Efficient syntheses of benzyl andn-octyl [1,3-13C2]acetoacetates, and their application to syntheses of13C-labelled pyrrole and13C-labelled hymecromone
Syntheses, Structures, and Binding Constants of Cyclic Ether and Thioether Adducts of Soluble Cadmium(II) Carboxylates. Intermediates in the Homopolymerization of Oxiranes and Thiiranes and in Carbon Dioxide Coupling Processes
作者:Donald J. Darensbourg、Sharon A. Niezgoda、Matthew W. Holtcamp、Jennifer D. Draper、Joseph H. Reibenspies
DOI:10.1021/ic9701120
日期:1997.5.1
demonstrated by (113)Cd NMR. A quantitative assessment of the binding of these base adducts of eta(3)-HB(3-Phpz)(3)Cd(acetate) was determined by measuring the temperature dependence of the equilibrium constants for the five- and six-coordinate derivatives. The presence of one sharp (113)Cd resonance in this equilibrium mixture is indicative of rapid intermolecular exchange between the five- and six-coordinate
Mechanism of the Iron(II)-Catalyzed Hydrosilylation of Ketones: Activation of Iron Carboxylate Precatalysts and Reaction Pathways of the Active Catalyst
作者:Tim Bleith、Lutz H. Gade
DOI:10.1021/jacs.6b02173
日期:2016.4.13
isolation of the catalytically active alkoxide intermediate, and DFT-modeling of the whole reaction sequence. The proposed reaction mechanism is characterized by a rate-determining σ-bond metathesis of an alkoxide complex with the silane, subsequent coordination of the ketone to the iron hydride complex, and insertion of the ketone into the Fe-H bond to regenerate the alkoxide complex.
Biosynthesis of porphyrins and related macrocycles. Part 16. Proof that the single intramolecular rearrangement leading to natural porphyrins (type-III) occurs at the tetrapyrrole level
作者:Alan R. Battersby、Christopher J. R. Fookes、Mary J. Meegan、Edward McDonald、Hanns K. W. Wurziger
DOI:10.1039/p19810002786
日期:——
established earlier is thus proved to take place at the tetrapyrole level. Synthesis of singly 13C-labelled bilane (2) followed by its enzymic conversion into uro'gen-III serves to register each of the pyrrole rings of the product relative to the initial bilane. Finally, methods for synthesis of the bilane are developed in two different doubly 13C-labelled forms to allow the following key points to be established
未重排的氨基甲基胆烷(2)是通过合理的途径合成的,并被脱氨酶和辅酶合成,并协同作用转化为uro'gen-III(3)。因此证明了较早建立的单个重排步骤发生在四吡咯水平。单独合成13 C标记的胆烷(2),然后将其酶促转化为uro'gen-III,相对于初始胆烷来说,该产物的每个吡咯环均具有配准作用。最后,以两种不同的双13 C标记形式开发了合成胆烷的方法,从而可以通过13 C nmr光谱学在很大程度上确定以下关键点:(a)随着胆烷体系被转化为尿根-III,发生了末端环D的分子内重排,并且(b)线性四吡咯被完整地转化为尿根-III。
Synthesis of [1-13C]-para-xylene and [2-13C]-para-xylene
Amide <i>Cis−Trans</i> Isomerization in Aqueous Solutions of Methyl <i>N</i>-Formyl-<scp>d</scp>-glucosaminides and Methyl <i>N</i>-Acetyl-<scp>d</scp>-glucosaminides: Chemical Equilibria and Exchange Kinetics
作者:Xiaosong Hu、Wenhui Zhang、Ian Carmichael、Anthony S. Serianni
DOI:10.1021/ja9086787
日期:2010.4.7
on anomeric configuration, with solutions of alpha-anomers containing less cis amide than those of beta-anomers. Confirmation of the presence of cis amide in MeGlcNAc solutions derived from quantitative (13)C saturation transfer measurements of CTI rate constants as a function of solution temperature, yielding activation parameters E(act), DeltaG degrees (), DeltaH degrees (), and DeltaS degrees ()