Pyrazolopyrimidines chemistry of

The amino-iminophosphorane (16.2) is cyclized by heating with an isocyanate. A closely related iminophosphorane (16.3) reacts with an isocyanate in unheated dichloromethane to form a new fused 2-iminopyrimidine. When the imino is replaced with a hydrazono function (R = ArNH), a similar 2-iminopyrimidine ring is produced. The chemistry of pyrazolopyrimidines has been reviewed [3360]. 

Heating the oxime of 2-aminobenzophenone with ethyl orthoformate gives quinazoline A -oxide. A pyrazolopyrimidine Af-oxide has been similarly synthesized the chemistry of pyrazolopyrimidines has been reviewed [33601. 

In previous work (85MI1 87AHC319), the synthesis and chemistry of pyrazolopyridines and pyrazolopyrimidines was surveyed. This chapter reports synthetic approaches to other aromatic 10 tt electron systems containing a pyrazole moiety, as well as the systems main chemical and physicochemical properties. 

The interesting biological activities reported for pyrazolopyrimidines have stimulated chemists to develop the chemistry of this class of compounds. In the last 20 years, an enormous number of papers and patents dealing with the chemistry or biological activity of pyrazolopyrimidines have been reported. However this article appears to be the first survey of the chemistry and biological activity of this class of compounds. 

Pyrazoles condensed to heteroaromatic five-and six-membered rings, 48, 223 Pyrazolopyridines, 36, 343 Pyrazolopyrimidines, chemistry of, 41, 319 Pyridazine chemistry, advances in, 49, 385 Pyridazines, 9, 211 24, 363 49, 385 Pyridine(s)... 

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