Hydrazines azomethine imines from

In situ generation of azomethine imines from furan-3-carbaldehyde and ]V,N -disubstituted hydrazines followed by cycloaddition to N-methylmaleimide results in a 2.8 1 mixture of pyrazolidines 94 and 95 (X = O) separatable by chromatography. Eurther Pd(0) catalyzed cyclization involving the aldehyde and hydrazine moieties leads to the formation of benzoxepines 96 and 97 (X = O) in good yield (Scheme 17 (2003X4451)). 

Finally, fully reduced heterocycles have been prepared either from a sequential azomethine imine cycloaddition-palladium-mediated cyclization process <2003T4451>, or from the reaction of A-( l-benzotriazolylalkyU-AyV-disubstitutcd hydrazine with methyl vinyl ether <1997JOC8210>. 

The azomethine imine (151), having the alkene attached to the terminal dipole nitrogen, was generated in situ from the corresponding hydrazine by reaction with benzaldehyde (Scheme 47).79 As is typical in these reactions, condensation at the more basic benzyl-substituted nitrogen occurred, rather than at the acyl-substituted nitrogen. Cyclization of (151) afforded the 5,5-fused pyrazolidine and no bridged product. 

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