Arbuzov-type reaction of acylphosphonites and N-alkoxycarbonylimine cations generated in situ with trifluoroacetic anhydride

A mild procedure for the synthesis of N-protected α-aminoalkylphosphinic acids by the reaction of N,N′-benzylidene- or N,N′-alkylidenebiscarbamates, trifluoroacetic anhydride and the corresponding alkylphosphonous acids in methylene chloride or toluene is described. The results obtained confirm the earlier proposed mechanism for amidoalkylation of hydrophosphorylic compounds involving an Arbuzov-type reaction step.     

Amidoalkylation of hydrophosphoryl compounds

A new mild procedure of the amidoalkylation of hydrophosphoryl compounds in a mixture of acetic anhydride and acetyl chloride was developed as a convenient method of constructing the α-aminophosphoryl fragment of the pseudo-α,α′-dipeptide molecule. The reaction intermediates N,N′-benzylidene- and N,N′-alkylidenebiscarbamates were detected, isolated, and identified. The report presents the results of studying the direct interaction of hydrophosphoryl compounds previously synthesized with biscarbamates in acetic anhydride and other solvents, the influence of the structure of phosphorus component and biscarbamate, and the effect of acid catalysis on the course of this two-component reaction. A new version of the mechanism of the three-component reaction of amidoalkylation of hydrophosphoryl compounds is suggested: it is regarded as a multistage process involving the stage of biscarbamate formation followed by the stage of Arbuzov-type reaction with the intermediate formation of acyliminium cation and P-OAc derivative with trivalent phosphorus.     

Preparation of 3-substituted and 2,3-disubstituted-4,4,4-trifluoro-2-butenoic acids—Perkin condensation of activated aromatic ketones

The Perkin reaction of the activated aromatic ketones (2,2,2-trifluoroacetophenone and its 4′-phenyl-derivative) with various condensing agents (acetic anhydride, propionic anhydride, phenylacetic acid/acetic anhydride) gives the title compounds in good or moderate yields, and high E-stereoselectivity. For some derivatives an appreciable amount of the Z isomer was also formed. Several of the resulting butenoic acids and their methyl esters are synthesised and characterised for the first time.     

Simplified syntheses of the water-soluble chiral shift reagents Sm-(R)-pdta and Sm-(S)-pdta

The chiral shift reagents Sm-(R)-pdta and Sm-(S)-pdta, which are based on (R)- or (S)-1,2-diaminopropane-N,N,N′,N′-tetraacetic acid were synthesized from easily accessible compounds in three simple steps, which makes the method suitable for laboratory-scale production. In addition, a new and efficient method for the preparation of pure anhydrous (R)- or (S)-1,2-diaminopropane-N,N,N′,N′-tetraacetic acid was developed.     

A stable intermediate: a new insight into the mechanism of Lewis acids-promoted formation of acylals from aldehydes

Treatment of m-nitrobenzaldehyde with acetic anhydride in the presence of Lewis acids, such as InBr₃, ZnBr₂, Cu(OTf)₂, gives a stable intermediate at the initial stage of reaction. Based on this new organic compound characterized by X-ray single crystal diffraction, a new mechanism for Lewis acids-promoted formation of acylals from aldehydes is proposed. Exchange reaction with different ratio of acetic anhydride to propionic anhydride, in the presence of Lewis acids, is studied.     

Anion recognition by N,N′-diarylalkanediamides

The preparation of N,N′-diarylalkanediamides from the respective aliphatic dicarboxylic acids and 4-nitroaniline via microwave-prompted reactions is presented. The most positive effect of microwave irradiation was observed for N,N′-bis(4-nitrophenyl)butanediamide. Anion binding studies on the obtained diamides were carried out in DMSO and acetonitrile using UV-vis and ¹H NMR spectroscopy. A mechanism for selective fluoride recognition by N,N′-bis(4-nitrophenyl)butanediamide in DMSO is proposed.     

Synthesis and some reactions of bis(triphenylstannyl)carbodiimide, N′-(triphenylstannyl)-N′-tritylcarbodiimide,and (triphenylstannyl)cyanamide

Some methods for preparing bis(triphenylstannyl)carbodiimide (I), N-(triphenylstannyl)-N′-tritylcarbodiimide (II), and (triphenylstannyl)cyanamide are described. (I) was found to react with 1,3-disubstituted thioureas in refluxing acetonitrile or toluene to give bis(triphenyltin) sulfide and the corresponding N,N′-disubstituted-N″-cyanoguanidine. Some evidence for a diorganocarbodiimide intermediate in this reaction was found. The reaction of(I) with thiourea in refluxing acetonitrile was found to give bis(triphenyltin) sulfide,(triphenylstannyl)cyanamide and unchanged thiourea. The reaction of (I) with cyanamide gave (triphenylstannyl)cyanamide. (Triphenylstannyl)cyanamide was found to react with bis(triphenyltin) oxide in refluxing acetonitrile to give (I). (Triphenylstannyl)cyanamide was found to disproportionate in refluxing benzene to give (I) and dicyandiamide. (II) was found to be more hydrolytically stable than (I). The SnN bonds in both (I) and (II) were found to be readily cleaved by acetic acid. It was found that triphenyltin iodide and triphenyltin chloride can be conveniently prepared in good yield by the reaction of bis(triphenyltin) oxide with either calcium iodide or calcium chloride in refiuxing acetonitrile.     

