1,2,4-Oxadiazole 3-methyl-5-

Chem. Abstracts. 1,2,4 Oxadiazole 3-methyl- 5-phenyl-1,2,4-oxadiazole... 

Although the boiling points of aliphatic mono- and disubstituted derivatives exceed 100°, they are also very volatile and can be codistilled with solvents. This is presumably the reason why dimethyloxadiazole, boiling at 124°, was only "perceived" and smelled in 1884 60), but could only recently be isolated (5, 44c). The vapour pressures of oxadiazole, methyl and dimethyl oxadia iole are summarized in Table 7. Their heat... 

Hydrazine verhalten sich gegeniiber 5-Chlor-l,2,4-oxadiazolen wie Amine und bilden 5-Hy-drazino-1,2,4-oxadiazole. Methyl-hydrazin reagiert regioselektiv am 1-N-Atom der Hy-drazin-G ruppe258 ... 

In order to clarify whether the presence of meta-oriented units would change the rate of oxadiazole methylation and thus would change the ultimate oxadiazole/hydrazide ratio in the fiber, identical polymerizations of all-para- and 50/50 para/meta-oriented monomer mixtures were sampled at various intervals, the polymer dope samples were coagulated and hydrolyzed in dioxane/ water and the polymer compositions determined. As data in Table III show, essentially identical oxadiazole/N-methyl hydrazide ratios were obtained for the all-para and the mixed para/meta compositions. 

Figure 10.8 Hyrdrolysis Reaction and Structure of a / -Phenylene oxadiazole/ //-Methyl hydrazide Copolymer...

H. C. Bach, F. Dobinson, K. R. Lea, and J. H. Saunders. High-strength/high-modulus fibers of p-phenylene oxadiazole/ -methyl hydrazide copolymers -a new class of high-performance organic materials. J. Appl. Polym. Set, 23 (7) 2125-2131, 1979. 

N N 3-( p-Bromophenyl)-4-methyl- 1,2,5-oxadiazole 2-oxide 3-(p-bromo-phenyl)-4-methyl-l,2,5-oxadiazole 5-oxide 3,4-diphenyl-l,2,5-oxadiazole... 

Oxazoles are easily cleaved. 2,5-Dialkyl-l,3,4-oxadiazoles (159) in aqueous solution with acid or base give hydrazides (if suitable substituents are present, further reaction can occur see Section 4.02.3.5.1). 3-Methyl-l,2,4-oxadiazole (160) is easily hydrolyzed to acetamidoxime (61CKL)292). 

Substituents cannot directly conjugate with /3-pyridine-like nitrogen atoms. Azole substituents which are not a or y to a pyridine-like nitrogen react as they would on a benzene ring. Conjugation with an a-pyridine-like nitrogen is much more effective across a formal double bond thus the 5-methyl group in 3,5-dimethyl-l,2,4-oxadiazole (323) is by far the more reactive. 

Additional nitrogen atoms facilitate such reactions, particularly if they are a or y to the alkyl group, and, if a, act across a formal double bond. Thus, the 5-methyl group in 3,5-dimethyl-l,2,4-oxadiazole is much more reactive than the 3-methyl group in this compound or the methyl groups in 2,5-dimethyl-l,3,4-oxadiazole (76AHC(20)65). 

Methyl groups on C-linked phenyl attached to oxazoles, isoxazoles and oxadiazoles react with benzylidineaniline to give stilbene derivatives (Scheme 51) <78AHC(23)l7l). 

A similar intramolecular trapping of the intermediate (511) from the photolysis of the corresponding methyl tetrazole-l,5-dicarboxylate (510) gave methyl 5-methoxy-l,2,4-oxadiazole-3-carboxylate (512). 

Oxadiazole, 2-amino-5-phenyl-mass spectra, 6, 429 methylation, 6, 431... 

Oxadiazole-3-carboxylic acid, 5-methoxy-methyl ester... 

In the A-oxides 46 the tautomerism of the oxygen atom attached to the oxadiazole nucleus was determined as AG 20 kcal moF The steric effect of the 9-methyl group of 7,9-dimethyl l,2,5-oxadiazolo[3,4-/]quinoline A-oxide 46, (Y = C—CH3 X = N = H = CH3) would not be expected to favor the presence... 

The 3-oxidotriazolopyridinium zwitterions 245 fail to react with DMAD unless magnesium bromide is present, when ring opening occurs (2000H(53 265) (Section IV.F). The thiol 268 adds methyl acrylate as expected the resulting ester is converted via the acid hydrazide, to an oxadiazole (89IJC(B)170). 

Chemical Name 17a methyl-5a -androstano[2,3-cl -[1,2,5] oxadiazol-17/3-ol Common Name —... 

The dione 1 is converted into 2,6-dichloro-4,l-benzoxazepin-5(3i/)-one (2) by the action of phosphoryl chloride in jV.lV-dimethylaniline. The crude product on treatment with 3-isocyano-methyl-5-isopropyl-l,2,4-oxadiazole gives the imidazobenzoxazepinone 3.36... 

Benzofurazan (benz-1,2,5-oxadiazole) reacted with bromine by addition to give a4,5,6,7-tetrabromo adduct. Bromine in hydrobromic acid solution 4-brominated both 5-methyl- and 5-bromo-benzofurazans (74JHC8I3). When 4,7-dinitrobenzofurazan was treated with ammonium chloride in refluxing acetic acid, nucleophilic displacement gave rise to the 4-chloro-7-nitro derivative (83URP1004375). Naphtho[l, 2-c]furazans (42) are mainly 4-halogenated, but there is minor substitution in the 8-position (73CHE1331). 

Ligand abbreviations (6-Mepy)(py)2tren and (6-Mepy)2(py)tren = tris[4-[(6-/ )-2-pyridyl]-3-aza-6-butenyl]amme, R = H or CH3 HB(pz)3 = hydro-tris(pyrazolyl)borate paptH = 2-(2-pyridylamino)-4-(2-pyridyl)thiazole phenmethoxa = 3-[2-(l,10-phenanthrolyl)]-5-methyl-l,2,4-oxadiazole pyimH = 2-(2 -pyridyl)itnidazole pybimH = 2-(2 -pyridyl)benzimidazole ppa = JV -(2-pyridylmethyl)picolineamidine tpmbn = tetrakis(2-pyridylmcthyl)-meso-2,3-butane-diamine tppn = tetrakis-(2-pyridylmethyl)-l-methyl-l,2-propanediainine tpchxn = tetrakis(2-pyridylmethyl)-tra s-l,2-cyclohexanediamine biz = 2,2 -bi-1,4,5,6-tetrahydropyrimidine. 

The initial retrosynthetic analysis of 1 resulted in the cleavage of the two amide bonds and a C-N bond leading to the four components oxadiazole carbonyl chloride 2, methyl iodide, 4-fluorobenzylamine (4-FBA) and the densely functionalized hydroxypyrimidinone 3 (Scheme 6.1). These synthetic disconnections were reasonable and should be applicable for long term route development. 

The original route for the synthesis of potassium 5-methyl-l,3,4-oxadiazole-2-carboxylate (39) via an intramolecular condensation of ethyl (2-acetylhydrazinyl)-(oxo)acetate (37) suffered from moderate yields (Scheme 6.10). 

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