With oxaziridines

Diaryloxaziridines are even less stable. With oxaziridines (66 Ar = Ph or 4-Me2NC6H4) acid amide formation at 25 °C proceeded in the course of 66 and 10 h respectively in the latter case there were equal amounts of H and aryl migration. Ethanol as solvent again accelerated the reaction, in the latter case by a factor of lO. ... 

The competitive attack at either oxygen or nitrogen by nucleophiles was the subject of a recent investigation (8IJOC6IO). Whereas triphenylphosphine reacted with oxaziridine (88)... 

Several alkenes are converted to aziridines by treating with oxaziridine (52) at elevated temperatures. Styrene, a-methylstyrene and their derivatives substituted in the benzene ring react smoothly, and so do 1,1-diphenylethylene, indene and acrylonitrile (74KGS1629). 

Diaziridines, discovered in 1958, six years after the oxaziridines, were almost immediately realized to be structural analogs of oxaziridines. Like these they showed oxidizing properties unexpected for other classes of organic nitrogen compound. Properties in common with oxaziridines include the rearrangement to open chain isomers on heating above 100 °C (for several diaziridines), and their hydrolytic behavior in acidic media, which leads to carbonyl compounds with conservation of the hetero-hetero bond. 

Ring enlargement of A-acyl compounds, generally observed with oxaziridines, is observed only occasionally with diaziridines. Under more forced conditions of acylation with acetic anhydride, oxadiazolines like (139) were obtained (76MIP50800). A 4-nitrobenzoyl derivative rearranged at room temperature (76JOC3229). 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

Oxidation of secondary amines with oxaziridine 144 provides moderate yields of hydroxylamines 145, although overoxidation invariably results in formation of nitrones 146 (equation 96). ... 

Electrophilic amination with oxaziridines 91S327. A-Sulfonyloxaziridines as reagents in asymmetric hydroxylation of eno-lates 92CRV919. 

Table 10. Asymmetric Sulfoxidation of Sulfides (R,SR2) with Oxaziridine 44...

Although few examples of the oxidation of a, -unsaturated ketones widi these recently established reagents (Section 2.3.2.1.2.iii) have been reported, the triplication is clearly plausible. The use of a chiral camphor-derived oxaziridine to effect this process has been reported. Thus (-t-l-kjellmanionone (123) was prepared by treatment of the precursor (122) with oxaziridine (45) in THF at -78 C. Aldiough the yield in this case was only moderate, it would be unwise to generalize at this stage. 

Treatment of chlorostyrene 98 with oxaziridine 99 in toluene at 100 °C gives aziridine 100 in 58% yield <2003JOC6497>. Similar reaction of styrene 101 with oxaziridine 102 at 50 °C for 50 h afforded the aziridine 103 in 52% yield (Equation 3) <2005TL2207>. 

The lithium enolate of propiophenone 104 with oxaziridine 77 gives the a-iV-BOC-amino ketone 105 in 31% yield <2005T8423>. In a similar manner, the lithium enolate of 106 afforded 107 in 50-70% yield <2005T8423>. 

Xanthate 169 with oxaziridine 33 gave -benzyl 0-isopropyl carbonothioate 172 and iJ-benzyl 0-isopropyl carbono(dithioperoxoate) 173 in a ratio of 93 7 <1997J(P1)2019>. The reaction is believed to go through sulfur oxidation to give sulfine intermediate 170 that rearranges to an oxathiirane 171 intermediate (Scheme 5). 

Treatment of 1,3,2-oxazaphospholidine 2-sulfide 176, bearing two amino residues at phosphorus, with oxaziridine 80 gave 1,3,2-oxazaphospholidine 2-oxide 177 in 92% yield <1997JOC6401>. It was interesting to note that the desulfurization occurred with complete stereoselectivity (>98% de) and with inversion of the configuration at the phosphoms, whereas use of w-chloroperbenzoic acid (MCPBA) resulted in retention of configuration affording 178 (Scheme 6). 

Adamantane 205 reacts with oxaziridine 206 at 22°C to give 1-adamantanol 207 in 73% yield <2005JA15391>. A catalytic version of this oxidation has been developed using catalytic amounts of the imine 208 and diselenide 209 with excess urea-H202 (UHP) as the oxidant. 

Epoxidation of alkenes with oxaziridines gives the corresponding epoxides in a rjiw-stereospecific manner and has been the subject of several reviews <1996CHEC-II(1A)365, 1999RCR183>. 

More recently, it was reported that treatment of alkene 214 with oxaziridine 206 at 22 °C afforded epoxide 215 in 85% yield <2005JA15391>. A catalytic variant of this reaction has been devised. Epoxidation of alkenes wdth A-phosphinoyloxaziridines has also been described <2003SL121>. 

Indole 228 with oxaziridine 218 gave epoxides 229 and 230 as a 5.5 1 mixture of diastereomers. The major product 229 is formed from epoxidation on the face opposite the isobutyl group <1998JA6417>. 

Table 23 Reaction of lithiated sulfoxide 290 with oxaziridines 291 <1995JCM360>...

The procedure consists of the addition of peracetic acid to a solution of the imine. The reaction temperature varies between room temperature and — 78°C. The selectivity of the reaction increases with the lowering of the reaction temperature. Ether and dichloromethane have often been used as solvents in the reaction, with oxaziridine yields ranging between 35-90%. Tables of some oxaziridines prepared by this method are included in two reviews, and these will not be listed in Table 1 except where new physical constants, better yields, and/or different methods of preparation have been reported. 

In some cases, the reaction of peracids with imineshas produced nitrones along with oxaziridines. It has been found that product selectivity depends on the structure of the imines and the reaction conditions, especially acidity. The formation of oxaziridines is predominant in the presence of alcohols or carboxylic acids, whereas the yield of nitrones is increased in aprotic media. 

Agawa and his co-workers have reported a series of investigations of the reactions of cumulenes with oxaziridines. Reaction with isocyanates led to oxadiazolidinones 86 45,70 same product obtained from nitrones and isocyanates. Detailed mechanistic information is not available and the classification of these reactions as cyclo-... 

Thiocyanates themselves also react with oxaziridines. The products are similar to those from carbon disulfide at 110°C but principally resemble those from isocyanates at lower temperatures. ... 

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