meta-Carborane-containing bismaleimides — New monomers for the synthesis of polyimides

The reaction of maleic anhydride with 1,7-bis(4,4-aminophenylamido)-m-carborane and 1,7-bis(4,4-aminophenylcarboxy)-m-carborane leads to the formation of the corresponding bis(maleamidocarboxylic acids) in quantitative yield. The subsequent dehydration of these compounds in a mixture of acetic anhydride and acetic acid in the presence of sodium acetate and triethylamine leads tom-carborane-containing bismaleimides, whose structure was indicated by IR spectroscopy. The chemical properties of these compounds were studied.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2446–2448, October, 1992.     

Synthesis and characterization of coordination polymers of a carboxylato cyclophane with metal [Zn(II) and Cd(II)]-2,2′-bipyridines

N,N′,N′′,N′′′-Tetrakis(3-carboxy-propionyl)-1,6,20,25-tetraaza-[6.1.6.1] paracyclophane, H₄cp has been complexed with metal (Zn(II) and Cd(II)) 2,2′-bipyridyls. The resulting complexes of the composition [{Zn(2,2′-bpy)}₂(cp)]_n·4H₂O 1 and [{Cd(2,2′-bpy)}₂(cp)]_n·5H₂O 2 (2,2′-bpy = 2,2′-bipyridine) have been characterized using spectroscopic (IR, solid state UV–Vis), elemental analysis and single-crystal X-ray diffraction measurements. In these complexes the cyclophane coordinates in different modes, and in complex 2, Cd(II) is hepta-coordinated. However, under harsh reaction conditions (using excess nitric acid and a longer reaction time) debranching of the cyclophane is observed in the reaction of Zn(2,2′-bpy)(NO₃)₂ with H₄cp, and a complex of the composition [Zn(2,2′-bpy)(Suc)]_n3 (suc = succinate) is isolated. Using non-covalent interactions, complexes 1 and 2 provide 3D supramolecular structures, whereas an infinite 1D chain structure is observed for complex 3. The thermal and photoluminescence properties of the complexes have also been studied.     

Synthesis of pyrrolo[2,3-c]2,7-naphthyridine derivatives by cascade heterocyclization reaction of 2-amino-4-cyanomethyl-6-dialkylamino-3,5-pyridinedicarbonitriles

Alkylation of the title pyridinedicarbonitriles with N-substituted chloroacetamides was found to give 5,6-diamino-8-dialkylamino-2,3-dihydro-2-oxo-1H-pyrrolo[2,3-c]2,7-naphthyridine-9-carbonitriles. The structure of obtained compounds was unambiguously confirmed by X-ray crystallographic study. The heterocyclization reaction proceeded regioselectively involving 3-CN group of the starting pyridines without participation of 5-CN. The reasons of the selectivity were discussed. An interaction of prepared naphthyridine derivatives with acetic acid anhydride and cyclohexanone yielded 2-dialkylamino-6,8,9,10-tetrahydro-5-methyl-9-oxopyrimido[4,5,6-ij]pyrrolo[2,3-c]2,7-naphthyridine-1-carbonitriles and 2-dialkylamino-4,5,6,8,9,10-hexahydro-9-oxospiro{pyrimido[4,5,6-ij]pyrrolo[2,3-c]2,7-naphthyridine-5,1′-cyclohexane}-1-carbonitriles, respectively. All fused 2,7-naphthyridines obtained were derivatives of novel heterocyclic systems.     

Poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) as powerful reagents for benzylic bromination

N,N,N′,N′-Tetrabromobenzene-1,3-disulfonamide [TBBDA], poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS], and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) [PBPS] can be used for bromination of benzylic positions in solvent.     

2-Amino-4-aryl-1-arylideneaminoimidazoles and Acylation Products: A Multinuclear ( 1H, 13C, 15N) NMR Study

The structure of 2-amino-4-aryl-1-arylideneaminoimidazoles in DMSO-d₆ solution was investigated by means of NMR spectroscopic methods (¹H, ¹³C, ¹⁵N). From these data the (E)-configuration at the excocyclic C=N bond and a strong preference for the conformer with the imidazole H-5 and the N=CH proton being spatially close (s-trans regarding the N–N bond) can be concluded. Reaction of the title compounds with acetic anhydride leads to mono and diacylation at the 2-amino group, whereas treatment with pivalic anhydride exclusively affords the corresponding monoacyl product. The mono- and diacylation products exhibit similar configurational and conformational properties as the parent compounds.     

