20609-08-9Relevant academic research and scientific papers
Asymmetric Hydroboration of Heteroaryl Ketones by Aluminum Catalysis
Lebedev, Yury,Polishchuk, Iuliia,Maity, Bholanath,Dinis Veloso Guerreiro, Miguel,Cavallo, Luigi,Rueping, Magnus
supporting information, p. 19415 - 19423 (2019/12/24)
A series of methyl aluminum complexes bearing chiral biphenol-type ligands were found to be highly active catalysts in the asymmetric reduction of heterocyclic ketones (S/C = 100-500, ee up to 99%). The protocol is suitable for a wide range of substrates and has a high tolerance to functional groups. The formed 2-heterocyclic-alcohols are valuable building blocks in drug discovery or can be used as ligands in asymmetric catalysis. Isolation and comprehensive characterization of the reaction intermediates support a catalysis cycle proposed by DFT calculations.
Chemoselective palladium-catalyzed deprotonative arylation/[1,2]-Wittig rearrangement of pyridylmethyl ethers
Gao, Feng,Kim, Byeong-Seon,Walsh, Patrick J.
, p. 976 - 983 (2016/02/05)
Control of chemoselectivity is one of the most challenging problems facing chemists and is particularly important in the synthesis of bioactive compounds and medications. Herein, the first highly chemoselective tandem C(sp3)-H arylation/[1,2]-Wittig rearrangement of pyridylmethyl ethers is presented. The efficient and operationally simple protocols enable generation of either arylation products or tandem arylation/[1,2]-Wittig rearrangement products with remarkable selectivity and good to excellent yields (60-99%). Choice of base, solvent, and reaction temperature play a pivotal role in tuning the reactivity of intermediates and controlling the relative rates of competing processes. The novel arylation step is catalyzed by a Pd(OAc)2/NIXANTPHOS-based system via a deprotonative cross-coupling process. The method provides rapid access to skeletally diverse aryl(pyridyl)methanol core structures, which are central components of several medications.
Rhodium Catalyzed Asymmetric Hydrogenation of 2-Pyridine Ketones
Yang, Hailong,Huo, Ningning,Yang, Ping,Pei, Hao,Lv, Hui,Zhang, Xumu
supporting information, p. 4144 - 4147 (2015/09/15)
Catalyzed by [Rh(COD)Binapine]BF4, the asymmetric hydrogenation of 2-pyridine ketones has been achieved with excellent enantioselectivities (enantiomeric excesses up to 99%) under mild conditions. This method is suitable for various kinds of 2-pyridine ketones and their derivatives. A number of enantiomerically pure chiral 2-pyridine-aryl/alkyl alcohols were prepared through hydrogenation, which can be used directly in organic synthesis.
1,2-Diarylethanols by alternative regioselective reductive ring-opening of 2,3-diaryloxiranes
Blasio, Nadia Di,Lopardo, Maria Teresa,Lupattelli, Paolo
experimental part, p. 938 - 944 (2009/07/19)
Non-symmetrical ￡rans-2,3-diaryloxiranes have been regioselectively opened by catalytic hydrogenation over Pd/C, NaBH4/Pd and [Cp 2TiCl]/H2O. Although in the catalytic hydrogenation reactions the epoxides were mainly opened at the β-carbon with respect to the substituted aryl ring in all cases, with the [Cp2TiCl]/H 2O system the regioselectivity was affected by the electronic properties of the aryl residues, the epoxides being opened on the carbon bearing the most electron-releasing or the least electron-withdrawing group. With the NaBH4/Pd system different regioisomers were obtained depending on the substituents. Starting from enantioenriched epoxides, no loss of optical purity was observed in the alcohols formed.
Charge migration in dicationic electrophiles and its application to the synthesis of aza-polycyclic aromatic compounds
Li, Ang,Kindelin, Patrick J.,Klumpp, Douglas A.
, p. 1233 - 1236 (2007/10/03)
Superacid-promoted reactions of dicationic electrophiles have been studied, and the positive charge centers are found to migrate apart in a predictable manner. Using isotopic labeling the charge migration is found in one system to occur through successive deprotonation-reprotonation steps. The charge migration chemistry is the basis for new general synthetic route to aza-polycyclic aromatic compounds.
New syntheses of substituted pyridines via bromine-magnesium exchange
Trécourt, Fran?ois,Breton, Gilles,Bonnet, Véronique,Mongin, Florence,Marsais, Francis,Quéguiner, Guy
, p. 1349 - 1360 (2007/10/03)
Bromine-magnesium exchange using iPrMgCl in THF at room temperature on 2-, 3- and 4-bromopyridines allowed the synthesis of various functionalized pyridines. The methodology was successfully used for the synthesis of 4- azaxanthone. Moreover, single exchange reactions observed on 2,6-, 3,5-, 2,3- and 2,5-dibromopyridines, with complete regioselectivity in the case of 2,3- and 2,5-dibromopyridines, afforded substituted bromopyridines, which were then involved in a second exchange step to provide difunctionalized pyridines. (C) 2000 Elsevier Science Ltd.
Reactions of Carbonyl Compounds with Benzyldibutyltelluronium Bromide Mediated by Different Strong Bases
Li, Sao-Wei,Zhou, Zhang-Lin,Huang, Yao-Zeng,Shi, Li-Lan
, p. 1099 - 1100 (2007/10/02)
Reactions of carbonyl compounds with benzyldibutyltelluronium bromide mediated by alkyllithium or Grignard reagent give homobenzylic aclohols, while those mediated by potassium t-butoxide give olefins.
Pentaalkylstiboranes. 1. Synthesis of Homobenzylic Alcohols, Homoallylic Alcohols, Ethyl 5-Aryl-5-hydroxypent-2-enoates, and β-Hydroxypropionic Acid Derivatives via Pentaalkylstiboranes
Huang, Yao-Zeng,Liao, Yi
, p. 1381 - 1386 (2007/10/02)
Although pentaalkylstiboranes have long been known, their applications in organic synthesis have not been exploited.It has been found that quaternary stibonium salts (n-Bu3SbCH2E)+X- (E = Ph, CH=CH2, CH=CHCO2Et, CO2Et, CN; X = Br, I, BPh4) on treatment with RLi (R = n-Bu, t-Bu, Ph) afford pentaalkylstiboranes, n-Bu3Sb(R)CH2E, which react with aromatic aldehydes to give, after subsequent hydrolysis, homobenzylic alcohols, homoallylic alcohols, ethyl 5-aryl-5-hydroxypent-2-enoates, and β-aryl-β-hydroxypropionitriles, respectively, in good to excellent yields.The reaction is chemoselective for aldehydes.
