Synthesis of 2,3-dihydroindoles, indoles, and anilines by transition metal-free amination of aryl chlorides

Aliphatic and aromatic amines react with 2- and 3-chlorostyrene in the presence of potassium tert-butoxide to give N-substituted 2,3-dihydroindoles in good yields. The combination of this domino-amination protocol with a suitable dehydrogenation reaction gives access to pharmacologically interesting indoles in a one-pot procedure. Overall product yields of N-substituted indoles >50% are obtained by this method starting from commercially available substrates. In addition to the intramolecular base-promoted amination of aromatic C-Cl bonds, metal-free intermolecular aminations of aryl chlorides with primary and secondary amines are described. The use of potassium tert-butoxide as base allows the synthesis of various anilines in good to excellent yields. Due to the formation of aryne intermediates, either N-substituted anilines or meta-substituted anilines are produced with excellent selectivities.     

Alkali Metal and Trimethylsilyl Carbamoselenothioates – Synthesis,Structure, and some Reactions

This paper describes the synthesis and some reactions of potassium, rubidium, cesium and trimethylsilyl carbamoselenothioates. The potassium salts were synthesized in 70–80 % yields by reacting the corresponding thiocarbamoyl chlorides with potassium selenide in acetonitrile. Furthermore, the rubidium and cesium salts were obtained in good yields by treating the trimethylsilyl esters with the corresponding metal fluorides. The crystal structure of acetonitrile‐solvated potassium N,N‐dimethylcarbamoselenothioate consisted of dimeric units, featuring μ‐carbamoselenothioate anions associated with potassium cations that are located on the upper and lower sides of a plane involving two opposing carbamoselenothioate groups. These heavier alkali metal salts readily reacted with alkyl halides to give both S‐ and Se‐alkyl esters. The reaction of the potassium salts with trimethylsilyl chlorides forms S‐ and Se‐trimethylsilyl carbamoselenothioates which are in equilibrium. The reaction of the salts and silyl esters with organo Group‐14 and ‐15 elements halides gave exclusively the corresponding Se‐substituted products in good yields.     

The synthesis of 8-allyl-2-styrylchromones by the modified baker-venkataraman transformation

Substituted-2-hydroxy-3-allylacetophenones 2 react with cinnamoyl chlorides 3 in potassium carbonate-acetone to give good yields of polyfunctional 1-(2-hydroxy-3-allylaryl)-5-aryl-4-pentene-1,3-diones 4 which exist in their enol forms 5 . These on acid catalysed cyclodehydration gave 70–80% yields of substituted 8-allyl-2-styrylchromones 6 .     

Suzuki coupling of potassium cyclopropyl- and alkoxymethyltrifluoroborates with benzyl chlorides

Efficient Csp(3)-Csp(3) Suzuki couplings have been developed with both potassium cyclopropyl- and alkoxymethyltrifluoroborates. Moderate to good yields have been achieved in the cross-coupling of potassium cyclopropyltrifluoroborate with benzyl chlorides possessing electron-donating or electron-withdrawing substituents. Benzyl chloride was also successfully cross-coupled to potassium alkoxymethyltrifluoroborates derived from primary, secondary, and tertiary alcohols.     

Chemoselective cross-coupling Suzuki-Miyaura reaction of (Z)-(2-chlorovinyl)tellurides and potassium aryltrifluoroborate salts

An ultrasound-assisted synthesis of functionalized vinylic chlorides is described by palladium-catalyzed cross-coupling reaction of potassium aryltrifluoroborate salts and (Z)-2-chloro vinylic tellurides. This procedure offers easy access to vinylic chlorides architecture that contains sterically demanding groups in good yields.     

Synthesis of 4-aryl-7-methoxy-9-thia-[1,3,4a]triazafluorene-2-selones via a three-component condensation of 6-methoxybenzothiazol-2-ylamine,potassium selenocyanate and an acyl chloride

Abstract

A simple, one-pot synthesis of six 4-aryl-7-methoxy-9-thia-[1,3,4a]triazafluorene-2-selones has been achieved in moderate to good yields via a three-component condensation of 6-methoxybenzothiazol-2-ylamine, potassium selenocyanate and variously substituted benzoyl chlorides in acetone at room temperature.     

