Carbocyclisation of alkynes with external nucleophiles catalysed by gold, platinum and other electrophilic metals

This tutorial review covers recent developments in catalytic carbocyclisation of functionalised alkynes with external nucleophiles catalysed by gold, platinum and other electrophilic metals. Substrates of such reactions require a tethered functionality to react with the alkyne to complete a carbocyclic ring. We classify the reactions according to the tethered functionalities to illustrate the diversity of the carbocyclisations; these substrates include: (1) alkyne-alkyne, (2) alkyne-allene, (3) alkyne-alkene, (4) oxo-alkynes and (5) oxo-diynes and triynes. Besides their mechanistic interest, these reactions meet atom economy criteria because complex and functionalised carbocyclic products are easily assembled in a cascade sequence from readily available alkynes and nucleophiles.