Conversion of Primary Alcohols and Butadiene to Branched Ketones via Merged Transfer Hydrogenative Carbonyl Addition-Redox Isomerization Catalyzed by Rhodium
Brian J. Spinello, Jessica Wu, Yoon Cho and Michael J. Krische*
*Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States,
Email: mkrische
mail.utexas.edu
B. J. Spinello, J. Wu, Y. Cho, M. J. Krische, J. Am. Chem. Soc., 2021, 143, 13507-13512.
DOI: 10.1021/jacs.1c07230
see article for more reactions
Abstract
A rhodium-catalyzed tandem butadiene-mediated carbonyl addition-redox isomerization converts primary alcohols to isobutyl ketones. Related reductive coupling-redox isomerizations of aldehyde reactants mediated by sodium formate also are reported.
see article for more examples
proposed mechanism
General Procedure From Alcohol Oxidation Level:
A resealable pressure tube (13 x 100 mm) was charged with Rh(cod)2BAr4F (11.8 mg, 0.01 mmol, 5 mol%), triphenylphosphine (5.8 mg, 0.022 mmol, 11 mol%), alcohol (0.20 mmol, 100 mol%), and potassium carbonate (13.8 mg, 0.1 mmol, 50 mol%). The tube was sealed with a rubber septum and purged with Ar for 1 min. Chlorobenzene (1.0 mL, 0.2 M with respect to alcohol) was injected, and the solution was cooled to -78 °C. Cold butadiene (89 µl, 1.0 mmol, 500 mol%) was added and the rubber septum was quickly replaced with a PTFElined screw cap. The tube was warmed to ambient temperature and placed in a 130 °C oil bath for 24 h. After cooling to room temperature, a small quantity of silica was added to the crude reaction mixture, which was concentrated in vacuo. The resultant powder was subjected to flash column chromatography (SiO2) to afford the reaction product.
Key Words
ID: J48-Y2021
