Phosphoryl azides as versatile new reaction partners in the Cu-catalyzed three-component couplings

Phosphoryl azide was successfully employed as an efficient reacting partner in the Cu-catalyzed three-component reaction with 1-alkynes and amines to produce the corresponding phosphoryl amidines in high yields. A range of fruitful applicability of the produced amidines was also demonstrated such as an alkoxide exchange and asymmetric alpha-alkylation of optically active BINOL-derived amidines.     

Ligand-free copper-catalyzed arylation of amidines

Copper-catalyzed cross-coupling reactions of amidine salts were utilized to synthesize monoarylated amidines in moderate to high yields with ligand-free conditions. DMF was the superior solvent for the N-arylation of benzamidines, while MeCN was used in the formation of N-aryl amidines in moderate to high yield.     

The polarography of amidines

Summary The polarographic properties of some aliphatic, arylaliphatic, phenoxyaliphatic and aromatic amidines have been investigated. Aliphatic and arylaliphatic amidines are not reducible in the range 0 to –1.8 volts versus the saturated calomel electrode. Phenoxyacetamidines are reduced to the phenol and acetamidine. Aromatic amidines are reduced to the benzylamine and ammonia. The half-wave potentials of both reducible classes of compound are independent of Ph over the range 7–9 Ph.     

Palladium‐Catalyzed Construction of Amidines from Arylboronic Acids under Oxidative Conditions

A valuable palladium‐catalyzed three‐component coupling reaction for the synthesis of amidines has been developed. Using arylboronic acids, isocyanides, and anilines as the reactants under oxidative conditions, various amidines were isolated in good yields with good functional group tolerances.     

NBS-mediated practical cyclization of N-acyl amidines to 1,2,4-oxadiazoles via oxidative N‒O bond formation

A reaction involving an efficient NBS-mediated oxidative N?O bond formation has been established for the synthesis of 1,2,4-oxadiazoles from readily accessible N-acyl amidines. The features of this synthetic method include simplicity of operation, mild reaction conditions, short reaction times, high yields, and eco-friendliness. The reaction also works well with crude N-acyl amidines obtained by amidation of simple benzoic acids and amidines to produce biologically relevant 1,2,4-oxadiazoles in a scalable fashion.     

In Situ Generation of Oxazole Ylide and Interception with Sulfonamide: Construction of Amidines Using Two Diazo Molecules

A novel generation of oxazole ylide and interception with sulfonamide have been well developed to construct fully substituted amidines. This copper‐catalyzed four‐component reaction incorporates two diazo molecules to target amidines and shows broad substrate scope, excellent functional groups tolerance and good to excellent yields.     

Preparation of N-substituted amidines2

N-substituted amidines can be prepared in good yield by heating equimolecular quantities of aryl nitriles and primary amines with AlCl₃. Also when a nitrile is kept at room temperature in contact with hydrogen chloride gas in dry ether in the presence of arylamine, amidines may be formed in good yields.     

Silver(I)-promoted conversion of thioamides to amidines: divergent synthesis of a key series of vancomycin aglycon residue 4 amidines that clarify binding behavior to model ligands

Development of a general Ag(I)-promoted reaction for the conversion of thioamides to amidines is disclosed. This reaction was employed to prepare a key series of vancomycin aglycon residue 4 substituted amidines that were used to clarify their interaction with model ligands of peptidoglycan precursors and explore their resulting impact on antimicrobial properties.     

Convenient synthesis of 5-trifluoroacetylated imidazoles by ring transformation of mesoionic 1,3-oxazolium-5-olates

Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with amidines to give 5-trifluoroacetylimidazoles (3) in moderate yield. The novel ring transformations of 1 into 3 occur via an initial attack of amidines on the C-2 position of the ring.     

Synthesis of N-Sulfonylformamidines by tert-butyl Hydroperoxide–Promoted,metal-free,direct oxidative dehydrogenation of aliphatic amines

A direct and convenient metal-free method to prepare sulfonyl amidines in the presence of aqueous tert-butyl hydroperoxide (T-HYDRO) has been developed. Different tertiary and secondary amines were tested for compatibility with the oxidative conditions and could be coupled with sulfonyl azides to form the corresponding amidines in moderate to good yields.     

Steroids. Synthesis of 1,4-oxazine derivatives of estrone

Estratrieno[3,2-b]-1,4-oxazin-3′-one (V) and estratrieno[3,4-b]-1,4-oxazin-3′-one (VI) have been converted to the corresponding amidines. The tautomerism of the thiones and the amidines are discussed.     

Reaction of perfluoroalkyltriazines with amidines of perfluoroalkylcarboxylic acids

Conclusions The amidines of perfluorocarboxylic acids and perfluorotriazines enter into exchange reaction at 20–60° to give an equilibrium mixture with new triazines and amidines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1118–1121, May, 1979.     

