Isoxazoles, dihydro

Isoxazole, 3-chloro-5-hydroxymethyl-oxidation, 6, 27 Isoxazole, 4-chloromethyI-reactions, 6, 53 Isoxazole, 5-chloro-3-phenyl-reactions, 6, 58 Isoxazole, 3-cyano-reactions, 6, 30 Isoxazole, diacyl-synthesis, 6, 79 Isoxazole, 3,4-dialkyl-synthesis, 6, 83 Isoxazole, 3,5-dialkyl-synthesis, 6, 83 Isoxazole, 4,5-dialkyl-synthesis, 6, 83 Isoxazole, 3,5-diamino-2-amino-l-azirines from, 7, 89 Isoxazole, 3,5-diaryl-synthesis, 6, 63 Isoxazole, 2,5-dihydro-synthesis, 6, 79 Isoxazole, 4,5-dihydro-dehydrogenation, 6, 4... 

Isoxazolo[5,4-d]isoxazole, 3a,6a-dihydro-structure, 6, 975 synthesis, 6, 1018 Isoxazoloisoxazoles synthesis, 3, 41 Isoxazoio[2,3-h]isoxazoies synthesis, 6, 1001 Isoxazolo[4,5-d]isoxazoles synthesis, 6, 989, 997... 

Polymorphic forms of I and II of 3- 2-[4-(6-fluorobenzo[r/ isoxazol-3-yl)-3,6-dihydro-2//-pyridin-l-yl]ethyl -2-methyl-6,7,8,9-tetrahydro-4//-pyrido [1,2-n]pyrimidin-4-one was characterized by IR spectroscopy (99MIP1). 

Accordingly, cyclic nitronates can be a useful synthetic equivalent of functionalized nitrile oxides, while reaction examples are quite limited. Thus, 2-isoxazoline N-oxide and 5,6-dihydro-4H-l,2-oxazine N-oxide, as five- and six-membered cyclic nitronates, were generated in-situ by dehydroiodination of 3-iodo-l-nitropropane and 4-iodo-l-nitrobutane with triethylamine and trapped with monosubstituted alkenes to give 5-substituted 3-(2-hydroxyethyl)isoxazolines and 2-phenylperhydro-l,2-oxazino[2,3-fe]isoxazole, respectively (Scheme 7.26) [72b]. Upon treatment with a catalytic amount of trifluoroacetic acid, the perhydro-l,2-oxazino[2,3-fe]isoxazole was quantitatively converted into the corresponding 2-isoxazoline. Since a method for catalyzed enantioselective nitrone cycloadditions was established and cyclic nitronates should behave like cyclic nitrones in reactivity, there would be a good chance to attain catalyzed enantioselective formation of 2-isoxazolines via nitronate cycloadditions. 

Enantiomerically pure 4.5-dihydro-3-[(/J)-(4-methylphenylsulfinyl)methyl]isoxazoles 16 arc readily available from the reaction of metalated 4,5-dihydro-3-methylisoxazoles 14 with (-)-menthyl (5)-4-methylbenzenesulfinate (15), under inversion of the configuration at sulfur, followed by separation of the resulting diastereoiners27-28. 

Dihydro-3- (/ )-(4-methylphenylsulfinyl)methyl isoxazoles 16 General Procedure28 ... 

Dihydro-3-(2-hydroxyalkyl)isoxazoles 20 General Desulfurization Procedure24 ... 

Both of the 4,5-tran.v-diaslereomers of 4,5-dihydro-4-(4-methoxyphenyl)-5-methyl-3-[(7 )-(4-methylphenylsulfinyl)methyl]isoxazole (24) show excellent stereoselection in reactions with aldehydes. Despite the bulky substituents at the 4,5-dihydroisoxazole nucleus, the stereochemical outcome of the reaction is controlled by the sulfoxide stereogenicity. The pairs of 4,5-dihydro-3-(2-hydroxyalkyl)-4-(4-methoxyphenyl)-5-methylisoxazoles, obtained by desulfurization of the corresponding aldol adducts, have the same configuration at the hydroxy-substituted carbon (C-2 ) and opposite configuration in the 4- and 5-positions of the dihydroisoxazole ring24. 

Aluminum oxide catalyzed addition of ethyl nitroacetate to racemic 2,3-cpoxy aldehydes 7 affords substituted 4,5-dihydroisoxazole 2-oxides through a regio- and stereospecific tandem nitroaldol cyclization process. High diastereoselectivities are observed in the reaction of cis-epoxyaldehydes to yield the ethyl, vi7 -4.5-dihydro-4-hydroxy-5-( I -hydroxyalkyl)-3-isoxazole-carboxylate 2-oxides, with tram configuration at the ring positions, whereas reactions of trans-and 3,3-disubstituted 2,3-epoxyaldehydes proceed with lower selectivities28. 

Benzopyran-3-one, l,4-dihydro-6,7-dimethoxy-], 55, 45 Isocyamde, benzyl-, 55, 98 Isocyanide, butyl-, 55, 98 ISOCYANIDE, tert-butyl- [Isocyamde, 1,1-dimethylethyl-], 55, 96 Isocyamde, cyclohexyl-, 55, 98 Isocyamde, dodecanyl-, 55, 98 Isocyamde, ethyl, 55,98 Isocyamde, methyl, 55, 98 Isocyamde, phenyl-, 55, 98 (-)-2,3 4,6-Di-0-isopropylidene-2-keto-L-gulomc acid, hydrate [L-jcy/o-2-Hex-ulosomc acid, bis-<9-( 1 -mcthylcthyl-ldene)-], 55,80, 81 ISOXAZOl F, 3-(4-chlorophenv1)-5-(4-methoxyphenyl)-, 55, 39 Isoxazole,5 -(4-chloropheny l)-3-(4-me th-oxyphenyl)-, 55,42... 

A one-pot synthesis of 3-methyl-5-aryl-4//-pyrrolo[2,3-<7]isoxazoles was performed in high yields by Sharpless epoxidation of 4-amino-3-methyl-5-styrylisoxazoles <06TL4957>. 1,2,4,5-Tetrazines were condensed with isoxazolylcyclobutanones in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7-dihydro-5//-[l,2]diazocin-4-ones <06JOC2480>. 

---