Pyrimidopyrimidines, synthesis

Pyrimido[4,5-d]pyrimidine-5,7-diones synthesis, 3, 363 Pyrimidopyrimidines synthesis, 4, 507 Pyrimido[ 1,2-a]pyrimidines reactivity, 3, 348 structure, 3, 337-338 synthesis, 3, 360 Pyrimido[ 1,6-a]pyrimidines reactivity, 3, 349 structure, 3, 338 synthesis, 3, 362 Pyrimido[ 1,6- c]pyrimidines reactivity, 3, 349 structure, 3, 338 synthesis, 3, 362 Pyrimido[4,5-d]pyrimidines applications, 3, 368 cleavage, 3, 350 reactions... 

The synthesis of pyrimidopyrimidines, pyrimidopyridazines and pteridines is illustrated in Scheme 31. Full details are given in the appropriate chapters of CHEC and CHEC-II. In addition to the syntheses that resemble those of quinazolines from anthranilic acid, the high reactivity of the... 

A lot of information about the structure, reactivity, and the best synthetic approaches for pyrimidopyrimidines has been described in CHEC-I. Additionally, some new methods of preparation of pyrimidopyrimidines have been reported in reviews on the synthesis of fused pyrimidines by Delia and Warner starting material in heterocyclic synthesis by Wamhoff, Dzenis, and Hirota <92AHC(55)129>. Pyrimidopyrimidines are especially interesting as structural analogues of natural compounds. 

A novel and versatile solid-phase synthesis of pyrimido[4,5- fJpyrimidine-2,4-diones has been reported <03S1739>. The key step is the reaction of the support-bound pyrimidine with isocyanates, involving formation of a carbamate intermediate, followed by a base-catalyzed intramolecular ring closure to give the polymer-bound pyrimidopyrimidines which are used in subsequent reactions providing 1,3-disubstituted 7-amino derivatives. 

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