Synthesis of 4,5-Dichloroisothiazole-3-carboxylic Acid Amides and Esters

Previously unknown 4,5-dichloroisothiazole-3-carboxylic acid amides and esters were synthesized by reactions of 4,5-dichloroisothiazole-3-carbonyl chloride with ammonia, heterocyclic and aromatic amines, and functionally substituted alcohols and phenols.     

Synthesis of functionally substituted isoxazole and isothiazole derivatives

Acylation of benzene and toluene with 5-phenyl- and 5-(p-tolyl)isoxazole-3-carbonyl chlorides gave 5-phenyl(or p-tolyl)isoxazol-3-yl phenyl(or p-tolyl)ketones which were reduced to the corresponding alcohols with sodium tetrahydridoborate in propan-2-ol. Selective reduction of the carboxy group in 4,5-dichloroisothiazole-3-carboxylic acid was achieved by the action of BH₃, and the aldehyde group in 4-formyl-2-methoxyphenyl 5-arylisoxazole-3-carboxylates and 4,5-dichloroisothiazole-3-carboxylates was reduced to hydroxymethyl group with sodium triacetoxyhydridoborate in benzene. Acylation of the resulting hydroxymethyl derivatives with 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides afforded the corresponding esters containing two azole fragments in their molecules.     

The preparation of 3-chlorobenzo[b] thiophene derivatives from cinnamie acids

The reaction of cinnamic acid derivatives with thionyl chloride and pyridine is a general procedure for the preparation of derivatives of 3-chlorobenzo[b] thiophene-2-carbonyl chloride from readily accessible starting materials. These compounds are easily converted to the corresponding acids, esters and amines.     

4-Functionally Substituted 3-Hetarylpyrazoles: VI. 1,3-Diaryl-4-isocyanatopyrazoles

1,3-Diaryl-4-isocyanatopyrazoles were obtained by reaction of 1,3-diarylpyrazole-4-carboxylic acids with ethyl chloroformate and sodium azide or by reaction of 1,3-diarylpyrazole-4-carbonyl chloride with trimethylsilyl azide. The title compounds react with amines, hydrazine hydrate, alcohols, phenols, and monochloroacetic acid to afford 4-pyrazolyl-substituted ureas, semicarbazides, urethanes, and amides respectively.     

Facile catalyzed acylation of heteroatoms using BiCl3 generated in situ from the procatalyst BiOCl and acetyl chloride

Acylation of a variety of alcohols, phenols, aliphatic and aromatic amines, a thiol and a thiophenol proceeds efficiently using BiCl₃ generated in situ from the procatalyst BiOCl and acetyl chloride in a solvent or under solventless conditions, furnishing the corresponding acylated derivatives in very good to excellent yields.     

Plant Coumarins: XVII. Synthesis and Transformations of 7-Hydroxy-2-oxo-2H-chromene-6-carboxamides

Russian Journal of Organic Chemistry - Umbelliferone-6-carbonyl chloride reacted with amines and α-, β-, and ω-amino acid methyl esters to afford the corresponding N-substituted...     

N-Methylcarbazole-3-carboxylic Acid and Its Amides

N-Methylcarbazole-3-carboxylic acid was synthesized from N-methyl-2-amino-4-carboxydiphenyl-amine through the corresponding diazo compound by a modified Pschorr procedure. The acid was converted into N-methylcarbazole-3-carbonyl chloride which was treated with amines containing benzo- and aza-crown ether moieties, as well as with 3-(dimethylamino)propylamine, to obtain the respective N-substituted amides.     

Novel and efficient method for esterification, amidation between carboxylic acids and equimolar amounts of alcohols, and amines utilizing Me2NSO2Cl and N,N-dimethylamines; its application to the synthesis of coumaperine, a natural chemopreventive dieneamide

Various carboxylic esters or amides were prepared in good to excellent yield between carboxylic acids and equimolar amounts of alcohols or amines under very mild conditions (0-45°C; within 3 h) using dimethylsulfamoyl chloride (Me₂NSO₂Cl; 1) combined with N,N-dimethylamines (Me₂NR: 2a; R=Me, 2b; R=Bu). The choice of the sulfamoyl chloride and the amine is crucial for the reaction; that is, sterically uncrowded amines accelerated the present esterification and amidation. This agent had some advantages over methanesulfonyl chloride (3)/amines as for the atom-economy, avoidance of side reactions, and had very high chemoselectivity toward the carboxyl group vs the hydroxyl group; the experiment was performed by the addition of 1 to the mixture of carboxylic acids and alcohols. Application of this method to the synthesis of coumaperine, a chemopreventive natural product, was performed using the present amidation as a key step.     

