Kainan Zhang

Rhodium-Catalyzed Decarboxylative Cycloaddition Route to Substituted Anilines

Journal of Organic Chemistry, Jun 3, 2011

A convenient method for preparing substituted anilines via a Rh-catalyzed [2 + 2 + 2] cycloadditi... more A convenient method for preparing substituted anilines via a Rh-catalyzed [2 + 2 + 2] cycloaddition reaction of diynes and 2-oxazolone was discovered. The initial cycloaddition adducts undergo facile decarboxylation of carbon dioxide to afford aniline products. Reaction conditions are mild, and only 3 mol % Rh catalyst is required. High regioselectivity was observed when an unsymmetrical diyne was used as a starting material.

An Expeditious Route to Eight-Membered Heterocycles By Nickel-Catalyzed Cycloaddition: Low-Temperature C sp 2C sp 3 Bond Cleavage

Angewandte Chemie, Jul 17, 2012

A cool break: 3-Azetidinone and a variety of diynes undergo a cycloaddition reaction catalyzed by... more A cool break: 3-Azetidinone and a variety of diynes undergo a cycloaddition reaction catalyzed by Ni/IPr to give dihydroazocine compounds (see scheme; IPr=1,3-bis(2,6-diisopropylphenyl)imidazolidene). The reaction involves a challenging C(sp)2-C(sp)3 bond cleavage step, yet, surprisingly, proceeds at low temperature.

Complete Double Epoxidation of Divinylbenzene Using Mn(porphyrin)-Based Porous Organic Polymers

ABSTRACT: A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excelle... more ABSTRACT: A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields via the Yamamoto−Ullmann couplings of tetrabromo spirobifluorene with several brominated porphyrin monomers. After isolation and demetalation, the metal-free PPOP can be postsyntheti-cally metalated to form a MnIII−PPOP that is catalytically active toward the selective double-epoxidation of divinylben-zene to divinylbenzene dioxide.

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Coupling of Vinyl Aziridines and Isocyanates

Tetrahedron letters, 2008

Thermal coupling of vinyl aziridines and phenyl isocyanate was evaluated. Although oxazolidinone ... more Thermal coupling of vinyl aziridines and phenyl isocyanate was evaluated. Although oxazolidinone products were predominant, some reactions afforded a seven-membered ring heterocycle. When Ni/IMes was employed as a catalyst, a wider array of vinyl aziridines underwent coupling reactions. The Ni catalyzed reactions generally afforded vinyl imidazolidinones as major products.

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Liquid-Phase Epitaxially Grown Metal-Organic Framework Thin Films for Efficient Tandem Catalysis Through Site-Isolation of Catalytic Centers

ChemPlusChem, 2016

A functional metal-organic framework (MOF) composed of robust porphyrinic material (RPM) based on... more A functional metal-organic framework (MOF) composed of robust porphyrinic material (RPM) based on the pillared-paddlewheel topology is prepared with large 3 D channels, and is used to perform a tandem epoxidation/CO2 insertion reaction. The designated system benefits from two metalloporphyrins: 1) a Mn-porphyrin, which catalyzes the epoxidation of an olefin substrate, and 2) a Zn-porphyrin, which catalyzes the epoxide opening. By using an automated liquid-phase epitaxial growth system, the RPM-MOF is also prepared in layer-by-layer fashion as an ultrathin film on a self-assembled-monolayer-coated silicon platform. Deployed as a tandem catalyst, the film version yields a substantially higher catalytic turnover number for tandem methoxy-styrene epoxidation followed by CO2 insertion than the bulk crystalline MOF samples.

Complete Double Epoxidation of Divinylbenzene Using Mn(porphyrin)-Based Porous Organic Polymers

ACS Catalysis, 2015

A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields ... more A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields via the Yamamoto−Ullmann couplings of tetrabromo spirobifluorene with several brominated porphyrin monomers. After isolation and demetalation, the metal-free PPOP can be postsynthetically metalated to form a Mn III −PPOP that is catalytically active toward the selective double-epoxidation of divinylbenzene to divinylbenzene dioxide.

