NMR and crystallographic evidence for polymorphism of the N-phenyl-N′-[1-(3-(phenyl-4-piperazinyl)propan-2-ol)]urea

NMR spectroscopy and single-crystal X-ray analysis have been used to characterize polymorphism of the racemate of the N-phenyl-N-[1-(3-(phenyl-4-piperazinyl)propan-2-ol)urea displaying an analgesic activity. The crystal structures of the monoclinic form,R _m witha=4.788(1),b=9.432(7),c=40.791(5) Å, =90.93(1)°, space groupP2₁/n,Z=4 and of the orthorhombic form,R _o witha=10.948(3),b=8.896(3),c=38.857(6) Å, space groupPbca,Z=8, have been determined. In addition, the crystal structure of an enantiomer orthorhombic,E _o, isolated from a conglomerate, witha=4.787(3),b=9.461(2),c=40.809(10) Å, space groupP2₁2₁2₁, Z=4, has also been determined. The three conformations have been compared when the molecules have the same relative configurations.     

New approach to the synthesis of 2,6-difluorobenzoyl isocyanate and its use in the preparation of N-(2,6-difluorobenzoyl)-N′-(polyfluoroaryl)ureas

The treatment of 2,6-difluorobenzoyl chloride with trimethylsilyl isocyanate gave 2,6-difluorobenzoyl isocyanate. This product reacts with polyfluoroaromatic amines to give the corresponding N-(2,6-difluorobenzoyl)-N-(polyfluoroaryl)urea, which hold potential as inhibitors for the biosynthesis of insect chitin.Institute of Chemistry, Bashkir Science Center, Urals Branch, Russian Academy of Sciences, 450054 Ufa. Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 468–470, February, 1992.     

Reaction of Spirocyclic Isopropylidene Malonates with Urea and N,N'-Disubstituted Ureas

Unsubstituted and N-substituted amides of 2-aryl-4-methyl-4-cyclohexene-1-carboxylic acids are formed during the fusion of 2'-aryl-2,2,4'-trimethyl-1,3-dioxan-5-spirocyclohex-4'-ene-4,6-diones with urea and N,N'-disubstituted ureas.     

硒催化的邻硝基苯胺类化合物的羰基化反应

用硒作催化剂，三乙胺为助催化剂，CO为羰基化试剂，通过氧化还原羰基化的方法，将邻硝基苯胺类化合物在分子内羰基化成环，反应生成相应的一系列环脲类物质，此催化合成方法的反应选择性近秋100％，收率较高，操作简单，并提出了可能的反应机理。     

2-Acylmethyl-1H-benzimidazoles in the Biginelli Reaction

By cyclocondensation of 2-acylmethyl-1H-benzimidazoles with aromatic aldehydes and urea according to the Biginelli reaction, we have obtained previously unknown 6-substituted 4-aryl-5-(2-benzimidazolyl)-2-oxo-1,2,3,4-tetrahydropyrimidines. We have developed an efficient procedure for conducting the three-component reaction at fairly low temperatures. We have analyzed the structural features of the synthesized compounds based on ¹H NMR spectra and IR spectroscopy.     

Synthesis of functionalized arylalkyl and diaryl ethers by [3+3] cyclization of 3-alkoxy- and 3-aryloxy-1-siloxy-1,3-butadienes with 3-(silyloxy)alk-2-en-1-ones

Functionalized diaryl ethers were prepared by [3+3] cyclization of 3-aryloxy-1-siloxy-1,3-butadienes with 3-(silyloxy)alk-2-en-1-ones.     

Self-assembly of tris(2-ureidobenzyl)amines: a new type of capped, capsule-like dimeric aggregates derived from a highly flexible skeleton

A set of tris(2-ureidobenzyl)amines 3 was prepared and their dimerization processes thoroughly investigated. In spite of their inherent flexibility, tris(ureas) 3 form dimeric aggregates both in the solid state and in solution. Evidence for the existence of these dimeric species was provided by a combination of techniques (X-ray analysis, NMR and IR spectroscopy, and ESI-MS). The association constants and thermodynamic parameters for the dimerization processes of selected tris(ureas) were determined and show that they are enthalpically driven. Heterodimerization experiments in solution reveal a high degree of self-recognition or narcissistic self-sorting. On the other hand, desymmetrized tris(ureas) derived from 3 self-assemble with modest regioselectivities depending on the terminal substituent of every urea functionality.     

Studies on the Reaction of α‐Chloroformylarylhydrazine Hydrochloride with Imidazole and 1,2,4‐Triazole

α‐Imidazolformylarylhydrazine 2 and α‐[1,2,4]triazolformylarylhydrazine 3 have been synthesized through the nucleophilic substitution reaction of 1 with imidazole and 1,2,4‐triazole, respectively. 2,2′‐Diaryl‐2H,2′H‐[4,4′]bi[[1,2,4]‐triazolyl]‐3,3′‐dione 4 was obtained from the cycloaddition of α‐chloroformylarylhydrazine hydrochloride 1 with 1,2,4‐triazole at 60 °C and in absence of n‐Bu₃N. The inducing factor for cycloaddition of 1 with 1,2,4‐triazole was ascertained as hydrogen ion by the formation of 4 from the reaction of 3 with hydrochloric acid. 4 was also acquired from the reaction of 3 with 1 and this could confirm the reaction route for cycloaddition of 1 with 1,2,4‐triazole. Some acylation reagents were applied to induce the cyclization reaction of 2 and 3.1 possessing chloroformyl group could induce the cyclization of 2 to give 2‐aryl‐4‐(2‐aryl‐4‐vinyl‐semicarbazide‐4‐yl)‐2,4‐dihydro‐[1,2,4]‐triazol‐3‐one 6. 7 was obtained from the cyclization of 2 induced by some acyl chlorides. Acetic acid anhydride like acetyl chloride also could react with 2 to produce 7D . 5‐Substituted‐3‐aryl‐3H‐[1,3,4]oxadiazol‐2‐one 8 was produced from the cyclization reaction of 3 induced by some acyl chlorides or acetic acid anhydride. The 1,2,4‐triazole group of 3 played a role as a leaving group in the course of cyclization reaction. This was confirmed by the same product 8 which was acquired from the reaction of 1 , possessing a better leaving group: Cl, with some acyl chlorides or acetic acid anhydride.