Utility of Hydrazines and Hydrazine Derivativces in Heterocyclic Synthesis

Abstract

r e h y d r a z i n e a n d a l k y l a n d a r p l s u b s t i t u t e d h y d r a z i n e s (I), a r y l a n d a r o y l h y d r a z i n e s I?), t h i o h y d r a z i n e s (3), a m i d r a z o n e s (4), h y d r a z i d i c h a l i d e s I?), h y d r a z o n e s ( 6 ) .s e m i c a r b a z i d e s , t h i o s e m i c a r b a z i d e s , a m i n o g u a n i d i n e (7), a n d d i a z o compounds 18).~lternatively, as has been previously suggested, addition of the substituted nitrogen of methylhydrazine to the cyan0 group might occur first and the reaction then proceeds as shown in the scheme below.117 Both authors on reconducting the above reaction have shown that it affords a mixture of two isomeric pyrazoles (35% and 27%13', 47% and 8%.13')These authors have shown on the bases of chemical evidences as well as IR, UV and 13c NMR spectra that the major product for which the 3-amino-4.5-dicyano-lmethylpyrazolestructure was formally assigned is really 5-amino-3,4-dicyano-1-methylpyrazole.When bifunctional alkylating agents reacted with hydrazines as shown below pyrazoles or fused pyrazole derivatives are formed. 1 4 2