20815-27-4Relevant articles and documents
Enantioselective Alkylation of 2-Alkylpyridines Controlled by Organolithium Aggregation
Gladfelder, Joshua J.,Ghosh, Santanu,Podunavac, Ma?a,Cook, Andrew W.,Ma, Yun,Woltornist, Ryan A.,Keresztes, Ivan,Hayton, Trevor W.,Collum, David B.,Zakarian, Armen
, p. 15024 - 15028 (2019)
Direct enantioselective α-alkylation of 2-alkylpyridines provides access to chiral pyridines via an operationally simple protocol that obviates the need for prefunctionalization or preactivation of the substrate. The alkylation is accomplished using chiral lithium amides as noncovalent stereodirecting auxiliaries. Crystallographic and solution NMR studies provide insight into the structure of well-defined chiral aggregates in which a lithium amide reagent directs asymmetric alkylation.
ZnMe2-Mediated, Direct Alkylation of Electron-Deficient N-Heteroarenes with 1,1-Diborylalkanes: Scope and Mechanism
Jo, Woohyun,Baek, Seung-Yeol,Hwang, Chiwon,Heo, Joon,Baik, Mu-Hyun,Cho, Seung Hwan
supporting information, p. 13235 - 13245 (2020/09/01)
The regioselective, direct alkylation of electron-deficient N-heteroarenes is, in principle, a powerful and efficient way of accessing alkylated N-heteroarenes that are important core structures of many biologically active compounds and pharmaceutical agents. Herein, we report a ZnMe2-promoted, direct C2- or C4-selective primary and secondary alkylation of pyridines and quinolines using 1,1-diborylalkanes as alkylation sources. While substituted pyridines and quinolines exclusively afford C2-alkylated products, simple pyridine delivers C4-alkylated pyridine with excellent regioselectivity. The reaction scope is remarkably broad, and a range of C2- or C4-alkylated electron-deficient N-heteroarenes are obtained in good yields. Experimental and computational mechanistic studies imply that ZnMe2 serves not only as an activator of 1,1-diborylalkanes to generate (α-borylalkyl)methylalkoxy zincate, which acts as a Lewis acid to bind to the nitrogen atom of the heterocycles and controls the regioselectivity, but also as an oxidant for rearomatizing the dihydro-N-heteroarene intermediates to release the product.
Odd-Even Effect on the Spin-Crossover Temperature in Iron(II) Complex Series Involving an Alkylated or Acyloxylated Tripodal Ligand
Ishida, Takayuki,Kashiro, Atsushi,Kohno, Wakana
supporting information, (2020/08/05)
In the context of magneto-structural study, a relatively short alkyl group was introduced to anionic spin-crossover (SCO) building blocks based on [Fe(py3CR)(NCS)3]-, where py3CR stands for tris(2-pyridyl)methyl derivatives. The linear alkyl and acyloxyl derivatives of Me4N[Fe(py3CR)(NCS)3] with R = CnH2n+1 (n = 1-7) and CnH2n+1CO2 (n = 1-6) were synthesized, and the magnetic study revealed that all the compounds investigated here exhibited SCO. The SCO temperature (T1/2) varied in 289-338 K for the alkylated compounds, and those of the acyloxylated ones were lower with a narrower variation width (T1/2 = 216-226 K). The crystal structures of the former with n = 3, 4, and 5 and the latter with n = 1, 4, 5, and 6 were determined, and various molecular arrangements were characterized. There is no structural evidence for a molecular fastener effect. The plots on T1/2 against n displayed a pronounced odd-even effect; the SCO temperatures of the homologues with even n are relatively higher than those of the homologues with odd n. The odd-even effect on T1/2 may be related with the entropy difference across the SCO, rather than crystal field modification or intermolecular interaction. The present work will help molecular design to fine-tune T1/2 by means of simple chemical modification like alkylation and acyloxylation.
Selective and Serial Suzuki-Miyaura Reactions of Polychlorinated Aromatics with Alkyl Pinacol Boronic Esters
Laulhé, Sébastien,Blackburn, J. Miles,Roizen, Jennifer L.
