Oxidation of carotenoids — I. Dihydrooxepin derivatives as products of oxidation of canthaxanthin and β,β-carotene
摘要:
Dihydrooxepin derivatives 1 and 2 were obtained by oxidation of canthaxanthin with m-CPBA and of beta,beta-carotene with molecular oxygen, respectively. (C) 1997 Elsevier Science Ltd.
The syntheses of 32 complexes of the type (η-C5H5)2Ti(OOCC6H4X)2 are reported together with their mass, 1H NMR, 13C NMR, mid- and far-IR spectra. The data are consistent with a model in which the TiOOC bond strength (weaker than that of TiCp and TiHal) is stabilized by electron-withdrawing substituents X on the phenyl rings. The electronic influence of X also extends into the cyclopentadienyl rings
的类型的32种复合物的合成(η-C 5 H ^ 5)2的Ti(OOCC 6 H ^ 4 X)2与它们的质量,一起报告1 H NMR,13 C NMR,中期和远红外光谱。该数据与通过苯环上的吸电子取代基X稳定了TiOOC键强度(比TiCp和TiHal的强度弱)的模型一致。X的电子影响也延伸到环戊二烯基环中。
Binucleating Aza‐Sulfonate and Aza‐Sulfinate Macrocycles — Synthesis and Coordination Chemistry
of S-oxygenated derivatives of a macrobinucleating hexaazadithiophenolatemacrocycle H2L1 of the Robson type towards nickel(II) and zinc(II) ions are reported. Nickelcomplexes of the hexaazadiphenylsulfonate ligand (L2)2− [(L2)NiII2(μ-L)]+ (L = m-Cl-OBz− (3), Cl− (4) and OAc− (6)] are readily obtained in high yields by oxidation of the respective [(L1)NiII2(μ-L)]+ parent complexes [L = m-Cl-OBz− (2)
acid (pH <4.5) and base (pH >11.5) catalysed acyl transfer to the solvent, giving the amides (12). But at intermediate pH (6–11) rearrangement to the N-acyl form (11)(the Mumm rearrangement) alone occurs. The specific rate of this O → N acyl group migration is pH independent and shows a low solvent effect (m 0.175). Substituents attached to carbon or nitrogen have the same effect (ρ–0.84). When the migrating
Copper(II)-catalyzed <i>ortho</i>-Benzoxylation of 2-Arylpyridines with Sodium Carboxylates
作者:Liping Li、Peng Yu、Jiang Cheng、Fan Chen、Changduo Pan
DOI:10.1246/cl.2012.600
日期:2012.6.5
Copper-catalyzed ortho-benzoxylation of an sp2 C–H bond by sodium carboxylates is described. The procedure tolerates carbomethoxy, formyl, bromo, and chloro groups, providing the benzoxylated products in moderate to good yields.
Indirect evidence for a Ni<sup>III</sup>–oxyl oxidant in the reaction of a Ni<sup>II</sup> complex with peracid
作者:Paolo Pirovano、Abigail R. Berry、Marcel Swart、Aidan R. McDonald
DOI:10.1039/c7dt03316h
日期:——
The reaction of a NiII complex and meta-chloroperoxybenzoic acid (m-CPBA) resulted in the formation of a long-lived NiIII–chlorobenzoate complex that is a capable hydrocarbon oxidant. Analysis of the post-reaction decay products showed the formation of oxidised derivatives of the supporting ligand (a benzoxazine), and heterolytic O–O bond scission in m-CPBA. This evidence indicates formation of a more
Ni II配合物与间-氯过氧苯甲酸(m -CPBA)的反应导致形成了长寿命的Ni III-氯苯甲酸酯配合物,是一种有效的烃类氧化剂。反应后衰变产物的分析表明,支撑配体(苯并恶嗪)的氧化衍生物形成,并且在m -CPBA中发生了杂合的O-O键断裂。该证据表明形成了更有效的瞬态Ni III-羟基物质,DFT计算进一步支持了这一点。