Search

We report the synthesis of all‐cis 1,2,4,5‐tetrakis (trifluoromethyl)‐ and all‐cis 1,2,3,4,5,6‐hexakis (trifluoromethyl)‐ cyclohexanes by direct hydrogenation of precursor tetrakis‐ or hexakis‐ (trifluoromethyl)benzenes. The resultant cyclohexanes have a stereochemistry such that all the CF3 groups are on the same face of the cyclohexyl ring. All‐cis 1,2,3,4,5,6‐hexakis(trifluoromethyl)cyclohexane is the most sterically demanding of the all‐cis hexakis substituted cyclohexanes prepared to date, with a barrier (ΔG) to ring inversion calculated at 27 kcal mol−1. The X‐ray structure of all‐cis 1,2,3,4,5,6‐hexakis(trifluoromethyl)cyclohexane displays a flattened chair conformation and the electrostatic profile of this compound reveals a large diffuse negative density on the fluorine face and a focused positive density on the hydrogen face. The electropositive hydrogen face can co‐ordinate chloride (K≈103) and to a lesser extent fluoride and iodide ions. Dehydrofluorination promoted decomposition occurs with fluoride ion acting as a base., All‐cis 1,2,4,5‐tetrakis (trifluoromethyl)‐ and all‐cis 1,2,3,4,5,6‐hexakis (trifluoromethyl)‐ cyclohexanes were prepared by direct aryl hydrogenation. All‐cis 1,2,3,4,5,6‐hexakis(trifluoromethyl)cyclohexane has a high barrier to ring inversion (ΔG≠=27 kcal mol−1) and a Janus face profile with a large diffuse negative density on the fluorine face, and a focused positive density on the hydrogen face which coordinates carbonyls and halides.

X.-J.W., I.A., J.A., and T.N. would like to acknowledge the European Union for a Marie Curie ITN Grant (Photo4Future, Grant No. 641861). C.S. acknowledges the European Union for a Marie Curie European post-doctoral fellowship (FlowAct, Grant No. 794072). We would like to thank the Engineering and Physical Sciences Research Council for financial support (EP/M02105X/1). C. L. thanks the Prof. & Mrs Purdie Bequests Scholarship and AstraZeneca for his PhD Studentship. A continuous‐flow, visible‐light‐promoted method has been developed to overcome the limitations of iron‐catalyzed Kumada–Corriu cross‐coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron‐catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application. Publisher PDF

The research leading to these results has received funding from the ERC under the European Union's Seventh Framework Programme (FP7/2007-2013)/E.R.C. grant agreement n° 279850 and the EPSRC (EP/J500549/1). A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. P.H.-Y.C. is the Bert and Emelyn Christensen Professor and gratefully acknowledges financial support from the Stone Family of OSU. Financial support from the National Science Foundation (NSF) (CHE-1352663) is acknowledged. D.M.W. acknowledges the Bruce Graham and Johnson Fellowships of OSU. D.M.W. and P.H.-Y.C. acknowledge computing infrastructure in part provided by the NSF Phase-2 CCI, Center for Sustainable Materials Chemistry (CHE-1102637). A combination of experimental and computational studies have identified a C=O•••isothiouronium interaction as key to efficient enantiodiscrimination in the kinetic resolution of tertiary heterocyclic alcohols bearing up to three potential recognition motifs at the stereogenic tertiary carbinol center. This discrimination was exploited in the isothiourea-catalyzed acylative kinetic resolution of tertiary heterocyclic alcohols (38 examples, s factors up to > 200). The reaction proceeds at low catalyst loadings (generally 1 mol %) with either isobutyric or acetic anhydride as the acylating agent under mild conditions Postprint

R.E.M. thanks the Royal Society and the Engineering and Physical Sciences Research Council (Grants EP/K025112/1, EP/K005499/1, EP/L016419/1) for funding work in this area and for providing a Ph.D. studentship to S.E.R. through the Criticat Centre for Doctoral training. R.E.M. and M. O. acknowledge the OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. J.Č., V.K., and M.T. acknowledge the Czech Science Foundation for the project of the Centre of Excellence (P106/12/G015) and J.Č has received funding from the European Union's Horizon2020 research and innovation programme under grant agreement No 640979. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement No. 312483—ESTEEM2 (Integrated Infrastructure Initiative–I3). The assembly-disassembly-organization-reassembly (ADOR) process has been used to disassemble a parent zeolite with the UOV structure type and then reassemble the resulting layers into a novel structure, IPC-12. The structure of the material has previously been predicted computationally and confirmed in our experiments using X-ray diffraction and atomic resolution STEM-HAADF electron microscopy. This is the first successful application of the ADOR process to a material with porous layers. Publisher PDF

The authors thank the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement no. 279850 (CMY, THW, JET). ADS thanks the Royal Society for a Wolfson Merit Award. N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes. Postprint

We gratefully acknowledge funding support from The Leverhulme Trust (RPG-2013-343) and EPSRC (EP/K005499/1). The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C3H5N2][V9O6F24(H2O)2] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V4+ S = 1/2 equation image ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V4+, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long-range magnetic order down to 2 K despite considerable antiferromagnetic exchange. Postprint Postprint

This work was supported by the EPSRC (EP/K016342/1 and DTG), the University of St Andrews, and by a Royal Society of Edinburgh/Scottish Government Fellowship (E.R.K.). Existing methods for the covalent functionalization of nanoparticles rely on kinetically controlled reactions, and largely lack the sophistication of the preeminent oligonucleotide-based noncovalent strategies. Here we report the application of dynamic covalent chemistry for the reversible modification of nanoparticle (NP) surface functionality, combining the benefits of non-biomolecular covalent chemistry with the favorable features of equilibrium processes. A homogeneous monolayer of nanoparticle-bound hydrazones can undergo quantitative dynamic covalent exchange. The pseudomolecular nature of the NP system allows for the in situ characterization of surface-bound species, and real-time tracking of the exchange reactions. Furthermore, dynamic covalent exchange offers a simple approach for reversibly switching—and subtly tuning—NP properties such as solvophilicity. Publisher PDF

Hydrolysis of germanosilicate zeolites with the IWW structure shows two different outcomes depending on the composition of the starting materials. Ge-rich IWW (Si/Ge=3.1) is disassembled into a layered material (IPC-5P), which can be reassembled into an almost pure silica IWW on treatment with diethoxydimethylsilane. Ge-poor IWW (Si/Ge=6.4) is not completely disassembled on hydrolysis, but retains some 3D connectivity. This structure can be reassembled into IWW by incorporation of Al to fill the defects left when the Ge is removed., Angewandte Chemie, 53 (27), ISSN:1521-3757, ISSN:0044-8249

H.B. acknowledges the generous financial support provided by an ERC Advanced Grant. The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of sub-valent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. While carbon is too electronegative to affect the reduction of elements of lower relative electronegativity, the highly reducing nature of the B=B double bond enables reactions with Se0 and Te0. The capacity of multiple bonds between boron to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions. Postprint