A new strategy for the synthesis of unsymmetrical phosphotriesters

A new strategy for the synthesis of unsymmetrical phosphotri-esters was reported: an alcohol was converted to unsymmetrical dialkyl phosphites firstly, which then reacted with the second alcohol or phenol to afford required unsymmitrical triesters in the presence of iodine in high yields under exceptionally mild conditions.     

Diels-Alder reactions in the presence of a minimal amount of water

Abstract

Diels-Alder reactions of neat reactive dienes and dienophiles are frequently vigorous and have a limited preparative value. It is possible to control the temperature of multi-gram scale Diels-Alder reactions by adding a minimal amount of water to neat reactants. In addition, the presence of water resulted in an increased reaction rate and formation of a higher purity product. The use of minimal amounts of other solvents, with lower heat capacities, did not give good results. Furthermore, some dienophiles, e.g. maleic anhydride, reacted poorly in a dilute water suspension or solution, but worked well in the presence of a minimal amount of water. This is an environmentally friendly, practical and efficient approach to preparation of Diels-Alder adducts on a multi-gram scale.     

A new route for the synthesis of 1,3-diketones

A simple route for the synthesis of 1,3-diketones by the reaction of acetylenic ketones with amines followed by hydrolysis of the resulting aminovinylketons is suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 710–714, April, 1995.     

A new method for the synthesis of aziridine derivatives

The photoinduced reaction ofN-trialkylstannyl-N-triorganylsilyl-substituted allylamines with perfluorocarbonyl iodides results in the formation of 1-triorganylsilyl-2-(,a-dihydroperfluoroalkyl)aziridines.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 3, pp 759–760, March, 1996.     

Efficient catalyst-free Domino approach for the synthesis of novel 2-benzazepine derivatives in water

A novel one-pot eco-friendly protocol for the synthesis of 2-benzazepine derivatives in water has been developed. 4-Chloro-3-formyl coumarin reacts with benzyl amines under catalyst-free conditions in aqueous medium to afford substituted 5-(2′-hydroxyaryl)-4-amido-2-benzazepines in excellent yields.     

Multicomponent synthesis of polysubstituted dihydroquinoline derivatives

A series of new poly-functionalized dihydroquinoline derivatives (26 examples) were synthesized via three-component reactions of aldehydes (1 equiv) and 1-arylethylidenemalononitriles (2 equiv) in ethylene glycol using NaOH as a base promoter under microwave irradiation. During these reaction processes, the domino construction of dihydroquinoline skeleton with concomitant formation of two new cycles was readily achieved in a one-pot operation and in an intermolecular manner.     

An efficient one-pot strategy for the synthesis of 4- methylene-2-thiazolidinethiones in water

Abstract

A simple and efficient, one-pot strategy for the preparation of 4-methylene-2-thiazolidinethiones has been developed. This protocol involved condensation of primary amines with carbon disulfide in water to generate the dithiocarbamate salts in situ, which coupled with 2,3-dibromopropene, followed by intramolecular cyclization to the corresponding heterocycles in moderate to good yields.     

Multicomponent reactions for the synthesis of new 3′-indolyl substituted heterocycles under microwave irradiation

A series of polysubstituted (3′-indolyl)pyrazolo[3,4-b]pyridine and (3′-indolyl)benzo[h]quinoline derivatives were synthesized via one-pot multicomponent reactions of aldehydes, 3-cyanoacetyl indoles with 5-aminopyrazol or naphthylamine under microwave irradiation. Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and straightforward procedure.     

A new synthesis of highly functionalized 2H-pyran derivatives

Ethyl oxo-(2-oxo-cycloalkyl)-ethanoates undergo a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates via intramolecular Wittig reaction to produce spiro-cyclobutene derivatives. These spiro systems undergo electrocyclic ring opening reaction to produce electron-deficient 1,3-dienes, which spontaneously cyclize to 2H-pyran derivatives.     

Multicomponent reactions for the synthesis of functionalized 1, 4-oxathiane-3-thiones under microwave irradiation in water

A series of substituted 1,4-oxathiane-3-thione derivatives were synthesized via one-pot multicomponent reactions of nitromethane, carbon disulfide and oxiranes in the presence of Et3N in water as the solvent under microwave irradiation. Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and straightforward procedure.     