A facile synthesis of potassium selenocarboxylates and their oxidation with XeF2 to diacyl diselenides: An X‐ray structural analysis of di(4‐methoxybenzoyl) diselenide

Several potassium selenocarboxylates were synthesized in moderate to good yields by the direct reaction of acyl chlorides with potassium selenide. The potassium salts were readily oxidized with XeF₂ to give diacyl diselenides in quantitative yields. The structure of di(4‐methoxybenzoyl) diselenide was established by X‐ray diffraction analysis. Intramolecular interactions between the carbonyl oxygen and the selenium that is connected to the opposite carbonyl group were observed. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 373–379, 1999     

A One‐pot,Four‐component Protocol for the Synthesis of 2‐Aroylimino‐3‐aryl‐4‐methyl‐5‐acetyl‐1,3‐thiazolines

A concise and efficient route for the synthesis of new 2‐aroylimino‐3‐aryl‐4‐methyl‐5‐acetyl‐1,3‐thiazolines in good to excellent yields is described. This involves the one‐pot, four‐component reaction of suitable aroyl chlorides, potassium thiocyanate, anilines, and 3‐chloropentane‐2,4‐dione in the presence of N‐methylimidazole.     

Synthesis and some Reactions of Alkali Metal Carbamotelluroates

Sodium and potassium carbamotelluroates [M(R₂NCOTe), M = Na, K, Rb, Cs] were synthesized in moderate to good yields by reacting carbamoyl chloride with the corresponding alkali metal tellurides. The salts readily reacted with trimethylsilyl chloride to form O‐trimethylsilyl carbamotelluroate (R₂NCTeOSiMe₃), which further reacted with RbF and CsF to lead to the corresponding heavy alkali metal carbamotelluroates. These salts reacted with alkyl iodide and carbamoyl chlorides to give the corresponding Te‐alkyl carbamotelluroates and dicarbamoyl tellurides in moderate yields.     

Formation of 6-formyl-7-hydroxy-8-methoxycoumarin and 5,8-dioxopsoralen by reaction of 8-methoxypsoralen with H2O2 and potassium superoxide (KO2) catalyzed by halogenated or perhalogenated 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides

The oxidation of 8-methoxypsoralen (2) with hydrogen peroxide and potassium superoxide catalyzed by 5,10,15,20-(2,4,6-trimethylphenyl)porphyrinatoiron(III) chlorides [Me12TPPFe(III)Cl] (1a) and 5,10,15,20-(2,6-dichlorophenyl)porphyrinatoiron(III) chlorides [Cl8TPPFe(III)Cl] (1b) in dichloromethane gives 6-formyl-7-hydroxy-8-methoxycoumarin (3) in moderate yields, whereas the oxidation of (2) with H2O2 catalyzed by 5,10,15,20-(2,6-dichlorophenyl)-beta-octahaloporphyrinatoiron(III) chlorides [Cl8betaX8TPPFe(III)Cl] (X=Cl, Br) (1c, 1d) gives specifically 5,8-dioxopsoralen (4) in moderate yields.     

Palladium-catalyzed decarboxylative arylation of potassium cyanoacetate: synthesis of α-diaryl nitriles from aryl halides

A palladium-catalyzed decarboxylative coupling of potassium cyanoacetate with aryl bromides and chlorides is described. The reaction conditions feature the absence of additional strong inorganic bases and provide ester functional group tolerance. With Pd(dba)(2) and XPhos ligand as the catalyst system, α-diaryl nitriles can be obtained in good yields.     

Highly regio- and stereoselective acylboration, acylsilation, and acylstannation of allenes catalyzed by phosphine-free palladium complexes: an efficient route to a new class of 2-acylallylmetal reagents

A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry.     

Ugi reaction of thiouridocarboxylic acids: A synthesis of thiourea-peptoids

Benzoylthioureidocarboxylic acids, prepared from benzoyl chlorides, potassium thiocyanate, and α-aminoacids, are used as acid components in the Ugi reaction to produce thiourea-peptoids in moderate to good yields.     

