One-pot three-component tandem reaction: Synthesis of aryl/alkyl cyanamides libraries and their further conversion into tetrazole derivatives

We have developed methodology for the synthesis of aryl/alkyl cyanamides from amines in one-pot four steps reaction using cheap, readily available and air stable copper source as catalyst under mild reaction conditions. We have also studied the application of cyanamides. In this connection, we could construct aryl tetrazolamine from cyanamides using click reaction     

Synthesis and Structure of Monomeric,Trimeric, and Mixed Phenylcyanamides

In a new synthetic approach phenylcyanamide (Hpca) was synthesized by methylation of phenylthiourea followed by a basic work‐up. All products along the synthetic route have been fully characterized by means of NMR, IR, and X‐ray studies. The first structural report of neutral mixed crystals of phenylcyanamide containing monomeric and trimeric Hpca is presented. Examination of these intriguing mixed crystals revealed the formation of distinct layers of monomeric and trimeric Hpca. These layers are interconnected by weak hydrogen bonds. The trimer represents triphenylisomelamine, which readily isomerizes to the triphenylmelamine in the melt, in accord with computations at the B3LYP level, indicating an exothermic process (ΔH=?49.4 kcal mol^?1). Pure trimeric Hpca (triphenylisomelamine) was obtained either by recrystallization of the mixed crystals from boiling water or by trimerization of monomeric Hpca in isopropanol for 12 h under reflux conditions. For comparison tritylcyanamide (Htca) and potassium phenylcyanamide as an [18]crown‐6 complex [K([18]crown‐6)pca] have been synthesized, and the solid‐state structures were determined using X‐ray diffraction techniques. The thermal behavior was studied by thermo‐analytical experiments. In agreement with the experimental results, computations predict an exothermic cyclotrimerization process for Hpca (ΔH=?41.3 kcal mol^?1).     

Alkoxycarbonylimines of hexafluoroacetone in reaction of [2+4]-cycloaddition

The [2+4]-cycloadditions of alkoxycarbonylimines of hexafluoroacetone to cyclopentadiene andN-nitriles have been studied. Alkoxycarbonylimines of hexafluoroacetone may be considered as both dienophiles and 1,3-heterodienes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1809–1813, September, 1995.     

A theoretical study on the structures and energetics of hypothetical TiM(NCN)3 compounds of the 3d transition metals

Quasi-ternary cyanamides and carbodiimides of general formula AB(NCN)(3) with A not equal B have neither been predicted nor synthesized. Thus, hypothetical compounds of that kind containing 3d transition metals were considered (A = Ti, B = Mn, Fe, Co, Ni, Cu) by means of density-functional calculations on 34 structural models, most of which were derived from chemically related phases. After performing structure optimizations based on the local-density approximation, the relative energetic orderings are rationalized in terms of geometrical factors such as molar volumes and polyhedral connections. Total-energy generalized-gradient calculations evidence that the most stable models are enthalpically favored with respect to the elements. Even at ambient temperatures, the ternary phases are predicted as being thermodynamically stable in terms of their Gibbs free formation energies, especially if energetically competing and low-lying binaries (TiC, TiN) can be excluded by a kinetic reaction control. The best models are characterized by low-spin magnetic transition metals found in octahedral coordination, and the TiN(6) and MN(6) polyhedra either share faces or edges.     

Addition–Hydroamination Reactions of Propargyl Cyanamides: Rapid Access to Highly Substituted 2‐Aminoimidazoles

A valuable pharmacophore , the 2‐aminoimidazole moiety, can be accessed with a variety of substitution patterns through an addition–hydroamination–isomerization sequence (see scheme; R¹,R⁴,R⁵=alkyl; R³=alkyl, aryl; R²=H, alkyl, aryl). The synthesis of the propargyl cyanamide precursors through a three‐component coupling enables the preparation of this important heterocyclic core structure in just three steps.

     

Cyanamides in cyclization reactions with anthranilates, 2-aminophenyl ketones, and methyl 2-(3-oxopiperazin-2-yl)acetate

Cyclization of aryl-, aroyl-, and (4,6-dimethylpyrimidin-2-yl)cyanamides with methyl anthranilates, 2-aminophenyl ketones, and methyl 2-(3-oxopiperazin-2-yl)acetate leads to 2-amino-3,4-dihydroquinazolin-4-one, 2-aminoquinazoline, and 6-amino-1,3,4,8,9,9a-hexahydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione derivatives, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 164–170, January, 2008.     

Ultrasound irradiation and green synthesized CuO-NiO-ZnO mixed metal oxide: An efficient sono/nano-catalytic system toward a regioselective synthesis of 1-aryl-5-amino-1H-tetrazoles

Abstract

An efficient approach has been reported that 1-aryl-5-amino-1H-tetrazoles are prepared from structurally diverse N-arylcyanamides and sodium azide using sono/nano-catalytic system. The mixed metal oxide nanoparticles (NPs) (CuO, NiO, and ZnO NPs) were prepared with utilizing aqueous leaves extracts of the Rheum ribes. In this study, the effect of the reaction condition was investigated on the catalytic activity and selectivity of mixed metal oxide NPs for the synthesis of aminotetrazole derivatives. In this regard, various reaction conditions were precisely compared such as reflux and ultrasonication (US). In this study, the regioselective synthesis of 1-aryl-5-amino-1H-tetrazoles with high yield was achieved by the synergistic effect between US irradiation and prepared nanocatalyst which showed the potential of sono/nano-catalytic system in organic synthesis. Furthermore, the as-prepared nanocatalyst could be reused and recovered from the reaction mixture for several times without consequential abate in its catalytic activity and selectivity.     

N-Cyanation of Primary and Secondary Amines with Cyanobenzio-doxolone (CBX) Reagent

An efficient electrophilic N-cyanation of amines with a stable and less-toxic cyanobenziodoxole reagent towards the synthesis of cyanamides is disclosed. This synthetically practicable strategy allows the construction of a wide variety of cyanamides under very mild and simple conditions with a broad functional group compatibility, and showcases a huge potential in late-stage modification of complex molecules.