Deuteriotrifluoroacetic Acid Research Articles

Quinolone Analogues 12: Synthesis and Tautomers of 2-Substituted 4-Quinolones and Related Compounds

The 4-quinolone-2-carboxylates 4a,b were converted into the 4-quinolone-2-carbohydrazides 5a,b, hydrazones 6,7,10, and related compounds 8,9,11. The 4-methoxyquinoline-2-carboxylate 12 was also transformed into the 4-methoxyquinoline-2-carbohydrazide 13, which was modified to the hydrazone 14 and related compound 15. The antimicrobial activities of compounds 6b and 14 are described together with the 4-oxo and 4-hydroxy tautomers of compounds 4-11 in deuteriodimethyl sulfoxide and deuteriotrifluoroacetic acid.

ChemInform Abstract: 13C-NMR Study of 4H-1,3,4-Thiadiazino(5,6-b)quinoxalines. A Proof for the N5-Deuteration in Deuteriotrifluoroacetic Acid.

The carbon signals of the 2-acylamino-4H-1,3,4-thiadiazino[5,6-b]quinoxalines 1a,b, 2-acylamino-4H-1,3,4-thiadiazino[5,6-b]quinoxaline 1,1-dioxides 2a,b, and 2-amino-4H-1,3,4-thiadiazino[5,6-b]quinoxaline 3 in deuteriodimethyl sulfoxide and in deuteriotrifluoroacetic acid were assigned by the nmr (HMBC, HMQC) spectroscopy. The comparison of the carbon chemical shifts in deuteriodimethyl sulfoxide with those in deuteriotrifluoroacetic acid clarified that compounds 1a, 1b, and 3 were deuterized at the N5-position in deuteriotrifluoroacetic acid, while the 1,1-dioxides 2a,b did not undergo the N5-deuteration in deuteriotrifluoroacetic acid.

A new tautomeric zwitterion form of 2‐acylamino‐4H‐1,3,4‐oxadiazino[5,6‐b]quinoxalines in solution

AbstractThe reaction of 2‐acyiamino‐8‐chloro‐4‐methyl‐4H‐1,3,4‐oxadiazino[5,6‐b]quinoxalines 2a‐d with methyl iodide/base gave the 8‐chloro‐4,10‐dimethyl‐4H‐1,3,4‐oxadiazino[5,6‐b]quinoxalin‐10‐ium‐2‐acylamidates 4a‐d, respectively. Comparison of the nmr spectral data between compounds 2a‐d and 4a‐d in deuteriodimethyl sulfoxide or in deuteriotrifluoroacetic acid established that compounds 2a‐d existed as the zwitterionic tautomers 2′a‐d in solution.

α-Linked Bifuran and α,α‘-Linked Tricycles Containing Furan and/or Thiophene. EPR Investigations and Electrochemical Behavior

The radical cations from 5,5‘-dimethyl-2,2‘-bifuran (1) and 5,5‘‘-dimethyl-2,2‘,5‘,2‘‘-terfuran (5), and from the α,α‘-linked triheterocycles containing thiophene and furan, bis(5-methyl-2-furyl)thiophene (6) and bis(5-methyl-2-thienyl)furan (7), were generated in fluid solution with trifluoroacetic acid (TFA) or mixtures of TFA and 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP), in the presence or absence of thallium(III) trifluoroacetate as oxidant, and analyzed by electron paramagnetic resonance. The hyperfine coupling (hc) constants were assigned by comparison with those from 5,5‘-dimethyl- (3) and 5,5‘-di-tert-butyl-2,2‘,5‘,2‘‘-terthiophene (4) and by investigation into the deuterated species generated in solution with deuteriotrifluoroacetic acid and, in the case of 5•+, 6•+, and 7•+ confirmed by theoretical calculations. The parent compounds 1, 5, 6, and 7 were synthesized by known procedures. Cyclic voltammetry of them in dimethylformamide using tetrabutylammonium hexafluorophosphate or perchlorate as el...

13C‐NMR study of 4H‐1,3,4‐thiadiazino[5,6‐b]quinoxalines. A proof for the N5‐deuteration in deuteriotrifluoroacetic acid

AbstractThe carbon signals of the 2‐acylamino‐4H‐1,3,4‐thiadiazino[5,6‐b]quinoxalines 1a,b, 2‐acylamino‐4H‐1,3,4‐thiadiazino[5,6‐b]quinoxaline 1,1‐dioxides 2a,b, and 2‐amino‐4H‐1,3,4‐thiadiazino[5,6‐b]quinoxaline 3 in deuteriodimethyl sulfoxide and in deuteriotrifluoroacetic acid were assigned by the nmr (HMBC, HMQC) spectroscopy. The comparison of the carbon chemical shifts in deuteriodimethyl sulfoxide with those in deuteriotrifluoroacetic acid clarified that compounds 1a, 1b, and 3 were deuterized at the N5‐position in deuteriotrifluoroacetic acid, while the 1,1‐dioxides 2a,b did not undergo the N5‐deuteration in deuteriotrifluoroacetic acid.

