28114-20-7Relevant articles and documents
Copper based coordination polymers based on metalloligands: Utilization as heterogeneous oxidation catalysts
Kumar, Gulshan,Hussain, Firasat,Gupta, Rajeev
, p. 16985 - 16994 (2019/01/03)
This work presents the synthesis and characterization of two Cu(ii)-based coordination polymers prepared by utilizing two different Co(iii)-based metalloligands offering appended arylcarboxylic acid groups. Both coordination polymers are three-dimensional in nature and present pores and channels filled with water molecules. Both coordination polymers function as heterogeneous catalysts for the epoxidation of various olefins using O2 while employing isobutyraldehyde as the coreductor and for peroxide-mediated oxidation of assorted benzyl alcohols. The catalytic results illustrate efficient oxidation reactions, whereas the hot-fltration test and leaching experiments indicate the true heterogeneous nature of the catalysis.
Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
supporting information, p. 18025 - 18032 (2017/12/08)
We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
Synthesis and Absolute Configuration of Two Natural Phenolic Homobenzyl Esters
Xu, Murong,Zhu, Shijun,Xu, Zejun,Wu, Yikang,Gao, Po
, p. 729 - 738 (2015/12/05)
Two recently identified natural phenolic homobenzyl esters, isolated from Phragmipedium calurum (an orchid) and Eupatorium fortunei TURCZ (a perennial herb in the Asteraceae family), respectively, were synthesized in enantiopure forms. By comparison of the optical rotations for the synthetic and the natural samples, the absolute configurations for the natural products were reliably assigned. The synthesis also enables establishment of the absolute configuration of a closely related natural homobenzyl alcohol and provided for the first time complete physical and spectroscopic data for two other natural homobenzyl esters. Two recently isolated natural phenolic homobenzyl esters were synthesized in enantiopure forms. The absolute configurations for these natural products were thus reliably assigned. En route to the total synthesis of the first target, complete physical and spectroscopic data for two other related natural products were made available for the first time. Configuration assignment of a third natural product was also achieved.
Manganese- and cobalt-based coordination networks as promising heterogeneous catalysts for olefin epoxidation reactions
Kumar, Girijesh,Kumar, Gulshan,Gupta, Rajeev
, p. 2603 - 2615 (2015/03/30)
We demonstrate the synthesis of Mn2+- and Co2+-based coordination networks using two Co3+-based metalloligands differing by the position of the appended arylcarboxylate groups. The structural analyses reveal topologically distinct networks with pores of variable dimensions allowing facile diffusion of substrates and/or reagents. All four networks function as heterogeneous catalysts for the olefin epoxidation reactions using tert-butyl-hydroperoxide without any requirement of solvent or additive. Control and optimization experiments illustrate recyclable network-based catalysts that make them attractive candidates for the "greener" oxidation chemistry processes.
