- Dichloroborane-dioxane: An exceptional reagent for the preparation of alkenyl- and alkylboronic acids
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Terminal alkynes and alkenes were conveniently hydroborated to the corresponding alkenyl- and alkyldichloroboranes using dichloroborane-dioxane in dichloromethane. These dichloroboranes were hydrolyzed by water to the corresponding alkenyl- and alkylboron
- Josyula, Kanth V. B.,Gao, Peng,Hewitt, Chris
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Read Online
- Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds
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The isolation and reactivities of two pentacoordinated phosphorus–tetracoordinated boron bonded compounds were explored. A highly Lewis acidic boron reagent and electron-withdrawing ligand system were required to form the pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl-trihydroborate, gave a THF stabilised phosphoranyl-borane intermediate upon a single hydride abstraction in THF. This compound could undergo a unique rearrangement, which involved a two-fold ring expansion, to give a fused bicyclic compound or it could act as a mono-hydroboration reagent. The hydroboration reactivity of the intermediate was found to be higher towards alkynes vs. alkenes, with good to moderate regioselectivity towards the terminal carbon. The second compound, a phosphoranyl-triarylborate, was found to have different reactivity as it was highly stable towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure.
- Havare, Nizam,Kano, Naokazu,Morokuma, Keiji,O'Brien, Nathan J.,Ramozzi, Romain,Uematsu, Ryohei
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- Environmentally responsible, safe, and chemoselective catalytic hydrogenation of olefins: ppm level Pd catalysis in recyclable water at room temperature
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Textbook catalytic hydrogenations are typically presented as reactions done in organic solvents and oftentimes under varying pressures of hydrogen using specialized equipment. Catalysts new and old are all used under similar conditions that no longer reflect the times. By definition, such reactions are both environmentally irresponsible and dangerous, especially at industrial scales. We now report on a general method for chemoselective and safe hydrogenation of olefins in water using ppm loadings of palladium from commercially available, inexpensive, and recyclable Pd/C, together with hydrogen gas utilized at 1 atmosphere. A variety of alkenes is amenable to reduction, including terminal, highly substituted internal, and variously conjugated arrays. In most cases, only 500 ppm of heterogeneous Pd/C is sufficient, enabled by micellar catalysis used in recyclable water at room temperature. Comparison with several newly introduced catalysts featuring base metals illustrates the superiority of chemistry in water.
- Gallou, Fabrice,Gao, Eugene S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
p. 6055 - 6061
(2020/10/14)
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- An efficient method for the hydrolysis of potassium organotrifluoroborates promoted by montmorillonite K10
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An efficient and non-expensive method for conversion of diverse potassium organotrifluoroborates to their corresponding boronic acids promoted by montmorillonite K10 using water as the reaction solvent is described. Further interconversion of potassium organotrifluoroborates to their corresponding boronic esters, via boronic acid intermediates was also successfully accomplished. The products were obtained in good yields, being the rate of hydrolysis influenced by the type of substituent present in the boronic acid.
- Silva, Renato L.,Santos, Cosme S.,Santos, Jonh A. M.,Oliveira, Roberta A.,Menezes, Paulo H.,Freitas, Juliano C. R.
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p. 1777 - 1785
(2018/09/04)
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- Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis
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The alkynylbenziodoxole derivatives are recently developed alkynylation reagents in organic synthesis, which demonstrate excellent radical alkynylation reactivity in photoredox catalysis reactions. Herein we report the synthesis of alkynylbenziodoxole derivatives with difluoro, monofluoro, monomethoxy, and dimethoxy substitution on the benziodoxole moiety, and investigated their radical alkynylation reactivity for the first time. A series of mechanistic experiments were conducted to study the radical acceptor and oxidative quencher reactivity of alkynylbenziodoxoles, in which unsubstituted alkynylbenziodoxoles played balancing roles in both processes, while electron-rich benziodoxole derivatives demonstrate synthetic advantages in some cases.
- Pan, Yue,Jia, Kunfang,Chen, Yali,Chen, Yiyun
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supporting information
p. 1215 - 1221
(2018/06/13)
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- Amino acid-promoted C-H alkylation with alkylboronic acids using a removable directing group
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Palladium-catalyzed C-H alkylation reaction with alkylboronic acids has successfully been developed using a removable pyridyldiisopropylsilyl directing group. The amino acid played a crucial role as a ligand in the reaction. The alkylation protocol is also applicable to the coupling of C(sp3)-H bonds with alkylboronic acids.
- Zhang, Yanghui,Zhang, Yu,Jiang, Hang,Chen, Dushen
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p. 4585 - 4589
(2016/06/09)
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- NOVEL BORONATE ETHER INTERMEDIATES FOR PREPARATION OF STATIN COMPOUNDS, PREPARATION METHOD THEREOF AND PREPARATION METHOD OF STATIN COMPOUNDS USING SAID BORONATE ETHER INTERMEDIATES
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The present invention relates to a novel boronate ether compound and a manufacturing method thereof. Provided is a novel boronate ether compound denoted by chemical formula 1 or chemical formula 2 as an intermediate to manufacture rosuvastatin calcium or pitavastatin calcium which is one of the statin based compounds to reduce the level of low density lipoprotein (LDL) of patients who have hyperlipidemia and are accordingly cured, and statin compounds with high purity are easily manufactured and separated compared with an existing patented method and are easily provided in a method of mass production.
