Cycloaddition reactions involving heterocyclic compounds as synthons in the preparation of valuable organic compounds. An effective combination of a computational study and synthetic applications of heterocycle transformations

Abstract

Publisher Summary By using computational tools, the chemical reactions can be aided in accomplishing transformation of the heterocycle into a valuable starting material in so far as its reactivity and selectivity toward certain chemical transformations are concerned. Utilizing semiempirical, ab initio, and density functional theory (DFT) methods, the chapter aims to demonstrate that this approach could be an integral part of complicated synthetic pathways for the preparation of chemicals. The chapter discusses this combinatory approach—namely, the incorporation of heterocyclic aromatic compounds as synthons into preparative synthetic schemes. The synthetic schemes used reflect the influence of computational results in the planning of the preparations of organic compounds performed in laboratories. They are used to demonstrate the validity of the computational (theoretical) and traditional synthetic chemistry to prepare an organic compound. The chapter discusses computational methodology, Diels–Alder reactions with five-membered heterocycles with one heteroatom—furan, pyrrole, and thiophene as dienophiles in reaction with acetylene, ethylene, and cyclopentadiene, addition of benzyne to furan, pyrrole, and thiophene, cycloaddition reactions with pyrrole as a diene for Diels–Alder reaction, Diels–Alder reactions with benzo[b] and benzo[c]-fused heterocycles. There are Diels–Alder reactions with five-membered heterocycles with two heteroatoms—addition of acetylene, ethylene, and cyclopropene to heterocycles with heteroatoms in the 1 and 2 positions, and the 1 and 3 positions. There are Diels–Alder reactions with five-membered heterocycles with three heteroatoms—addition of acetylene, ethylene, and cyclopropene to heterocycles with heteroatoms in 1, 2, and 3 positions and in the 1, 2, and 4 positions, addition of cyclopropene to heterocycles with heteroatoms in the 1, 2, and 5 positions. There is also investigation of the role of 1, 3, 4-oxadiazole as a diene in Diels–Alder reactions. There is detailed description of the cycloaddition reactions with activated heterocycles that have two or three heteroatoms.