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[reaction: see text] Grubbs catalyst, Cl2(Cy3P)2Ru=CHPh, was found to catalyze the cross-metathesis of monosubstituted allenes to 1,3-disubstituted allenes in varying yields. 相似文献
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(+/-)-4,12-Dihydroxy[2.2]paracyclophane [(+/-)-PHANOL] is readily prepared from [2.2]paracyclophane by an improved synthetic protocol. Enzymatic kinetic resolution of its bis-acetate proceeds with good enantioselection. Separation, hydrolysis, and recrystallization provides both enantiomers of PHANOL in high enantiopurity. 相似文献
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Synthesis,Characterisation and Reactivity of Copper(I) Amide Complexes and Studies on Their Role in the Modified Ullmann Amination Reaction
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Simon Sung Dr. D. Christopher Braddock Prof. Alan Armstrong Dr. Colin Brennan Dr. David Sale Dr. Andrew J. P. White Dr. Robert P. Davies 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7179-7192
A series of copper(I) alkylamide complexes have been synthesised; copper(I) dicyclohexylamide ( 1 ), copper(I) 2,2,6,6‐tetramethylpiperidide ( 2 ), copper(I) pyrrolidide ( 3 ), copper(I) piperidide ( 4 ), and copper(I) benzylamide ( 5 ). Their solid‐state structures and structures in [D6]benzene solution are characterised, with the aggregation state in solution determined by a combination of DOSY NMR spectroscopy and DFT calculations. Complexes 1 , 2 and 4 are shown to exist as tetramers in the solid state by X‐ray crystallography. In [D6]benzene solution, complexes 1 , 2 and 5 were found by using 1H DOSY NMR to exist in rapid equilibrium between aggregates with average aggregation numbers of 2.5, 2.4 and 3.3, respectively, at 0.05 M concentration. Conversely, distinct trimeric, tetrameric and pentameric forms of 3 and 4 were distinguishable by one‐dimensional 1H and 1H DOSY NMR spectroscopy. Complexes 3 – 5 are found to react stoichiometrically with iodobenzene, in the presence or absence of 1,10‐phenanthroline as an ancillary ligand, to give arylamine products indicative of their role as potential intermediates in the modified Ullmann reaction. The role of phenanthroline has also been explored both in the stoichiometric reaction and in the catalytic Ullmann protocol. 相似文献
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J. -Y. Parlange R. D. Braddock 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1980,31(5):653-656
Summary A first integral of the diffusion equation exists for similarity solutions when the diffusivity obeys a power or exponential law. Structure of the solutions in both cases and connection to an optimization result are discussed for an arbitrary diffusivity.
Résumé Une intégrale première de l'équation de diffusion existe pour les solutions similaires quand le coefficient de diffusion obéit une loi de puissance arbitraire ou une loi exponentielle. La structure des solutions est discutée dans les deux cas ainsi que leur relation avec les résultats d'optimisation pour une diffusion arbitraire.相似文献
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J. -Y. Parlange W. L. Hogarth C. Fuentes J. Sprintall R. Haverkamp D. Elrick M. B. Parlange R. D. Braddock D. A. Lockington 《Transport in Porous Media》1994,17(3):249-256
The interaction of a wetting front with an impervious surface can be described very easily in the early stages of interaction by using a superposition principle. After the time when the superposition principle fails to describe the interaction properly, two flow regimes are analysed. For most of the interaction the profile is only affected by the impervious surface near that surface and in particular the inflow into the soil layer is unchanged. Then, only at the very end of the process is the inflow decreasing because of the impervious surface. 相似文献
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Braddock DC Cansell G Hermitage SA White AJ 《Chemical communications (Cambridge, England)》2006,(13):1442-1444
Bromoiodinanes--conveniently and directly prepared from iodobenzenecarbinols and N-bromosuccinimide, and characterised for the first time crystallographically--act as electrophilic bromine donors. 相似文献
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Braddock DC Bhuva R Millan DS Pérez-Fuertes Y Roberts CA Sheppard RN Solanki S Stokes ES White AJ 《Organic letters》2007,9(3):445-448
[reaction: see text] Sharpless asymmetric dihydroxylation was regioselective for the trans olefin in an E vs Z vs terminal triene substrate. To test a biosynthetic hypothesis, the resulting diol underwent diastereoselective bromoetherification to provide the des-chloro core of marine natural products obtusallenes II and IV. Alternatively, anionic chloride ring-opening of a Z-beta,gamma-unsaturated epoxide gave separable regioisomeric halohydrins. Bromoetherification gave the fully elaborated core of obtusallenes II and IV with all of the relative stereochemistry correctly set. 相似文献
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D. Christopher Braddock King Kuok Hii John M. Brown 《Angewandte Chemie (International ed. in English)》1998,37(12):1720-1723
Different cyclization products are formed with different Lewis acids in the ene cyclization of 5-hexenals (see scheme on the right; a: methylaluminum bisphenoxide, b: Me2AlCl, c: Sc(OSO2CF3)3). This is not surprising, but it is gratifying that these result can be rationalized with an internally consistent model. 相似文献