, p. 4440 - 4443 (2016/09/09)
Among cross-coupling reactions, the Suzuki-Miyaura transformation stands out because of its practical advantages, including the commercial availability and low toxicity of the required reagents, mild reaction conditions, and functional group compatibility. Nevertheless, few conditions can be used to cross-couple alkyl boronic acids or esters with aryl halides, especially 2-pyridyl halides. Herein, we describe two novel Suzuki-Miyaura protocols that enable selective conversion of polychlorinated aromatics, with a focus on reactions to convert 2,6-dichloropyridines to 2-chloro-6-alkylpyridines or 2-aryl-6-alkylpyridines.
INDOLIZINE-BASED DYES FOR DYE-SENSITIZED SOLAR CELL
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Page/Page column 33; 36, (2016/04/01)
Compounds for use as sensitizer dyes in dye-sensitized solar cells.
AGENT FOR IMPROVING PERMEATION OF A DRUG INTO A NAIL AND AN EXTERNAL TREATING AGENT CONTAINING THE SAME
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Page/Page column 7, (2010/04/23)
The present invention herein provides a compound which promotes drug-permeation into nails. A penetrating promoter comprises, for instance, the following formulas. R1, R2 and R3 are alkyl groups having a carbon number of 1 to 15 and have OH groups at their ends.
Studies on the amino-heck reactions of unsaturated ketones o-phosphinyloximes for the preparation of substituted pyridines
Zhu, Jia-Liang,Su, Yi-Lin,Chan, Yu-Hui,Chen, I-Chia,Liao, Chuan-Chen
experimental part, p. 369 - 387 (2009/06/08)
The amino-Heck cyclization process has been applied into a range of γ,δ-unsaturated ketone O-diethylphosphinyloximes 1 and δ,ε-unsaturated ketone O-diethylphosphinyloximes 7. Under the specific catalytic conditions developed by us, these substrates were found to preferentially undergo the 6-endo cyclization to give the formation of 2-substituted pyridines 3 and substituted methylpyridines 8, respectively, in moderate to good yields. Besides, several interesting aspects on the effects of phosphinyl groups, solvents, bases and molecular sieves on the regioselectivity of the cyclization of 1 have also been realized.
Palladium-catalyzed amino-heck reaction of γ,δ-unsaturated ketone O-diethylphosphinyloximes: A new synthesis of substituted pyrroles and indoles
Zhu, Jia-Liang,Chan, Yu-Hui
scheme or table, p. 1250 - 1254 (2009/04/06)
γ,δ-Unsaturated ketone O-diethylphosphinyloximes, readily prepared from the corresponding ketones, were used as starting materials for the intramolecular amino-Heck reactions. In the presence of a catalytic amount of Pd(PPh3)4 in DBU, cyclization reactions occurred preferentially via a 5-exo fashion to afford a variety of 2-substituted 5-methyl-1H-pyrroles and several indole derivatives in moderate to high yields. Georg Thieme Verlag Stuttgart.
A new efficient synthesis of pyridines
De Kimpe, Norbert,Keppens, Marian,Fonck, Gwendolien
, p. 635 - 636 (2007/10/03)
Cyclic six-membered imines, i.e. 2,3,4,5-tetrahydropyridines, are efficiently converted under mild conditions into the corresponding pyridines by highly regioselective α, α-dichlorination with N-chlorosuccinimide (NCS) followed by double dehydrochlorination with methanolic bases.
PHOTOCHEMICAL GENERATION OF ALIPHATIC RADICALS FROM BENZOPHENONE OXIME ESTERS: SIMPLE SYNTHESIS OF ALKYLBENZENES AND ALKYLPYRIDINES
Hasebe, Masato,Tsuchiya, Takashi
, p. 3239 - 3242 (2007/10/02)
Photolysis of benzophenone oxime esters, prepared with aliphatic carboxylic acids and benzophenone oxime, in benzene and pyridine generates various primary, secondary and tertiary aliphatic radicals selectively, and corresponding alkylbenzenes and alkylpyridines are produced in good yields, respectively.