Recent Developments in the Synthesis, Reactions, and Biological Activities of Pyrimido[4,5-c] Isoquinolines from Pyrimidine Derivatives (Part II)

Isoquinoline, quinoline, and pyrimidine are heterocyclic compounds with great potential for developing new drugs. When combined in isoquinoline-pyrimidine-inspired hybrids, they demonstrate numerous beneficial biological properties. Recently, many studies have focused on the synthesis and medicinal chemistry applications of pyrimido[4,5-c]isoquinoline ring systems (PyisoQs4,5- c). This review offers a comprehensive overview of the synthesis of Py-isoQs4,5-c using pyrimidine, 6-amino-1,3-dimethyl-pyrimidine-dione, 6-amino-2-thioxopyrimidinone, 5-chlorodimethylpyrimidin- 4-amine, ethyl benzoate, cyclohexane-dione, cyclopentadiene, benzoquinone, naphthalene-dione, dihydronaphthalenone, isophthalonitrile, dihydroxybenzaldehyde, cycloheptanone, furan-methanol, dimethyl but-2-ynedioate, and their derivatives. These compounds are synthesized through various chemical reactions, including condensation, cyclocondensation, alkylation, substitution, one-pot three-component, cross-coupling, Vilsmeier, Suzuki–Miyaura, Diels- Alder reactions, and Pictet–Spengler reactions. These synthetic approaches allow for the efficient construction of Py-isoQs4,5-c, facilitating further exploration and investigation of their potential medicinal applications.