- Difunctionalization of Alkenylpyridine N-Oxides by the Tandem Addition/Boekelheide Rearrangement
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A convenient and efficient approach for the difunctionalization of alkenylpyridine N-oxides through the tandem addition/Boekelheide rearrangement has been developed. The C-O and C-X (S, O, Cl) bonds are constructed simultaneously at the α- and β-positions under mild reaction conditions in 100% atom economy, which complements previously reported α- or β-functionalizations.
- Xun, Xudong,Zhao, Man,Xue, Jianzhong,Hu, Tao,Zhang, Ming,Li, Guofeng,Hong, Liang
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supporting information
p. 8266 - 8269
(2019/10/16)
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- Synthesis and crystal structures of α-phenyl- and α-trifluoromethyl-α-(2-pyridyl-N-oxide)ethanols and α-phenyl-α-(2-pyridyl-N-oxide)ethylene
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The X-ray structures of two α-substituted α-(2-pyridyl-N-oxide) ethanols, the α-phenyl- (3a) and α-trifluoromethyl- (3b) derivatives, were determined. On dehydration of 3a, compound 4a was obtained. This study brought a clear proof that the α-(2-pyridyl-N-oxide)ethanols are formed following oxidation with peroxides of their corresponding pyridines. A different molecular packing was observed for the α-trifluoromethyl derivative due to an additional hydrogen bonding. Compound 3a crystallized in the monoclinic space group P 21/n with unit cell parameters a = 5.7416(1) A, b = 14.3841(4) A, c = 13.2821(3) A, β = 94.918(2)°, V = 1092.90(4) A3, Z = 4, D = 1.308 Mg/m 3. Compound 3b crystallized in the triclinic space group P -1 with unit cell parameters a = 6.1209(2) A, b = 8.1938(4) A, c = 9.4675(4) A, α = 73.363(3)°, β = 73.166(3)°, γ = 71.659(3)°, V = 421.32(3) A3, Z = 2, D = 1.633 Mg/m 3. Compound 4a crystallized in the monoclinic space group P 2 1/n with unit cell parameters a = 9.3579(3) A, b = 12.7340(3) A, c = 9.8579(3) A, β = 117.3249(15)°, V = 1043.63(5) A3, Z = 4, D = 1.255 Mg/m3.
- Modec, Barbara,Stephan, Michel
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experimental part
p. 386 - 390
(2011/10/17)
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- DiPAMP's big brother "i-Pr-SMS-Phos" exhibits exceptional features enhancing rhodium(I)-catalyzed hydrogenation of olefins
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Switching Knowles DiPAMP's {DiPAMP = l,2-bis[(o-anisyl)(phenyl)phosphino] ethane} MeO groups with i-PrO ones led to the iPr-SMS-Phos {i-Pr-SMS-Phos = l,2-bis[(o-isopropoxyphenyl)(phenyl)phosphino]ethane} ligand which displayed a boosted catalyst activity coupled with an enhanced enantioselectivity in the rhodium(I)catalyzed hydrogenation of a wide-range of representative olefinic substrates (dehydro-a-amido acids, itaconates, acrylates, enamides, enol acetates, α,α-diarylethylenes, etc). The rhodium(I)-(i-PrSMS-Phos) catalytic profile was investigated revealing its structural attributes and robustness, and in contrast to the usual trend, 31P NMR analysis revealed that its methyl (Z)-α-acetamidocinnamate (MAC) adduct consisted of a reversed diastereomeric ratio of 1.4:1 in favour of the most reactive diastereomer.
- Stephan, Michel,Sterk, Damjan,Mohar, Barbara
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supporting information; experimental part
p. 2779 - 2786
(2010/03/25)
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