Derivatives of l-azetines

Three preparations of 1-azetine iV-oxides have been reported. Oxidation of the 2-aryl-l-azetine (222) with MCPBA gives the nitrone (223) (79CB3914 . However, similar treatment of 2-alkoxy-l-azetines fails to give the corresponding iV-oxides but yields products derived from oxaziridines (cf. Section 5.09.4.2.3). 

Cyclization of 3,3-dimethyl-2-hydroximino-4-tosyloxybutane (272) with 1,6-bis-(dimethylamino)naphthalene is reported to occur via iV-alkylation to give the 1-azetine Af-oxide (273) as an unstable oil which decomposes over a few days at room temperature (74TL4283). 

The 4-thioxoazetidin-2-one (281) (c/. Section 5.09.3.3.5) is reported to undergo exclusive 5-alkyIation on treatment with methyl iodide in the presence of base to yield the 2-methylthio-l-azetin-4-one (282) (80TL4247). 

A series of 3-imino-2-aryl-l-azetines has been prepared by cycloaddition of nitrile ylides to isocyanides. Thus generation of the nitrile ylides (215) in the presence of cyclohexyl isocyanide gives the 3-cycIohexyIimino-2-aryI-l-azetines (205). Similar 1-azetines are formed by interception of nitrile ylides with a-methylbenzyl isocyanide (72AG(E)47) cf. Section 5.09.4.2.2). 

---