- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- Taylor, Nicholas P.,Gonzalez, Jorge A.,Nichol, Gary S.,García-Domínguez, Andrés,Leach, Andrew G.,Lloyd-Jones, Guy C.
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supporting information
p. 721 - 729
(2022/01/04)
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- Rhodium-Catalyzed Double Alkyl-Oxygen Bond Cleavage: An Alkyl Transfer Reaction from Bis/Tris(o-alkyloxyphenyl)phosphine to Aryl Acids
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An unprecedented rhodium-catalyzed selective cleavage of double alkyl-oxygen bonds of bis/tris(o-alkyloxyphenyl)phosphine has been realized, in which P atom functions as a directing group and simple aryl acids are the methyl group acceptor to provide methyl esters and a quaternary phosphonium salt. The preliminary mechanism was investigated via an 18O labeling experiment and stoichiometric reaction between a Rh-A crystal and an aromatic acid.
- Zhou, Hui,Zhang, Jinlong,Yang, Huameng,Xia, Chungu,Jiang, Gaoxi
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supporting information
p. 3406 - 3412
(2016/10/21)
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- A phosphine-mediated stereocontrolled synthesis of Z-enediynes by a vicinal dialkynylation of ethynylphosphonium salts
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Z-Enediynes are prepared by a vicinal dialkynylation of triaryl(arylethynyl)phosphonium cations. The method, which proceeds under mild transition metal-free conditions, can be conducted on multigram scale as a one-pot, phosphine-mediated synthetic cycle giving enediyne products with excellent control of configuration.
- Reichl, Kyle D.,Radosevich, Alexander T.
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supporting information
p. 9302 - 9305
(2014/08/05)
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- Preparation of N-phenyl-(S)-prolinol-derived P,N-ligands and their application in Pd-catalyzed asymmetric allylic alkylation
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Several NPN-type ligands bearing two chiral pyrrolidinyl groups derived from N-phenyl-(S)-prolinol were prepared by two synthetic methods. Their palladium-complex-catalyzed asymmetric allylic alkylation of malonates with 1,3-diphenyl 2-propenyl acetate delivered the products with good to high enantioselectivities (84-97% ee), including an optically active fluorine-containing compound.
- Jiang, Biao,Huang, Zuo-Gang,Cheng, Ke-Jun
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p. 942 - 951
(2007/10/03)
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- PHOSPHORORGANISCHE VERBINDUNGEN 101. TERTIAERE PHOSPHINE MIT ORTHOALKOXYPHENYL-GRUPPEN. Synthese und Eigenschaften
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Alkylphenylethers, ortho-lithiated in good yields, are transformed according to scheme (1) to the triarylphosphines ArPPh2, Ar2PPh and Ar3P (Ar contains in all cases an ortho-alkoxy group) (Table 1.).Hydroquinonedialkylethers can be lithiated twice, forming the compounds 102 and 103.Table 2 summarizes some arylalkylethers (71 - 101) which were lithiated; table 7 presents 12 new arylalkylethers.The syntheses of triarylphosphines with one or two bulky groups (105 - 110) and of triarylphosphines with one or two 3,4-dialkoxyphenyl groups (111 - 114) are reported.The 31P-spectra of the compounds prepared are discussed with respect to the validity of the Tolman-rule.
- Horner, L.,Simons, G.
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p. 189 - 210
(2007/10/02)
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- Chemistry of crown ethers. Part XXII. Synthesis and complexing properties of monophospha-crown ethers
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The synthesis of phenyl- and tert-butyl-phosphadibenzo-18-crown-6 and phenyl-phosphadibenzo-21-crown-7 is described.The complexation of alkali metal cations and rhodium(I) by these macrocycles and their phosphine oxides has been studied by NMR methods.The
- Zon, A. van,Torny, G. J.,Frijns, J. H. G.
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p. 326 - 330
(2007/10/02)
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