Our recently studies on three types of reactions with hydrogen transfer as a key step,including catalytic asymmetric proton transfer reactions using"chiral proton transfer shuttle",catalytic B—H bond insertion containing a hydrogen atom transfer,and iron-catalyzed hydrosilylation reactions containing hydride transfer were briefly introduced.
Basic ion-exchange resins,one kind of polystyryl-supported tertiary amine,were demonstrated to be highly efficient and recyclable catalysts for the fixation of carbon dioxide with aziridines under mild conditions,leading to the formation of 5-aryl-2-oxazolidinone with excellent regio-selectivities.Notably,neither solvents nor any additives were required,and the catalyst could be recovered by simple filtration and directly reused at least five times without significant loss of catalytic activity and selectivity.The present protocol has been applied to reactions of epoxides/propargyl amines with CO_(2)/CS2.This solvent-free process thus represents environmentally friendly catalytic conversion of CO_(2) into value-added chemicals and may have potential in various continuous flow reactors in industry.
LIU AnHuaHE LiangNianPENG ShiYongPAN ZhongDaWANG JingLunGAO Jian
A new protocol for the synthesis of 2-deoxy-C-aryl-glycosides and 2-deoxy-C-alkyl-glycosides via iridium-catalyzed directed C—H glycosylation with glycals is reported.The method is amenable for both the C_(2)C—H glycosylation of indoles and the methyl C—H glycosylation of secondary methyl amines under the control of an N-linked benzoxazole directing group.The benzoxazole group can be cleanly removed by the treatment of KOH or LiAlH_(4).
Wanjun ZhuQikai SunHai ChangHui-Xing ZhangQuanquan WangGong ChenGang He
Ring opening of extremely hydrophobic epoxides with water, amines, sodium azide and thiophenol was realized in the mixture solvent of water and 1, 4-dioxane under reflux condition. Hot water was believed to act as a mild Brφnsted acid catalyst in the epoxide-opening reactions.
The title compound diethyl 2-(3,4-dichloroisothiazol-5-yl)-4-(trifluoromethyl)-4,5-dihydrothiazol-4-yl-3-methylbenzoate(C15H9Cl2F3N2O2S2, Mr = 441.26) was prepared from methyl 3,4-dichloroisothiazole-5-carboxylate as the starting material by four steps of reaction. Its structure was characterized by IR, 1H-NMR, 13C-NMR, EA and single-crystal X-ray diffraction. The crystal of the title compound belongs to the monoclinic system, space group P21/c with a = 8.8437(18), b = 16.128(3), c = 12.305(3), β = 91.68(3)o, V = 1754.4(6) 3, Z = 4, Dc = 1.671 g/cm3, μ(Mo Ka) = 0.71073 mm-1, F(000) = 888, R = 0.0384 and w R = 0.0778. Weak π-π interactions occur between the isothiazole rings and phenyl rings of adjacent molecules to form a one-dimensional chain and stabilize the crystal structure. Bioassay indicates that the title compound has good activity against the fungi and TMV tested.
A very simple molecular cation, 4-(4-dimethylaminophenyl)-2,6-diphenylpyrylium, has been demonstrated to have a function of molecular half-adder and half-subtractor according to the detectable spectroscopic changes of the molecular system in response to the inputs of acid and base. Distinct algebraic operations can be performed in this reconfigurable molecular logic system.
Since organoboron compounds readily undergo a diverse array of transformations and are widely used in various fields,the development of C-B-bondforming reactions have attracted considerable attention.Herein,we report a new method for forming C-B bonds by means of Cu-catalyzed ring-opening/borylation reactions of cyclopropenes.This method provides efficient access to a new type of stable allylborane-Lewis base adduct,which is a versatile synthon.The configuration of the products can be well controlled with this method,and some of the configurations we obtained are inaccessible by other catalytic methods for generating allylborons.Mechanistic studies indicated that the reactions proceed via insertion of an alkenyl Cu carbene—generated in situ by cyclopropene ring opening—into the B-H bond;the ring-opening step determines both the rate and stereochemistry.
