One-Pot Synthesis of 2,3-Disubstituted Pyrimido[1,2-

An effective synthesis for 2,3-disubstituted pyrimido[1,2-b]indazole from 3-aminoindazole and two amino acids was developed. This strategy has been demonstrated with a variety of 3-aminoindazole and amino acids, and it has been successfully scaled up to gram-scale synthesis, highlighting the practicality and application value of the protocol. Furthermore, the utilization of amino acids not only reduces the formation of byproducts but also renders the reaction more environmentally friendly. Mechanistic studies revealed that I2 promoted the decarboxylation of amino acids and the subsequent oxidative cyclization process.