Synthesis,Crystal Structure and Biological Activity of 5-(2-Methylphenyl)-1,3,4-oxadiazol-2(3H)-one Derivatives

3-Methyl-5-(2-methylphenyl)-1,3,4-oxadiazol-2(3H)-one(6) and N,N-diethyl-2-(2-methylbenzoyl)-hydrazinecarboxamide(7) were designed and synthesized from 5-(2-methylphenyl)-1,3,4-oxadiazol-2(3H)-one(5) by substituting and ring-opening, respectively. The target compounds were confirmed by IR, 1H NMR spectroscopy, MS, elemental analysis and single-crystal X-ray diffraction. Compound 6(C10H10N2O2, Mr = 190.20) crystallizes in the triclinic system, space group P 1 with a = 7.4645(16), b = 10.868(2), c = 12.970(3) A, α= 110.542(2), β= 98.142(2), γ=99.766(2)°, V = 947.7(3) A3, Z = 4, F(000) = 400, Dc = 1.333 g/cm3, μ= 0.095 mm-1, the final R =0.0550 and wR = 0.1483 for 2956 observed reflections with I 2γ(I). Compound 7(C13H19N3O2, Mr= 249.31) crystallizes in the monoclinic system, space group C2/c with a = 18.926(3), b =12.1853(17), c = 14.740(2) o,(I) = 125.6380(10)°, V = 2762.7(7) A3, Z = 8, F(000) = 1072, Dc=1.199 g/cm3, μ= 0.083 mm-1, the final R = 0.0554 and w R = 0.1468 for 2395 observed reflections with I 2σ(I). The preliminary bioassay results indicate that compound 6 exhibits notable fungicidal activities against Fusarium graminearum, Botrytis cinerea, Rhizoctonia cerealis and Colletotrichum capsici at the concentration of 100 μg/mL.     

Benzoxazol-2 (3H)-one and 1,3,4-oxadiazol-2(3H) -one derivatives from substituted enaminones and ketoenamines

Enaminones and ketoenamines bearing a hydrazine type substituent undergo side chain thermal cyclization, the former into benzoxazol-2 (3H)-one derivatives and the latter into 1, 3, 4-oxadiazol-2 (3H)-one derivatives. Factors affecting such reactions are discussed.     

5-(1-Alkenyl)-1, 3, 4-oxadiazol-2(3H)-one

3-(2-alkenoyl)-thiocarbazic acid O-methyl esters 1 are desulfurated by bromine and the unknown intermediates are transformed by alkali to 5-(1-alkenyl)-1, 3, 4-oxadiazol-2(3H)-ones ( 2 ). This type of oxadiazolone substitution is not realizable by the common ring closure of hydrazides with phosgene due to pyrazolidinone ring closure of unsaturated acids with hydrazine.     

6-(3-氨基苯基)-4, 5-二氢哒嗪-3(2H)-酮的合成

以苯、丁二酸酐为原料,经傅克酰基化,硝化,与水合肼反应三步反应合成6-(3-氨基苯基)-4,5-二氢哒嗪-3(2H)-酮(1),总收率为58.3%。由3-(3-硝基苯甲酰基)丙酸(3)合成化合物1的过程中,在雷尼镍(Raney Ni)的催化下与水合肼反应,一步完成了苯环上硝基的还原和成环。重点考察了该步反应的物料配比、反应时间对产率的影响。结果表明,水合肼与化合物3的摩尔比11.7∶1,回流反应4 h,产率为82.7%。     

A facile retro-ene reaction of 5-(methoxyamino)-3-aryl-1,3,4-oxadiazol-2(3H)-ones

5-(N-Methoxy-N-methyl)amino-3-aryl-1,3,4-oxadiazol-2(3H)-ones 3 undergo a heteroretro-ene reaction in refluxing methanol in which the leaving enophile is formaldehyde. The resulting 5-(methylimino)-3-aryl-1,3,4-oxadiazolidin-2-one 4 may be viewed as a kinetic product which tautomerizes to the more stable 5-(methylamino)-3-aryl-1,3,4-oxadiazol-2(3H)-one 5 as the thermodynamic product. Comparison of calculated reaction energies reveals that the presence of the heterocyclic ring facilitates the retro-ene reaction, but the expulsion of formaldehyde is predicted to be highly exothermic even in its absence.     