Simple and efficient synthesis of N-alkyl and N-aryl succinimides in hot water

A new, simple synthesis of succinimides is described. The reactions were carried out under the ultimate green conditions excluding both catalyst and organic solvent by applying simple stirring at 100?°C. A wide variety of N-susbstituted succinimides have been prepared in high yields by using succinic acid and primary amines in hot water. Yield of N-alkyl substituted succinimides were found to be higher than those of N-aryl substituted succinimides.     

Palladium-catalyzed cross-coupling reactions of amines with alkenyl bromides: a new method for the synthesis of enamines and imines

The palladium-catalyzed cross-coupling reaction of alkenyl bromides with secondary and primary amines gives rise to enamines and imines, respectively. This new transformation expands the applicability of palladium-catalyzed C-N bond forming reactions (the Buchwald-Hartwig amination), which have mostly been applied to aryl halides. After screening of different ligands, bases, and solvents, the catalytic combination [Pd(2)(dba)(3)]/BINAP in the presence of NaOtBu in toluene gave the best results in the cross-coupling of secondary amines with 1-bromostyrene (dba=dibenzylideneacetone, BINAP=2,2'-bis(diphenylphosphino)-1,1'-binaphthyl). The corresponding enamines are obtained cleanly and in nearly quantitative yields. However, steric hindrance seems to be a limitation of the reaction, as amines carrying large substituents are not well converted. The same methodology can be applied to the coupling of secondary amines with 2-bromostyrene. Moreover, the reaction with substituted 2-bromopropenes allows regioselective synthesis of isomerizable terminal enamines without isomerization of the double bond. The best catalytic conditions for the cross-coupling of 1-bromostyrene with primary amines include again the use of the Pd(0)/BINAP/NaOtBu system. The reaction gives rise to the expected imines in very short times and with low catalyst loadings. A set of structurally diverse imines can be prepared by this methodology through variations in the structure of both coupling partners. However, 2-bromostyrene failed to give good results in this coupling reaction, probably due to product inhibition of the catalytic cycle. Competition experiments of vinyl versus aryl amination reveal that the reaction occurs preferentially on vinyl bromides.     

Design, synthesis and anti-HBV activity of novel bis（trifluoroethyl）phosphonomethyl ether derivatives of acyclovir

A series of novel bis(trifluoroethyl)phosphonomethyl ether derivatives of acyclovir was synthesized and their in vitro anti-HBV activity was evaluated in HepG2 2.2.15 cells.In contrast to acyclovir,most of the described phosphonates emerged as potent inhibitors of HBV replication.Especially,the most active compound 11 with IC_(50)value of 2.92μmol/L was 33 times more potent than acyclovir with IC_(50)value of 100μmol/L.     

Multicomponent reactions in the synthesis of dihydropyrimidine-containing podands having tuberculostatic activity

Dihydropyrimidinethione podands, as well as podands containing 2-thienyl substituents have been synthesized via the multicomponent Biginelli reaction. Tuberculostatic activity of the novel podands was shown to depend on the polyether unit length. In particular, activity of dihydropyrimidinethione podands against laboratory strains of Mycobacterium tuberculosis, H₃₇Rv, M. avium, M. terrae, and the clinical strain of multi-drug resistant M. tuberculosis (MDR), increases with a shortening of the polyether unit length.     

One-pot synthesis of phosphorylsuccinates and triphenylphosphanylidenesuccinates containing a thioamido group

Abstract

Stable substituted dialkyl phosphorylsuccinates were synthesized, as a mixture of two diastereoisomers, in high yields using one-pot reaction of dialkyl acetylenedicarboxylates, trialkyl phosphites, and thioamides in CH₂Cl₂ at room temperature. Using triphenylphosphine instead of phosphites, afforded stabilized triphenylphosphanylidenesuccinates. DFT calculations at B3LYP/6-31?+?G(d) level indicated that among four possible conformational diastereoisomers of dimethyl 2-(dimethoxyphosphoryl)-3-ethanethioamidosuccinate, the (2R,3S) and (2S,3S) diastereomers are the most stable forms.