Formation of methyl 2-arylhydrazono-3-oxobutanoates and 2-arylhydrazono-3-oxobutanenitriles during the coupling reaction of arenediazonium ions with methyl 3-aminocrotonate and 3-aminocrotononitrile

1995 ◽  
Vol 73 (2) ◽  
pp. 169-175 ◽  
Author(s):  
D. Sean Brown ◽  
Jason V. Jollimore ◽  
Marcus P. Merrin ◽  
Keith Vaughan ◽  
Donald L. Hooper
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Diazonium Coupling ◽  
High Yields ◽  
Hydrolysis Of ◽  
C Nmr

Reaction of aryldiazonium salts with methyl 3-aminocrotonate (1) affords high yields of the methyl 2-arylhydrazono-3-oxobutanoates (4); analogous diazonium coupling with 3-aminocrotononitrile (2) gives the 2-arylhydrazono-3-oxobutanenitriles (5). The hydrazones are the product of diazonium coupling at the C2-vinylic carbon, concomitant with hydrolysis of the 3-amino substituent to the 3-oxo derivative; there is no evidence for the formation of a triazene (6), which would be the product of N-coupling. All hydrazones (4a–e and 5a–d) have been fully characterized by IR and 1H and 13C NMR spectroscopy; the NMR spectra of the methyl 2-arylhydrazono-3-oxobutanoates (4) suggest the presence of two isomeric intramolecularly H-bonded forms in solution. Selected compounds were further characterized by elemental analysis and mass spectrometry. A mechanism is proposed for the conversion of 1 or 2 into 4 or 5, and these observations are compared with previously reported observations of diazonium coupling reactions with unsaturated systems. Keywords: hydrazone, diazonium, aminocrotonate, aminocrotononitrile, hydrogen bonding.

Zirconocene-mediated selective synthesis of 1,4-bis(alkynyl)benzenes

2020 ◽  
Vol 44 (9-10) ◽  
pp. 571-575
Author(s):  
Bo Zhang ◽  
Hongmei Qu ◽  
Zhongxuan Li ◽  
Yuanyuan Zhai ◽  
Xiaolu Zhou ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dimethyl Ester ◽  
Acid Ethyl Ester ◽  
Coupling Reactions ◽  
Benzene Derivatives ◽  
Phenylene Ethynylene ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
High Yields ◽  
C Nmr

A series of novel 1,4-bis(alkynyl)benzene derivatives were synthesized from trimethylsilyl-substituted alkynes by the mediation of zirconocene with excellent regioselectivity in high yields. The 3,6-bis(trimethylsilyl)-4,5-dialkylphthalic acid dimethyl esters were prepared by cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclopentadienes to dimethyl acetylenedicarboxylate. After iodination with iodine monochloride, 3,6-diiodo-4,5-dialkylphthalic acid dimethyl esters reacted with terminal alkynes to prepare the corresponding 1,4-bis(alkynyl)benzene derivatives by Sonogashira coupling reactions. After removal of trimethylsilyl, 4,5-dibutyl-3,6-bis(ethynyl)phthalic acid dimethyl ester (compound 3) reacted with 4-iodobenzoic acid ethyl ester and 2-iodothiophene, respectively, to obtain the corresponding products 4a and 4c. Compound 3 can be extended to higher oligomers, which reacted with 1-bromo-4-iodobenzene and phenylacetylene in a stepwise manner under Sonogashira conditions to give the phenylene-ethynylene oligomer 5 in an isolated yield of 85%. The structures of the products were confirmed by 1H NMR spectroscopy, 13C NMR spectroscopy, and MS. The optical properties of the 1,4-bis(alkynyl)benzene derivatives were studied by UV-Vis spectroscopy and fluorescence spectra. The results indicated that some can be developed into potential photovoltaic materials.

Synthesis of a Contrapositionally Substituted Cyclohexa-meta-phenylene: A Ready-to-Use Precursor for Cyclohexa-meta-phenylene-Based Materials

Synlett ◽  
2019 ◽  
Vol 30 (16) ◽  
pp. 1886-1890
Author(s):  
Ifzan Arshad ◽  
Aamer Saeed ◽  
Pervaiz Ali Channar ◽  
Syeda Aaliya Shehzadi ◽  
Rana Muhammad Irfan
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Coupling Reaction ◽  
Suzuki Coupling ◽  
Coupling Reactions ◽  
Iodine Monochloride ◽  
Synthetic Route ◽  
Metal Catalyzed ◽  
Yamamoto Coupling ◽  
Trimethylsilyl Groups

A contrapositionally substituted derivative of cyclohexa-meta-phenylene ([6]CMP) was synthesized by an intramolecular Yamamoto coupling reaction of an appropriate terphenyl unit containing a trimethylsilyl substituent. Iododesilylation of the trimethylsilyl groups of the product with iodine monochloride was used to incorporate iodo groups, an important functionality for metal-catalyzed coupling reactions. The iodo groups were also converted into a (pinacolato)boryl groups, another important functionality for coupling reactions. The diborylated [6]CMP is expected to be a versatile potential comonomer and a precursor for the synthesis of CMP-based materials. The synthetic route to the disubstituted [6]CMP included lithiation, Pd-catalyzed borylation, Suzuki coupling, and Yamamoto coupling. The structure of the product was established by NMR spectroscopy and mass spectrometry.