Synthesis of 3-acylamino-2-oxazolidinone derivatives through cyclic transformations of 5-aryl (or benzyl)-1,3,4-oxadiazol-2(3H)-one derivatives

New 3-acylamino-2-oxazolidinone derivatives 3 were obtained in good yields by reaction of 5-aryl (or benzyl)3-(2-hydroxyethyl)1,3,4-oxadiazol-2(3H)ones 1 with sodium ethylate. Treatment of ethyl 5-aryl-2-oxo-1,3,4-oxadiazole-3(2H)-acetates 7 with aromatic aldehydes in the presence of sodium ethylate or sodium hydride afforded 3-acylamino-5-aryl-4-ethoxycarbonyl-2-oxazolidinone derivatives as two trans- 5 and cis- 6 racemics. Only RS,SR-racemates were obtained with acetophenone under the same conditions.     

Synthesis of 3-(5-Aryl-1,3,4-oxadiazol-2-yl)chromones

A general method was proposed for the synthesis of 3-(5-aryl-1,3,4-oxadiazol-2-yl)chromones starting from 3-formylchromone. This aldehyde yields acylhydrazones, from which the corresponding unstable nitrile imines are generated. These intermediates undergo intramolecular 1,3-dipolar cycloaddition.     

Synthesis of 3(2- and 4-Pyridinyl)-1,3,4-oxadiazol-2(3H)ones

The synthetic objective of preparing halo- and halo- plus alkoxy-substituted pyridyloxadiazolones was achieved by allowing an alkali metal salt of an oxadiazolone to displace a leaving group on a halo- or halo- plus alkoxy-substituted pyridine, respectively. Other routes failed to give the desired compounds, and they are briefly discussed.     

Cyclic transformations of 5-aryl(or benzyl)-3-(2-bromoethyl- 1,3,4-oxadiazol-2(3H)-ones into 1-aminoimidazolidin-2-one and 5,6-dihydro-4H-1,3,4-oxadiazine derivatives

5-Aryl(or benzyl)-3-(2-bromoethyl)-1,3,4-oxadiazol-2(3H)-ones 3 have been prepared. They were reacted with secondary alkylamines without any change of the heterocycle to give amino derivatives 6 , but with primary alkylamines, cyclic transformation occurred to give 1-acylamino-3-alkylimidazolidin-2-ones 7 . In the presence of sodium alcoholate, bromo compounds 3 were transformed into 2-aryl(or benzyl)-4-alkoxycarbonyl-5,6-dihydro-4H-1,3,4-oxadiazines 9 .     

Synthesis of 3-(5-Aryl-1,3,4-oxadiazol-2-yl)chromones

A general procedure was proposed for the synthesis of 3-(5-aryl-1,3,4-oxadiazol-2-yl)chromones by reaction of 3-formylchromone with aroylhydrazines, transformation of the corresponding acylhydrazones into 1,3-dipoles by the action of bromine in the presence of sodium acetate, and intramolecular ring closure.     

New synthesis of 4,5-dihydro-1,2,4-triazin-3(2H)-one derivatives through cyclic transformation of 1,3,4-oxadiazol-2(3H)-one derivatives

Some 5-aryl(or benzyl)-2-oxo-1,3,4-oxadiazole-3(2H)-acetones or acetophenones 2 were easily prepared. These compounds reacted with hydrazine derivatives to give 4,5-dihydro-1,2,4-triazin-3(2H)-one derivatives 3 , 4 and 6 in good yields. With phenylhydrazine, the intermediate hydrazones 5 were obtained. Their conversion into triazinones necessitated the presence of sodium ethylate.     

Reaktionen von 3-substituiertem 5-Trifluormethyl-1,3,4-oxadiazol-2(3H)-on mit Nucleophilen

Reactions of 3-Substituted 5-Trifluoromethyl-1,3,4-oxadiazol-2(3H)-one with Nucleophiles The 3-substituted 5-trifluoromethyl-1,3,4-oxadiazolones 3, 4, 13 , and 15 are attacked by N- and S-nucleophiles either at the ring C-atom C(2) or C(5). Depending on the nature of the substituent and the nucleophile, the ring-opening products 7, 10, 12 , and 14 or the ring-enlargement products 16 are formed. The reaction of 4 with thiols is a novel variant of the Grob-type fragmentation. The reactivity of the 1,3,4-oxadiazolones is compared with that of the analogous 1,3,4-thiadiazolones. The structures of the new compounds were elucidated by ¹H- and ¹³ C-NMR spectroscopy.     