13C‐NMR study on the tautomerism of 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines between the hydrazone imine and diazenylenamine forms

AbstractThe 13C‐nmr study was carried out for the tautomerism of the 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihy‐droquinoxalines 1a‐g and 2a‐e between the hydrazone imine A and diazenylenamine B forms, providing the carbon chemical shifts for the tautomers A and B of compounds 1a‐g and 2a‐e. The comparison of the carbon chemical shifts for the tautomer B of compounds 1d, 1f, and 2b in deuteriodimethyl sulfoxide with those in deuteriotrifluoroacetic acid showed that the C4a, C5, and diazenyl carbons were considerably shielded presumably due to the azo N‐deuteration in deuteriotrifluoroacetic acid.

Chemistry of thienopyridines.XL. Reactions of 7-acetyl-4-(1-carboethoxy-1-cyano)methylene-4,7-dihydrothieno-[2,3-b]pyridine. Part3: Kinetics of hydrolysis

The kinetics of hydrolysis of 7-acetyl-4-(1-carboethoxy-1-cyano)methylene-4,7-dihydrothieno[2,3-b]pyridine (1) in undried DMSO-d6 to give ethyl 2-(4-thieno[2,3-b]pyridyl)cyanoacetate and acetic acid at ambient temperature was investigated by 1H nmr spectrometry. The reaction is pseudo first order in the concentration of 1 with a rate constant of 9 × 10−4 per minute, not noticeably altered by the addition of deuteriotrifluoroacetic acid. The hydrolysis is, however, catalyzed by means of added pyridine-d5 (k = 37 × 10−4 per minute). The pyridine is presumed to serve as a transfer agent for the acetylium ion as in acetylations with acetyl chloride and acetic anhydride.

1H NMR spectra of cis‐2,6‐diphenylpiperidines and cis‐2,6‐diphenyl‐4‐piperidones

Abstract1H NMR spectra of t‐3‐ethyl‐r‐2,c‐6‐diphenylpiperidine, t‐3‐ethyl‐r‐2,c‐6‐diphenyl‐4‐piperidone and several related compounds have been obtained in deuteriochloroform and deuteriotrifluoroacetic acid solutions, and compared with the spectra of their hydrochlorides in deuteriochloroform‐hexadeuteriodimethyl sulphoxide solutions. The effects of the structural changes 4‐CH2 → have been observed on the chemical shifts of ring and substituent protons, and on the non‐equivalence of the diastereotopic protons of the ethyl groups.

Syntheses and properties of a trimethyltetradehydro[23]annulenone and a trimethyltetradehydro[25]annulenone

The syntheses of 2,9,14-trimethyl-10,11,12,13-tetradehydrocyclotricosenone (6) and 2,11,16-trimethyl-12,13,14,15-tetradehydrocyclopentacosenone (7) are described. Examination of the 1H n.m.r. spectra indicates that (6) is diatropic, whereas (7) is paratropic, and these ring currents are increased by dissolution in deuteriotrifluoroacetic acid.

Ring‐chain tautomerism of acetone N‐methylated thiosemicarbazones

AbstractRing‐chain tautomerism of acetone N‐methylated thiosemicarbazones was studied by nmr spectroscopy. Acetone thiosemicarbazone, acetone 2‐methylthiosemicarbazone, and acetone 4‐methylthiosemicarbazone exist as chain forms in DMSO‐d6 and ring forms in deuteriotrifluoroacetic acid. However, the compound obtained by reaction of acetone with 2,4‐dimethylthiosemicarbazide exists only as the ring form 3,5,5‐trimethyl‐1,3,4‐thiadiazolidine‐2‐methylimine both in DMSO‐d6 and in deuteriotrifluoroacetic acid, due to steric hindrance of the three methyl groups.

Ring‐chain tautomerism of aldehyde n‐methylated semicarbazones

AbstractRing‐chain tautomerism of thirty‐six aldehyde semicarbazones was studied by nmr spectro‐scopy. The 2,4‐dimethylsemicarbazones of benzaldehyde, p‐tolualdehyde, p‐anisaldehyde, and P‐chlorobenzaldehyde exist as chain forms in DMSO‐d6, but as both ring and chain forms in deuteriotriiluoroacetic acid. Unlike these semicarbazones, the aldehyde semicarbazones of N‐unsubstituted semicarbazide, 2‐methylsemicarbazide, and 4‐methylsemicarbazide did not cyclo‐isomerize in either DMSO‐d6 or deuteriotrifluoroacetic acid. These results indicate that protona‐tion of the C=N nitrogen atom and steric hindrance of the 2‐methyl group with an aromatic group at the C=N carbon atom in the chain form cause cycloisomerization to ring isomers.

