An efficient synthesis of β-amino esters via Zn(OTf)2-catalyzed Mannich-type reaction

A Zn(OTf)₂-catalyzed Mannich-type reaction of the electron-deficient aromatic amines with the electron-deficient aromatic aldehydes and diethyl malonic ester was described. This three-component reaction afforded the corresponding β-amino esters in good yields.     

Formation of 3-Hydroxyalkyl Carbamates from Carbon Dioxide,Amines and Oxetanes

The reactions of carbon dioxide, primary or secondary aliphatic amines and oxetanes at a CO₂ pressure of 40 atm at 100–120°C without any catalysts afforded new monocarbamates of 1,3-propanediols, with concomitant formation of amino alcohols from oxetanes and amines.     

An efficient synthesis of dithiocarbamates under ultrasound irradiation in water

Abstract  

Multicomponent reactions with ultrasonic activation have been used as a simple, rapid, atom economic, and green method for the synthesis of dithiocarbamate derivatives in water. The one-pot, three-component condensation of primary and secondary amines with carbon disulfide and unsaturated carbonyl compounds or alkyl halides under ultrasonic irradiation was developed as a green and fast protocol for the rapid high-yielding preparation of dithiocarbamates in water.     

Ultrasound mediated green synthesis of rhodanine derivatives: Synthesis,chemical behavior,and antibacterial activity

A variety of rhodanine derivatives were synthesized via a three-component reaction of carbon disulfide, amines, and dialkyl acetylenedicarboxylate in polyethylene glycol under conventional stirring or ultrasound irradiation. The sonochemical-assisted procedure provides an improved and accelerated conversion when compared to the conventional reaction, with increased rate of reaction and quality of product obtained. The product formed, 2a, could be readily converted to bis-rhodanine under microwave conditions. Moreover, the pyranothiazoles 9a,b were prepared from the corresponding rhodanines 2a,b and malononitrile. Fifteen compounds were screened for their antibacterial activities against nine human, animal and plant pathogenic Gram-positive and Gram-negative bacteria using the agar well diffusion method. Out of these derivatives, compounds 2g and 2h were the most effective against all tested bacteria.     

Synthesis of 2-sulfanylidene-1,3-thiazolidin-4-one derivatives

Three-component condensation of primary amines with carbon disulfide and dialkyl maleates afforded the corresponding alkyl (3-R-4-oxo-2-sulfanylidene-1,3-thiazolidin-5-yl)acetates whose structure was confirmed by independent synthesis and IR and ¹H NMR spectroscopy.     

Synthesis of tetrahydrophthalazine and phthalamide (phthalimide) derivatives via palladium-catalysed carbonylation of iodoarenes

1,2,3,4-Tetrahydrophthalazin-1-one and 1,2,3,4-tetrahydrophthalazin-1,4-dione derivatives were synthesised in high (up to 85%) and low yields using 2-iodobenzyl bromide and 1,2-diiodobenzene as bifunctional substrates, respectively. Iodoarenes, carbon monoxide and various hydrazine derivatives as N-nucleophiles were used in a three-component palladium-catalysed cascade hydrazinocarbonylation. A similar palladium-catalysed reaction, the aminocarbonylation of 1,2-diiodobenzene, resulted mainly in the formation of two types of major products depending on the amine N-nucleophiles: the use of primary amines yielded N-substituted phthalimides in double carbonylation, while secondary amines react with one of the iodoarene functionalities affording the corresponding 2-iodobenzamides. Due to double carbon monoxide insertion at one or both iodoarene functionalities, ketocarboxamide-carboxamide or bis-ketocarboxamide derivatives could be isolated by the modification of the reaction conditions. Some mechanistic details of the ring-closure reactions and the conditions leading to side-products are also discussed.     

