Iridium-catalyzed C-C coupling via transfer hydrogenation: carbonyl addition from the alcohol or aldehyde oxidation level employing 1,3-cyclohexadiene.
Under hydrogen autotransfer conditions employing a catalyst derived from [Ir(cod)Cl]2 and BIPHEP, 1,3-cyclohexadiene (CHD) couples to benzylic alcohols 1a-9a to furnish carbonyl addition products 1c-9c, which appear as single diastereomers with variable quantities of regioisomeric adducts 1d-9d. Under related transfer hydrogenation conditions employing isopropanol as terminal reductant, identical carbonyl adducts 1c-9c are obtained from the aldehyde oxidation level. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH).
Bower
John F
JF
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Patman
Ryan L
RL
Krische
Michael J
MJ
D000438:Alcohols / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D053138:Cyclohexenes / Q000737:chemistry*; D006865:Hydrogenation; D007495:Iridium / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D000438:Alcohols; D000447:Aldehydes; D053138:Cyclohexenes; D007659:Ketones; D007495:Iridium; C034005:1,3-cyclohexadiene