- Insight into Copper Catalysis: In Situ Formed Nano Cu2O in Suzuki-Miyaura Cross-Coupling of Aryl/Indolyl Boronates
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A ligand-free copper catalyzed Suzuki-Miyaura coupling of 3,5-diiodopyridine with aryl and indole boronates has been explored in good to excellent yields. In situ generation of nano-Cu2O from CuCl2 under the reaction conditions has been discovered for the first time. The generality of the reaction was further demonstrated by the arylation of 5-iodopyrimidine, iodopyridines, iodobenzenes, and diiodobenzenes and resulted in good to moderate yields. Moreover, bisindole alkaloid Scalaridine A has been successfully synthesized in 60% overall yield.
- Ranjani, Ganapathy,Nagarajan, Rajagopal
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supporting information
p. 3974 - 3977
(2017/08/14)
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- COMPOUND LIBRARY PREPARATION PROCESS BASED ON EXCHANGE REACTION BETWEEN DIFERENTLY SUBSTITUTED DIOXABOROLANES OR DIOXABORINANES
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The present invention relates to the preparation of a compound library comprising the following steps: ? i. Having available at least two different compounds each comprising at least a dioxaborolane or dioxaborinane ring. In said compounds: ? -the boron of the dioxaborolane or dioxaborinane ring is directly linked to a carbon atom of a hydrocarbon radical; ? -at least one carbon atom of the dioxaborolane or dioxaborinane ring is monosubstituted, the other carbon atoms are non- substituted or monosubstituted; ? -in at least two compounds, the hydrocarbon radicals linked to the boron are different; ? - in at least two compounds, either the dioxaborolane or dioxaborinane ring carbon atoms are differently substituted and/ or the size varies. ? ii. Reacting the compounds of step (i.) and forming, by a boronic ester metathesis reaction, the library comprising at least four different compounds. The present invention also relates to a compound library. Illustrative for the present invention is the following figure:
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Page/Page column 31-32
(2017/03/21)
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- Stability of boronic esters - Structural effects on the relative rates of transesterification of 2-(phenyl)-1,3,2-dioxaborolane
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Relative rates of reaction of the achiral cyclic phenylboronic ester 2-(phenyl)-1,3,2-dioxaborolane with a wide variety of structurally modified diols, have been studied to understand the factors influencing the relative stabilities of boronic esters. It is found that the alkyl substituents on the α-carbons of diols slow down the transesterification, but produce thermodynamically more stable boronic ester. Six-membered boronic esters are thermodynamically more stable than their corresponding five-membered analogs. Amongst cyclic 1,2-diols, cis-1,2-cyclopentanediol displaces ethylene glycol instantaneously whereas trans-1,2-cyclopentanediol is totally unreactive, which suggests that the cis-stereochemistry of the 1,2-diol is a prerequisite for transesterification. Among the 1,5-diols, diethanolamine displaces ethylene glycol quite rapidly forming a more stable bicyclic chelate in which nitrogen is attached to boron by a coordinating bond (as evident by 11B NMR spectroscopy). The oxygen atom of di(ethylene glycol) and the sulfur atom of 2,2′-thiodiethanol do not assist in displacing the ethylene glycol from their boronic esters.
- Roy, Chandra D.,Brown, Herbert C.
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p. 784 - 790
(2007/10/03)
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- On the Chemistry of Binding Sites, IV: On an Unusual Increase in Reactivity of Arylboronic Acids by Neighbouring Groups
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ortho-Substituted arylboronic acids were investigated for subsequent use as binding sites.The introduction of different aminomethyl groupings resulted in a strong acceleration of the adjustment of the equilibrium of the esterification with diols as well as the transesterification of such esters.The rate of the transesterification was investigated with suitable systems by dynamic NMR spectroscopy.According to an estimation the enhancement compared with the unsubstituted compound amounted to 8 orders of magnitude.Most of the compounds showed a strong B-N-coordination as was shown by 11B NMR.There proved, however, to be no simple relation between B-N-coordination and the catalytic activity of the neighbouring groups.Neighbouring groups containing oxygen, sulfur, and fluorine showed no enhancement of esterification or transesterification and no coordination with the boron.
- Lauer, Manfred,Boehnke, Helmut,Grotstollen, Reiner,Salehnia, Mohammad,Wulff, Guenter
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p. 246 - 260
(2007/10/02)
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- Diol lipids - Communication 27. Identification of C2-C4-diols in the form of cyclic esters of phenylboric acid by the method of combined gas chromatography and mass spectrometry
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1. A new method was proposed for the analysis of small quantities of C2-C4-diols, formed in the cleavage of lipids, based on combined gas-chromatography and mass spectrography of their phenylborate esters. 2. Phenylborate esters of d
- Batrakov,Panosyan,Ushakov,Rozynov,Bergel'son
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p. 1662 - 1668
(2007/10/10)
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