Halogenative Annulation Reactions of Alkyne-Tethered N- and O-Containing Arenes: Methods for Accessing Aryl-Fused Halogenated N- and O-Heterocycles

Abstract

AbstractHalogenative annulation of alkyne-tethered N- and O-containing arenes represents a general strategy for the construction of various halogenated N- and O-heterocycles. The methods employed are useful in producing valuable synthetic building blocks carrying C(sp2)–halide functional groups, which are useful synthetic handles, especially for cross-coupling reactions and a myriad of other transformations. When the alkyne is tethered to the heteroatom via an aromatic ring, the reaction gives rise to aryl-fused halogenated heterocycles. In this Short Review, various past and present halogenative annulation methods to construct aryl-fused halogenated N- and O-heterocycles are examined, with a focus on more recent technologies and the various roles of the participating halogenating agents. Additionally, future directions for this age-old, but still very useful, reaction are considered.1 Introduction2 Synthesis of Aryl-Fused Halogenated N-Heterocycles2.1 Aryl-Fused Halogenated 5-Membered N-Heterocycles2.2 Aryl-Fused Halogenated 6-Membered N-Heterocycles2.3 Aryl-Fused Halogenated 7-Membered N-Heterocycles3 Synthesis of Halogenated O-Heterocycles3.1 Aryl-Fused Halogenated 5-Membered O-Heterocycles3.2 Aryl-Fused Halogenated 6-Membered O-Heterocycles3.3 Aryl-Fused Halogenated 7-Membered O-Heterocycles4 Conclusion