SYNTHESIS OF SUBSTITUTED PYRAZOLO {[}1,5-A] PYRIMIDINES

The reaction of 3-amino-4-cyanopyrazole (1) with ethyl acetoacetate, acetyl acetone, and ethyl cyanoacetate give pyrozoIo{[}1,5-a]pyrimidine derivatives 2, 4, and 7 respectively. Compound 2 reacts with phosphorous oxychloride to give the corresponding 7-chloro derivative 3. Compound 4 reacts with hydroxyl amino to give N-hydroxy-3-carboximidamide 5 which was converted by acetic anhydride to 3-(5-methyl-1,2,4-oxadiazol-3-yl) derivative 6. Coumpound 1 also react with diethyl malonate to give N,N-bis(4-cyano-5-pyrazoly) malonamide 8 and ethyl(4-cyano-5-pyrazolyl) malonamide 9. Ethyl(4-cyano-5-pyrazolyl) malonamidate 9 with acetic acid yielded pyrazolo{[}1,5-a] pyrimidine derivative 10. Other members of this ring system results from treatment of 1 with arylidine malononitrile, and ethyl arylidine cyanoacetate derivatives to yield compounds 11, and 12 respectively. Compound 1 reacts with activated acetylene to give pyrazolo {[}1,5-a]pyrimidine derivatives 13a and 13b.