Theoretical design of new bridge-ring insensitive high energy compounds by selected normal Diels-Alder reactions between NH_(2)-substituted oxazoles and NO_(2)/NF_(2)/NHNO_(2)-substituted ethylenes/acetylenes

In this work,NH_(2)-substituted oxazoles and NO_(2)/NF_(2)/NHNO_(2)-substituted ethylenes/acetylenes were designed and used as dienes and dienophiles,respectively,in order to develop new bridge-ring insensitive high energy compounds through the Diels-Alder reaction between them.The reaction type,reaction feasibility and performance of reaction products were investigated in detail theoretically.The results showed that dienes most possibly react with dienophiles through the HOMO-diene controlled normal Diels-Alder reaction at relatively low energy barrier.Tetranitroethylene could react with the designed dienes much more easily than other dienophiles,and was employed to further design 29 new bridge-ring energetic compounds.Due to high heat of formation,density and oxygen balance,all designed bridge-ring energetic compounds have outstanding detonation performance,16 of them have higher energy than HMX(1,3,5,7-tetranitro-1,3,5,7-tetrazocine)and 2 others even possess comparative energy with the representative of high energy compounds CL-20(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane).The predicted average h50 value of these bridge-ring energetic compounds is 83 cm,showing their low impact sensitivity.The NH2 groups could obviously impel the proceeding of Diels-Alder reactions,but would slightly decrease the energy and sensitivity performance.In all,the new designed bridge-ring compounds have both high energy and low sensitivity,and may be produced through Diels-Alder reactions at relatively low energy barrier.This paper may be helpful for the theoretical design and experiment synthesis of new advanced insensitive high energy compounds.

A Case of Abnormal Bishler-Napieralski Cyclization Reaction,Leading to Form Benzyl Oxazole Derivatives

A benzyl oxazole compound 3 was obtained with an excellent yield of 90% when N-acetyl-(2'-methoxy-4',5'-methylenedioxy)-phenylalanine methyl ester 1 was refluxed in POCl1/benzene. However, the anticipated product 3,4-dihydrosioquinoline-3-carboxylic acid methyl ester 2 could not be found. The mechanism was discussed in this article.

A Fluorescence Optical Fiber Sensor for Amrinon Using a New Oxazole Compound

A new oxazole compound, 1,4 bis(naphtho[1,2 d][1,3]oxazol 2 yl)benzene(BNOB) was synthesized and incorporated into a thin plasticized polymeric membrane for sensing Amrinon. The sensor exhibits a linear response to Amrinon in the range of 7 98×10 -7 —1 52×10 -4 mol/L at pH 3 28—4 04. The response mainly originates from the Primary Inner Filter Effect, which causes a decrease in the fluorescence intensity of the sensor membrane. The distinct advantages of the proposed sensor are of full reversibility, high sensitivity and selectivity as well as short response time(<1 min), indicating that the sensor can be used to monitor Amrinon in serum samples.

Electrochemical construction of 2,5-diaryloxazoles via N–H and C(sp_(3))-H functionalization

An efficient N–H and C(sp~3)-H functionalization of aryl ketones with benzylamines/amino acids was developed under mild conditions by virtue of anodic oxidation. A variety of functionalized 2,5-diaryloxazoles were obtained with good to excellent yields. Moreover, some important natural products can be prepared by this method. The reaction features a broad substrate scope, scalability, metal-free and chemical oxidant-free.

Two novel 2,5-diphenyl oxazole derivatives from Gymnotheca chinensis

Two novel 2,5-diphenyl oxazole derivatives,named gymnothecaoxazoles A（1） and B（2）,were isolated from the whole parts of endemic medicinal plant of Gymnotheca chinensis（Saururaceae）.The structures of the new compounds were elucidated by extensive NMR and MS data,and the structure of compound 1was further confirmed by X-ray crystal diffraction analysis.

A Facile One-pot Synthesis of 2,5-Disubstituted Oxazoles Us-ing Poly[styrene(iodosodiacetate)]

Disubstituted oxazoles were prepared conveniently by treatment of aromatic -methyl ketones and nitriles with poly[styrene(iodosodiacetate)] in a one-pot manner.

Synthesis and bioactivity of novel pyrazole oxime derivatives containing oxazole ring

A series of novel pyrazole oxime derivatives containing oxazole ring were designed and synthesized. The title compounds were structurally confirmed by 1H NMR, 13C NMR spectra and elemental analyses. Preliminary bioassay results showed that some of the title compounds displayed promising fungicidal activity besides insecticidal and acaricidal activity. Particularly, compound 8c exhibited potent fungicidal activity against cucumber Pseudoperonospora cubensis beyond good insecticidal activity against Aphis craccivora and Nilaparvata lugens.

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

A novel generation of oxazole vlide 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.

