Oxaziridine 2,5-dihydro

As a final example of regioselective control (Scheme 25), sulfonium ylides usually give nitrones when reacted with nitroso groups via oxaziridine intermediates. However, 7-aryl-2-dimethylamino-3,4,5,6-tetrahydropteridine-4,6-diones 120 were directly formed when nitrosopyrimidine 121 reacted with dimethylphenacylsulfonium bromides 122 instead of the isomeric 5-oxides <1996H(43)437>. It was also reported that the resulting pteridines were reduced to give 7,8-dihydro derivatives 123 with sodium dithionite (Table 7). 

Methyl-6-butyl-5.6-dihydro- E5, 824 (R-CN/CH20 + En) 2,4,4,5,5-Pentamethyl-5,6-dihydro-E5, 824f. (R-CN/CH20 + En) Oxaziridin... 

Dimethyl-2-ethyl-6-propyl-3,4-dihydro- E14a/2. 744 (En-N-En 4- CH20) Oxaziridin 3-Butyl-2-cyclohexyl-X/4, 460... 

Dihydro-2-hydroxy-2-methyl-l(2//)-naphthalenone (7), a model for many natural products, is obtained in >95% ee via oxidation of the sodium enolate of 3,4-dihydro-2-methyl-1 (2f/)-naphthalenone (5) with ( + )-[(8,8-dichlorocamphoi)sulfonyl]oxaziridine (6)88. This material was obtained in less than 16% ee using (j-)-(camphorsulfonyl)oxaziridine 26. 

The reaction of 2-isopropyl-5,5-dimethyl-5,6-dihydro-2//-l,3-oxazine 306 with MCPBA leads to formation of the corresponding A -alkyl oxaziridine 307 as a single isomer <1995T139>. Due to the preferential conformation of imine 306, the imine double bond is exclusively oxidized anti to the f-propyl moiety. Oxidation of imine 308 with MCPBA gave oxaziridine nitroxide 309 in 90% yield <2000TL8787> and similar oxidation of 310 gave oxaziridine 311 in 74% yield <2005S1496>. 

Secondary amines reacted to form hydrazines in yields of 90% and better. Aniline can be converted to phenylhydrazine. Sometimes the addition was followed by the elimination of water rather than the aminated nucleophile. For example, treatment of 3,3-pentamethyleneoxaziridine with methoxide ion produced cyclohexanone oxime (9-methyl ether. Formanilide reacted with 3-phenyloxaziridine in the presence of sodium ethoxide to produce benzaldehyde phenyUiydrazone. " Of considerable interest is the reaction of Schiff bases with these oxaziridines to produce diaziridines. Other examples are given in Schmitz recent review. One intramolecular version of this kind of amination is known oxaziridine 57 was converted to benzophenone and 5,6-dihydro-4H-l, 2-thiazine 58 upon heating. ... 

Modest to low ees are reported for the oxaziridine mediate asymmetric hydroxylation of 4,5-dihydroisoxazoles (177) to 4,5-dihydro-4-isoxazolols (178) (Equation (42)) <93JOC759i>. Dichloro oxaziridine (+)-(74) and the lithium enolate, generated in the presence of TMEDA, gave the best results. Transition state TS-2 predicts the absolute configuration of the product which was confirmed by chemical correlation. 

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