Solventfree route to βenamino dichloromethyl ketones and application in the synthesis of novel 5dichloromethyl1Hpyrazoles

An efficient procedure to prepare a series of five 4amino1,1dichloro3penten2ones CHCl2COCHCMeNR1R2, where R1R2 HPh, HBn, HCH2CH2OH, CH24,CH22OCH22 from the solventfree reaction of 1,1dichloro4methoxy3penten2one with primary and secondary amines is reported. 1,1Dichloro4methoxy3penten2one was reacted with hydrazine hydrochloride, phenylhydrazine hydrochloride and semicarbazide hydrochloride to obtain 5dichloromethyl3methylpyrazoles. Aminoguanidine hydrochloride and 1,2dimethylhydrazine dihydrochloride were also reacted with 1,1dichloro4methoxy3penten2one to obtain 5dichloromethyl3methylpyrazoline and 5dichloromethyl1,2,3trimethyl pyrazolium chloride, respectively. All cyclocondensation reactions were performed in onepot procedures. J. Heterocyclic Chem., 2009.