The Alkynylative Difunctionalization of Alkenes

Abstract

Given alkynyl group is an important functional unit, a variety of efficient methods have been developed to construct alkynyl‐containing compounds. Among them, the alkynylative difunctionalization of alkenes is one of the most straightforward and efficient strategies for preparing these compounds and so has made great progress in recent years, including the catalytic asymmetric manner. However, there is no comprehensive review to summarize these studies. This review is aimed at comprehensively summarizing the alkynylative difunctionalization of alkenes, which is presented in terms of alkynylation‐initiated and alkynylation‐terminated difunctionalizations of alkenes. We hope that this review will help to encourage more researchers to further explore in this field.

Palladium(II)‐Catalyzed Markovnikov Hydroalkynylation of Unactivated Terminal Alkenes†

“…[2] Therefore, numerous efforts have been devoted to developing methodologies for efficient synthesis of alkynes. [3] Thus, a series of transition metal-catalyzed hydroalkynylation of alkenes have been developed via insertion of alkenes into alkynyl-metal species, such as Pd, [4] Ni, [5] Rh, [6] Ir, [7] Cu, [8] Co, [9] etc. [10] However, only reactive alkenes, such as α,β-unsaturated ketones, styrenes, enamides, and strained alkenes (e.g., norbornadienes and cyclopropane) are feasible for the reaction (Scheme 1a).…”

Electrophotocatalytic tri- or difluoromethylative cyclization of alkenes

“…Alkenes are ubiquitous in industrial chemicals and are the second most frequently encountered functional group in natural products, 1 and olefin difunctionalization offers a straightforward and powerful strategy to construct structurally complex molecules, installing two chemical bonds across an alkene using readily available feedstocks. 2 In this regard, radical cyclization of alkenes has proven to be a particularly fruitful line of research, providing a huge number of functionalized carbo-/heterocycles potentially useful in the chemical, pharmaceutical or material industries. 3 Alkenes are in general highly reactive towards radicals as well as electrophiles and prone to oligomerization and oxidative breakdown.…”

“…As a result, it is of much concern in alkene chemistry to identify reaction conditions mild enough to enable manageable functionalizations with good chemoselectivities. 1–3 Over the past few decades, many intriguing radical-involved cyclization reactions of alkenes have been developed, yet they are often enough both condition- and substrate-dependent due to the diversity of alkenes. 4–7 Furthermore, they, especially oxidative cyclizations, are mainly limited to cyclizations of activated alkenes.…”

Palladium-Catalyzed 1,1-Alkynyloxygenation of 2-Vinylbenzoates with Alkynyl Bromides

“…The introduction of an alkyne in this 1,1-carbooxygenation reaction would serve as a valuable method in view of the synthetic utility of an alkyne functionality, including as a component in click reactions. 10,11 We report herein on the Pd-catalyzed 1,1-alkynyloxygenation of 2-vinylbenzoates using alkynyl bromides, leading to the formation of 3-alkynylated isochroman-1-ones (Scheme 1c). 12 We recently reported on the use of bromoalkynes in the Pdcatalyzed 1,1-alkynylbromination of terminal alkenes (Scheme 2a).…”