Oxidants 2- -3-phenyl-oxaziridine

In order to optimize oxidation conditions of diethyl(2-methylpyrrolidine-2-yl) phosphonate into the corresponding nitrone, a comparative analysis of the action of various oxidants such as H2O2, m-CPBA, Oxone, 2-phenylsulfonyl-3-phenyl-oxaziridine (PSPO), DMD, and A-methylrnorpholine /V-oxide in the presence of a catalytic quantity of tetrapropylammonium perruthenate (NMO/TPAP) has been made (92). 

Triethoxy-l,2A5-oxaphospholene (112) reacts at room temperature with 2-(p-tolyl)-3-phenyl-oxaziridine (63d) to give a /Miydroxy-y-ketophosphate (113) in 82% yield (Equation (26)) (91TL5313). It seems likely that an oxirane intermediate is initially formed which rearranges on work-up to (113). Asymmetric oxidation with (+ )-[(8,8-dichlorocamphoryl)sulfonyl]oxaziridine (74) gave (113) in 49% ee and 88% isolated yield. The absolute configuration of (113) was not established. 

Multigram quantities of A-methoxycarbonyl-3-phenyloxaziridine (53a) and A-Boc-3-phenyl-oxaziridine (53b) are produced by carefully controling the oxidation of the corresponding imines with buffered Oxone in biphasic media (Equation (49)) <91CC435,93JOC4791). The principle product is amide (190) if the oxidation is carried out at room temperature or with MCPBA. 

The asymmetric hydroxylation of A-non-substituted ethyl 2-carbamoyl-2-phenylacetate in THF was mediated by Davis oxaziridine, 2-(benzenesulfonyl)-3-phenyl-oxaziridine as oxidant in the presence of a combination of rare-earth metal alkoxide Pr(OPr )3 and the ligand A-((S)-l-(2-hydroxyphenylcarbamoyl)-2-methylpropyl)-2-hydroxybenzamide as catalyst afforded enantioenriched (68-92% ee) (R)-ethyl 2-carbamoyl-2-hydroxy-2-phenylacetate (yield 39-96%) with a densely... 

In 6-methyl- and 6-phenylphenanthridine 5-oxide (181 R = CH3, Ph), rearrangement of the intermediate oxaziridine is accompanied by methyl or phenyl migration, and 5-methyl- and 5-phenyl-6-(5 )-phenanthridinones (182 R = CH3, Ph) are isolated in high yield on irradiation in ethanol,156 In benzene solution, however, the photolysis is more complex,156 and the principal products of irradiation of 6-phenylphenanthridine 5-oxide are 2-benzamido-2 -hydroxybi-phenyl, 6-phenylphenanthridine, and 5-phenyl-6-(5i/)-phenanthri-done. 

Until quite recently the isolation of optically active seienoxides has been limited to those contained in steroids (isolated as diastereoisomeis). < The difficulty in obtaining these compounds was attributed to the racemization through the achiral hydrated intermediates. Simple optically active sel enoxides (S-11% ee) were first prepared by kinetic resolution. Direct oxidation of selenides to seienoxides was first reported using optically active oxaziridine derivatives under anhydrous conditions, but the extent of the asymmetric induction was somewhat unsatisfactory with methyl phenyl selenide as substrate (8-9% Recently much improved enantiomeric excesses (45-73%) were achieved with new oxaziridine reagents such as (70). An attempt at the asymmetric oxidation of more bulky selenides was independently carried out using Bu OCl in the presence of (-)-2-octanol (equation 55), but resulted in unsatisfactory enantioselectivities (ee 1%). Much better results were obtained by the oxidation of p-oxyalkyl aryl selenides (ee 18-40% equation 56) 27 gjyj selenides (ee 1-28%) using... 

Earlier 3-phenyl-2- /t-butyloxaziridine 129 was reported not to be able to oxidize sulfides to sulfoxides even on heating and to undergo thermal rearrangement to A -/r /z-butyl-a-phenylnitrone. However, Shimizu et al. demonstrated that under 800 MPa at 100 °C, this oxaziridine behaves as an oxidant and was able to oxidize thioanisole to the sulfoxide <1997J(P1)3491>. 

Chloro-2-methyl-4-phenylquinazoline 1-oxide gives l-acetyl-5-chloro-3-phenyl-l//-indazole on irradiation. This transformation is believed to proceed by rearrangement of the oxaziridines formed as primary isomerization products. ... 

The remarkable stability reportedfor 2-phenyl-3,3-dibenzoyloxaziridine in the face of Padwa s inability to isolate oxaziridines but only amides upon oxidation of jV-phenylacylimine derivatives and the lability of nitrones 80 and 82 has recently been shown to be in error.The product from the thermal or photochemical isomerization of A -phenyl-C,C-dibenzoylnitrone is the expected rearrangement product, A -benzoylphenylglyoxanilide. 

Enantioselective oxidation of Z-aryl cinnamyl allylic selenide (83) with oxaziridine (—)-(69) gave 1-phenyl allyl alcohol (85) via an allyl selenoxide-selenate [2,3] sigmatropic rearrangement (Scheme... 

The Movassaghi group has investigated the stereoselective C2 to C3 migration of a 2-phenyl substituent on diastereomerically pure hydroxyindolenines 13 [18]. The requisite hydroxyindolenines were prepared via oxidation of 2-phenyl L-tryptophan with Davis oxaziridine (3-n-butyl-l,2-benzisothiazole-l,1-dioxide oxide). The oxidation step proceeded with modest diastereoselectivity, providing a 2 1 mixture of the (3R) and (35)-hydroxyindolenines 13 that were separated. As illustrated for... 

Whereas the photochemically induced reactions of pyridine JV-oxides can yield a wide range of products, the substitution of phenyl groups results in the isolation of 1,3-oxazepines (663) and (664), formed via the isomeric oxaziridines (661) and (662), The irradiation of polychlorinated p3rridine... 

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