Oxaziridines

Biographical Sketches

Jitendra Kumar Mishra was born in 1980 in Gorakhpur (U.P.), ­India. He completed his B.Sc. (1999) and M.Sc. (2001) degrees in organic chemistry from D.D.U. Gorakhpur University, Gorakhpur. He is currently working as a DRDO-JRF for his Ph.D. degree under the supervision of Prof. M. P. Kaushik at the Defence Research and Development Establishment in Gwalior, India.

Introduction

<P>Oxaziridines were first discovered in 1956 [1] and have been widely investigated, principally for two reasons. The ­presence of an inherently weak N-O bond in a strained ring promised a group of compounds of unusually high ­reactivity. In addition, this system possesses the structural elements that seem to be required in order to observe ­stereochemical isomerism at nitrogen: ring strain and an atom with unshared electron pairs attached to the ­nitrogen. </P>

<P>Oxaziridines can be used as both oxygenating and aminating agents in their reactions with a wide variety of nucleophiles. Oxaziridines with small groups on N, for example hydrogen or methyl, act as aminating agents, whereas those with bulky or electron withdrawing groups on N preferentially transfer the oxygen atom. Oxaziridine-­mediated processes are of interest due to the easy accessibility of the reagents and their potential for asymmetric ­induction.</P>

Abstracts

<TD VALIGN="TOP"> (A) For asymmetric oxygenation of chiral imide enolates: Evans and coworkers have found that the a-hydroxylation reactions of chiral enolates derived from oxazolidinone carboximide proceed with exceptional facility with the oxidant 2-(phenyl­sulfonyl)-3-phenyl oxaziridine. The following carboximides were transformed into their respective Z-sodium enolates (1.2 equiv of NaN(Me₃Si)₂, THF, -78 °C) with slight excess of oxaziridine. [2] </TD><TD VALIGN="TOP">

</TD><TD VALIGN="TOP"> (B) For asymmetric oxidation of ketone enolates: The reagent-controlled asymmetric oxidation of trisubstituted enolate anions can be done by enantiomerically pure camphorsulfonyl oxaziridine. [3] </TD><TD VALIGN="TOP">

</TD><TD VALIGN="TOP"> (C) For epoxidation of alkenes: Epoxidation of alkenes are also possible by using oxaziridine. [4] </TD><TD VALIGN="TOP">

</TD><TD VALIGN="TOP"> (D) For epoxidation of alkenes (with perfluorinated oxaziridines):
Alkyl-substituted olefins are epoxidized by perfluoro-cis-2,3-­dialkyl oxaziridines under mild conditions. Similarly electron ­deficient substrates (e.g. a,b-enones) can also be epoxidized. [5] </TD><TD VALIGN="TOP">

</TD><TD VALIGN="TOP"> (E) For amination of N-nucleophiles: Oxaziridines can be used as an aminating reagent for N-amination of 2° amines. [6] </TD><TD VALIGN="TOP">

</TD><TD VALIGN="TOP"> (F) For N-acylamidation: Direct N-acyl transfer as a method for protected hydrazine syn­thesis has also been shown to proceed in good yield with a wide ­variety of substrates. [7] </TD><TD VALIGN="TOP">

</TD>

References

<A NAME="RV11505ST-1">1</A> Emmons WD. J. Am. Chem. Soc.  1956,  78:  6208 

<A NAME="RV11505ST-2">2</A> Evans DA. Morrissey MM. Dorow RL. J. Am. Chem. Soc.  1985,  107:  4346 

<A NAME="RV11505ST-3">3</A> Davis FA. Sheppard AC. Chen B.-C. Serajul Haque M. J. Am. Chem. Soc.  1990,  112:  6679 

<A NAME="RV11505ST-4">4</A> Davis FA. Abdul-Malik NF. Awad SB. Harakal ME. Tetrahedron Lett.  1981,  22:  917 

<A NAME="RV11505ST-5">5</A> Arnone A. Desmarteau DD. Novo V. Petrov VA. Pregnolato M. Resnati G. J. Org. Chem.  1996,  61:  8805 

<A NAME="RV11505ST-6">6</A> Andreae S. Schmitz E. Synthesis  1991,  327 

<A NAME="RV11505ST-7">7</A> Schmitz E. Fechner-Simon H. Schramm S. Liebigs Ann. Chem.  1969,  725:  1