Gold In Total Synthesis: Alkynes as Carbonyl Surrogates

摘要

Alkyne hydration, or the addition of an equivalent of water across a carbon-carbon triple bond, is a valuable transformation in the context of chemical synthesis. The stability and ease of installation of the alkyne allows a chemist to mask the reactivity of a carbonyl moiety, thus providing greater flexibility in synthetic planning. As taught to first year organic chemists, an alkyne can be transformed into a ketone by a variety of means, most notably by the use of an electrophilic mercury salt. Given the toxicity of mercury, a range of alternate transition-metal catalysts have been developed, with gold complexes taking a leading role. The general mechanism of this transformation is shown in Scheme 1, and in many cases, alcohols can be used in place of water to provide enol ether or acetal products, depending on the conditions and the substrate.