Facile synthesis of 2-(substituted amino)-4H-thieno[3,2-e]-1,3-thiazin-4-ones

Interaction between 2,5-dichlorothiophene-3-carbonyl isothiocyanate, accessible via 2,5-dichlorothiophene-3-carbonyl chloride, and model heterocyclic amines produced the respective 2,5-dichloro-N-(substituted aminocarbonothioyl)thiophene-3-carboxamides. Upon heating, the deprotonated form of the latter underwent intramolecular cyclization to deliver the corresponding 2-(substituted amino)-4H-thieno[3,2-e]-1,3-thiazin-4-ones. The structures of these new bicyclic derivatives and their acyclic precursors are based on microanalytical and spectral (IR, MS, and NMR) data.     

Reductive cleavage of an SiCl3 group by amine hydrochlorides and base

A new procedure has been developed for removing the SiCl₃ group from α-trichlorosilyl-substituted amines. In this procedure the trichlorosilyl substrate is treated first with amine hydrochloride in CH₃CN, followed by hydrolysis with aqueous hydroxide. Using this sequence, amines corresponding to replacement of the trichlorosilyl group with hydrogen can be conveniently isolated in good yields for all tested cases. Evidence suggests the intermediacy of an unstable chlorosilane species formed by probable nucleophilic attack of chloride. In conjunction with the addition reaction fo HSiCl₃ to enamines to form the α-trichlorisilyl amines, the cleavage completes a new method for the transformation of enamines to amines which could be a useful alternative to either catalytic hydrogenation or metal hydride reduction.     

3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxo-qinoxaline-2-carbonyl azide as a highly sensitive fluorescence derivatization reagent for primary,secondary and tertiary alcohols in high-performance liquid chromatography

3,4-Dhydro-6,7-dimethoxy-4-methyl-3-oxo-quinoxaline-2-carbonyl azide is a highly senstive fluorescence derivatization reagent for primary, secondary and tertiary alcohols for high-performance liquid chromatography. Reaction conditions are optimized with benzyl alcohol, n-hexanol, cyclohexanol and 2-methyl-2-butanol. The reagent reacts with the alcohols in benzene to produce the corresponding fluorescent carbamic acid esters, which can be separated on a reversed-phase column YMC Pack C₈ with aqueous methanol as eluent. the detection limits for the alchols are 2–5 fmol per 10-μl njection. The reagent also reacts with hydroxysteroids with primary, secondary and/or tertiary alcoholic group(s) to form fluorescent derivatives. Hydroxycarboxylic acids and phenols do not give any chromatographic peaks.     

The “Borrowing Hydrogen Strategy” by Supported Ruthenium Hydroxide Catalysts: Synthetic Scope of Symmetrically and Unsymmetrically Substituted Amines

The N‐alkylation of ammonia (or its surrogates, such as urea, NH₄HCO₃, and (NH₄)₂CO₃) and amines with alcohols, including primary and secondary alcohols, was efficiently promoted under anaerobic conditions by the easily prepared and inexpensive supported ruthenium hydroxide catalyst Ru(OH)_x/TiO₂. Various types of symmetrically and unsymmetrically substituted “tertiary” amines could be synthesized by the N‐alkylation of ammonia (or its surrogates) and amines with “primary” alcohols. On the other hand, the N‐alkylation of ammonia surrogates (i.e., urea and NH₄HCO₃) with “secondary” alcohols selectively produced the corresponding symmetrically substituted “secondary” amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or secondary amines produced. Under aerobic conditions, nitriles could be synthesized directly from alcohols and ammonia surrogates. The observed catalysis for the present N‐alkylation reactions was intrinsically heterogeneous, and the retrieved catalyst could be reused without any significant loss of catalytic performance. The present catalytic transformation would proceed through consecutive N‐alkylation reactions, in which alcohols act as alkylating reagents. On the basis of deuterium‐labeling experiments, the formation of the ruthenium dihydride species is suggested during the N‐alkylation reactions.     

A Mild and Efficient Method for Chemoselective Silylation of Alcohols Using Hexamethyldisilazane in the Presence of Silica Chloride

Reaction of alcohols with hexamethyldisilazane in the presence of silica chloride provides efficiently the corresponding trimethylsilyl ethers. This system discriminates absolutely amines and thiols from alcohols.     

