Acetic Acid Mediated Coupling of 2-Aminonicotinamides with Ortho Esters: A Convenient, Scalable Synthesis of 2,3-Substituted Pyrido[2,3-<i>d</i>]pyrimidines
Substituted pyrido[2,3-d]pyrimidines are synthesized in good to excellent yields by treatment of various 2-aminonicotinamides with triethyl orthopropionate or triethyl orthoacetate in the presence of acetic acid.