3- Methyl-l,2,4-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). 

Auf analoge Weise erhalt man 5-Chlormercuri-3-methyl-l,2,4-oxadiazol (Schmp. 180° Zers.), das mit j2 Molaquivalent Quecksilber(II)-chlorid auskristallisiert, in 50% Ausbeute. 

Die Reaktion von 5-Aryl-3-methyl-l,2,4-oxadiazol mit Benzylalkohol, Benzylamin oder Phe-nyl-methanthiol bei 200°, die zu einer Vielzahl vonProdukten fiihrt, ist eingehend mechanistisch untcrsucht worden279. 

Preparation of 5-(2-bromo-3,5-dimethyl-3H-imidazol-4-yl)-3-methyl-[l,2,4]-oxadiazole... 

On the other hand, replacement of the morpholino moiety (ring C) by a 3-methyl-l,2,4-oxadiazol-5-yl g oup produces active compounds (2013EJMC533). Compounds 78a—d (F yne 27) show lower activity compared to linezolid against standard S. aureus, but a direct comparison could not be performed because the test were performed on racemic mixtures. Nevertheless, as a racemate, thioamide derivatives 78c,d showed major activity against MRSA strains, with MIC values twofold lower than those of reference drug. Moreover, a safety profile similar to HnezoHd was evidenced by means of cytotoxicity data on PK15, HaCat, and HepG2 cell lines. 

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. 

Monaca et al. (2003) examined the effect of the SSRI citalopram on REMS in 5-HTia and 5-HTib knockout mice. Citalopram suppressed REMS in wild-type and 5-HTib mice but not in 5-HT,A I mutants. The 5-HTja receptor antagonist WAY 100635 prevented the citalopram-induced inhibition of REMS in wild-type and 5-HTib knockout mice. However, pretreatment with the 5-HTib receptor antagonist GR 127935 [2 -methyl-4 -(5-methyl-(l,2,4)oxadiazol-3-yl)-biphenyl-4-carboxylic acid ((4-methoxy-piperazine-l-yl)-phenyl)amide] was ineffective in this respect. It was concluded that the action of citalopram on REMS in the mouse depends exclusively on the activation of 5-HT,A receptors. Notwithstanding this, there is unequivocal evidence showing that administration of selective 5-HTib receptor agonists suppresses REMS in the rat. 

The protected 5-amino-l-ribofuranosyl-4-(5-methyl-l,2,4-oxadiazol-3-yl)imidazole 58 (Equation 4) undergoes MHR to afford the 3-acetamidoimidazopyrazole 59 in dimethyl formamide (DMF) or DMSO as solvent at... 

A few examples, illustrating the principle of this type of degenerate rearrangement, are the thermo-induced equilibrium shift of 3-benzoylamino-5-methyl-l,2,4-oxadiazole into 3-acetylamino-5-phenyl-l,2,4-oxadiazole and the isomerization of 5-benzoyl-methylfuroxan oxime into 4-[a-nitroethyl]-3-phenylfurazan (82G181) (Scheme 1.8). They are extensively discussed in Chapter IV. 

One of the earlier examples of a degenerate ring transformation involving the participation of a three-atom side chain is the interconversion of the isomers 3-benzoylamino-5-methyl-l,2,4-oxadiazole (133, X = H) and 3-acetylamino-5-phenyl-l,2,4-oxadiazole (134, X = H) (Scheme IV.51) (75JHC985 89H(29)737). Heating each of these compounds at 181°C furnished an identical equilibrium mixture of isomers, in which mixture isomer 134 (X = H) is predominant (X134/133 at 181°C is about 6.4). These data indicate that the conversion of isomer 133 (X = H) into 134 (X = H) is dri-... 

The 5-methyl-3-phenyl-l,2,4-oxadiazole (84) is deprotonated by bases to an anion, which adds to the carbonyl group of ketones or of CO2 (Scheme 31) <89JCS(Pl)2047>. In contrast, the methyl group of (85) is not lithiated by butyllithium. Instead, the reagent adds to the 4,5-bond (Equation (19)) <70CJC2006>. 

Methyl-phenyl)-3-phenyl-l,2,4-oxadiazol (R = 2-CH3-C6H4 R2 = 12 ml i-0.08 molj 2-Me-... 

Das durch Pcriodat-Oxidation von 0-Acetoxy-N-(l-amino-ethyliden)-hydroxylaminen erhsilt-liche 1-Hydroximino-l-nitroso-ethan setzt sich mit Benzylhalogeniden zu 3-Aryl-5-methyl-l,2,4-oxadiazol-4-oxiden um56 ... 

R - CjH, (3-Elhyl-l,2,4-oxadiazol-5-yl)-[(3-ethyl-l,2,4-oxudiazol-5-yl)-methyl-amino]-methan-, Sdp. 92-93°/4 Torr (530 Pa)... 

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