A New and Facile Synthesis of Novel Pyrazolothienopyrimidines and Imidazopyrazolothienopyrimidines

4‐Amino‐3‐methyl‐1‐phenyl‐1H‐thieno[2,3‐c]pyrazole‐5‐carboxamide ( 5 ), which was synthesized by an innovative method, was used as a versatile precursor for synthesizing pyrazolothienopyrimidines and imidazopyrazolothienopyrimidines compounds. Reaction of amino thienopyrazole carboxamide 5 with triethyl orthoformate afforded thienopyrazolopyrimidine 6 . Chlorination of the latter compound, using phosphorus oxychloride afforded the chloro pyrazolothienopyrimidine 7 , which underwent nucleophilic substitution reactions with various primary and secondary amines to give the alkyl (aryl) amino pyrimidine compounds 8a–d . On the other hand, the reaction of chloropyrimidine 7 with thiourea afforded the pyrimidine thione compound 9 , which was alkylated with α‐halogentaed compounds to afford the S‐alkylated derivatives 10a–c . Also, chloroacetylation of the amino carboxamide 5 using chloroacetyl chloride yielded the chloromethyl pyrazolothienopyrimidine 12 , which underwent nucleophilic substitu‐ tion reactions with various primary and secondary amines to afford the alkyl (aryl) aminomethyl compounds 13a–f . The latter Compounds underwent Mannich reaction to give imidazopyrimidothieno‐ pyrazoles 14a–c . The newly synthesized compounds and their derivatives were fully characterized by elemental and spectral analysis.     

Transaminierungen am dimethylaminodifluorarsin

Dimethylaminodifluorarsine reacts with secondary amines with the formation of dialkylaminodifluorarsines. The same compounds are formed by the reaction of AsF₃ with secondary amines. Mechanistic and steric effects associated with these reactions are discussed and IR, ¹H, and ¹⁹F NMR spectral data presented.The reaction of dimethylaminofluorarsine with primary amines yields polymeric aminoarsines.     

Stereoselective Mannich reactions catalyzed by Tröger’s base derivatives in aqueous media

A Tröger’s base derivative (5,12-dimethyl-3,10-diphenyl-1,3,4,8,10,11-hexaazatetracyclo [6.6.1.0^2,6.0^9,13]pentadeca-2(6),4,9(13),11-tetraenes) was used as an efficient catalyst for the three-component Mannich reactions of aromatic aldehydes and aromatic amines with ketones in water at room temperature. This rapid reaction afforded the corresponding β-amino ketones in good yields with excellent stereoselectivity.     

Synthesis and antimicrobial activity of some new coumarin and dicoumarol derivatives

PTC reaction of coumarin derivative 1 with alkyl halides afforded C₄ oxygen alkylation products 2a-d in appreciative yield, whereas with phenyl isothiocyanate gives the C₃ addition product 4 ; also, one-pot three-component PTC reaction was investigated. Treatment of coumarin 1 with aromatic aldehydes in different molar ratios gives 3-arylidene derivatives 7a,b and the dicoumarol derivatives 8a,b . Pyrano chromene 9 and pyrano pyridine 10 were obtained by reaction of arylidene 7a with ethyl acetoacetate through Michael cycloaddition reaction. The stability of pyrone ring in 3-arylidene 7 and dicoumarol 8 towards different nucleophilic reagents under reflux and/or fusion conditions has been studied by the action of hydrazine hydrate, ammonium acetate, methyl amine, and p-toluidine afforded compounds 11 and 13a-c . The antimicrobial activity of some synthesized compounds has been investigated.     

OH−/Silica-Mediated One-Pot Synthesis of Dithiocarbamates Under Solvent-Free Conditions

Abstract

An efficient, versatile, and environmentally benign method for the synthesis of dithiocarbamates under solvent-free conditions is reported. The Michael addition of electron-deficient alkenes with alkyl or aryl amines and CS₂ in the presence of OH^?/silica in a one-pot three-component reaction protocol gave the corresponding dithiocarbamates in good to excellent yields. This method is suitable for a wide range of amines and a variety of Michael acceptors in solvent-free conditions. The results of the present work show the desired products in excellent yields.     

