Synthesis of Oxaziridines

The use of chiral solvents in this photorearrangment has been shown to promote asymmetric synthesis of oxaziridines,54 and application of the cyclization to highly substituted azoxy compounds provides a route to oxadiaziridines.55... 

The synthesis of oxaziridine-fused quinazolinones 277 follows a different route. Quinazolinones 274 (R = Et, nPr, n-hexyl) can readily be prepared by reacting 2-oxo-l-cyclohexanecarboxamide with aldehydes in the presence of ammonia solution. In the reaction of 274 and monoperoxyphthalic acid, the hydroxyoxaziridines 277 were formed via the presumed intermediates 275 and 276. No spectroscopic evidence was given for 277, nor was its relative configuration investigated [76JPR(318)895]. 

The synthesis of oxaziridines has been the subject of several comprehensive reviews and therefore is only briefly discussed here <84CHEC-I(7)195, 85MI 112-01, 89T5703,91S327,92CRV919). 

The synthesis of oxaziridines from Schiff bases and peracids, as reported by Krimm, ° Emmons, and Horner and Jurgens, is still the most popular procedure for their preparation [Eq. (1)]. 

The synthesis of oxaziridines can be accomplished from imines, nitrones or carbonyl compounds ... 

Cyclization. A new approach to the synthesis of oxaziridines involves the reaction of tosyl chloride in aqueous alkaline solution with a cyclic nitrone this reaction appears to be mechanistically similar to the cyclization of diol monotosylates in epoxide synthesis. This method has been applied to heterocyclic steroidal nitrones (276). ° Photo-oxidation of cyclohexylamine may... 

There are only few reactions known introducing substituents to the H-bearing nitrogen of oxaziridines. (V-Alkylation of l-oxa-2-azaspiro[2.5]octane (3,3-pentamethylene-oxaziridine 52) with r-butyl chloride to give (53) was carried out for structure proof of (52). This reaction is of no preparative importance, since N-alkylated oxaziridines are easily obtained by ring synthesis. 

Oxathiane dioxides lithiated 641 synthesis of 638, 647 Oxathiane oxides, synthesis of 352 Oxathiolane oxides, synthesis of 241 Oxaziridines 72, 254, 826 as optically active oxidizing agents 291 Oxazolidinones 826 Oxazolines 619, 788... 

The enantioenriched sulfoxide intermediate 72 (R = CH2OH), obtained by asymmetric 5-oxidation with a chiral oxaziridine (89 11 enantiomeric ratio), has provided a highly enantioselective synthesis of the benzothiepin derivative 71 (4R, 5R). The aldehyde intermediate 72 (R = CHO) was cyclized asymmetrically to 71 (4R, 5R) with >98 2 enantiomeric ratio. Base treatment (f-BuOK, -10°C, THF) of the racemic benzothiepin 73... 

Enantioselective synthesis of a-hydroxy phosphonates can also be achieved by asymmetric oxidation with camphorsulfonyl oxaziridines (Scheme 2-60).156 Reasonable yields can usually be obtained. (+)-147a or (+)-147b favors formation of the (S )-product, as would be expected, because these oxidations proceed via a transition state that parallels that previously discussed for the stereoselectivity observed with ketones.157... 

Oxamidobis-ethyl(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 3 115 Oxane bonds, silylation and, 22 702-703 Oxazine soluble dyes, 7 373t Oxaziridines, 9 372-373 2-Oxazolines, microwave-assisted synthesis of, 76 576 Oxazoles, 27 151... 

The Reformatsky type of reaction with Zn(0) was performed in situ and led to somewhat unstable phosphonodiamidite (step a) which was coupled with 5 -DMTr-thymidine to give the intermediate mononucleoside phospho-noamidite (step b). The latter was further coupled with 3 -acetyl-thymidine (step c). Couplings described in steps b and c were activated by tetrazole. The intermediate dinucleoside phosphonite was oxidized with (lS)-(+)-(10-camphorsulphonyl)oxaziridine (step d) or sulfurized with Beaucage reagent. The phosphonoamidites mentioned above were used in the solid-phase chemical synthesis of phosphonoacetate and thiophosphonoacetate oligonucleotides. 

In 1976, the synthesis of oxaziridininm salt 66 was reported by Lusinchi and coworkers (Fig. 23) [128-130]. Salt 66 was obtained by either methylation of the corresponding oxaziridine with FSO Me or oxidation of the corresponding iminium salt with peracid. Subsequently, Hanquet and coworkers prepared oxaziridininm salt 67 by methylation of the corresponding oxaziridine with Meerwein s salt (MejO BF ") or oxidation of the A -methyl isoquinoUnium fluoroborate salt with peracid [131, 132],... 

The oxaziridine ring system has been formed by the oxidation of C=N double bond . The two-step synthesis of iV-phosphinoyloxaziridines 16 from oximes 15 was described (equation 7) . Irradiation of hydroperoxynitrones 18, prepared by dye-sensitized photooxygenation of 2-methoxyfuran in the presence of oximes 17, led to fraw -oxaziridines 19 in yields up to 89% (equation 8) ". ... 

This procedure is representative of a general procedure, for the synthesis of trans-2-sulfony1oxaziridines previously reported on a small scale (Table I). trans-2-(Phenylsulfonyl)-3-(p-nitrophenyl)oxaziridine was prepared on a 0.16-molar scale in greater than 85% yield. The Baeyer-Vill iger-type oxidation of the sulfonimine affords only the trans-oxaziridine. The synthesis of the sulfonimine (PhS02N=CHPh) directly from the sulfonamide and... 

The easy N-amination of Pro by the oxaziridine reagent 72 82 allows for a step-by-step synthesis of 89 where N-amination is performed on the growing peptide and Np-coupling of the A-amino proline residue is carried out classically with the activated ester procedure (Scheme 27). 109 ... 

For other uses of oxaziridines in synthesis, see 2-Arenesulfonyloxaziridines, this volume. 

A number of other miscellaneous transformations of hetero-aromatic A-oxides have been reported. Of particular interest is the application189 of the photolysis of 2-cyanoquinoline 1-oxides to the synthesis of 1-aminocarbostyrils 2-cyano-4-methylquinoline 1-oxide is converted into the quinolinone by irradiation in dichloromethane solution in the presence of a secondary amine, and the conversion presumably takes place via the intermediate oxaziridine [Eq. (45)]. 

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