- Transition-Metal-Free Regioselective Alkylation of Quinoline N-Oxides via Oxidative Alkyl Migration and C?C Bond Cleavage of tert-/sec-Alcohols
-
An unprecedented C2-alkylation of quinoline N-oxide derivatives via C?C bond activation of tert- and sec-alkyl alcohol is described using hypervalent iodine (III) reagent PhI(OAc)2 (PIDA). This regioselective alkylation using mild hypervalent iodine reagents is more practical, operationally simple and transition metal free. The reaction proceeds efficiently with a broad range of substrates including quinoline, isoquinoline, and pyridine N-oxides using a variety of tert-/sec- alcohols. From experimental outcome, we also propose a rationalized mechanism, mediated by PIDA. (Figure presented.).
- Sen, Chiranjit,Ghosh, Subhash C.
-
p. 905 - 910
(2018/01/11)
-
- Pd(II)-catalyzed monoarylation of 2-phenylpyridine N-oxide with iodobenzene in water
-
A Pd(II)-catalyzed activation and arylation of C(sp2)–H bond directed by pyridine N-oxide in water is achieved with high regioselectivity to form monoarylated products in yields up to 91%. The wide substrate scope highlights the flexibility of the catalyst. The reaction mechanism was proposed and the application of this method was taken as an example by the synthesis of COX-2 inhibitor analog.
- Zhang, Wei,Li, Zhengkai,Zhang, Yihan,Yang, Li,Zhou, Xiangge
-
supporting information
p. 793 - 802
(2017/04/06)
-
- Palladium-catalyzed direct C-H arylation of pyridine N-oxides with potassium aryl- and heteroaryltrifluoroborates
-
An efficient ligand-free Pd(OAc)2-catalyzed selective arylation of pyridine N-oxides using potassium (hetero)aryltrifluoroborates as coupling partners via C-H bond activation was achieved in the presence of TBAI. This approach has a broad subst
- Li, Mengli,Li, Xing,Chang, Honghong,Gao, Wenchao,Wei, Wenlong
-
supporting information
p. 2421 - 2426
(2016/03/01)
-
- Arylation of pyridine N-oxides via a ligand-free Suzuki reaction in water
-
We report a practical and highly efficient protocol for the arylation of pyridine N-oxides with arylboronic acid through palladium-catalyzed Suzuki reaction in water. This ligand-free Suzuki reaction is performed in the presence of diisopropylamine and gi
- Liu, Chun,Zhang, Shao-Ke,Zhang, Yi-Xia,Jin, Zi-Lin
-
-
- Substitution of the nitro group with Grignard reagents: Facile arylation and alkenylation of pyridine N-oxides
-
The unprecedented substitution of a nitro group with aryl or alkenyl groups of Grignard reagents affords 2-aryl or alkenylpyridine N-oxides in modest to high yields with high chemoselectivity. This protocol allows a simple and clean synthesis of various 2
- Zhang, Fang,Zhang, Song,Duan, Xin-Fang
-
p. 5618 - 5620
(2013/01/15)
-
- Silver-catalyzed 2-pyridyl arylation of pyridine N-oxides with arylboronic acids at room temperature
-
A novel direct arylation of pyridine N-oxides with arylboronic acids through C-H functionalization has been developed. This new reaction is performed at room temperature using catalytic silver(I) nitrate in the presence of potassium persulfate and give 2-
- Mai, Wenpeng,Yuan, Jinwei,Li, Zhicheng,Sun, Gangchun,Qu, Lingbo
-
supporting information; experimental part
p. 145 - 149
(2012/02/04)
-
- Inhibition of 1-deoxy-d-xylulose-5-phosphate reductoisomerase by lipophilic phosphonates: SAR, QSAR, and crystallographic studies
-
1-Deoxy-d-xylulose-5-phosphate reductoisomerase (DXR) is a novel target for developing new antibacterial (including antituberculosis) and antimalaria drugs. Forty-one lipophilic phosphonates, representing a new class of DXR inhibitors, were synthesized, among which 5-phenylpyridin-2-ylmethylphosphonic acid possesses the most activity against E. coli DXR (EcDXR) with a K i of 420 nM. Structure-activity relationships (SAR) are discussed, which can be rationalized using our EcDXR:inhibitor structures, and a predictive quantitative SAR (QSAR) model is also developed. Since inhibition studies of DXR from Mycobacterium tuberculosis (MtDXR) have not been performed well, 48 EcDXR inhibitors with a broad chemical diversity were found, however, to generally exhibit considerably reduced activity against MtDXR. The crystal structure of a MtDXR:inhibitor complex reveals the flexible loop containing the residues 198-208 has no strong interactions with the 3,4-dichlorophenyl group of the inhibitor, representing a structural basis for the reduced activity. Overall, these results provide implications in the future design and development of potent DXR inhibitors.
