Rh(III)-Catalyzed Regio- and Chemoselective [4 + 1]-Annulation of Azoxy Compounds with Diazoesters for the Synthesis of 2<i>H</i>-Indazoles: Roles of the Azoxy Oxygen Atom
作者:Zhen Long、Zhigang Wang、Danni Zhou、Danyang Wan、Jingsong You
DOI:10.1021/acs.orglett.7b00631
日期:2017.6.2
tandem C–H alkylation/intramolecular decarboxylative cyclization of azoxy compounds with diazoesters for the synthesis of 3-acyl-2H-indazoles is disclosed. The azoxy instead of the azo group enables a distinct approach for cyclative capture, leading to a [4 + 1]-annulation rather than a classic [4 + 2] manner. The azoxy oxygen atom is traceless after annulation, and further removal from the product is
Aqueous Biphasic Oxidation: A Water-Soluble Polyoxometalate Catalyst for Selective Oxidation of Various Functional Groups with Hydrogen Peroxide
作者:Dorit Sloboda-Rozner、Peter Witte、Paul L. Alsters、Ronny Neumann
DOI:10.1002/adsc.200303156
日期:2004.2
catalyst in aqueous biphasic reaction media to effect oxidation of alcohols, diols, pyridine derivatives, amines and aniline derivatives with hydrogenperoxide. The catalyst was shown by 183W NMR to be stable in aqueous solutions in the presence of H2O2 and showed only minimal non-productive decomposition of the oxidant. Secondary alcohols were selectively oxidized to ketones, while primary alcohols tended
在水性双相反应介质中,将“三明治”型多金属氧酸盐Na 12 [(WZn 3(H 2 O)2 ] [(ZnW 9 O 34)2 ])用作氧化催化剂,以实现醇,二醇,吡啶的氧化183 W NMR表明该催化剂在H 2 O 2存在下在水溶液中稳定。并且仅显示出极少的氧化剂非生产性分解。仲醇被选择性地氧化成酮,而伯醇则倾向于被氧化成相应的羧酸,尽管在伯醇存在下仲醇被选择性地氧化。邻苯二甲酸二醇以非常高的产率产生碳-碳键裂解产物。吡啶衍生物被氧化成各自的N-氧化物,但是强吸电子部分抑制了氧化反应。伯胺被氧化为肟,但在原位显着水解。苯胺衍生物根据芳环中的取代方式被氧化成相应的a氧基或硝基产物。证明了催化剂的回收和再循环。
Highly selective reduction of nitrobenzenes to azoxybenzenes with a copper catalyst
A convenient protocol for highly selective delivery of azoxybenzenes from reduction of nitrobenzenes was developed by utilizing a coppercatalyst. A variety of functional groups and substitution were well tolerated.
molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic
在医药和工业应用中起重要作用的芳族偶氮化合物在合成中仍然面临巨大挑战。在此,我们报道了一种氧化钼化合物[N(C 4 H 9)4 ] 2 [Mo 6 O 19 ](1),用过氧化氢作为绿色氧化剂催化苯胺的选择性氧化。苯胺的氧化可以完全选择性地实现,通过改变添加剂和溶剂避免使用化学计量的金属氧化剂,从而分别提供各种对称/不对称的偶氮苯和and氧基苯化合物。初步的机理研究表明,高活性的反应性和难以捉摸的钼亚胺配合物是中间的。
Rh(III)-Catalyzed [4 + 1]-Annulation of Azoxy Compounds with Alkynes: A Regioselective Approach to 2<i>H</i>-Indazoles
作者:Zhen Long、Yudong Yang、Jingsong You
DOI:10.1021/acs.orglett.7b00982
日期:2017.6.2
A rhodium-catalyzed regioselective C–H activation/cyclization of azoxycompounds with alkynes has been disclosed to construct a variety of 2H-indazoles. A [4 + 1]-cycloaddition rather than a normal [4 + 2] mode is observed in the process of cyclative capture along with an oxygen-atom transfer and a C≡C triple bond cleavage. This protocol features a broad substrate scope, a good functional group tolerance