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Stable and catalytically active iron porphyrin-based porous organic polymer: Activity as both a redox and Lewis acid catalyst

Scientific reports, Jan 16, 2015

A new porphyrin-based porous organic polymer (POP) with BET surface area ranging from 780 to 880 ... more A new porphyrin-based porous organic polymer (POP) with BET surface area ranging from 780 to 880 m(2)/g was synthesized in free-base form via the reaction of meso-tetrakis(pentafluorophenyl) porphyrin and a rigid trigonal building block, hexahydroxytriphenylene. The material was then metallated with Fe(III) imparting activity for Lewis acid catalysis (regioselective methanolysis ring-opening of styrene oxide), oxidative cyclization catalysis (conversion of bis(2-hydroxy-1-naphthyl)methanes to the corresponding spirodienone), and a tandem catalytic processes: an in situ oxidation-cyclic aminal formation-oxidation sequence, which selectively converts benzyl alcohol to 2-phenyl-quinazolin-4(3H)-one. Notably, the catalyst is readily recoverable and reusable, with little loss in catalytic activity.

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An Expeditious Route to Eight-Membered Heterocycles By Nickel-Catalyzed Cycloaddition: Low-Temperature CC Bond Cleavage

Ultrahigh Surface Area Zirconium MOFs and Insights into the Applicability of the BET Theory

Journal of the American Chemical Society, Jan 27, 2015

An isoreticular series of metal-organic frameworks (MOFs) with the ftw topology based on zirconiu... more An isoreticular series of metal-organic frameworks (MOFs) with the ftw topology based on zirconium oxoclusters and tetracarboxylate linkers with a planar core (NU-1101 through NU-1104) has been synthe-sized employing a linker expansion approach. In this series, NU-1103 has a pore volume of 2.91 cc g-1 and a geometrically calculated surface area of 5,646 m2 g-1, which is the highest value reported to date for a zirconium-based MOF, and among the largest that have been reported for any porous material. Success-ful activation of the MOFs was proven based on the agreement of pore volumes and BET areas obtained from simulated and experimental isotherms. Critical for practical applications, NU-1103 combines for the first time ultrahigh surface area and water stability, where this material retained complete structural in-tegrity after soaking in water. Pressure range selection for the BET calculations on these materials was guided by the four so-called "consistency criteria". The...

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ChemInform Abstract: An Expeditious Route to Eight-Membered Heterocycles by Nickel-Catalyzed Cycloaddition: Low-Temperature C(sp 2 )-C(sp 2 ) Bond Cleavage

ChemInform, 2013

Epoxidation of the Commercially Relevant Divinylbenzene with [ tetrakis -(Pentafluorophenyl)porphyrinato]iron(III) Chloride and Its Derivatives

Industrial & Engineering Chemistry Research, 2015

Fluorinated Fe-porphyrins, especially [tetrakis(pentafluorophenyl)porphyrinato]iron(III) chloride... more Fluorinated Fe-porphyrins, especially [tetrakis(pentafluorophenyl)porphyrinato]iron(III) chloride (tetrakis(pentafluorophenyl)porphyrinato = TPFPP) (TPFPP)FeCl (Fepor-2a), were found to be highly efficient for catalyzing the double epoxidation of divinylbenzene (DVB) to divinylbenzene dioxide (DVBDO), a novel component of epoxy resin formulation. The electronic properties of the catalysts are highly dependent on the substituents on the phenyl groups of these metalloporphyrins. The electron-rich fluorinated Fe-porphyrins are more selective toward epoxidation but are more vulnerable toward decomposition in H 2 O 2. On the other hand, the electron deficient Fe-porphyrins are more stable, yet more Lewis acidic, which facilitates the formation of byproducts such as epoxide ring opening and overoxidation.

