Oxazoline Derivatives Research Articles

Studies on 2-Aziridinecarboxylic Acid. V. Formation of Dehydroamino Acid Containing Peptides via the Isomerization by NaI of 2-Aziridinecarboxylic Acid Containing Peptides

Abstract The 2-aziridinecarboxylic acid residue in peptides was isomerized with NaI in an acetone solution into the corresponding dehydroalanine or dehydro-2-aminobutyric acid derivatives, but not into the corresponding 2-oxazoline derivatives.

Convenient method for synthesis of 2-methyl-glyco[2,1-d]-2-oxazolines

A convenient method was proposed for the synthesis of oxazoline derivatives of mono- and oligosaccharides in high yields and under mild conditions, which exclude the destruction of the glycoside linkage in the oligosaccharides.

Partially benzylated oxazoline derivatives of 2-acetamido-2-deoxy- D-glucopyranose as “standardized intermediates” for oligosaccharide synthesis. preparation of disaccharides having the sequences β- D-Glc pNAc(1→x)- D-Gal and β- D-Glc pNAc(1→4)- D-GlcNAc

Three benzyl tri- O-benzyl-l-thio-β- D-galactopyranosides ( 5, 6, and 7) were prepared from the corresponding O-acyltri- O-benzyl- D-galactopyranosyl bromides ( 1a-c) via the benzylxanthates 2a-c and the fully protected benzyl thiogalactosides 3a-c. The α anomer ( 4) of 5 resulted from the reaction of bromide 1a with α-toluenethiol. Conditions were found for the successful coupling of O-acetyl-di- O-benzyl derivatives ( 8 and 13) of 2-methyl-(1,2-dideoxy-α- D-glucopyrano)-[2,1- d]-2-oxazoline to the thiogalactosides 5-7, and to a partially protected glycoside ( 16) or 2-acetamido-2-deoxy- D-glucose. The products were fully substituted disaccharides of 2-acetamido-2-deoxy-β- D-glucose linked 1→3 ( 9a), 1→6 ( 11a), 1→4 ( 14a), and 1→4 ( 17a), respectively. Cleavage of the single, temporary protecting group ( O-acetyl) from these compounds gave partially deblocked disaccharides capable of chain extension from position 3′ ( 9b and 11b) or 4′ ( 14b and 17b).

ASYMMETRIC TRANSFORMATION OF 2-PHENYLALKANOIC ACIDS VIA OXAZOLINE DERIVATIVES

Abstract Asymmetric transformation of 2-phenylalkanoic acids via oxazoline derivatives was investigated. (S)-Phenylalaninol was used as a chiral auxiliary in the transformation, and the acids were obtained in the optical yields of 29–53%.

Asymmetric Transformation of 2-Chloroalkanoic Acids via Oxazoline Derivatives

Asymmetric Transformation of 2-Chloroalkanoic Acids via Oxazoline Derivatives

O-benzylated oxazoline derivatives of 2-acetamido-2-deoxy- d-glucopyranose from 1-propenyl glycosides. synthesis of the propenyl glycosides and their direct cyclization

1-Propenyl 2-acetamido-3,4,6-tri- O-acetyl-2-deoxy-α- and β- d-glucopyranosides ( 3α, 3β) were obtained by the successive isomerization and acetylation of the known allyl glycosides 1α and 1β. The allyl glycosides were also converted, via their benzylidene 4,6-acetals, into the 4,6-di- O-benzyl-3- O-(2-butenyl) derivatives 9α and 9β. The simultaneous decrotylation and isomerization of 9β, followed by acetylation, gave 1-propenyl 2-acetamido-3- O-acetyl-4,6-di- O-benzyl-2-deoxy-β- d-glucopyranoside ( 11). The 4- O-acetyl-3,6-di- O-benzyl isomer ( 18) of 11 was synthesized from 1β by a route involving selective, partial benzoylation, and then protection of O-4 as the 2-tetrahydropyranyl ether. As previously described, the 1-propenyl β-glycosides 3β, 11, and 18, and the tri- O-benzyl analog 5β, were converted in near-quantitative yield into the corresponding, substituted oxazolines by the action of mercuric chloride and mercuric oxide in boiling acetonitrile. An optimized procedure for this cyclization is given. The 1H-n.m.r. spectra of the tri- O-acetyl ( 19) and the 4- O-acetyl-3,6-di- O-benzyl ( 21) oxazolines indicate a modified 0 S 2, conformation for these compounds.

Heterocycles from substituted amides. VII Oxazoles from 2‐isocyanoacetamides

AbstractCertain heretofore unknown tertiary α‐isocyanacetanilides 1 are reported for the first time, prepared by methods necessarily different from those employed to prepare the previously cited aliphatic α‐isocyano‐acetamides 2. Like 2, 1 has been shown to readily undergo dialkylation with alkyl halides. Moreover, 1 also gives rise to oxazole and oxazoline derivatives upon reaction with acyl halides and aldehydes, respectively, resembling the similarly activated α‐isocyano esters and sulfones. Further, in a demonstrable ring‐chain tautomeric equilibration, apparently restricted to tertiary amides, 1 readily cyclizes, providing the only known synthesis of 5‐amino‐2,4‐unsubstituted oxazoles 3. In other examples 4‐chloro and 4‐alkyl‐5‐amino‐oxazoles are produced. The materials and reactions are characterized, and compared with previous related studies.

