Biologically active isoxazoles

Novel steroids which contain an isoxazole fused ring within the structure have biological activity which is primarily contraceptive (74MI41604, 79MI41607, 79USP4160027) and a variety of other indications (75USP3869467, 75ZOB2090). 

Furazano[3,4-/]quinoxaline, 7,8-diphenyl-synthesis, 6, 412 Furazanothiophene synthesis, 6, 417 Furazans, 6, 393-426 biological activity, 6, 425 bond angles, 6, 396 bond lengths, 6, 396 coordination compounds, 6, 403 diamagnetic susceptibilities, 6, 395 dipole moments, 6, 395, 400 heats of combustion, 6, 400 heterocyclic ring reactions, 6, 400-403 IR spectra, 6, 398 isoxazoles from, 6, 81 mass spectra, 6, 399 microwave spectroscopy, 6, 395, 396 MO calculations, 6, 395 monosubstituted... 

AH-Pyrrolo[3,4-c]isoxazole, 3-amino-biological activity, 6, 1024 4H-Pyrrolo[3,4- c]isoxazole-5(6/7)-carboxylic acid, 3-amino-ethyl ester... 

VII. Biologically Active Deriv atives of the Isoxazole Series. . . 421... 

The extensive investigation of the biological activity of organic compounds that is so characteristic of the last few decades, has also revealed active compounds in the isoxazole series. The main advances have been achieved in recent years. 

Hydrolysis of the isoxazole herbicide isoxaflutole rapidly produces a biologically active diketonitrile that is further degraded to products, which are partly bound to soil components and partly degraded to CO2 (Beltran et al. 2000 Lin et al. 2002 Taylor-Lovell et al. 2002) (Figure 1.24). 

Isoxazoles are privileged aromatic heterocycles due to their wide spectrum of biological activities and their use as versatile building blocks in organic synthesis. Recent progress in the field of transition-metal-catalyzed cross-coupling reactions on isoxazole systems has been summarized and discussed <06EJO3283>. 

I.4.I.4. Synthetic Biologically Active Compounds Silyl- and carbonyl-substituted isoxazoles have been prepared and screened for their cytotoxic activity (497). Some exhibited moderate cytotoxicity toward the HT-1080 and MG-22A cell lines. The highest activity level has been displayed by 3-methyl-5-diphenyl-methylsilylisoxazole. 

A review of isoxazole compounds (covering the period 1963—1977) discusses their synthesis, reactivity, and physiological and physicochemical properties naturally occurring and biologically active isoxazoles are included.27 Some Saudi Arabian plants have been screened for alkaloids.28 Aristolochic acids I (28 R = H) and D (28 R = OH), which are cytotoxic to mammalian systems, are also cytotoxic to non-tumorous plant cells.29... 

The generation from furoxans of other heterocyclic systems, some of which show useful biological activity (see Section 4.22.5), has been the subject of intensive investigation. The following subsections summarize the conversion of benzofuroxans into quinoxaline and benzimidazole oxides, the rearrangement of 4-substituted benzofuroxans, and the transformation of monocyclic furoxans into isoxazoles and isoxazolines, furazans, and pyrazolines. More detailed discussion is to be found in recent comprehensive reviews (75S415, 76H(4)767, 81AHC(29)251>. 

At the time of the earlier review many biologically active isoxazole and reduced isoxazole derivatives had been reported, including the naturally occurring antituberculosis antibiotic cycloserine (119), the monoamine oxidase inhibitor isocarboxazid (120), and isoxazolosteroids showing anabolic... 

The pronounced biological activity has rendered many substituted isoxazoles an important motif in medicinal chemistry. For instance, isoxazoles are potent and selective agonists of human cloned dopamine D4 receptors [87], they exhibit GABAa antagonist [88] analgesic, antiinflammatory, ulcerogenic [89] COX-2 inhibitory [90, 91] antinociceptive [92], and anticancer [93] activity. 

The isoxazole, isoxazoline, and isoxazolidine rings are frequently present in biologically active compounds and are used as building blocks in the synthesis of new potential drugs. 

The biological activity of substituted isoxazoles has made them a focus of medicinal chemistry and the significant pharmaceutical activity of several naturally occurring examples is well-documented <05CRV2723>. Moreover, the facile cleavage of the N-O bond of the isoxazole nucleus under simple reaction conditions is the reason for the numerous applications of this system as synthetic intermediates for the construction of molecular assemblies including different heterocycles and natural products <05CRV4237>. 

Synthesis and biological activity of steroid isoxazoles 00KGS291. 

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