Synthesis of 3-(3-Acetyl-5-aryl-2,3-dihydro-1,3,4-oxadiazol-2-yl)chromones

A method is proposed for the synthesis of 3-(3-acetyl-5-aryl-2,3-dihydro-1,3,4-oxadiazol-2-yl)chromones which consists of the conversion of 3-formylchromones to aroylhydrazones and their subsequent heterocyclization using acetic anhydride.     

Reaction of 6-methyl-2-methylthio-3-(2-thioxo-1,3,4-oxadiazol-5-yl)methyl-4(3H)-pyrimidinone with amines

The reaction of 6-methyl-2-methylthio-3-(2-thioxo-1,3,4-oxadiazol-5-yl)methyl-4(3H)-pyrimidinone with butyland benzylamine and also with piperidine and morpholine has been studied. It was found that the primary amines not only open the 1,3,4-oxadiazole ring to form the corresponding thiosemicarbazides but also substitute the methylthio group at position 2 in the pyrimidine ring. Morpholine can only open the 1,3,4-oxadiazole ring but piperidine can also substitute the methythio group to give an oxadiazolethione piperidinium salt.Vilnius University, Vilnius 2734, Lithuania. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1129, August, 1998.     

3-（3-乙酰基-5-芳氧亚甲基-2,3-二氢-1,3,4-噁二唑-2-基）色酮类化合物的合成

3-（3-乙酰基-5-芳氧亚甲基-2;3-二氢-1;3;4-噁二唑-2-基）色酮类化合物的合成;噁二唑啉;色酮;合成     

Synthesis of 2-and 6-chloro-3-(5-methyl-1,3,4-oxadiazol-2-yl)pyridines

A convenient synthesis of 2- and 6-chloro-3-(5-methyl-1,3,4-oxadiazol-2-yl)pyridines, 3 and 10 , utilizing the readily available amide 7 is described. Incorporation of the 3-t-butylamino-2-hydroxypropoxy side chain onto 3 provided 2 , a potential bioisostere of 1 . The antihypertensive activities of 2 and 12 were evaluated in the spontaneously hypertensive rat model.     

The preparation of 5-(2-aminophenyl)-1,3,4-oxadiazole-2(3H)-one and its rearrangement to 3-amino-2,4(1H,3H)-quinazolinedione

When anthranilic acid hydrazide is reacted with 1,1-carbonyldiimidazole inTHF 5-(2-aminophenyl)-1,3,4-oxadiazole-2(3H)-one (4) is formed. It can also be prepared from 1-o-aminobenzoyl-4,4-dimethylsemicarbazide which eliminates methylamine when boiled withDMF. On heating the 5-(2-aminophenyl)-1,3,4-oxiadiazole above its melting point it rearranges to 3-amino-2,4(1H,3H)-quinazolinedione (5).

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Die Darstellung von 5-(2-Aminophenyl)-1,3,4-oxadiazol-2(3H)-on und dessen Umlagerung in 3-Amino-2,4(1H,3H)-chinazolindion

Zusammenfassung Bei der Reaktion von Anthranilsäurehydrazid mit 1,1-Carbonyldiimidazol inTHF wird 5-(2-Aminophenyl)-1,3,4-oxadiazol-2(3H)-on (4) gebildet. Dieses kann auch aus 1-o-Aminobenzoyl-4,4-dimethylsemicarbazid dargestellt werden, welches beim Kochen mitDMF Methylamin eliminiert. Beim Erhitzen von 5-(2-Aminophenyl)-1,3,4-oxadiazol über seinen Schmelzpunkt tritt Umlagerung zu 3-Amino-2,4(1H,3H)-chinazolindion (5) ein.

     

Synthesis of 5-aryl-3-carbazoyl-1,3,4-oxadiazol-2(3H)-one. Derivatives and their ring transformation into 5-benzamido-1,2,4-triazolidine-3,5-dione derivatives

Some 5-aryl-3-carbazoyl-1,3,4-oxadiazol-2(3H)-one derivatives 6 and 9 have been synthesized in two ways. The expected thermal ring transformation into 2,5-disubstituted 1,3,4-oxadiazoles did not occur but, by acid hydrolysis of 5-aryl-3-[3-benzylidene-2-methyl(or phenyl)carbazoyl]-1,3,4-oxadiazol-2(3H)-ones 6 , a new ring transformation took place and the corresponding 4-benzamido-1-methyl(or phenyl)-1,2,4-triazolidine-3,5-dione derivatives 11 were formed. The 4-amino-1-phenyl-1,2,4-triazolidine-3,5-dione ( 19 ) has been prepared and its structure was confirmed by some reactions.