Transition Metal‐Catalyzed Hydroalkoxylation of Alkynes: An Overview

Abstract

Oxygen-bearing motifs, mainly the congener heterocycles are ubiquitous due to their presence in various natural products and bioactive scaffolds. Although in literature, several strategies have been developed for their synthesis, hydroalkoxylation of alkynes has come forward as a method of choice and has been used extensively. In particular, hydroalkoxylation of alkynes has gained enormous attention from the synthetic community due to the rapid access to a very useful and reactive synthetic intermediate like 'enol ether'. Furthermore, to manifold the utility of these methods, reports have been developed elaborating the generation of 'enol ether' using hydroalkoxylation and their usage in various reactions in cascade or tandem manner. This review focuses on recent development on the hydroalkoxylation of alkynes for the synthesis of oxygen-containing entities.

Titanium-catalyzed highly stereoselective anti-Markovnikov intermolecular hydroalkoxylation of alkynes to prepare Z-enol ethers

“…The transition metal-catalyzed hydroalkylation of alkynes has been proven to be an atom-economical and efficient method for obtaining enol ethers. Nevertheless, most of these investigations were severely limited to intramolecular hydroalkoxylation reactions, 12 and entropy reduction leading to high regio- and stereo-selective intermolecular hydroalkoxylation of alkyne remains challenging. 13 As an effective solution to this issue, the catalytic intermolecular hydroalkoxylation reaction has been sporadically documented.…”

Hydroalkoxylation-Initiated Cascade on Sulfone-Tethered Aryl Alkynols Gives Cyclic and Spiro-Heterocyclic β-Ketosulfones

“…Among these, hydroalkoxylation of alkynes has gained traction in recent years as it can be used in cascade processes, which increase molecular complexity rapidly in a single-pot process. , In this context, various types of cascade transformations involving cycloaddition, Prins cyclization, Friedel–Crafts alkylation/arylation reactions, rearrangements, etc. in combination with hydroalkoxylation of alkyne have been described . While transition-metal-catalyzed hydroalkoxylation cascades of alkynes have been encountered frequently, corresponding metal-free approaches are scarce in the literature .…”

“…in combination with hydroalkoxylation of alkyne have been described. 3 While transition-metal-catalyzed hydroalkoxylation cascades of alkynes have been encountered frequently, corresponding metal-free approaches are scarce in the literature. 4 This is somewhat intriguing given the cost and environmental considerations, as the latter are likely to fall under the regime of sustainable chemistry more often than the former.…”

Gold-Catalyzed Divergent N/O-Vinylations of trans-2-Butene-1,4-amino Alcohols with Alkynes and the Cascade Rearrangements/Cyclizations to Dihydropyrroles and Dihydrofurans

“…The transition-metal-catalyzed vinylation of amines and alcohols via the addition to alkynes is arguably one ideal approach to the synthetically essential enamine and vinyl ether building blocks . Such a strategy was generally atom economical and waste free and, more importantly, could be highly regio- and stereoselective.…”