Cooperative Use of Brønsted Acids and Metal Catalysts in Tandem Isomerization Reactions of Olefins

Abstract

Dual catalysis constitutes a growing field of the organic synthesis. It is a useful methodology, which allows for a discovery of new and more efficient transformations. This concept article describes tandem reactions, which comprise of an isomerization of the double bond and following transformation, whereby a combination of a homogeneous metal catalyst and Brønsted acid is used. The aim is to highlight the versatility of this catalyst combination.This publication is part of the Young Researchers Series. More information regarding these excellent researchers can be found on the ChemCatChem homepage. Figure 1. Combinations of homogeneous metal and Brønsted acid catalysts and topic of this concept article. [M] = metal complex; HA = Brønsted acid.

Nickel/Brønsted Acid-Catalyzed Chemo- and Enantioselective Intermolecular Hydroamination of Conjugated Dienes

“…As an extension of our studies with nickel-catalyzed carbon-carbon bond formations (Li et al., 2019b, Wang et al., 2019), we turned our attention to carbon-heteroatom bonds. Inspired by the recent reports on metal/Brønsted acid dual catalysis (Adamson et al., 2017, Dion and Beauchemin, 2011, Han et al., 2018, Kathe and Fleischer, 2019, Lin et al., 2019, Liu and Feng, 2018, Löber et al., 2001, Park and Malcolmson, 2018, Yang and Dong, 2017, Zhou and Hartwig, 2008), we have developed a novel, room temperature nickel/Brønsted acid-catalyzed asymmetric hydroamination using conjugated dienes as a limiting reagent (Figure 1D). This protocol can transform a wide array of primary and secondary amines into allylic amines in high yields with excellent enantioselectivities.…”

gem-Dialkyl Effect in Diphosphine Ligands: Synthesis, Coordination Behavior, and Application in Pd-Catalyzed Hydroformylation

“…Hydroformylation of internal alkenes will be inherently slower than terminal alkenes, as the linear aldehyde remains the major product irrespective of the octene isomer that is used as the substrate. Isomerization from the internal octenes to 1-octene will need to occur prior to hydroformylation, , which seems to be equally fast for both ligands according to the olefin composition. The subsequent hydroformylation of 1-octene is faster for L1 than for L2 , as seen in runs 1 and 2.…”

Tandem Acid/Pd‐Catalyzed Reductive Rearrangement of Glycol Derivatives

“…To our surprise, the investigations revealed the occurrence of an unprecedented tandem [1,2]‐rearrangement–reduction sequence via an aldehyde. The transformation is promoted by a dual catalyst system based on a combination of Brønsted acid and a unique metal catalyst comprising a Pd source and the bidentate ligand α,α′‐bis(di‐ tert ‐butylphosphino)‐ o ‐xylene (dtbpx, L1 ) . Pd/ L1 systems exhibit an exceptional selectivity in olefin carbonylation reactions due to the electron‐richness and steric properties of the ligand and are hence of great industrial interest .…”

“…The transfor-mation is promotedb yadual catalyst system based on ac ombination of Brønsted acid and au nique metal catalyst comprising aP ds ource and the bidentate ligand a,a'-bis(di-tert-butylphosphino)-o-xylene (dtbpx, L1). [11] Pd/L1 systems exhibit an exceptional selectivity in olefin carbonylation reactions due to the electron-richness and steric properties of the ligand [12] and are hence of great industrial interest. [13] Furthermore, carbonylation can be preceded by isomerization making the transformation potentially valuable for the valorization of other renewable feedstocks like cashew nut shell liquid [14] and plant oils.…”