- Deng, Lisheng,Diao, Jiasheng,Chen, Pinhong,Pujari, Venugopal,Yao, Yuan,Cheng, Gang,Crick, Dean C.,Prasad, B. V. Venkataram,Song, Yongcheng
-
p. 4721 - 4734
(2011/09/19)
-
- COPPER-CATALYZED C-H BOND ARYLATION
-
The present invention is a one-step method for efficiently converting carbon-hydrogen bonds into carbon-carbon bonds using a combination of aryl halides, a substrate, and a copper salt as catalyst. This method allows faster introduction of complex molecular entities, a process that would otherwise require many more steps. This invention is particularly relevant for the organic synthesis of complex molecules such as, but not limited to, pharmacophores and explosives.
- -
-
Page/Page column 23
(2009/04/24)
-
- A general method for copper-catalyzed arylation of arene C-H bonds
-
A general method for copper-catalyzed arylation of sp2 C-H bonds with pKa's below 35 has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide or K3PO4 base, and DMF, DMPU, or mixed DMF/xylenes solvent. A variety of electron-rich and electron-poor heterocycles such as azoles, caffeine, thiophenes, benzofuran, pyridine oxides, pyridazine, and pyrimidine can be arylated. Furthermore, electron-poor arenes possessing at least two electron-withdrawing groups on a benzene ring can also be arylated. Two arylcopper-phenanthroline complex intermediates were independently synthesized.
- Do, Hien-Quang,Khan, Rana M. Kashif,Daugulis, Olafs
-
supporting information; experimental part
p. 15185 - 15192
(2009/03/12)
-
- Piperazine and piperidine compounds
-
A group of new piperazine and piperidine compounds having interesting advantageous pharmacological properties and have the formula (a) wherein A represents a heterocyclic group having 5-7 ring atoms wherein 1-3 heteroatoms selected from the group O, N and
- -
-
-
- Synthesis, rotamer orientation, and calcium channel modulation activities of alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates
-
A group of racemic alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3- nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates (13a-q) was prepared using a modified Hantzsch reaction that involved the condensation of a 3- or 6-substituted-2-pyridinecarboxaldehyde (7a-j) with an alkyl or 2- phenethyl 3-aminocrotonate (11a-d) and nitroacetone (12). Nuclear Overhauser (NOE) studies indicated there is a significant rotamer fraction in solution where the pyridyl nitrogen is oriented above the 1,4-dihydropyridine ring, irrespective of whether a substituent is located at the 3- or 6-position. A potential H-bonding interaction between the pyridyl nitrogen free electron pair and the suitably positioned 1,4-dihydropyridine NH moiety may stablize this rotamer orientation. In vitro calcium channel antagonist and agonist activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays, respectively. Compounds having an i-Pr ester substituent acted as dual cardioselective calcium channel agonists (GPLA)/smooth muscle-selective calcium channel antagonists (GPILSM), except for the C-4 3-nitro-2-pyridyl compound which exhibited an antagonist effect on both GPLA and GPILSM. In contrast, the compounds with a phenethyl ester group, which exhibited antagonist activity (IC50 = 10-5- 10-7 M range) on GPILSM, were devoid of cardiac agonist activity on GPLA. Structure-activity relationships showing the effect of a substituent (Me, CF3, C1, NO2, Ph) at the 3- or 6-position of a C-4 2-pyridyl moiety and a variety of ester substituents (Me, Et, i-Pr, PhCH2CH2-) upon calcium channel modulation are described. Compounds possessing a 3- or 6-substituted- 2-pyridyl moiety, in conjuction with an i-Pr ester substituent, are novel 1,4-dihydropyridine calcium channel modulators that offer a new drug design approach directed to the treatment of congestive heart failure and may also be useful as probes to study the structure-function relationships of calcium channels.
- Iqbal, Nadeem,Akula, Murthy R.,Vo, Dean,Matowe, Wandikayi C.,McEwen, Carol-Anne,Wolowyk, Michael W.,Knaus, Edward E.
-
p. 1827 - 1837
(2007/10/03)
-
- Selenium catalyzed conversion of δ-phenyl- γ-alkenyl oximes into 2-phenylpyridines
-
δ-Phenyl-γ-alkenyl oximes react with an excess of ammonium persulfate and catalytic amounts of diphenyl diselenide in the presence of trifluoromethanesulfonic acid in acetonitrile to afford 2-phenylpyridines and 2-phenylpyridine N-oxides in moderate yields.
- Tiecco, Marcello,Testaferri, Lorenzo,Bagnoli, Luana,Marini, Francesca,Santi, Claudio,Temperini, Andrea
-
p. 2679 - 2686
(2007/10/03)
-