Cyclocondensations of (+)-camphor derived enaminones with hydrazine derivatives

Abstract Reactions of 3-[( E )-(dimethylamino)methylidene]-(+)-camphor and (1 R ,5 S )-4-[( E )-(dimethylamino)methylidene]-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one with hydrazine derivatives were studied. Treatment of 3-[( E )-(dimethylamino)methylidene]-(+)-camphor with hydrazines afforded the corresponding fused pyrazoles. Similarly, fused pyrazoles were obtained upon reaction of (1 R ,5 S )-4-[( E )-(dimethylamino)methylidene]-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one with ortho -unsubstituted phenylhydrazines, while reactions with ortho -substituted phenylhydrazines and with hydrazine hydrochloride resulted in ‘ring switching’ type of transformation to furnish 2-aryl-4-[(1 S ,3 R )-3-hydroxy-2,2,3-trimethylcyclopentyl]-1,2-dihydro-3 H -pyrazol-3-ones.