Synthesis of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(arylamino)prop-2-en-1-one: advances in the mechanism of Combes 2-trifluoromethyl and 2-perfluoroalkyl quinolines synthesis

We report a new synthesis and our study of the mechanism of formation of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one starting from 3-(R-phenoxy)-3-perfluoroalkyl-prop-2-enals and arylamines. Reactivity study of the intermediates confirmed that 3-perfluoroalkyl-N,N′-diphenyl-1,5-diazapentadienes are the synthetic intermediates of the synthesis of 2-perfluoroalkylquinolines. The mechanism of the reaction of 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one with POCl₃ was studied. To our knowledge this is the first detection and isolation of N,N′-diaryldiazapentadiene derivatives as intermediates in the Combes F-alkyl substituted quinoline synthesis starting from enaminoketones. Finally, we succeeded isolating and identifying unsymmetrically substituted 2-perfluorolakyldiazapentadiene.     

Acetic anhydride to the rescue: Facile access to privileged 1,2,3,4-tetrahydropyrazino[1,2-a]indole core via the Castagnoli-Cushman reaction

Indole-fused cyclic anhydrides earlier deemed unreactive in the Castagnoli-Cushman reaction with imines have been rendered valid participant in this process. The new reaction format involves the use of respective indole-based dicarboxylic acids and in situ cyclodehydration of the latter by acetic anhydride. This finding validates a fundamentally new approach to synthesizing compounds based on the privileged 1,2,3,4-tetrahydropyrazino[1,2-a]indole core characterized by hitherto undescribed substitution pattern.     

Synthesis of aromatic aldehydes via 2-aryl-n,n'-diacyl-4-imidazolines

Diacylimidazolium ions yield adducts with aromatic compounds. Thus the N,N'-diacetylimidazolium ion and indole gives 1,3-diacetyl-2-(3-indolyl)-4-imidazoline. Less reactive substrates such as thiophene, anisole and 1,3-dimethylbenzene fail to react with this reagent but do form adducts (e.g. 1,3-bis-(trifluoroacetyl)-2-(2-thienyl)-4-imidazoline) with an imidazole/trifluoroacetic anhydride reagent. All of the adducts could be converted to the corresponding aldehyde under mild conditions. The synthetic scope of the new synthesis is similar to that of the Vilsmeier-Haack reaction.     

Three-component sequential synthesis of N,N′-disubstituted 5-arylidenedihydropyrimidine-2,4-dione

A three-component sequential process consisting in (1) in situ formation of carbodiimides by Staudinger reaction, (2) reaction with 2-(bromomethyl)-3-aryl-2-propenoic acids, and (3) final cyclization of the resulting N-acylurea intermediates in order to obtain the synthesis of an array of N,N′-disubstituted 5-arylidenedihydropyrimidine-2,4-dione under mild conditions is presented.     

2-Amino-4-aryl-1-arylideneaminoimidazoles and Acylation Products: A Multinuclear (<Superscript>1</Superscript>H, <Superscript>13</Superscript>C, <Superscript>15</Superscript>N) NMR Study

Summary. The structure of 2-amino-4-aryl-1-arylideneaminoimidazoles in DMSO-d₆ solution was investigated by means of NMR spectroscopic methods (¹H, ¹³C, ¹⁵N). From these data the (E)-configuration at the excocyclic C=N bond and a strong preference for the conformer with the imidazole H-5 and the N=CH proton being spatially close (s-trans regarding the N–N bond) can be concluded. Reaction of the title compounds with acetic anhydride leads to mono and diacylation at the 2-amino group, whereas treatment with pivalic anhydride exclusively affords the corresponding monoacyl product. The mono- and diacylation products exhibit similar configurational and conformational properties as the parent compounds.     

A novel method for the reduction of sulfoxides with the N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide (TBBDA)/PPh3 system

A new method is described for the reduction of sulfoxides to sulfides using N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide [TBBDA] in combination with triphenylphosphine. Good to excellent yields, short reaction times, high efficiency and facile isolation of the desired products are the advantages of this method.     

An Efficient One‐Pot Three‐Component Synthesis of Some New Polyhydroquinolines via Enaminone Intermediates

For a wide spectrum of pharmacological effects of polyhydroquinolines, this study introduces a developed safe, simple, higher yields and fast method for the synthesis of some new hexahydroquinoline derivatives using one‐pot three‐component cyclocondensation reaction, via the reaction of 1,3‐cyclohexanedione with primary amine and arylidinemalononitrile or salicylaldehyde derivatives. The prepared compounds were reacted with different reagents as N ,N‐dimethylformamide dimethylacetal, acetic anhydride, sulphuric acid, and hydrazine hydrate forming several polycyclic hexahydroquinoline and acridine derivatives. All these new compounds have been characterized by spectral data and expected to be effective pharmaceutical drugs.     

Acid-catalyzed condensation of 2,2′-diamino-1,1′-biaryls for the synthesis of benzo[c]carbazoles

2,2′-Diamino-1,1′-biaryls were found to undergo ring-closure condensation reaction to afford benzo[c]carbazoles in good to excellent yield. Coupled with the synthesis of 2,2′-biaryldiamines from diaryl hydrazides via [3,3]-sigmatropic rearrangement, it constitutes a new efficient synthetic method for benzo[c]carbazoles and related compounds.