Ligand-Controlled Palladium-Catalyzed Decarboxylative Heck Coupling for Regioselective Access to Branched Olefins

ACS Catalysis, vol. 13, pp. 10085–10093

Abstract

A highly chemo- and regioselective decarboxylative Heck-type coupling of carboxylic acids and terminal olefins has been developed using a catalytic system composed of Pd(OAc) 2 in the presence of phosphine-sulfonamido ligands. Using the bulky ligand L1 leads to high selectivity for 1,1-disubstituted (branched; b) olefins that are generally difficult to obtain. The influence of all relevant reaction parameters was evaluated using a combination of design of experiments and one factor at a time optimization. The coupling of dimethoxy-benzoic acid with various olefinic substrates gave the corresponding branched olefins with excellent regioselectivity (b/l up to 42:1) in up to 80% isolated yields. In contrast, using the less bulky ligand L2 results in the inverse regioselectivity leading to the 1,2-disubstituted (linear; l) product again in high yield of 86% (b/l = 1:26). Detailed investigation of the mechanistic pathways by DFT calculations reveals that the sterically demanding aryl substituent at the sulfonamide group of ligand L1 favors the pathway via 1,2-insertion with an energy preference of 4.4 kcal/mol, thus furnishing the 1,1-disubstituted branched olefins. In contrast, the 2,1-insertion reaction is advantageous by 1.3 kcal/mol for the analogous less bulky ligand L2 leading to the linear products.

Authors 6

1. Sangeth Jenthra Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

2. Totan Mondal Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

3. Gregor Kemper Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

4. Marcus Lantzius‐Beninga Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

5. Markus Hölscher corresponding Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

6. Walter Leitner corresponding Aachen Institut für Technische und Makromolekulare Chemie

   Max Planck Institute for Chemical Energy Conversion · RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

   Max Planck Institute for Chemical Energy Conversions, Mülheim an der Ruhr, Nordrhein-Westfalen 45470, Germany