Aziridine preparation

Derivatives of Aziridines Prepared by Reduction of Oximes with Lithium Aluminum Hydride... 

The V-phtha 1 imidt)aziridine prepared, from benzofuran, was cleaved with hot methanol with good regioselectivity and presumed trans stereochemistry to give 10 and 11, although the trans configuration of the methoxyamine was not shown by HNMR25. 

The yields and diastcrcomcric ratios of the aziridines prepared from alkenes 2 and lead tetraacetate or phenyliodoso diacetate in dichloromethane are reported below. 

Generally, the aziridines prepared by the nitrene or dihydrotriazole routes are used as precursors of /(-functionalized amines through ring-opening reactions, but in certain cases the dihydrotriazoles can be directly converted to /3-functionalized amines8b l57. 

Dihydrotriazoles were prepared diastereoselectively by cycloaddition of aryl azides to enol ethers and, under controlled conditions, enamines6-7. In only a few cases were the aziridines prepared by photochemical decomposition of thus formed dihydrotriazoles 84-85. 

Aziridine prepared from acetophenone Cf C S Dewey and R A. BafEord, J Org Chem, 30, 491 (1965). Aziridine prepared from phenylacetaldehyde. 

Thermal rearrangement of isoxazolines provides yet another route to aziridines. Prepared by 1,3-dipolar cycloaddition of A-methyl-C-trifluoromethylnitrone (148) to phenylacetylene, isoxazoline 149 was transformed in refluxing toluene into cA-aziridine 150 (81%)."° The clean cis stereochemistry is consistent with interpretation of the mechanism as an allowed 1,3-sigmatropic rearrangement, a four-... 

The resulting 7V (Ses)aziridines are valuable synthetic intermediates. The electron-withdrawing character of the Ses-group allows ring opening of the aziridines by nucleophiles under mild conditions (eq 2), as is the case with activated A-(Ns)aziridines prepared from [7V (/7-nitrobenzenesulfonyl)imino]phenyliodane (PhI=NNs) or 7V-(Ts)aziridines. 

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