Ruthenium-catalyzed C-C bond forming transfer hydrogenation: carbonyl allylation from the alcohol or aldehyde oxidation level employing acyclic 1,3-dienes as surrogates to preformed allyl metal reagents.
Under the conditions of ruthenium-catalyzed transfer hydrogenation, commercially available acyclic 1,3-dienes, butadiene, isoprene, and 2,3-dimethylbutadiene, couple to benzylic alcohols 1a-6a to furnish products of carbonyl crotylation 1b-6b, carbonyl isoprenylation 1c-6c, and carbonyl reverse 2-methyl prenylation 1d-6d. Under related transfer hydrogenation conditions employing isopropanol as terminal reductant, isoprene couples to aldehydes 7a-9a to furnish identical products of carbonyl isoprenylation 1c-3c. Thus, carbonyl allylation is achieved from the alcohol or the aldehyde oxidation level in the absence of preformed allyl metal reagents. Coupling to aliphatic alcohols (isoprene to 1-nonanol, 65% isolated yield) and allylic alcohols (isoprene to geraniol, 75% isolated yield) also is demonstrated. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH).
Shibahara
Fumitoshi
F
Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Bower
John F
JF
Krische
Michael J
MJ
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D000466:Alkadienes / Q000737:chemistry*; D000498:Allyl Compounds / Q000138:chemical synthesis*; D001592:Benzyl Alcohols / Q000737:chemistry; D002384:Catalysis; D006865:Hydrogenation; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry
D000438:Alcohols; D000447:Aldehydes; D000466:Alkadienes; D000498:Allyl Compounds; D001592:Benzyl Alcohols; D012428:Ruthenium