Sterically Encumbered and Poorly Electron-Donating Oxaphosphaadamantane Ligands for the Pd-Catalyzed Telomerization of Butadiene with Methanol

• Published in: Organic process research & development Vol. 23; no. 8; pp. 1654 - 1658
• Main Authors: Klinkenberg, Jessica L, Lawry, Kevin P
• Format: Journal Article
• Language: English
• Published: American Chemical Society 16-08-2019
• Subjects: palladium; industry; butadiene telomerization; 1-octene; oxaphosphaadamantane ligand
• ISSN: 1083-6160; 1520-586X
• DOI: 10.1021/acs.oprd.9b00018

Oxaphosphaadamantane ligands bearing a variety of aryl and alkyl substituents were synthesized as catalyst promoters in the Pd-catalyzed telomerization of butadiene with methanol. At high methanol concentrations (14 M), ligands with electron-donating substituents on the aryl ring generate catalysts that lead to some of the highest conversions of butadiene and selectivities for 1-methoxy-2,7-octadiene under the conditions tested. Specifically, the ligand 1,3,5,7-tetramethyl-6-(2-methoxyphenyl)-2,4,8-trioxa-6-phosphaadamantane, when combined with a Pd­(II) precursor, forms a catalyst that converts 96% of butadiene with 94% selectivity for 1-methoxy-2,7-octadiene at 70 °C and is highly active for telomerization at a low reaction temperature (40 °C).