SYNTHESIS OF 1,4,5,6-TETRAHYDROPYRIDAZINE

摘要

PURPOSE:To easily produce the subject compound useful as an intermediate for herbicide in high yield and purity in two steps by using an easily and inexpensively available 4-halogenobutylaldehyde dialkyl acetal, reacting the compound with hydrazine and cyclizing the reaction product. CONSTITUTION:The objective compound of formula III useful as a raw material for agricultural chemicals, pharmaceuticals, dyes, photographic materials, etc., can be produced by reacting 1mol of a 4-halogenobutylaldehyde dialkyl acetal of formula I (R is lower alkyl; two R groups together form a ring; Hal is halogen) with 1.0 to 20mol of hydrazine, its hydrate or its aqueous solution in the absence of solvent or in a solvent such as methanol preferably at 0 to 160 deg.C for 1 to 24hr and reacting the resultant 4-hydrazinobutylaldehyde dialkyl acetal of formula II with an acid such as hydrochloric acid in a solvent such as methanol by conventional method preferably at 0 to 110 deg.C for 30min to 24hr, thereby eliminating the acetal protection group and effecting intramolecular cyclization of the compound.