Copolymerization of propylene oxide and carbon disulfide with diethylzinc–electron-donor catalyst

Copolymerization of propylene oxide with carbon disulfide was studied by using a catalyst consisting of diethylzinc (ZnEt₂) and various electron donors. Tertiary amines, tertiary phosphines, and hexamethylphosphoric triamide were the effective donors for the copolymerization, but ZnEt₂–water, alcohol, and primary or secondary amines having high activities for the homopolymerization of propylene oxide were not effective for the copolymerization of propylene oxide and carbon disulfide. The copolymers obtained were of low molecular weight and had a monomer unit ratio (CS₂/PO) of 0.5–0.7. In addition, a considerable amount of 1,3-oxathioran-4-methyl-2-thion was isolated as a by-product.     

Efficient synthesis of polycyclic dispirooxindoles via domino Diels–Alder cyclodimerization reaction

Three-component reactions of 4-cyanopyridine or ethyl isonicotinate with electron-deficient alkynes and isatins in dimethoxyethane at room temperature afforded spiro[3H-indole-3,2′-[2H,9aH-pyrido[2,1-b][1,3]oxazine] derivatives. Alternately, the similar three-component reaction at elevated temperature resulted in polycyclic dispirooxindole derivatives. The reaction mechanism is believed to involve sequential generation and cycloaddition of Huisgen's 1,4-dipole, and Diels–Alder cyclodimerization reaction. The similar three-component reactions containing acenaphthenequinone and phenanthrenequinone also afforded corresponding polyheterocyclic derivatives.     

1,2-Dihydro-2-thioxo-4H-3,1-benzothiazin-4-one: formation from carbon disulfide and isatoic anhydride

The reaction of isatoic anhydride (1) with carbon disulfide at room temperature unexpectedly afforded 1,2-dihydro-2-thioxo-4H-3,1-benzothiazin-4-one (2). The use of ¹³C-labeled carbon disulfide elucidated that CS₂ was entirely incorporated into the product.     

Electrogenerated Base-Promoted Synthesis of Dithiocarbamate Acid Esters and 3-(N-Substituted-amino)-2-cyanodithiocrotonates from Primary or Secondary Amines and Carbon Disulfide

Electrogenerated cyanomethyl anion promotes the reaction between primary or secondary amines, carbon disulfide, and alkyl or benzyl halide. Secondary amines are converted to alkyl or benzyl dithiocarbamates, whereas primary amines give N-substituted alkyl or benzyl 3-amino-2-cyanodithiocrotonates. The mechanisms are discussed.     

Thiocarbamyolation of amine-containing compounds

Thiocarbamoylation of primary and secondary aliphatic amines with tetramethylthiuram disulfide in various solvents at different temperatures was studied. At 110°C, the reactions with primary amines afforded mixed,N,N-dimethyl-N′-alkyl(cycloalkyl)thioureas and symmetricalN,N′-dialkyl(cycloalkyl)thioureas as the final products, while the reactions with secondary amines gave mixtures of dithiocarbamate salts with “symmetrical” derivatives predominating.     

Thiocarbamoylation of amine-containing compounds

Thiocarbamoylation of aliphatic amines with tetramethylthiuram disulfide (TMTD) was studied. The reactions were established to proceed according to a two-stage mechanism. In the first stage,S-(thiocarbamoyl)thiohydroxylamines and dimethyl dithiocarbamates are formed. The latter exist in equilibrium with dimethyldithiocarbamic acid, which can undergo decomposition to give dimethylamine and carbon disulfide. In the second stage, several competitive transformations of these intermediates into the final products occur,viz., (1) the reactions of CS₂ with primary amines on heating (70–110 °C) yield mixed and symmetrical thioureas and the reactions of CS₂ with secondary amines give symmetrical dithiocarbamates, and (2) insertion of CS₂ intoS-(thiocarbamoyl)thiohydroxylamines affords thiuram disulfides. Thiuram disulfides formed from primary amines decompose to give isothiocyanates, which are converted into thioureas by condensation with amines, whereas thiuram disulfides which are obtained in the reactions with secondary amines and which cannot form thioureas react with amines analogously to TMTD. For Part 4, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 334–342, February, 2000.     