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Paragraph 0113-0115
(2017/01/02)
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- Reactions of CF3-substituted boranes with α-diazocarbonyl compounds
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Boranes substituted with a CF3-group can be generated from methyl boronic esters RB(OMe)2 and Me3SiCF3/KF followed by treatment with Me3SiCl. These boranes are stable only in coordinating solvents, and due to the increased Lewis acidity of boron, react rapidly with α-diazocarbonyl compounds to give the products of transfer of the organic group from boron. Alkyl, aryl, vinyl, and alkynyl boronic esters can be used in this reaction.
- Elkin, Pavel K.,Levin, Vitalij V.,Dilman, Alexander D.,Struchkova, Marina I.,Belyakov, Pavel A.,Arkhipov, Dmitry E.,Korlyukov, Alexander A.,Tartakovsky, Vladimir A.
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supporting information; experimental part
p. 5259 - 5263
(2011/10/31)
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- Observations on the deprotection of pinanediol and pinacol boronate esters via fluorinated intermediates
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(Chemical Equation Presented) Methods for the deprotection of pinanediol and pinacol esters of various boronic acids via fluoroborane intermediates were evaluated. Treatment of the boronate esters with potassium hydrogen difluoride normally gives trifluor
- Inglis, Steven R.,Woon, Esther C. Y.,Thompson, Amber L.,Schofield, Christopher J.
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supporting information; experimental part
p. 468 - 471
(2010/03/25)
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- Thermal and microwave hydrolysis of organotrifluoroborates mediated by alumina
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Hydrolysis of organotrifluoroborates to the corresponding organoboronic acids is readily achieved under either thermal or microwave conditions in the presence of alumina. The organoboronic acid products are obtained in good to excellent yields with essent
- Kabalka, George W.,Coltuclu, Vitali
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experimental part
p. 6271 - 6272
(2010/01/11)
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- Lithium aminoborohydrides 16. Synthesis and reactions of monomeric and dimeric aminoboranes
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(Chemical Equation Presented) Aminoboranes are synthesized in situ from the reaction of the corresponding lithium aminoborohydrides (LABs) with methyl iodide, trimethylsilylchloride (TMS-Cl), or benzyl chloride under ambient conditions. In hexanes, the reaction using methyl iodide produces aminoborane and methane, whereas in tetrahydrofuran (THF) this reaction produces amine-boranes (R1R2HN:BH3) as the major product. The reaction of iPr-LAB with TMS-Cl or benzyl chloride yields exclusively diisopropylaminoborane [BH2-N(iPr)2] in THF as well as in hexanes at 25°C. Diisopropylaminoborane and dicyclohexylaminoborane exist as monomers due to the steric requirement of the alkyl group. All other aminoboranes studied are not sterically hindered enough to be monomers in solution, but instead exist as a mixture of monomers and dimers. The dimers are four-membered rings formed through boron-nitrogen coordination. In general aminoboranes are not hydroborating reagents. However, monomelic aminoboranes, such as BH2-N(iPr)2, can reduce nitriles in the presence of catalytic amounts of LiBH4. This BH 2-N(iPr)2/LiBH4 reducing system also reduces ketones, aldehydes, and esters. Diisopropylaminoborane, synthesized from iPr-LAB, can be converted into boronic acids by a palladium-catalyzed reaction with aryl bromides. Aminoboranes derived from heterocyclic amines, such as pyrrole, pyrazole, and imidazole, can be prepared by the direct reaction of borane/tetrahydrofuran (BH3:THF) with these heterocyclic amines. It has been reported that pyrazole-derived aminoborane forms a six-membered dimer through boron-nitrogen coordination, where as, pyrrolylborane forms a dimer through boron-hydrogen coordination. Pyrrolylborane monohydroborates both alkenes and alkynes at ambient temperatures. Hydroboration of styrene with pyrrolylborane followed by hydrolysis gives the corresponding boronic acid, 2-phenylethylboronic acid, in 40% yield. Similarly phenylacetylene is mono-hydroborated by pyrrolylborane, to give E-2-phenylethenylboronic acid in 50% yield.
- Pasumansky, Lubov,Haddenham, Dustin,Clary, Jacob W.,Fisher, Gary B.,Goralski, Christian T.,Singaram, Bakthan
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p. 1898 - 1905
(2008/09/18)
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- ATORVASTATIN INTERMEDIATES AND METHOD FOR PRODUCING THE SAME
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The present invention provides a novel boronate ether of Formula 1 useful for the synthesis of atorvastatin, and a preparation method thereof.
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Page/Page column 7
(2008/12/08)
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- P1 Phenethyl peptide boronic acid inhibitors of HCV NS3 protease
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A series of peptide boronic acids containing extended, hydrophobic P1 residues was prepared to probe the shallow, hydrophobic S1 region of HCV NS3 protease. The p-trifluoromethylphenethyl P1 substituent was identified as optimal with respect to inhibitor potency for NS3 and selectivity against elastase and chymotrypsin.
- Priestley,De Lucca, Indawati,Ghavimi, Bahman,Erickson-Viitanen, Susan,Decicco, Carl P.
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p. 3199 - 3202
(2007/10/03)
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