percent).
Example 662- (3 -Methoxy-5-morpholin-4-yl-phenyl)-3 ,3 -dimethyl- 1 ,2,3 ,4-tetrahydro-quinoline-6- carboxylic acidA mixture of 4-amino-benzoic acid ethyl ester (6.1 g, 36.9 mmol) and 3-bromo-5- methoxy-benzaldehyde (8.0 g, 36.9 mmol) in ethanol (100 mL) was prepared. The reaction mixture was heated to reflux for 2 hours. Then the reaction mixture cooled to room temperature. The solvent was removed in vacuo and the residue was washed with ether to afford 4-[l-(3-bromo-5-methoxy-phenyl)-methylidene]-amino}-benzoic acid ethyl ester (4.5 g, 34%) as a white solid: LC/MS m/e calcd for Ci7Hi6BrN03 M+: 362.2, observed: 362.1.
34%
In ethanol; for 2h;Reflux;
A mixture of 4-amino-benzoic acid ethyl ester (6.1 g, 36.9 mmol) and <strong>[262450-65-7]3-bromo-5-methoxy-benzaldehyde</strong> (8.0 g, 36.9 mmol) in ethanol (100 mL) was prepared. The reaction mixture was heated to reflux for 2 hours. Then the reaction mixture cooled to room temperature. The solvent was removed in vacuo and the residue was washed with ether to afford 4-[1-(3-bromo-5-methoxy-phenyl)-methylidene]-amino}-benzoic acid ethyl ester (4.5 g, 34%) as a white solid: LC/MS m/e calcd for C17H16BrNO3 M+: 362.2, observed: 362.1
With dmap; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; In dichloromethane; at 20℃; for 3h;Inert atmosphere;
General procedure: A suspension of 8A or 8B, Ethyl 4-aminobenzoate (1 equiv), DMAP (0.5equiv) and EDCI (1-2 equiv) in CH2Cl2 were stirred for 3 h. They were performed under an atmosphere of Nitrogen gas. The reaction mixture was diluted with 10 volumes CH2Cl2. The organic phase was washed sequentially with 1M HCl , saturated aqueous NaHCO3, and brine, dried over MgSO4 , filtered and concentrated . It is used in the next step without further purication.
A mixture of 165 g (1 mol) of ethyl p-aminobenzoate, 112.35 g (1.05 mol) of N-methylaniline, 159 g (1.5 mol) of trimethyl orthoformate and 10.2 g (0.1 mol) of a specific surface area of 137 m2 / g Gamma-type activated alumina into the 500ml reaction flask,Stirring and heating to 50 ~ 60 , incubation reaction 2h. Open the vacuum pump, and gradually increase the vacuum, vacuum distillation of the resulting methanol, to no methanol distillation.The reaction solution was filtered while hot, the recovered active alumina was repeatedly used and the mother liquor was distilled under reduced pressure to give a pale yellow viscous liquid N- (4-ethoxycarbonylphenyl) -N'-methyl-N'-phenyl Formamidine 270 g, yield 95.7%, purity 99.5%.
165 g (1 mol) of ethyl p-aminobenzoate, 117.7 g (1.1 mol) of N-methylaniline, 10 g of p-toluenesulfonic acid,200mL with toluene toluene added to the 1000mL reaction flask, stirred and warmed to 50-60 C, 2h dropwise 59.53g (1.1mol) formic acid(Content of 85%),Heating to reflux reaction, continue to separate the generated water, the reaction of about 5h to stop water when there is no water. The reaction solution was distilled off with atmospheric toluene recovery agent, toluene was recovered, the remaining vacuum distillation reaction solution,A pale yellow viscous liquid N- (4-ethoxycarbonylphenyl) -N'-methyl-N'-phenyl formamidine 262g, yield 93%, purity 99.4%.
With acetic acid; In Petroleum ether; at 50 - 65℃; for 2.25h;Green chemistry;Catalytic behavior;
1) Accurately weigh 16.5 g of ethyl p-aminobenzoate, 16.5 g of trimethyl orthoformate, 16.8 g of N-methylaniline into a 150 mL three-necked flask, and add 60 mL of petroleum ether to a three-necked flask and place it in magnetic stirring. A dropping funnel, a water separator and a thermometer were placed on the three-necked flask, and the outer wall of the water separator was pre-passed with a freezing liquid of -5 C. A three-necked flask was placed in a magnetic stirrer. 2) Stir and raise the temperature to a temperature of 50 C in a three-necked flask .9 g of glacial acetic acid was added dropwise to the reaction vessel within 15 min, and the reaction was kept for 0.6 h; The temperature was raised to 50 C, the reaction was 0.8 h; the temperature was further raised to 65 C, and the reaction was 0.6 h; The liquid in the lower layer of the water separator is continuously separated, and the reflux is stopped at the upper end of the water separator. 3) The reaction mixture was desolvated under a vacuum, then added 60 mL of toluene, cooled to 40 C; 4) Washing 3 times with hydrochloric acid aqueous solution of pH=2, using 50 mL of hydrochloric acid aqueous solution each time, washing for 8 min each time; then washing with 0.6 mol/L sodium bicarbonate aqueous solution 30 mL, adjusting pH to 8; finally washing 3 times with distilled water Every time you use40 mL of distilled water. 5) The organic layer after the water washing treatment was transferred to a rotary steaming flask for vacuum distillation, and the temperature of the vacuum distillation was controlled at about 125 C, and the product was purified by distillation under reduced pressure, the yield was 98%, and the chroma value was 26 Hazen.
With thionyl chloride; In toluene; at 20℃; for 19.5h;
General procedure: 33.8 g (0.25 mol) of N-methylformylaniline, 12.5 g of toluene, and 1.65 g (0.01 mol) of ethyl paraaminobenzoate were added to the reaction device. After stirring and dissolving, 29.8 g of sulfoxide was added dropwise. (0.25 mol), after stirring (about 70 min), continue stirring for 20 min.Then add 225g of toluene, and then add 39.6g (0.24mol) of ethyl p-aminobenzoate step by step. After the addition (about 90min), stir at room temperature for 18h.The material was orange-yellow, and the purity of UV-1 was 93.0% by sampling (HPLC, the same below). The material liquid was heated to 55 ± 1 C and kept for 7 hours. The material liquid was yellow. The purity of UV-1 was 97.3%. Continue heating the material liquid to 90 ± 1 , stop heating, and recover sulfoxide. Cool the recovered sulfoxide to 35 ± 1 , neutralize it with 10wt% sodium carbonate aqueous solution to pH = 6, and control the temperature below 35 . After neutralization, let it stand and separate layers, and layer Desolvation of the organic layer,68.3 g of ultraviolet absorber UV-1 is obtained,The yield was 96.7% and the purity was 99.6%.
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