Bifunctional Heterogeneous Catalysis of Silica–Alumina‐Supported Tertiary Amines with Controlled Acid–Base Interactions for Efficient 1,4‐Addition Reactions

We report the first tunable bifunctional surface of silica–alumina‐supported tertiary amines (SA–NEt₂) active for catalytic 1,4‐addition reactions of nitroalkanes and thiols to electron‐deficient alkenes. The 1,4‐addition reaction of nitroalkanes to electron‐deficient alkenes is one of the most useful carbon–carbon bond‐forming reactions and applicable toward a wide range of organic syntheses. The reaction between nitroethane and methyl vinyl ketone scarcely proceeded with either SA or homogeneous amines, and a mixture of SA and amines showed very low catalytic activity. In addition, undesirable side reactions occurred in the case of a strong base like sodium ethoxide employed as a catalytic reagent. Only the present SA‐supported amine (SA–NEt₂) catalyst enabled selective formation of a double‐alkylated product without promotions of side reactions such as an intramolecular cyclization reaction. The heterogeneous SA–NEt₂ catalyst was easily recovered from the reaction mixture by simple filtration and reusable with retention of its catalytic activity and selectivity. Furthermore, the SA–NEt₂ catalyst system was applicable to the addition reaction of other nitroalkanes and thiols to various electron‐deficient alkenes. The solid‐state magic‐angle spinning (MAS) NMR spectroscopic analyses, including variable‐contact‐time ¹³C cross‐polarization (CP)/MAS NMR spectroscopy, revealed that acid–base interactions between surface acid sites and immobilized amines can be controlled by pretreatment of SA at different temperatures. The catalytic activities for these addition reactions were strongly affected by the surface acid–base interactions.     

Fe3O4@SiO2‐copper sucrose xanthate as a green nanocatalyst for N‐, O‐ and S‐arylation

Formation of C(sp²)–X bonds was carried out using a Fe₃O₄@SiO₂‐copper(I) sucrose xanthate nanoparticle catalyst with the aid of the copper(I) xanthate moiety in the catalyst which was prepared from the reaction between sucrose and carbon disulfide through an alkaline medium via the traditional Zeise approach. Various techniques were employed for the characterization of these novel nanoparticles. Three sorts of heteroatoms, N, O and S, successfully underwent heteroatom arylation to produce secondary or tertiary amines, ethers and thioethers, respectively.     

Novel nitrogen ligands based on imidazole derivatives and their application in asymmetric catalysis

Recently prepared chiral amines have been used in the preparation of novel tridentate ligands based on an imidazole ring with an additional (hetero)ring. The synthesis was carried out by the reaction of chiral amines with suitable aldehydes (2-phenylimidazole-4-carbaldehyde, 2-hydroxybenzaldehyde or pyridine-2-carbaldehyde) under reductive conditions (H₂/Pd or NaBH₄). All ligands prepared showed strong hydrogen bonds in d₆-DMSO solution, which resulted in hindered imidazole tautomerism. The observed hindered tautomerism was studied by ¹H NMR spectroscopy. The structures of the prepared ligands were also confirmed by APCI mass spectroscopy. Both chiral amines and tridentate compounds have been applied as ligands in copper (II)-catalyzed nitroaldol reactions (Henry reaction). Various reaction conditions for the Henry reaction have been studied (influence of temperature, molar ratio, solvent or copper (II) precursors). The compounds prepared with the two imidazole rings showed fast reaction times and a reversal in enantioselectivity compared to other chiral amines.