4747-13-1Relevant articles and documents
Photoinduced Cross-Coupling of Aryl Iodides with Alkenes
Liu, Yuliang,Li, Haoyu,Chiba, Shunsuke
supporting information, p. 427 - 432 (2021/01/26)
A protocol for photoinduced cross-coupling of aryl iodides having polar π-functional groups or elongated π-conjugation with alkenes has been developed. The radical cascade mechanism involving generation of aryl radicals via C-I bond homolysis of photoexcited aryl iodides and their subsequent addition to alkenes is proposed. The method enables iodide-selective cross-coupling over other halogen leaving groups with functional group compatibility on both arene and alkene motifs.
Ketal derivative of drug and preparation method thereof, pharmaceutical composition and application
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Paragraph 0139-0141, (2021/02/10)
The invention relates to a ketal derivative of a drug, and a preparation method thereof, a pharmaceutical composition and application. The ketal derivative comprises a compound as shown in a formula (I) (See the specification), a racemate, a stereoisomer, a tautomer or pharmaceutically acceptable salts thereof. The ketal derivative provided by the invention can significantly improve the physical,chemical and/or pharmaceutical properties of an original starting drug.
Dual-gold(I)-generated trifluoromethylation of terminal alkynes with Togni's reagent
Siah, Huey-San Melanie,Fiksdahl, Anne
supporting information, p. 24 - 33 (2017/03/10)
The interaction of a Au(I) catalyst (JohnPhosAu(I)-MeCN/SbF6) and the Togni's reagent 1, as a source of electrophilic trifluoromethyl group, has been studied in order to develop gold-catalysed alkyne trifluoromethylation reactions. Alkyne-CF3products were prepared in moderate yields (up to 46%) by electrophilic trifluoromethylation of terminal arylalkynes with Togni's reagent 1 in the presence of sub-stoichiometric amounts of gold catalyst (25%). The proposed addition-elimination reaction mechanism proceeds through a Au-Togni Reagent complex with a linear Togni Reagent-O-Au(I)-P-(phosphane) coordination mode (X-ray analysis). Alkyne deprotonation gives rapid formation of protonated Togni Reagent and a σ,π-acetylide dual-Au complex, confirmed by X-ray analysis. It was shown that the σ,π-dual-Au complex activates for trifluoromethylation, most likely by transfer of a [LAu]+fragment to the alkyne substrate. The resulting reactive π-Au+-alkyne intermediate probably undergoes O-/CF3-addition of Togni Reagent, and final elimination of Togni alcohol gives the alkyne-CF3product.
Synthesis of acid-sensitive connection unit and its use in DNA sequencing
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Paragraph 0263-0267, (2018/02/04)
The invention discloses a synthesis method of an acid sensitive connection unit, and a use of the acid sensitive connection unit in DNA sequencing. The structural formula of the acid sensitive connection unit is shown in the specification. In the structural formula, R is NH2 or N3, m is an integer from 0 to 44, and n is an integer from 0 to 44; R1 and R2 respectively represent an aliphatic alkyl group, or R1 and R2 respectively represent an aromatic derivative, or R1 is a phenyl group, a naphthyl group, a phenyl derivative or a naphthyl derivative, and R2 is an aliphatic alkyl group or hydrogen; or R2 is a phenyl group, naphthyl group, a phenyl derivative or a naphthyl derivative, R1 is an aliphatic alkyl group or hydrogen, or R1 and R2 form a cyclohexyl group, a cyclopentyl group or a cyclobutyl group. A reversible terminal obtained through connecting the acid sensitive connection unit with nucleotide and fluorescein can be used in DNA sequencing-by-synthesis. The reversible terminal can be used in the DNA sequencing; and raw materials required by the synthesis method are simple and can be easily obtained, and the synthesis process is a routine chemical reaction, so the method can realize large scale popularization use.
Coupling Reaction of Enol Derivatives with Silyl Ketene Acetals Catalyzed by Gallium Trihalides
Nishimoto, Yoshihiro,Kita, Yuji,Ueda, Hiroki,Imaoka, Hiroto,Chiba, Kouji,Yasuda, Makoto,Baba, Akio
supporting information, p. 11837 - 11845 (2016/08/05)
A cross-coupling reaction between enol derivatives and silyl ketene acetals catalyzed by GaBr3took place to give the corresponding α-alkenyl esters. GaBr3showed the most effective catalytic ability, whereas other metal salts such as BF3?OEt2, AlCl3, PdCl2, and lanthanide triflates were not effective. Various types of enol ethers and vinyl carboxylates as enol derivatives are amenable to this coupling. The scope of the reaction with silyl ketene acetals was also broad. We successfully observed an alkylgallium intermediate by using NMR spectroscopy, suggesting a mechanism involving anti-carbogallation among GaBr3, an enol derivative, and a silyl ketene acetal, followed by syn-β-alkoxy elimination from the alkylgallium. Based on kinetic studies, the turnover-limiting step of the reaction using a vinyl ether and a vinyl carboxylate involved syn-β-alkoxy elimination and anti-carbogallation, respectively. Therefore, the leaving group had a significant effect on the progress of the reaction. Theoretical calculations analysis suggest that the moderate Lewis acidity of gallium would contribute to a flexible conformational change of the alkylgallium intermediate and to the cleavage of the carbon?oxygen bond in the β-alkoxy elimination process, which is the turnover-limiting step in the reaction between a vinyl ether and a silyl ketene acetal.
Reactions of Cp2TiMe2 with ferrocene and (n5-Cp)Co(n4-C4Ph4) derived esters and amides: A new route for 1-methylvinyl and methyl ketone derived metal sandwich compounds
Singh, Jatinder,Ghosh, Sanjib,Deb, Mayukh,Elias, Anil J.
