Aziridines 2-alkoxy— from

Better reagents than lithium aluminum hydride alone are its alkoxy derivatives, especially di- and triethoxyaluminohydrides prepared in situ from lithium aluminum hydride and ethanol in ethereal solutions. The best of all, lithium triethoxyaluminohydride, gave higher yields than its trimethoxy and tris(/er/-butoxy) analogs. When an equimolar quantity of this reagent was added to an ethereal solution of a tertiary amide derived from dimethylamine, diethylamine, W-methylaniline, piperidine, pyrrolidine, aziridine or pyrrole, and the mixture was allowed to react at 0° for 1-1.5 hours aldehydes were isolated in 46-92% yields [95,1107], The reaction proved unsuccessful for the preparation of crotonaldehyde and cinnamaldehyde from the corresponding dimethyl amides [95]. 

Exposure of the (cycloalkenyl)methyl carbamates 304 to iodosylbenzene in the presence or absence of Rh2(OAc)4 gives the tricyclic aziridines 305 (Scheme 88) (02OL2137). Reactions of 305 with nucleophiles, facilitated with tosic acid or lithium perchlorate, proceed with cleavage of the C-N edge bond and afford the tf 7 z-spirooxazolidinones 306. Intramolecular aziridination of the indolyl carbamate 307 with DAIB, on the other hand, requires Rh(II)-catalysis and leads directly to the acetoxy-substituted YDi-spirooxazolidinone 308 (Scheme 88) (02OL2137). When iodosylbenzene is used instead of DAIB and alcohols are available in the reaction medium, alkoxy-substituted syn-spirooxazolidinones 309 are obtained. Whereas the conversion of 304 to 305 appears to proceed by direct cyclization of intermediate iminoiodanes, the production of 308 from 307 was attributed to the intervention of a rhodium nitrene, which collapses to 308 through zwitterionic intermediates (02OL2137). 

JV-cyano]- and [7V-(methylsulfonyl)alkoxy-carbimidoyl]nitrenes, generated in situ from the corresponding azides by 300 nm UV light, convert a variety of alkenes cleanly and stereospecifically to the corresponding aziridines <89JOC3945>. 

During 1981-1983, Kozlowska-Gramsz and Descotes published several pa-pers dealing with the preparation of aminosaccharide derivatives from cyclic vinyl ethers and glycals. The key step was aziridination of the double bond by photochemically generated ethoxycarbonylnitrene, which produced 1,2-epi-mines as intermediates. The 1,2-epimines were cleaved in situ by the alcohol present in the reaction mixture to give vicinal alkoxy amines as mixture of stereoisomers. 

The Neber rearrangement of oxime 0-sulfonates to 2//-azirines (or a-amino ketones, after aqueous acid workup) has been reviewed, together with the modified Neber , involving /V,/V,A-trimethylhydrazonium iodides.With an excess of base, the a-amino acetal can be formed from the 2//-azirine via the unstable 2-alkoxy aziridine. 

A review on the base-promoted rearrangement of oxime 0-derivatives, commonly O-sulfonates, and the similar reaction of AA A-trimethylhydrazonium iodides to give 2H-azirines or, upon subsequent aqueous acidic workup, a-amino ketones has been reported. With excess base, a-amino ketal is formed from the 2//-azirine via an unstable 2-alkoxy aziridine which can be isolated or hydrolysed in situ to a-amino ketone. ... 

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