Nickel- and Brønsted Acid-Catalyzed Redox-Neutral Coupling of 1,3-Dienes and Aldehydes for Synthesis of Dienols

Abstract

Dienols are important structural motifs in organic molecules, but most of the traditional synthetic methods required multistep prefunctionalization of substrates, leading to stoichiometric waste and low atom economy. Herein, we report a redox-neutral coupling of simple 1,3-dienes and aldehydes via nickel and Brønsted acid dual catalysis, providing a highly atom-economical and by-product-free route to various dienols with up to 94% yield and up to 50∶1 EE/EZ ratio. The use of 2-isopropoxyphenol as a Brønsted acid co-catalyst was critical to the reactivity and selectivity.

Ni-catalyzed hydroalkylation of olefins with N-sulfonyl amines

“…Inspired by the previous observations that compounds bearing active protons (e.g. TsNH 2 , phenol) could promote opening of the fivemembered nickellacycle intermediate via protonation 50,54,[62][63][64] , as well as studies of transmetallation on boronates [65][66][67][68][69] , we proposed that a boronate facilitates exchange of the sulfonamidyl group on the nickel, leading to rapid opening of the nickellacycle (a to b in Fig. 1c).…”

Palladium- and Brønsted acid-catalyzed enantio-, site- and E/Z-selective addition of alkylidenecyclopropanes with imines

“…On the basis of the experimental results and the previous literature, 10,11 a plausible catalytic cycle is proposed in Scheme 4. First, the oxidative addition of the in situ generated Pd(0) to the proximal C–C bond of ACPs 1 generates a cyclic Pd( ii ) complex I .…”

“…Recently, dual catalysis by transition metal and a Brønsted acid has been proven to be a powerful strategy for redox-neutral coupling of alkenes and carbonyl compounds. 11 Thus, a series of Brønsted acids were tested in this reaction. Pleasingly, both the reactivity and the selectivity were improved with the addition of N -Boc-L- tert -Leucine (Boc-L-Tle-OH).…”

Catalytic transformations of alkenes via nickelacycles

“…In a recent study, Ye and co-workers demonstrated the effective use of a catalytic amount of Brønsted acid, specifically PhB(OH) 2 , in hydroalkenylation of aldehydes with styrene and related derivatives (Scheme 50). 124,125 Both the alcoholic solvent and PhB(OH) 2 were crucial to the reaction's success, leading the authors to suggest that a coordinated complex involving PhB(OH) 2 and ethanol might serve as a superior acid catalyst. Furthermore, Han and Liu 126 investigated the reaction mechanisms of nickel-catalysed hydroalkenylation of aldehydes with styrenes using DFT calculations.…”