A series of substituted Delta(2)-1,2,4-oxadiazolines(4,5-dihydro-1,2,4-oxadiazoles) 12 have been prepared by 1,3-dipolar cycloaddition of nitrile oxides to imines and are found, upon treatment with KOBu(t), to undergo cycloreversion to give nitriles and amide anions. These can be protonated to give secondary amides or treated in situ with alkyl halides to give tertiary amides in moderate to good overall yield, although the reaction is restricted to examples with an aromatic substituent at the 5-position. The 1,4,2-dioxazoles 15, formed by cycloaddition of benzonitrile oxide to aromatic aldehydes, similarly undergo cycloreversion allowing direct conversion either into substituted benzoic acids or their methyl esters.
|Number of pages
|Journal of the Chemical Society, Perkin Transactions 1
|Published - 7 Apr 1996
- 1.3-DIPOLAR CYCLOADDITIONS