Science of Synthesis

Liang, Y.; Wen, Z.; Cabrera, M.; Howlader, A. H.; Wnuk, S. F., Science of Synthesis Knowledge Updates, (2020) 1, 328.

Transition-metal-catalyzed cross-coupling reactions are one of most versatile methods for introducing C—C bonds at different positions of the purine ring. Currently, among different transition metals, palladium-catalyzed cross-coupling reactions are possibly the most effective and widely used methods for the synthesis of various purine derivatives. Various ligands and palladium complexes have been developed and employed for the preparation of chemically modified purine analogues. Several named reactions, such as Sonogashira, Suzuki–Miyaura, Stille, Negishi, and Heck cross-coupling reactions, have been employed for the alkylation, alkenylation, arylation, and alkynylation at the positions 2, 6, and 8 of purine or its derivatives. In this section, approaches resulting in the formation of new bonds between purine ring carbons and external sp-, sp2-, or sp3-carbons are discussed.