|
|Section2= }} An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxazidines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to amides and participate in () cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center. ==History== Oxaziridine derivatives were first reported in the mid-1950s by Emmons and subsequently by Krimm and Horner and Jürgens. Whereas oxygen and nitrogen typically act as nucleophiles due to their high electronegativity, oxaziridines allow for electrophilic transfer of both heteroatoms. This unusual reactivity is due to the presence of the highly strained three membered ring and the relatively weak N-O bond. Nucleophiles tend to attack at the aziridine nitrogen when the nitrogen substituent is small (R1= H), and at the oxygen atom when the nitrogen substituent has greater steric bulk. The unusual electronics of the oxaziridine system may be exploited to perform a number of oxygen and nitrogen transfer reactions including, but not limited to: α-hydroxylation of enolates, epoxidation of alkenes, selective oxidation of sulfides and selenides, amination of ''N''-nucleophiles and ''N''-acylamidation. The Peroxide process for the industrial production of hydrazine through the oxidation of ammonia with hydrogen peroxide in the presence of ketones was developed in the early 1970s.〔. .〕〔.〕 Chiral camphorsulfonyloxaziridines proved useful in the syntheses of complex natural product, such as taxol which is marketed as a chemotherapy agent. Both the Holton Taxol total synthesis and the Wender Taxol total synthesis feature asymmetric α-hydroxylation with camphorsulfonyloxaziridine. : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「oxaziridine」の詳細全文を読む スポンサード リンク
|