, p. 85 - 91 (2016/07/06)
Reactions of Cp2TiMe2, with the ester derivatives of organometallic sandwich compounds (n5-RC5H4)Fe(n5-C5H5) and (n5-RC5H4)Co(n4-C4Ph4) (R=ester groups) gave products having R=C(CH2)Me, instead of the expected vinyl ethers indicating conversion of the ester units by Cp2TiMe2 to methyl ketones followed by methylenation. A reaction of Cp2TiMe2 with the diester (n5-RC5H4)Co(n4-C4Ph3R)(R=C(O)OMe) also gave similar results. The study has also been successfully extended to metal sandwich derived amides, thio and seleno esters. By controlling the amount of Cp2TiMe2, the reactions were also stopped at the methyl ketone stage and the methyl ketones were isolated in good yields and characterized. The method provides an easy and direct access to convert organometallic sandwich derived esters and related compounds to 1-methylvinyl derived products.
Acyl-carbene and methyl-carbene coupling via migratory insertion in palladium complexes
Meana, Isabel,Albeniz, Ana C.,Espinet, Pablo
, p. 5494 - 5499 (2012/11/07)
The migratory insertion reaction of a carbene into a palladium-acyl bond has been observed both for monoaminocarbenes and for methoxycarbenes. The acyl derivative [PdCl(COMe){C(NEt2)Ph}(PPh3)] undergoes an acyl-carbene coupling, leading to the enolate-type complex [PdCl{C(COMe) (NEt2)Ph}(PPh3)]2 (2). This complex decomposes either by reductive elimination to give the iminium salt or by protonation of the enolate to give a ketoamine. In a similar fashion, the reaction of [Pd 2(μ-Cl)2(COMe)2(SMe2) 2] with [W(CO)5{C(OMe)Ph}] leads to an undetected palladium enolate that, after protonation, is stabilized by coordination to palladium ([PdCl2{(OH)MeC=CPh(OMe}(SMe2)], 8). The reaction of [Pd2(μ-Cl)2Me2(SMe 2)2] with [W(CO)5{C(OMe)-Ph}] leads to the migratory insertion of the carbene into the Pd-methyl group to give an alkyl palladium complex. The transfer of CO from tungsten, followed by insertion into the Pd-Me group, also occurs. This leads to the formation of a Pd-COMe group, which also undergoes migratory insertion of the carbene fragment. These results support that migratory insertion is a key C-C coupling step, as proposed for the new Pd-catalyzed transformations that use carbene precursors.
Gallium tribromide catalyzed coupling reaction of alkenyl ethers with ketene silyl acetals
Nishimoto, Yoshihiro,Ueda, Hiroki,Yasuda, Makoto,Baba, Akio
supporting information; experimental part, p. 8073 - 8076 (2012/08/29)
A 'Ga'llant couple: The α-alkenylation of esters was accomplished by GaBr3-catalyzed coupling between alkenyl ethers and ketene silyl acetals. In this reaction system, various alkenyl ethers, including those with vinyl and substituted alkenyl groups, were applicable, and the scope of applicable ketene silyl acetals was sufficiently broad. The mechanism is also discussed. Copyright
A marcus treatment of rate constants for protonation of ring-substituted α-methoxystyrenes: Intrinsic reaction barriers and the shape of the reaction coordinate
Richard, John P.,Williams, Kathleen B.
, p. 6952 - 6961 (2008/02/09)
Rate and equilibrium constants were determined for protonation of ring-substituted α-methoxystyrenes by hydronium ion and by carboxylic acids to form the corresponding ring-substituted α-methyl α-methoxybenzyl carbocations at 25°C and I = 1.0 (KCl). The thermodynamic barrier to carbocation formation increases by 14.5 kcal/mol as the phenyl ring substituent(s) is changed from 4-MeO- to 3,5-di-NO2-, and as the carboxylic acid is changed from dichloroacetic to acetic acid. The Bronsted coefficient a for protonation by carboxylic acids increases from 0.67 to 0.77 over this range of phenyl ring substituents, and the Bronsted coefficient β for proton transfer increases from 0.63 to 0.69 as the carboxylic acid is changed from dichloroacetic to acetic acid. The change in these Bronsted coefficients with changing reaction driving force, ?α/?ΔG°av = ?β/ ?ΔG°av = 1/8Λ = 0.011, is used to calculate a Marcus intrinsic reaction barrier of Λ = 11 kcal/mol which is close to the barrier of 13 kcal/mol for thermoneutral proton transfer between this series of acids and bases. The value of α = 0.66 for thermoneutral proton transfer is greater than α = 0.50 required by a reaction that follows the Marcus equation. This elevated value of β may be due to an asymmetry in the reaction coordinate that arises from the difference in the intrinsic barriers for proton transfer at the oxygen acid reactant and resonance-stabilized carbon acid product.
A new and highly effective organometallic approach to 1,2-dehalogenations and related reactions
Azzena, Ugo,Pittalis, Mario,Dettori, Giovanna,Pisano, Luisa,Azara, Emanuela
, p. 3892 - 3900 (2008/03/12)
We investigated the reductive elimination of several functionalized and non-functionalized vic-dibromides with 1,2-diphenyl-, 1,1,2,2-tetraphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodioethane. The reaction, involving some of the less expensive organic and inorganic reagents, proceeds under mild conditions, and is tolerant of a variety of functional groups. Extension of this procedure to similar 1,2-disubstituted compounds was also investigated. Reductive eliminations run on stereochemical probe compounds strongly suggest that this reaction proceeds via a "single electron" reductive elimination reaction pathway.