Mononuclear complexes of amide-based ligands containing appended functional groups: Role of secondary coordination spheres on catalysis
Bansal, Deepak,Kumar, Gulshan,Hundal, Geeta,Gupta, Rajeev
, p. 14865 - 14875 (2015/02/19)
Amide-based ligands H2L1, H2L2 and H2L3 containing thiazole, thiazoline and benzothiazole appended groups have been used to synthesize Zn2+ (1 and 3), Cd2+ complexes (2 and 4), and a Mn2+ complex (5). In all cases, potentially multidentate ligands create a meridional N3 coordination environment around the M(ii) ion whereas additional sites are occupied by labile nitrate ions in 1-4 and MeOH in 5. Interestingly, metal complexation caused the migration of protons from amidic N-H sites to the appended heterocyclic rings in complexes 1-4. Structural studies show that the protonated heterocyclic rings in these complexes create a hydrogen bond based cavity adjacent to the metal ion. Importantly, binding studies confirm that the substrates are bound within the complex cavity closer to the Lewis acidic metal in all complexes including the oxidation-sensitive Mn ion in complex 5. All complexes have been utilized as the reusable and heterogeneous catalysts for ring-opening reactions of assorted epoxides, cyanation reactions of various aldehydes, and epoxidation reactions of several olefins. This journal is
Formation of persulphate from sodium sulphite and molecular oxygen catalysed by H5PV2Mo10O40-aerobic epoxidation and hydrolysis
Rubinstein, Amir,Carmeli, Raanan,Neumann, Ronny
, p. 13247 - 13249 (2015/05/20)
The H5PV2Mo10O40 polyoxometalate catalysed the electron transfer oxidation of sulphite to yield a sulphite radical, SO3- that upon addition of O2 yielded a peroxosulphate species efficient for the H5PV2Mo10O40 catalysed epoxidation of alkenes. The acidic polyoxometalate further catalysed hydrolysis of the epoxide to give vicinal diols in high yields. This journal is
Organocatalytic enantioselective synthesis of 1,3,5-polyols by means of iterative asymmetric epoxidation: Their application to the total synthesis of polyrhacitide A
Kumaraswamy, Gullapalli,Murthy, Akula Narayana,Sadaiah, Kadivendi
experimental part, p. 3179 - 3186 (2012/06/01)
We have developed a pragmatic route to the stereogenic skipped 1,3,5-polyols. The strategic transformation includes an organocatalytic enantioselective asymmetric epoxidation, which is either syn- or anti-selective as genesis of chirality and successive SN2 opening reaction by an appropriate functionalized nucleophile, followed by hydroboration/oxidation to generate stereoisomers in good yield. The critical intermediate generated en route to this process is employed in the total synthesis of polyrhacitide A.
Regioselective epoxidation of different types of double bonds over large-pore titanium silicate Ti-β
Sasidharan, Manickam,Bhaumik, Asim
experimental part, p. 60 - 67 (2010/12/18)
Regioselective epoxidation of different types of double bonds located within the cyclic and acyclic parts of bulky olefins has been investigated using large-pore titanium silicate Ti-β in the presence of dilute aqueous H 2O2 as oxidant under mild liquid-phase conditions. Our experimental results revealed that side-chain vinylic double bonds are selectively epoxidized than those in the cyclohexene-ring. The epoxidation tendency of various bulky olefins with different positional and/or geometric isomers over Ti-β follows the order: terminal -CC- > ring -CC- ≈ bicyclic ring -CC- > allylic C - H bond. Unlike 4-vinyl-1-cyclohexene, epoxidation of an equimolar mixture of cyclohexene and 1-hexene under identical conditions using Ti-β exhibits completely different selectivity and product distributions. Steric factor and accessibility of reactants to active Ti-sites are responsible for the observed regioselectivity of bulky alkenes.
Stereocontrol of 5,5-spiroketals in the synthesis of cephalosporolide H epimers
Tlais, Sami F.,Dudley, Gregory B.
supporting information; experimental part, p. 4698 - 4701 (2011/01/12)
A blueprint for controlling the stereochemistry of oxygenated 5,5-spiroketals using chelation effects is provided. Chelation specifically of zinc salts (other protic and Lewis acids were less effective) between the spiroketal oxygen and an appropriately positioned alcohol group overrides normal biases in the preparation of 5,5-spiroketals, as illustrated by the stereocontrolled synthesis of epimeric cephalosporolide H isomers. This study provides new and valuable information for prescribing the chirality of the stereogenic core of 5,5-spiroketals.
Catalytic decarbonylation of epoxyaldehydes: Applications to the preparation of terminal epoxides
Morandi, Bill,Carreira, Erick M.
experimental part, p. 2076 - 2078 (2011/04/15)
A catalytic decarbonylation reaction for epoxyaldehydes is reported. This reaction may be sequentially used with known asymmetric methods to access optically active mono- and disubstituted terminal epoxides, as illustrated for a key example. Georg Thieme Verlag Stuttgart.
