Recent Advances in Mono‐ and Difunctionalization of Unactivated Olefins

Abstract

Olefins are synthetically useful building blocks in modern organic synthesis. Direct functionalization of olefins; represent one of the most explored transformations in synthetic chemistry due to their easy availability and reactivity towards large number of reactants affording diverse range of organic compounds. In recent times, the development of new protocols for the functionalization of olefins is a growing realm. A plethora of olefin functionalization methodologies have been reported in the literature through ionic and free radical mechanisms including single electron transfer (SET) in the last two decades. This review gives an overview of mono-and difunctionalization of unactivated olefins, with an emphasis on the mechanistic details. Functionalization of Unactivated Olefins via Visible-Light Photocatalysis Iridium Photo-Catalyzed Reactions CarbofunctionalizationGlorius and co-workers reported an efficient visible-light mediated three component dicarbofunctionalization of olefins 2 using simple benzylic Katritzky salts 1 as radical precursors (Scheme 1). [8] In this protocol, abundant styrenes, electron-rich heterocycles, and benzylic amines were successfully employed to afford a number of densely functionalized 1,1-diarylalkanes. The optimal reaction conditions for this reaction are [Ir-(dtbbpy)(ppy) 2 ](PF 6 ) (1 mol%) as the photocatalyst in MeCN under irradiation with visible light for 16 h. Under the optimum [a

Trifunctionalization of Cinnamyl Alcohols Provides Access to Brominated α,α-Difluoro-γ-lactones via a Photoinduced Radical–Polar–Radical Mechanism

“…Subsequent single electron reduction of this radical, generating a carbanion, or oxidation of the radical, creating a carbocation, followed by polar reactions with an electrophile or nucleophile, respectively, completes the RPC process. The novel features of RPC reactions have inspired the synthetic community to develop conceptually new transformations, providing efficient access to complex organic molecules via the construction of multiple new bonds . Herein, we describe the first example of a novel radical–polar–radical transformation in one pot to prepare functionalized lactones from readily available cinnamyl alcohols via Giese addition/lactonization/halogen-atom transfer (XAT) processes (Scheme ).…”

An iron-catalyzed multicomponent reaction of cycloketone oxime esters, alkenes, DABCO·(SO2)2 and trimethylsilyl azide

“…Vicinal difunctionalization of alkenes is a powerful and direct approach for rapidly increasing the molecular complexity as two functional groups are installed in a single process. 7 In this area, the ability of alkenes to act as sulfonyl radical acceptors to yield β-functionalized sulfones has been demonstrated with the generation of β-hydroxy, 8 β-alkoxy 9 and β-amino 10 sulfonyl compounds. Especially for β-aminosulfones, in 2019, Li and co-workers 10 a reported the first example of electrochemical intermolecular 1,2-aminosulfonylation of alkenes by using sodium sulfinates as the precursors of sulfonyl units.…”

Intermolekulare Carbosilylierung von α‐Olefinen mit C(sp3)−C(sp)‐Bindungsknüpfung unter Neubildung von Silyliumionen

“…Regioselektive Difunktionalisierungen von Alkenen mit Knüpfung einer Kohlenstoff‐Kohlenstoff‐ und einer Kohlenstoff‐Heteroatom‐Bindung in einem einzigen Syntheseschritt erfahren gegenwärtig erneutes Interesse [1] . Diese Reaktionen sind normalerweise Dreikomponentensysteme, bei der eine an die ungesättigte Einheit addiert und die andere danach mit der gebildeten, reaktiven Zwischenstufe gekuppelt wird.…”

“…Knüpfung einer Kohlenstoff-Kohlenstoff-und einer Kohlenstoff-Heteroatom-Bindung in einem einzigen Syntheseschritt erfahren gegenwärtig erneutes Interesse. [1] Diese Reaktionen sind normalerweise Dreikomponentensysteme, bei der eine an die ungesättigte Einheit addiert und die andere danach mit der gebildeten, reaktiven Zwischenstufe gekuppelt wird. Das lässt sich auf verschiedene Art und Weise erreichen, und für die Carbosilylierung von Alkenen überwiegen kürzlich entwickelte radikalische Methoden (Schema 1, oben).…”