Tuesday, 4 April 2017

Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

 

Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

*Corresponding authors

Abstract

In the presence of CuCl and ButOLi, PdCl2/dppe catalyzes the reaction of (benzo)oxazoles or (benzo)thiazoles with 1-aryltriazenes to yield arylated products of (benzo)oxazoles or (benzo)thiazoles. Functional groups including F, Cl, CF3, COOEt, CN, OMe, NMe2, Py, and thienyl groups can be tolerated.
Graphical abstract: Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

    str5
3a (11.2 mg, 38%) were obtained along with unreacted 1 (1.1 mg, 4%).
1H NMR (400 MHz, CS2/CDCl3) δ 8.39 (d, J = 8.0 Hz, 2H), 7.60 (t, J = 7.4 Hz, 1H), 7.50 (t, J = 7.7 Hz, 2H), 7.41 (d, J = 7.8 Hz, 1H), 7.29 (s, 1H), 7.04 (d, J = 7.8 Hz, 1H), 5.95 (s, 1H), 2.76 (s, 3H), 2.52 (s, 3H);
13C NMR (100 MHz, CS2/CDCl3, all 1C unless indicated) δ 196.06 (C=O), 167.78 (C=O), 152.39, 152.08, 151.38, 150.04, 149.83, 149.22, 148.81, 148.52, 148.26, 147.93, 147.86, 147.73, 147.36, 147.18, 147.14 (2C), 146.91, 146.86, 146.41, 146.40, 145.99 (2C), 145.95, 145.92, 145.53, 145.37, 145.33, 144.82 (2C), 144.80, 144.72, 144.54, 144.42, 144.31, 144.14, 143.84, 143.65, 143.42, 143.31, 143.05, 142.13, 141.93, 141.79, 141.72 (2C), 141.69, 141.55, 141.35, 141.24, 141.10, 140.63, 140.14, 139.93 (aryl C), 138.84, 137.70, 137.54 (aryl C), 137.47, 137.38, 135.44 (aryl C), 133.14 (aryl C), 129.16 (2C, aryl C), 128.72 (2C, aryl C), 128.61 (aryl C), 125.80 (aryl C), 125.42 (aryl C), 115.11 (aryl C), 83.58 (sp3 -C of C60), 69.89 (sp3 -C of C60), 62.42 (sp3 -C of C60), 56.81 (sp3 -C of C60), 26.84, 22.25;
UV-vis (CHCl3) λmax nm (log ε) 251.0 (5.1), 318.5 (4.6), 403.5 (4.0), 440.0 (3.9), 525.5 (3.2), 703.5 (2.5);
FT-IR ν/cm-1 (KBr) 2922, 2860, 1668, 1599, 1499, 1439, 1366, 1304, 1236, 1180, 1086, 1020, 964, 858, 802, 748, 691, 604, 528;
MALDI-TOF MS m/z calcd for C76H16NO2 [M+H]+ 974.1176, found 974.1165.

Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

Abstract

A regioselective and highly efficient electrochemical method for direct acylation and carboxylation of a [60]fulleroindoline has been developed. By using inexpensive and readily available acyl chlorides and chloroformates, both keto and ester groups can be easily attached onto the fullerene skeleton to afford 1,2,3,16-functionalized [60]fullerene derivatives regioselectively. In addition, a plausible mechanism for the formation of fullerenyl ketones and esters is proposed, and their further transformations under basic and acidic conditions have been investigated.

Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

    str5
3a (11.2 mg, 38%) were obtained along with unreacted 1 (1.1 mg, 4%).
1H NMR (400 MHz, CS2/CDCl3) δ 8.39 (d, J = 8.0 Hz, 2H), 7.60 (t, J = 7.4 Hz, 1H), 7.50 (t, J = 7.7 Hz, 2H), 7.41 (d, J = 7.8 Hz, 1H), 7.29 (s, 1H), 7.04 (d, J = 7.8 Hz, 1H), 5.95 (s, 1H), 2.76 (s, 3H), 2.52 (s, 3H);
13C NMR (100 MHz, CS2/CDCl3, all 1C unless indicated) δ 196.06 (C=O), 167.78 (C=O), 152.39, 152.08, 151.38, 150.04, 149.83, 149.22, 148.81, 148.52, 148.26, 147.93, 147.86, 147.73, 147.36, 147.18, 147.14 (2C), 146.91, 146.86, 146.41, 146.40, 145.99 (2C), 145.95, 145.92, 145.53, 145.37, 145.33, 144.82 (2C), 144.80, 144.72, 144.54, 144.42, 144.31, 144.14, 143.84, 143.65, 143.42, 143.31, 143.05, 142.13, 141.93, 141.79, 141.72 (2C), 141.69, 141.55, 141.35, 141.24, 141.10, 140.63, 140.14, 139.93 (aryl C), 138.84, 137.70, 137.54 (aryl C), 137.47, 137.38, 135.44 (aryl C), 133.14 (aryl C), 129.16 (2C, aryl C), 128.72 (2C, aryl C), 128.61 (aryl C), 125.80 (aryl C), 125.42 (aryl C), 115.11 (aryl C), 83.58 (sp3 -C of C60), 69.89 (sp3 -C of C60), 62.42 (sp3 -C of C60), 56.81 (sp3 -C of C60), 26.84, 22.25;
UV-vis (CHCl3) λmax nm (log ε) 251.0 (5.1), 318.5 (4.6), 403.5 (4.0), 440.0 (3.9), 525.5 (3.2), 703.5 (2.5);
FT-IR ν/cm-1 (KBr) 2922, 2860, 1668, 1599, 1499, 1439, 1366, 1304, 1236, 1180, 1086, 1020, 964, 858, 802, 748, 691, 604, 528;
MALDI-TOF MS m/z calcd for C76H16NO2 [M+H]+ 974.1176, found 974.1165.

Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

Abstract

A regioselective and highly efficient electrochemical method for direct acylation and carboxylation of a [60]fulleroindoline has been developed. By using inexpensive and readily available acyl chlorides and chloroformates, both keto and ester groups can be easily attached onto the fullerene skeleton to afford 1,2,3,16-functionalized [60]fullerene derivatives regioselectively. In addition, a plausible mechanism for the formation of fullerenyl ketones and esters is proposed, and their further transformations under basic and acidic conditions have been investigated.

1,5-bis-(2-furanyl)-1,4-pentadien-3-one (FAF)

A catalytic aldol condensation system enables one pot conversion of biomass saccharides to biofuel intermediates

Abstract

Producing bio-intermediates from lignocellulosic biomass with minimal process steps has a far-reaching impact on the biofuel industry. We studied the metal chloride catalyzed aldol condensation of furfural with acetone under conditions compatible with the upstream polysaccharide conversions to furfurals. In situ far infrared spectroscopy (FIR) was applied to guide the screening of aldol condensation catalysts based on the distinguishing characteristics of metal chlorides in their coordination chemistries with carbonyl-containing compounds. NiCl2, CoCl2, CrCl3, VCl3, FeCl3, and CuCl2 were selected as the potential catalysts in this study. The FIR results further helped to rationalize the excellent catalytic performance of VCl3 in furfural condensation with acetone, with 94.7% yield of biofuel intermediates (C8, C13) in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) solvent. Remarkably, addition of ethanol facilitated the acetal pathway of the condensation reaction, which dramatically increased the desired product selectivity over the furfural pathway. Most significantly, we demonstrate for the first time that VCl3 catalyzed aldol condensation in acidic medium is fully compatible with upstream polysaccharide hydrolysis to monosaccharide and the subsequent monosaccharide isomerization and dehydration to furfurals. Our preliminary results showed that a 44% yield of biofuel intermediates (C8, C13) can be obtained in one-pot conversion of xylose catalyzed by paired metal chlorides, CrCl2 and VCl3. A number of prior works have shown that the biofuel intermediates derived from the one-pot reaction of this work can be readily hydrogenated to biofuels.
Graphical abstract: A catalytic aldol condensation system enables one pot conversion of biomass saccharides to biofuel intermediates
1,5-bis-(2-furanyl)-1,4-pentadien-3-one (FAF)
FAF is a yellow solid.1H NMR (400 MHz, CDCl3, TMS) δ 7.51 – 7.46 (m, 4H), 6.92 (d, J = 15.6 Hz, 2H), 6.69 (d, J = 3.4 Hz, 2H), 6.50 – 6.49 (m, 2H);13C NMR (100 MHz, CDCl3) δ 188.1, 151.6, 144.9, 129.2, 123.2, 115.8, 112.6