622-39-9Relevant articles and documents
Photocatalytic Hydromethylation and Hydroalkylation of Olefins Enabled by Titanium Dioxide Mediated Decarboxylation
Zhu, Qilei,Nocera, Daniel G.
supporting information, p. 17913 - 17918 (2020/12/04)
A versatile method for the hydromethylation and hydroalkylation of alkenes at room temperature is achieved by using the photooxidative redox capacity of the valence band of anatase titanium dioxide (TiO2). Mechanistic studies support a radical-based mechanism involving the photoexcitation of TiO2 with 390 nm light in the presence of acetic acid and other carboxylic acids to generate methyl and alkyl radicals, respectively, without the need for stoichiometric base. This protocol is accepting of a broad scope of alkene and carboxylic acids, including challenging ones that produce highly reactive primary alkyl radicals and those containing functional groups that are susceptible to nucleophilic substitution such as alkyl halides. This methodology highlights the utility of using heterogeneous semiconductor photocatalysts such as TiO2 for promoting challenging organic syntheses that rely on highly reactive intermediates.
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.
Palladium acetate-catalyzed one-pot synthesis of mono- And disubstitued pyridines
Mikami, Shunya,Toyota, Masahiro
, p. 1315 - 1321 (2019/08/01)
A Pd-catalyzed one-pot synthesis of mono- and disubstituted pyridines was developed. The substituted pyridines were obtained from ketones or an aldehyde and 1,3-diaminopropane using a combination of catalytic Pd(OAc)2 and Cu(OAc)2. High-concentration reaction conditions enabled this catalytic reaction to be acid-free.
A nitrogen-ligated nickel-catalyst enables selective intermolecular cyclisation of β- And γ-amino alcohols with ketones: Access to five and six-membered N-heterocycles
Singh, Khushboo,Vellakkaran, Mari,Banerjee, Debasis
supporting information, p. 2250 - 2256 (2018/05/30)
Owing to the great demand for the synthesis of N-heterocycles, development of new reactions that utilise renewable resources and convert them into key chemicals using non-precious base metal-catalysts is highly desirable. Herein, we demonstrated a sustainable Ni-catalysed dehydrogenative approach for the synthesis of pyrroles, pyridines, and quinolines by the reaction of β- and γ-amino alcohols with ketones via C-N and C-C bond formations in a tandem fashion. A variety of aryl, hetero-aryl, and alkyl ketones having free amine, halide, alkyl, alkoxy, alkene, activated benzyl, and pyridine moieties were converted into synthetically interesting 2,3 and 2,3,5-substituted bicyclic as well as tricyclic N-heterocycles with up to 90% yields. As a highlight, we demonstrated the synthesis of an interesting pyrrole derivative by intermolecular cyclisation of a steroid hormone with phenylalaninol.
Nickel-Catalyzed Hydrogenolysis and Conjugate Addition of 2-(Hydroxymethyl)pyridines via Organozinc Intermediates
Hanna, Luke E.,Harris, Michael R.,Domon, Kenji,Jarvo, Elizabeth R.
supporting information, p. 6304 - 6307 (2017/12/08)
2-Hydroxymethylpyridines undergo nickel-catalyzed hydrogenolysis upon activation with a chlorophosphate. Reactions employ diethylzinc and are proposed to proceed through secondary benzylzinc reagents. Quenching with deuteromethanol provides straightforward incorporation of a deuterium label in the benzylic position. Intramolecular conjugate additions with α,β-unsaturated esters are also demonstrated and support the intermediacy of a benzylzinc complex.
Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5
Groenhagen, Ulrike,Maczka, Michael,Dickschat, Jeroen S.,Schulz, Stefan
, p. 1421 - 1432 (2014/07/22)
Streptomyces sp. FORM5 is a bacterium that is known to produce the antibiotic streptazolin and related compounds. We investigated the strain for the production of volatiles using the CLSA (closed-loop stripping analysis) method. Liquid and agar plate cultures revealed the formation of new 2-alkylpyridines (streptopyridines), structurally closely related to the already known 2-pentadienylpiperidines. The structures of the streptopyridines A to E were confirmed by total synthesis. The analysis of the liquid phase by solvent extraction or extraction with an Oasis adsorbent showed that streptazolin and 2-pentadienylpiperidine are the major compounds, while the streptopyridines are only minor components. In the gas phase, only the streptopyridines could be detected. Therefore, an orthogonal set of analysis is needed to assess the metabolic profile of bacteria, because volatile compounds are obviously overlooked by traditional analytical methods. The streptopyridines are strain specific volatiles that are accompanied by a broad range of headspace constituents that occur in many actinomycetes. Volatiles might be of ecological importance for the producing organism, and, as biosynthetic intermediates or shunt products, they can be useful as indicators of antibiotic production in a bacterium.
TRANSITION METAL-CATALYZED ALKYLATION OF C-H BONDS WITH ORGANOBORON REAGENTS
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Page/Page column 6; 62; 67-68, (2008/06/13)
One aspect of the present invention relates to methods for functionalization of 2-arylpyridine and arylpyrazoles with organoboron reagents in the presence of a transition metal catalyst to furnish alkylated arylpyridines and arylpyrazoles via regioselective functionalization of sp2 -hybridized C-H bonds at a position ortho to the point of attachment of the pyridine or pyrazole ring to the aromatic nucleus, hi other embodiments, the present invention provides for alkylation of sp3-hybridized C-H bonds in alkylpyridines.
Palladium-catalyzed alkylation of sp2 and sp3 C-H bonds with methylboroxine and alkylboronic acids: Two distinct C-H activation pathways
Chen, Xiao,Goodhue, Charles E.,Yu, Jin-Quan
, p. 12634 - 12635 (2008/02/05)
Palladium-catalyzed alkylations of sp2 and sp3 C-H bonds with either methylboroxine or alkylboronic acids were developed. Ag2O or AgCO3 is used as a crucial oxidant and promoter for the transmetalation step. Ether, ester, alcohol, and alkene functional groups are tolerated. A new C-H activation pathway differing from the cyclometalation process is elucidated using methylboroxine as the coupling partner. Copyright
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.
Katalytische Cocyclisierungen von Ethin mit Nitrilen an Bis(η2-ethen)(η6-toluol)eisen als Katalysator
Schmidt, U.,Zenneck, U.
, p. 187 - 190 (2007/10/02)
The reactive arene complex bis(η2-ethene)(η6-toluene)iron co-cyclotrimerizes acetylene and nitriles RCN (R = CH3, C2H5, n-C3H7, i-C3H7, C6H5) catalytically to give pyridine derivatives.In the case of acrylonitrile the reaction fails.
