Intermolecular cycloadditions amide derivations

Carbonyl ylides derived from nitrogen-substituted carbonyl moieties provided for the synthesis of very stable push-pull dipolar intermediates. Although these compounds are quite stable, they still have sufficient reactivity to engage in cycloaddition and related processes. Carbonyl ylides derived from amides have been trapped in intermolecular cycloadditions to give aminals (Scheme 4.34) (56). 

De Kimpe and Boeykens (22) reported synthesis of the p-lactam derivatives 107 via cycloaddition of azides with 2-methyleneazetidines (104) (Scheme 9.22). Because of electronic control, the intermolecular cycloaddition of the azide with the enamine double bond resulted in the formation of the triazoline intermediate 105, ring opening and rearrangement of which gave the imino lactam 107. Although all attempts to convert compound 107 to the corresponding p-lactam 108 under acidic conditions were unsuccessful, under basic conditions compound 107 was converted into the p-amino amides 109. 

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