ChemInform Abstract: CYCLIZATION REACTIONS BY THE USE OF 1,2‐BIS(TRIMETHYLSILYL)IMINO‐1,2‐DIPHENYLETHANE

Imidazole (3) or oxazoline (4) derivatives are obtained by the reactions of 1,2-bis(trimethylsilyl)imino-1,2-diphenylethane with carbonyl compounds after thermolysis or methanolysis of the common intermediate (2) of which thermal stability seems to depend on the electronic character of R.

Synthetic and conformational aspects of trimethylammonium-methyl substituted 2-oxazolines as potential cholinergics

The effects of some structural features on the cholinergic activity of 2-oxazoline derivatives has been investigated. Improved synthetic approaches to the 2-oxazoline ring system are developed, and several new fluorinated 2-oxazolines are described. The extensive NMR data give insight into the rotameric behaviour of the substituents.

CYCLIZATION REACTIONS BY THE USE OF 1,2-BIS(TRIMETHYLSILYL)IMINO-1,2-DIPHENYLETHANE

Abstract Imidazole (3) or oxazoline (4) derivatives are obtained by the reactions of 1,2-bis(trimethylsilyl)imino-1,2-diphenylethane with carbonyl compounds after thermolysis or methanolysis of the common intermediate (2) of which thermal stability seems to depend on the electronic character of R.

ChemInform Abstract: STUDIES ON HYDROXY AMINO ACIDS. VI. FORMATION OF THE OXAZOLINE DERIVATIVES FROM N‐ACYL‐β‐HYDROXY AMINO ACID PEPTIDES

AbstractBei Detosylierung der aus den N‐Acylaminosäurederivaten (I) erhältlichen O‐Tosylderivate (II) entstehen hauptsächlich Oxazolinderivate (III).

Studies on Hydroxy Amino Acids. VI. Formation of the Oxazoline Derivatives from N-Acyl-β-hydroxy Amino Acid Peptides

Abstract Oxazoline derivatives were mainly obtained from the O-tosyl-N-acyl-β-hydroxy amino acid peptides by β-elimination reaction. Dehydroalanine or hydantoin derivatives were isolated when the urethane type acyl groups were used.

Syntheses of Surface Active 2-Oxazoline Derivatives and Their Properties

An attempt has been made to prepare surfactants containing oxazoline ring such as 2-alkyl-2-oxazoline organic salt and N-alkyl-4, 4-dimethyl-2-oxazolinium bromide.2-Alkyl-2-oxazoline was formed by the ring closure of N-β-chloroethyl fatty amide made by condensing a fatty acid (C10-C14) with etanolamine followed by chlorination and 4, 4-dimethyl-2-oxazoline was prepared from formic acid and 2-amino-2-methyl-1-propanol.From the experimental results it was found rhat the organic salts of oxazoline were generally superior in surface tension lowering ability and wetting power, but inferior in foaming power and emulsifying power to the oxazolinium salts.

The characterization of isomeric oxazoline derivatives by mass spectrometry

Geometric and positional isomers of the Δ2-oxazoline ring system have been characterized by their mass spectral fragmentation patterns. The composition of the major ions in the spectra have been determined by high resolution mass spectrometry. A fragmentation pathway for the formation of these ions is presented.

Thermal rearrangement of xanthates to dithiolcarbonates—I

During the pyrolysis of β-dialkylaminoalkyl S-methyl xanthates, dl- trans-2-dimethylaminocyclohexyl S-methyl xanthalate was rearranged without elimination to the corresponding dithiolcarbonate while the cis isomer suffered over-all elimination. It has been suggested that the dimethylamino group attached to the carbon carrying the xanthate group induces the rearrangement. Other examples studied support this mechanism. 2-Benzamidoethyl S-methyl and dl- trans-2-benzamidocyclohexyl S-methyl xanthates have been converted to the corresponding oxazoline derivatives.

2-Aryl-4-methyl-4-chlorocarbonyl-oxymethyl-2-oxazolines : Chemical reactivity and infra-red spectra

2-Aryl-4-methyl-4-chlorocarbonyl-oxymethyl-2-oxazolines have been shown to exhibit a particular reactivity towards nucleophilic reagents. This reactivity is to be attributed to the presence of the chlorocarbonic ester function. Reaction of the above 2-oxazolines with ammonia (or dimethylamine) results in ring opening, with the formation of benzamide (or N,N-dimethyl-benzamide) and 4-methyl-4-chloromethyl-oxazolidin-2-one (or 4-methyl-4-N,N-dimethylaminomethyl-oxazolidin-2-one). The presence of the chlorocarbonic ester function also affects the position of the C=N band in the infra-red spectrum of these 2-oxazoline derivatives; this band is shifted approximately 40 cm −1 towards lower wavelengths in comparison with the absorption band of structurally related compounds which do not possess the chlorocarbonic ester group. A possible reaction mechanism is proposed together with a correlation of the chemical and spectroscopical findings.

THE STRUCTURES AND CHEMISTRY OF THE PRODUCTS FROM THE REACTION OF AMINO ALCOHOLS WITH CARBON DISULPHIDE

A study of the infrared spectra of the oxazoline derivatives, which are formed by the condensation of carbon disulphide with amino alcohols, shows that they possess the oxazolidine-2-thione structure rather than the tautomeric 2-thiol-2-oxazoline structure. 2-Benzylamino-4,4-dimethyl-2-oxazoline was formed by the reaction of benzylamine with 2-methylmercapto-4,4-dimethyl-2-oxazolinium iodide. 5-Diethylaminomethyl-2-oxazolidone and its methylation product also have been prepared.