Synthetic utility of ammonium salts in a Cu-catalyzed three-component reaction as a facile coupling partner

Ammonium salts were found to be a convenient and inexpensive reagent in the Cu-catalyzed three-component reaction with terminal alkynes and sulfonyl or phosphoryl azides leading to N-unprotected amidines. Thus obtained amidines bearing 2-bromobenzenesulfonyl moiety were efficiently cyclized by the Cu-catalyzed intramolecular N-arylation to give an important pharmacophore skeleton of 2H-1,2,4-benzothiadiazine 1,1-dioxides. Conveniently, two tandem catalytic procedures could be readily operated in one pot.     

Highly efficient synthesis of α-amino amidines from ynamides by the Cu-catalyzed three-component coupling reactions

Using ynamides as one of the reacting components, the Cu-catalyzed three-component reaction of sulfonyl or phosphoryl azides and amines affords α-amino amidines in high yields under mild conditions. Synthetic utility of the produced compounds was demonstrated in the diastereoselective alkylation of α-amino amidines bearing a chiral oxazolidinone moiety. It was also shown that α-amino imidates could be readily prepared by employing alcohols instead of amines.     

Synthese De (1,2a)Benzimidazolo-1,3,5,2-triazaphosphorine-2-oxides

The reaction of hexamethylphosphotriamide or methylphosphonic bis(dimethylamide) compounds with amidines derived from N-Benzimidazoyl imidates 1 leads to (1,2a)benzimidazolo-1,3,5,2-tiazaphosphorine-2-oxides 4 in good yields. If the condensation is realized at room temperature, N-phosphonic amidines 3 can be isolated as intermediates. The isolated compounds 2 , 3 , and 4 are identified by spectroscopic methods: IR, 1 H, 13 C, 31 P, NMR, and M.S.     

A New Regioselective Synthesis of 1,2,5-Trisubstituted 1H-Imidazoles and Its Application to the Development of Eprosartan

A new method is presented for the preparation of 1,2-disubstitued-1H-imidazole-5-carboxaldehydes by the reaction of N-monosubstituted amidines with 2-halo-3-alkoxy-2-propenals. The reaction is highly regioselective with ratios of 1,2,5:1,2,4-imidazolecarboxaldehydes ranging from 85:15 to 100:0. This methodology could be extended with similar results to the synthesis of imidazole-5-nitriles by the reaction of 2-bromo-3-methoxy-2-propenenitrile with N-monosubstituted amidines.     

A metal-free three components procedure for the synthesis of perfluoroalkyl substituted amidines

An interesting multicomponent reaction for the synthesis of perfluoroalkyl substituted amidines has been developed. By using perfluoroalkyl iodides, tert-butyl isocyanides and amines as the substrates, the reactions proceed via somophilic isocyanide insertion. In this catalytic system, no transition-metal catalyst, additional ligands and additives were required. The reaction proceed smoothly and a variety of desired amidines were obtained in moderate to excellent yields.     

Copper‐Catalyzed Cyclization/aza‐Claisen Rearrangement Cascade Initiated by Ketenimine Formation: An Efficient Stereocontrolled Synthesis of α‐Allyl Cyclic Amidines

An efficient and convenient synthesis of α‐allyl cyclic amidines has been achieved by applying a novel cascade reaction. Copper(I)‐mediated in situ N‐sulfonyl ketenimine formation from the reaction of a terminal alkyne with sulfonyl azide is followed by an intramolecular nucleophilic attack on the central carbon atom by an allylic tertiary amine, and then an aza‐Claisen rearrangement takes place through a chair transition state to furnish the titled amidines with complete stereocontrol.     

Synthesis of 4-dialkylaminopyridine derivatives through ring-rearrangement of 3-nitro-2H-pyran-2-one acetamidines

A new synthesis of substituted 4-dialkylaminopyridines was developed, starting from 3-nitropyran-2-one N-functionalized amidines. Secondary amines were reacted with the amidines in a sealed tube and in ethanol as the solvent yielding exclusively 4-dialkylaminopyridine derivatives or a mixture with 4-methylpyridine derivative, depending on the C-α-linked substituents of the starting amidine. Structural elucidation of the 4-dialkylaminopyridines revealed their existence as two tautomeric forms, depending on the solvent.     

Efficient microwave access to polysubstituted amidines from imidoylbenzotriazoles

Microwave reactions of primary and secondary amines with imidoylbenzotriazoles 6a-w gave diversely substituted amidines 7a-Aa in 76-94% yields. Convenient preparations of a variety of amides 5a-Ab (87-96%) and imidoylbenzotriazoles 6a-w (56-95%) have also been developed using microwave irradiation under mild conditions and short reaction times. These results demonstrate further the advantages of microwave synthesis and introduce a new application of imidoylbenzotriazoles in the preparation of polysubstituted amidines.