Microwave Assistant Synthesis and Crystal Structures of Two Substituted Oxazole Isoxazole Carboxamides

Two novel substituted phenyl oxazole isoxazole carboxamides have been synthesized by microwave assistant technology.The target compounds were characterized by IR,1H NMR,13C NMR and HRMS,and their single-crystal structures were further determined by X-ray diffraction.3-Phenyl-4-(2΄-methyl-2΄-isopropyl-1΄,3΄-oxazole)-5-methyl isoxazole carboxamide(6a)crystallizes in monoclinic system,space group P21/c with a=6.2137(12),b=19.923(4),c=13.748(3)Å,β=92.30(3)°,V=1700.6(6)Å3,Dc=1.228 Mg/m3,Z=4,F(000)=672,μ(MoKα)=0.084 mm-1,R=0.0526 and wR=0.1259.3-(2΄-Fluoro-6΄-chloro-phenyl)-4-(2΄-methyl-2΄-ethyl-1΄,3΄-oxazole)-5-methyl isoxazole carboxamide(6b)crystallizes in triclinic system,space group P with a=7.8750(16),b=10.596(2),c=11.725(12)Å,β=102.05(3)°,V=859.5(3)Å3,Dc=1.363 Mg/m3,Z=2,F(000)=368,μ(MoKα)=0.250 mm-1,R=0.0738 and wR=0.1941.Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.Compounds 6a and 6b show safener activity on maize against the injury of chlorsulfuron.

Gold-catalyzed oxazoles synthesis and their relevant antiproliferative activities

Nine 5-aryl-2-methyloxazole derivatives were synthesized via gold-catalyzed alkyne oxidation. All of the compounds have been screened for their antiproliferative activities against MCF-7 cell （human breast carcinoma）, A549 cell （human lung carcinoma） and Hela cell （human cervical carcinoma） lines in vitro. The results revealed that compounds 1b, 1c and 1d exhibited strong inhibitory activities against the MCF-7 cell lines （with ICso values of 4.6, 9.7 and 2.2 μmol/L, respectively）.

Synthesis of novel 1,3-oxazole derivatives with insect growth-inhibiting activities

Straightforward and direct synthesis of 2-substituted-5-oxazolecarbaldehydes was achieved by treating propargylamides with mercury（II）perchlorate as catalyst and ammonium cerium（IV）nitrate as oxidant agent through intramolecular cyclization.These structurally interesting outcomes beneft to synthesize2,5-disubstituted-1,3-oxazoles with armyworm growth regulating activities.

Rh-Catalyzed Formal[3+2]Cyclization for the Synthesis of 5-Aryl-2-(quinolin-2-yl)oxazoles and Its Applications in Metal lons Probes

Main observation and conclusion A facile and efficient strategy for the synthesis of 5-aryl-2-(quinolin-2-yl)oxazoles via rhodium-catalyzed formal[3+2]cyclization of 4-aryl-1-tosyl-1H-1,2,3-triazoles with quinoline-2-carbaldehydes has been described.The protocol employs mild conditions and offers good yields of diverse 2,5-aryloxazole derivatives with a broad reaction scope.It is amenable to gram-scale synthesis and easily transformation.Moreover,this 5-aryl-2-(quinolin-2-yl)oxazole skeleton is indeed a new fluorophore and its applications in metal ions probes are also investigated and showed fluorescent responses to mercury ion.

Design and Synthesis of Polyoxazole-based Macrocycles Tethered with a Phosphonate Group

We present the design and synthesis of polyoxazole-based macrocycles containing a phosphonate group.A reliable route was established that allows for convenient and versatile incorporation of various phosphonate functionalities such as phosphonate ester,acid,and salt at the macrocyclic ring periphery.Such unprecedented macrocyclic compounds are anticipated to be appealing candidates as telomerase inhibitors.

A Convenient Synthesis of 2-Arylnaphtho[1,2-d]oxazole Derivatives Promoted by Triethylamine

A variety of 2-arylnaphtho[ 1,2-d]oxazole derivatives were efficiently synthesized in moderate to high yields by the reaction of aromatic aldehydes with 1-amino-2-naphthol derivatives in the presence of triethylamine in refluxing ethanol in air. Seven new 2-arylnaphtho[1,2-d]oxazole derivatives were obtained and characterized by the spectral data and elemental analysis. In addition, the X-ray crystal structures of 2-[4-（N,N-dimethylamino）phenyl]naphtho[ 1,2-d] oxzole （3d） and 1, 1＇-bis（naphtho[ 1,2-d]oxazol-2-yl）ferrocene （3n） have been determined.

Facile Synthesis of 5-Trifluoromethyl-2,4-disubstituted Oxazoles via a Copper（Ⅱ）-Catalyzed and TBHP/I2- Mediated Tandem Oxidative Cyclization

In the presence of Cu（OAc）2·H2O, a variety of 5-trifluoromethyl-2,4-disubstituted oxazoles were easily synthesized via t-BuOOH （TBHP）/I2-mediated tandem oxidative cyclization from readily available starting materials aryl methanamines and α-trifluoroacetyl-substituted ketones or esters under mild conditions, The mechanism was proposed.