Hydrazine keto adds

Tetrahydro-l,2-diazocinones (166) are formed in good yield by cyclization of e-keto adds with hydrazine in dilute solution. Standard transformations lead to the hexahydro derivatives (167) and (168) and the octahydrodiazocine (169) (73BSF2029). 

Scheme 17 shows a synthesis of variably substituted dihydropyridazinones starting from y-keto adds 60, which were esterified with Wang alcohol resin to give 61. Initial attempts at sequential formation of hydrazones by reacting the ketone moiety with hydrazines and subsequent cyclization of the solid-phase-bound hydrazone did not work satisfactorily. Therefore, the authors developed a one-pot procedure in which the sohd-phase-bound y-keto acid 61 was reacted with an excess of substituted hydrazines in THF at elevated temperature. They isolated a range of dihydropyridazinones with R = Me, Ph and = H, alkyl, 4-MeOC6H4. 2-Acetyl-benzoic acid was a further template of a y-keto add which was reacted successfully giving benzo-fused derivatives [30]. 

Aldehydes reducing sugars formates lactates tartrates some quinones phenols a-hydroxyketones a-diketones (hot) uric add reducing bases such as hydrazines, semicarbazides, guanidine, hydroxylamines and some primary amines. Some derivatives of j8-keto-adds. 

Ethyl acetoacetate (CH3COCH2COOC2H5) gives the reactions of a carbonyl (C=0) group, such as formation of cyanohydrin with HCN, bisulfate addition compound with sodium bisulfate, and phenyl hydrazone derivative with phenyl hydrazine. In addition to these, it behaves as an unsaturated alcohol (enol) as it evolves hydrogen on treatment with sodium, shows reddish-violet coloration with ferric chloride, and decolorizes bromine water and adds diazomethane. These chemical properties of ethyl acetoacetate suggest that it exists in two forms a saturated ketone 11 (keto-form) and an unsaturated alcohol 12 (enol-form) that is an example of prototropy (Scheme 3.46). 

---