Hetarynes, Cycloalkynes, and Related Intermediates

Abstract

Hetarynes are transient species formally derived from heteroaromatic rings via abstraction of two hydrogen atoms and have been engaged as an important tool for the synthesis of complex natural products. Hetarynes have been studied since long time. But previously, hetarynes generation strategies had many limitations such as the use of stoichiometric amount of oxidant, strong base, and/or formation of various side products. With the progress of time, mild methods for hetarynes generation have been achieved and thus hetarynes are much more accessible now and used for complex synthetic targets. Strained cycloalkynes and related intermediates like 1,2‐cycloalkadienes are also recently gaining interest across the synthetic community due to their easy access from the corresponding silyltriflate precursors. Using hetarynes or strained cycloalkynes as potential intermediate various makaluvamines, lysergic acid, members of the welwitindolinone, indolactam alkaloids, indole diterpenoid tubingensin A, tubingensin B, ellipticine, macrostomine, eupolauramine, perlolidine, guanacastepenes O, and guanacastepenes N can be accessed. A brief history of hetarynes, cycloalkynes, and related intermediates, different methods of generation, various types of reactions, and applications in total synthesis are discussed in brief in this chapter.