Conversion of tertiary alcohols to tert-alkyl azides by way of quinone-mediated oxidation-reduction condensation using alkyl diphenylphosphinites

A novel method for the preparation of alkyl azides from alcohols by way of oxidation-reduction condensation is described. In this reaction, the sterically-hindered tert-alkyl phosphinites that are prepared from the corresponding alcohols are converted into tert-alkyl azides with almost complete inversion of their stereochemistry: the obtained alkyl azides are then successfully reduced to afford the corresponding amines on treatment with LiAlH₄, thus, a versatile method for the preparation of chiral amines from the corresponding chiral alcohols is established.     

Ritter Reaction with Cyclopropyl Ketones and Cyclopropyl Alcohols: Synthesis of N-Actyl- γ-Keto and N-Acyl Hohoallyl Amines

A variety of conjugated cyclopropyl ketones and cyclopropylcarbinyl alcohols were reacted with two nitriles viz. CH₃ CN and CH₂[dbnd]CH-CN in presence of cone. H₂ SO₄. It was found that with appropriate substitutions cyclopropyl ketones gave N-Acyl-γ-keto amines whereas cyclopropylcarbinyl alcohols gave the corresponding N-Acyl homoallylic amines in reasonably good yields. The olefins obtained had E-stereo-chemistry. With bicyclic cyclopropylcarbinyl alcohols the ring expanded products were formed. A plausible rationale is provided to account for these observations     

Microwave-enhanced bismuth triflate-catalyzed epoxide opening with aliphatic amines

In the presence of a catalytic amount of Bi(OTf)₃·4H₂O and under microwave irradiation, neat mixtures of epoxides and amines afforded smoothly the corresponding 2-amino alcohols. A wide variety of aliphatic amines were reacted with cycloalkene oxide, styrene oxide, and stilbene oxide. The reaction proceeded rapidly and afforded the 2-amino alcohols in high up to quantitative yields. All products could be obtained without aqueous work-up by simple filtration.     

Some aliphatic esters of benzoxazolin-2-one-3-carboxylic acid

Phosgene and benzoxazolin-2-one in the presence of diethylaniline gives benzoxazolin-2-one-3-carbonyl chloride. The latter and aliphatic alcohols, in the presence of a hydrogen chloride acceptor, gives esters of benzoxazolin-2-one-3-carboxylic acid.     

Facile synthesis of 2-(substituted amino)-4<Emphasis Type="Italic">H</Emphasis>-thieno[3,2-<Emphasis Type="Italic">e</Emphasis>]-1,3-thiazin-4-ones

Interaction between 2,5-dichlorothiophene-3-carbonyl isothiocyanate, accessible via 2,5-dichlorothiophene-3-carbonyl chloride, and model heterocyclic amines produced the respective 2,5-dichloro-N-(substituted aminocarbonothioyl)thiophene-3-carboxamides. Upon heating, the deprotonated form of the latter underwent intramolecular cyclization to deliver the corresponding 2-(substituted amino)-4H-thieno[3,2-e]-1,3-thiazin-4-ones. The structures of these new bicyclic derivatives and their acyclic precursors are based on microanalytical and spectral (IR, MS, and NMR) data. Correspondence: Rajab Abu-El-Halawa, Chemistry Department, Faculty of Science, Al al-Bayt University, Mafraq, Jordan.     

1,1'-Binaphthyl-2,2'-diyl phosphoroselenoyl chloride as a chiral molecular tool for the preparation of enantiomerically pure alcohols and amines

Enantiomerically pure phosphoroselenoyl chloride bearing a binaphthyl group was synthesized. This phosphoroselenoyl chloride was used to discriminate and resolve simple secondary alcohols. Stereospecific conversions of diastereomerically pure phosphoroselenoic acid esters, obtained by reaction of the chloride with simple secondary alcohols, to enantiomerically pure alcohols and amines were also achieved.     

Iron-catalyzed cascade reaction of ynone with o-aminoaryl compounds: a Michael addition-cyclization approach to 3-carbonyl quinolines

An efficient iron-catalyzed cascade Michael addition-cyclization of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones, and o-aminobenzyl alcohols with ynones for the synthesis of 3-carbonyl quinolines is reported. The reactions proceed to afford 3-carbonyl quinoline derivatives with or without substituent at the C-4 position in good to high yields using Iron(III) chloride hexahydrate as the catalyst in the air.