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N-Heterocyclic Carbene Bound Nickel(I) Complexes and Their Roles in Catalysis

Organometallics, 2011

New paramagnetic Ni(I)(IMes)(2)X (IMes: 1,3-bis-(2,4,6-trimethylphenyl)-imidazol-2-ylidene) were ... more New paramagnetic Ni(I)(IMes)(2)X (IMes: 1,3-bis-(2,4,6-trimethylphenyl)-imidazol-2-ylidene) were prepared from the reaction of Ni(IMes)(2) with aryl halides. Products that would arise from oxidative addition were not observed. In contrast, Ni(II)(tmiy)(2)(X)(Ar) was formed from the oxidative addition of aryl halides to Ni bound by a sterically-less hindered NHC ligand, tmiy (tetramethylimidazol-2-ylidene). The paramagnetic Ni(I)(IMes)(2)X complexes were compared to known Ni(0) and Ni(II) catalysts for Kumada and Suzuki coupling reactions. Stoichiometric reactions between the Ni(I)(IMes)(2)X complexes with aryl halides and transmetallating agents were also evaluated.

Rhodium-Catalyzed Decarboxylative Cycloaddition Route to Substituted Anilines

The Journal of Organic Chemistry, 2011

A convenient method for preparing substituted anilines via a Rh-catalyzed [2 + 2 + 2] cycloadditi... more A convenient method for preparing substituted anilines via a Rh-catalyzed [2 + 2 + 2] cycloaddition reaction of diynes and 2-oxazolone was discovered. The initial cycloaddition adducts undergo facile decarboxylation of carbon dioxide to afford aniline products. Reaction conditions are mild, and only 3 mol % Rh catalyst is required. High regioselectivity was observed when an unsymmetrical diyne was used as a starting material.

Suzuki-Miyaura coupling of heteroaryl boronic acids and vinyl chlorides

Chemical Communications, 2012

All reactions were conducted under an atmosphere of N 2 using standard Schlenk techniques or in a... more All reactions were conducted under an atmosphere of N 2 using standard Schlenk techniques or in a N 2 filled glove-box unless otherwise noted. Toluene was dried over neutral alumina under N 2 using a Grubbs type solvent purification system. Pd(OAc) 2 and SPhos was purchased from Strem and used without further purification. N-BOC-5methoxy-2-indolylboronic acid (1), 1-chlorocyclopentene (a) and CsF were purchased from Sigma-Aldrich and used without further purification. Isopropanol was distilled and degassed prior to use. All the other heteroaryl boronic acids were purchased from Frontier Scientific. The heteroaryl boronic acids were stored at-40 ºC in the refrigerator within the glove box. The vinyl chlorides 1-chloro-2-methylpropene and (Z)-2-chloro-2butene were purchased from TCI America. 3-Chloro-5,5-dimethyl-2-cyclohexen-1-one was bought from Alfa Aesar. 4-Chloro-1,2,5,6-tetrahydro-1-tosylpyridine 1 was prepared according to the literature procedure. All other reagents were purchased and used without further purification unless otherwise noted.

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An Expeditious Route to Eight-Membered Heterocycles By Nickel-Catalyzed Cycloaddition: Low-Temperature C sp 2C sp 3 Bond Cleavage

Angewandte Chemie International Edition, 2012

for providing HRMS and single-crystal X-ray crystallographic data, respectively. We also thank As... more

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Coupling of vinyl aziridines and phenyl isocyanate

Tetrahedron Letters, 2008

Thermal coupling of vinyl aziridines and phenyl isocyanate was evaluated. Although oxazolidinone ... more Thermal coupling of vinyl aziridines and phenyl isocyanate was evaluated. Although oxazolidinone products were predominant, some reactions afforded a seven-membered ring heterocycle. When Ni/IMes was employed as a catalyst, a wider array of vinyl aziridines underwent coupling reactions. The Ni catalyzed reactions generally afforded vinyl imidazolidinones as major products.

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Nickel-catalyzed reactions of vinyl aziridines and aziridinylen-ynes

Tetrahedron letters, 2008

Ni/NHC was found to catalyze the rearrangement of vinyl aziridines and aziridinylen-ynes under mi... more

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