ChemInform Abstract: THE EPR SPECTRA OF RADICAL IONS GENERATED FROM QUINOXALINE IN TRIFLUORO‐ AND DEUTERIOTRIFLUOROACETIC ACID

Chemischer InformationsdienstVolume 9, Issue 3 Physical Organic Chemistry ChemInform Abstract: THE EPR SPECTRA OF RADICAL IONS GENERATED FROM QUINOXALINE IN TRIFLUORO- AND DEUTERIOTRIFLUOROACETIC ACID J. ELORANTA, J. ELORANTASearch for more papers by this authorR. KOSKINEN, R. KOSKINENSearch for more papers by this author J. ELORANTA, J. ELORANTASearch for more papers by this authorR. KOSKINEN, R. KOSKINENSearch for more papers by this author First published: January 17, 1978 https://doi.org/10.1002/chin.197803065AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue3January 17, 1978 RelatedInformation

Reaction of nortricyclene with deuteriotrifluoroacetic acid. Evidence for the formation of edge-protonated cyclopropane intermediate

Reaction of nortricyclene with deuteriotrifluoroacetic acid. Evidence for the formation of edge-protonated cyclopropane intermediate

The EPR Spectra of Radical Ions Generated from Quinoxaline in Trifluoro- and Deuteriotrifluoroacetic Acid.

The EPR Spectra of Radical Ions Generated from Quinoxaline in Trifluoro- and Deuteriotrifluoroacetic Acid.

Additions to bicyclic olefins. VIII. Electrophilic addition of trifluoroacetic acid and deuteriotrifluoroacetic acid to norbornene and related bicyclic olefins. Evidence for the capture of the the unsymmetrical (classical) 2-norbornyl cation

Additions to bicyclic olefins. VIII. Electrophilic addition of trifluoroacetic acid and deuteriotrifluoroacetic acid to norbornene and related bicyclic olefins. Evidence for the capture of the the unsymmetrical (classical) 2-norbornyl cation

Studies of heterocyclic compounds. Part XIV. 1,6a-Dithia-6-azapentalenes

6-Methyl-1,6a-dithia-6-azapentalenes have been synthesised by the reaction of 3-(2-dimethylaminovinyl)-1,2-dithiolium (Vilsmeier) salts or 6a-thiathiophthens with methylamine. 1,6a-Dithia-6-azapentalenes form stable charge-transfer complexes with 1,3,5-trinitrobenzene. The significance of the 1H n.m.r. spectra of 1,6a-dithia-6-azapentalenes is discussed in relation to their structure. 1,6a-Dithia-6-azapentalenes are basic; they form stable 3-(2-methylaminovinyl)-1,2-dithiolium salts with perchloric acid. 1H N.m.r. spectral studies show that protonation of 1,6a-dithia-6-azapentalenes in trifluoroacetic acid occurs predominantly at the nitrogen atom, to form the 3-(2-methylaminovinyl)-1,2-dithiolium cations. The co-existence of low equilibrium concentrations of the corresponding C(4)-protonation products with the major products was inferred from the occurrence of H–D exchange in deuteriotrifluoroacetic acid. Exceptionally, 2,5,6-trimethyl-1,6a-dithia-6-azapentalene gave the N-and theC(4)-protonation product in comparable amounts. Variable temperature 1H n.m.r. spectral studies show that 5-t-butyl- and 5-methyl-3-(2-dimethylaminovinyl)-1,2-dithiolium perchlorate in CD3CN exist at low temperatures (–20 to –50°) as mixtures of two of two trans-isomers, owing to restricted rotation at the 3,1′-and C(2′), N-bonds. At +60° rapid interconversion of the isomers gives a time-averaged spectrum corresponding to the presence of a single trans species. Similar temperature-dependent behaviour was shown by the structurally related 5-t-butyl-and 5-methyl-3-(2-methylaminovinyl)-1,2-dithiolium perchlorates.

Diazepines. Part XIII. Relative reactivities of positions 5 and 6 in electrophilic substitution reactions of 2,3-dihydro-1,4-diazepinium salts measured by deuterium exchange kinetics

Kinetics and activation parameters have been measured for deuteriation at position 6 of 2,3-dihydro-5,7-dimethyl-1,4-diazepinium perchlorate by deuteriosulphuric acid in deuterium oxide, and the data are compared with those for the corresponding deuteriation catalysed by primary phosphate ions. In contrast, protons at positions 5 and 7 in two other diazepines were only slightly affected by dilute deuteriosulphuric acid. In anhydrous deuteriotrifluoroacetic acid protons at positions 5 and 7 were completely unaffected. The relative reactivities of positions 6 and 5 (or 7) are discussed. The ratio of the reactivities is 109 and the difference in activation energies is 61 kJ mol–1.