A novel tunable regioselective synthesis of pyrazolo[3,4-d]pyrimidine derivatives via aza-Wittig/Ag(I) or base-promoted tandem reaction has been developed. This approach provides a simple and efficient way to construct pyrazolo[3,4-d]-pyrimidine derivatives under mild conditions.

Here the iron-catalyzed rapid synthesis of 4-amino-quinazoline via [3+2] cycloaddition reaction of quinazoline-3-oxides and carbodiimides followed by ring opening process had been described. This reaction process could be effectively shortened with microwave-assistant.