Application of Ugi/Diels-Alder Tandem Reaction in the Construction of Heterocyclic Compounds

Heterocyclic compounds are widely present in natural products and drug molecules and many of them also have potential biological activities and pharmacological effects. Therefore, methodologies toward rapid and efficient construction of heterocyclic compound libraries have become one of the research hotspots in the fields of organic synthesis and pharmaceutical chemistry. Ugi reaction has unique advantages in diversity-oriented synthesis to generate a large number of target products with structural complexity. Meanwhile, Diels-Alder [4 + 2] cycloaddition reaction can efficiently form carbon-carbon bonds to access various heterocyclic rings with good stereo- and region-selectivity. Nowadays, Ugi/Diels-Alder tandem reaction, which combine merits of the two, presents enormous advantages and infinite potential in synthesis of heterocyclic compounds. In this paper, the recent advances in Ugi/Diels-Alder tandem reaction is summarized and reviewed according to the types of dienes in DA reactions, such as furan, pyrrole, thiophene, oxazole, 1,2,4-triazine, benzene, and unsaturated bond with aromatic ring.