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

The mechanism of formation of 2,7-dimethyl-2,6-octadiene in the synthesis of 3-methylene-7-methyl-1,6-octadiene

1983 ◽  
Vol 48 (7) ◽  
pp. 1864-1866
Author(s):  
Jan Bartoň ◽  
Ivan Kmínek
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Alkali Metal ◽  
Chromatographic Analysis ◽  
Solid Phase ◽  
Reaction Pathway ◽  
Mechanism Of Formation ◽  
Gas Chromatographic Analysis ◽  
C Nmr ◽  
Visual Observations

2,7-Dimethyl-2,6-octadiene is formed in the catalytic solution for the dimerization of 2-methyl-1,3-butadiene to β-myrcene (3-methylene-7-methyl-1,6-octadiene), as revealed by mass spectrometry and 13C NMR spectroscopy. Visual observations together with the results of gas chromatographic analysis of the catalytic solution suggest that the formation of 2,7-dimethyl-2,6-octadiene is associated with the transition of the alkali metal (sodium) from the solid phase into the solution. A reaction pathway is suggested accounting for the formation of 2,7-dimethyl-2,6-octadiene in the system.

Synthesis of the six isomeric thieno[c]-fused 1,5- and 1,6-naphthyridines

1991 ◽  
Vol 56 (11) ◽  
pp. 2340-2351 ◽  
Author(s):  
Salo Gronowitz ◽  
Johan Malm ◽  
Anna-Britta Hörnfeldt
Keyword(s):  
Nmr Spectra ◽  
Coupling Reaction ◽  
One Pot ◽  
C Nmr

trough the use of Pd(0)-catalyzed coupling between 2- and 4-formyl-3-thiopheneboronic acids and 3-amino-2-bromopyridine and 4-acetamido-3-bromopyridine, convenient one-pot procedures for the preparation of thieno[2,3-c]-1,5-naphthyridine, thieno[3,4-c]-1,5-naphthyridine, thieno-[2,3-c]-1,6-naphthyridine, and thieno[3,4-c]-1,6-naphthyridine have been developed. In order to obtain thieno[3,2-c]-1,6-naphthyridine 2-(tributylstannyl)-3-thiophene aldehyde had to be used, since the organometallic partner in the coupling reaction, 3-formyl-2-thipheneboronic acid, is too easily deboronated. The effect of silver(I) oxide and thallium(I) carbonate on the coupling was studied. 1H and 13C NMR spectra of the six isomeric thieno{c]-fused 1,5- and 1,6-naphthyridines are discussed.

A New Dimeric Derivative of Ethoxyquin from Its Reaction with Alkylperoxy Radicals

1993 ◽  
Vol 58 (8) ◽  
pp. 1914-1918 ◽  
Author(s):  
Jaroslav Kříž ◽  
Luděk Taimr
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Peroxy Radicals ◽  
Methyl Group ◽  
Alkylperoxy Radicals ◽  
C Nmr

The structure of a new compound formed in the reaction of ethoxyquin with alkylperoxy radicals was resolved by 1H and 13C NMR spectroscopy (including COSY, NOESY, HHC RCT and SSLR INEPT techniques) and confirmed by mass spectrometry. The structure suggest participation of 4-methyl group of ethoxyquin in the deactivation of peroxy radicals. A mechanism of this reaction is proposed.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

Regiospecific Palladium-Catalyzed Cross-Coupling Reactions Using the Operational Equivalent of 1,3-Dilithiopropyne

Synthesis ◽  
2020 ◽  
Vol 52 (16) ◽  
pp. 2387-2394 ◽  
Author(s):  
Jorge A. Cabezas ◽  
Natasha Ferllini
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Terminal Alkyne ◽  
Copper Iodide ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Palladium Catalyzed ◽  
High Yields

A regiospecific palladium-catalyzed cross-coupling reaction using the operational equivalent of the dianion 1,3-dilithiopropyne, with aromatic iodides is reported. This reaction gives high yields of 1-propyn-1-yl-benzenes and 2-(propyn-1-yl)thiophenes in the presence of catalytic amounts of palladium(0) or (II) and stoichiometric amounts of copper iodide. No terminal alkyne or allene isomers were detected. Reaction conditions were very mild and several functional groups were tolerated.

scholarly journals Thiol–ene coupling reaction achievement and monitoring by “in situ” UV irradiation NMR spectroscopy

RSC Advances ◽  
2020 ◽  
Vol 10 (42) ◽  
pp. 25214-25222
Author(s):  
Natalia Toncheva-Moncheva ◽  
Miroslav Dangalov ◽  
Nikolay G. Vassilev ◽  
Christo P. Novakov
Keyword(s):  
Nmr Spectroscopy ◽  
Uv Irradiation ◽  
Glycidyl Ether ◽  
Coupling Reaction ◽  
Polyethylene Glycols ◽  
Coupling Reactions ◽  
Uv Illumination ◽  
Allyl Glycidyl Ether

An “In situ” LED UV illumination NMR setup for achievement of initiator-free coupling reactions of allyl-functionalized poly(allyl glycidyl ether) with polyethylene glycols thiols.

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