Cyanoacetaldehyde - New Synthetic Applications of an Old Compound Syntheses with Nitriles, XCI

Article abstract of DOI:10.1007/BF00808679

Various reactions of cyanoacetaldehyde (1), freshly prepared by ozonization of (E)-1,4-dicyano-2-butene or allylcyanide, are described.Thus, conversion of 1 with anilines gave β-phenylaminoacrylonitriles 2a-e.Reaction of 1 with hydrazines led to the corresponding hydrazones 3a-e, which could be cyclized under alkaline conditions to 5-aminopyrazoles 4a-d.An aldol-type condensation product 5a could be obtained by reaction of 1 with sodiumphenoxide.Treatment of 1 with dimethylformamide-dimethylacetal led to the formation of (E)-3-dimethylamino-2-formylpropenenitrile (6), a very useful synthon in synthetic chemistry.For the determination of the structure of 6 the method of steady state diffferential NOEs was used.Reaction of 6 with hydrazines gave 1-substituted-4-cyanopyrazoles 7a-k. Keywords.Cyanoacetaldehyde; Hydrazones; Cyanopyrazoles; Aminopyrazoles.