Abstract
Heterocyclic compounds, five-membered components in particular, are of great significance in organic and pharmaceutical chemistry. This review highlights the substantial progress and examples, which have been made in the last decade to construct fivemembered heterocycles by transition metal-catalyzed cyclization of propargylic compounds. Propargylic compounds are versatile threecarbon building blocks in heterocyclic chemistry. They can be easily and efficiently prepared by nucleophilic addition of alkynyl anions to carbonyl compounds and the successive substitution reactions. Current trends have focused on and expanded the flexible applications of propargylic compounds in many aspects of organic syntheses. Heterocyclic syntheses involving transition metal complexes have become of common use in past decades because a transition metal-catalyzed reaction has a potential to directly build complicated molecules from readily accessible starting materials under mild conditions. Transition metal elements encompassing Ag, Au, Cu, Fe, Zn, Hg, Ru, Re, Ir, Rh, Ni, Pd, Pt, Sc and the like demonstrate intriguing catalytic activity in the aforesaid transformations. They are able to drive reactions either or both as Lewis acids and most commonly triple-bond activation agents by the formation of σ- or π-complexes. As a consequence, a variety of stages are set for new diversity-oriented routes to five-membered heterocycles such as furans, pyrroles, thiophenes, oxazoles, imidazoles, thiazoles, benzofurans, benzothiophenes, indoles and the like. Owing to the structural importance in biologically active natural and unnatural compounds, some of the nonaromatic five-membered heterocyclic compounds are also included with this review.
Keywords: Transition metal, cyclization, propargylic compound, heterocycle, cascade reaction, Heterocyclic compounds, furans, thiophenes, oxazoles, imidazoles, thiazoles, benzofurans, benzothiophenes, Au-Catalyzed Reactions, Pd-Catalyzed Reactions, cycloisomerization (ACCI) sequence, regioselectivities
Call for Papers in Thematic Issues
Catalytic C-H bond activation as a tool for functionalization of heterocycles
The major topic is the functionalization of heterocycles through catalyzed C-H bond activation. The strategies based on C-H activation not only provide straightforward formation of C-C or C-X bonds but, more importantly, allow for the avoidance of pre-functionalization of one or two of the cross-coupling partners. The beneficial impact of ...read more
Related Books
Advances in Organic Synthesis
The Synthetic Methods, Structures, and Properties of the Ca-C σ Bond Organocalcium Containing Compounds
Advances in Organic Synthesis
Chemistry of Bipyrazoles: Synthesis and Applications
Advances in Organic Synthesis
Advanced Nanocatalysis for Organic Synthesis and Electroanalysis
Advances in Organic Synthesis
Advances in Organic Synthesis
9