O‐Triorganosilyl Carbamoselenoates – Synthesis and Reactions

A series of O‐triorganosilyl carbamoselenoates were isolated in good yields from the reaction of sodium or potassium carbamoselenoates with triorganosilyl chlorides. The O‐silyl carbamoselenoates readily reacted with RbF and CsF and with organo‐germanium, ‐tin, and ‐lead halides and gave the corresponding heavy alkali metal and Se‐substituted Group 14 organometal and carbamoselenoates in moderate to good yields.     

Potassium boc-protected secondary aminomethyltrifluoroborates: synthesis and suzuki-miyaura cross-coupling reactions

Seven potassium Boc-protected secondary aminomethyltrifluoroborates were prepared in a standardized two-step process. The Suzuki-Miyaura cross-coupling reaction was studied with this new class of nucleophiles, and a large variety of aryl and hetaryl chlorides provided the desired products in good to excellent yields, thereby allowing easy access to secondary aminomethyl substructures.     

Immobilization of copper in organic-inorganic hybrid materials: a highly efficient and reusable catalyst for the Ullmann diaryl etherification

The immobilization of copper in organic-inorganic hybrid materials catalyzing the Ullmann reaction has been described. Phenols reacted with aryl iodides, aryl bromides and aryl chlorides smoothly in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper catalyst. The protocol involved the use of DMSO as the solvent, and potassium fluoride as the base. The reactions generated the corresponding cross-coupling products in good to excellent yields. Furthermore, the silica-supported copper could be recovered and recycled by a simple filtration of the reaction solution and used for 10 consecutive trials without loss of its reactivity.     

An Efficient Synthesis of Polymethylene-bis-aroyl Thiourea Derivatives under the Condition of Phase Transfer Catalysis

A number of 1,3-disubstituted derivatives are associated with various types of biological activity [1]. Some thioureas are useful as herbicides, insecticides and plant-growth regulators. Treatment of acylisothiocyanates, prepared from aroyl chlorides (0.0431mol) and potassium thiocyanate (33ml ofa 33% KSCN solution) using tetrabutylammonium bromides as a catalyst, were treated with aniline to yield the corresponding thioureas. However, probable hydrolysis of the aroyl chlorides led to decreased yields. The reaction of acid chlorides with different phenylthioureas or N1-acetyl-N3-arylthioureas requires high temperature and long reaction times. None of the other reported methods proved satisfactory. As a continuation of our earlier work on the biological activity of these compounds, [2-5] we now report acid chlorides are quantitatively converted to the acylisothiocyanates under solid-liquid phase-transfer conditions using PEG-400 as the catalyst. Treatment of these isothiocyanates with polymethylenediamines provides compounds 3 in high yields (scheme 1). The results were summarized in table 1.     

Synthesis of 2-trifluoromethyl-1(substituted aryl)-4(1H)-quinolones using trifluoroacetamidoyl chlorides

A simple two-step procedure for the preparation of 2-trifluoromethyl-1(substituted aryl)-4(1H)-quinolones utilizing electrophilic trifluoroacetamidoyl chlorides as the starting materials is described. The cyclization of trifluoromethyl enaminone intermediates with potassium carbonate in hot dimethylformamide produce the trifluoromethylated 4(1H)-quinolones in good to excellent yields.     

Synthesis of 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles by the reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles with sodium iodide

The reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles 1 with sodium iodide in N,N‐dimethyl‐formamide gave the corresponding 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles 2 in good yields. Successive treatment of 1 with titanium(IV) chloride and potassium carbonate resulted in the formation of N‐acyl‐1‐cyanocyclopropanecarboxamides 4 . The same compounds 2 were also obtained by treatment of 4 with sodium iodide. The starting compounds 1 were synthesized by the reaction of 2‐amino‐4,5‐dihydro‐3‐furan‐carbonitrile with acyl chlorides in pyridine.     

Synthesis of 2-amino-5-substituted-1,3,4-oxadiazoles using 1,3-dibromo-5,5-dimethylhydantoin as oxidant

A scalable synthesis of 5-substituted-2-amino-1,3,4-oxadiazoles via oxidation of a thiosemicarbazide precursor is described. The thiosemicarbazide intermediates are easily accessed from the corresponding acid chlorides. Oxidative cyclization using 1,3-dibromo-5,5-dimethylhydantoin as the primary oxidant, in the presence of potassium iodide, gives a variety of oxadiazoles in good yields. This methodology utilizes a commercially inexpensive and easily handled oxidant.