Enantioselective Carbonyl Allylation, Crotylation, and tert-Prenylation of Furan Methanols and Furfurals via Iridium-Catalyzed Transfer Hydrogenation

• Published in: Journal of organic chemistry Vol. 75; no. 5; pp. 1795 - 1798
• Main Authors: Bechem, Benjamin, Patman, Ryan L, Hashmi, A. Stephen K, Krische, Michael J
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 05.03.2010; Amer Chemical Soc
• Subjects: Acetates - chemistry; Allyl Compounds - chemistry; Catalysis; Chemistry; Chemistry, Organic; Exact sciences and technology; Furaldehyde - chemistry; Furans - chemistry; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Hydrogenation; Iridium - chemistry; Methanol - chemistry; Molecular Structure; Organic chemistry; Physical Sciences; Preparations and properties; Pyrones - chemistry; Science & Technology; Stereoisomerism; ACTIVATION; REAGENTS; ALCOHOL; LIGANDS; MECHANISM; ALDEHYDE OXIDATION LEVEL; ACETATE; CHIRAL LEWIS-ACID; ASYMMETRIC ALLYLATION; BIS(((S)-BINAPHTHOXY)(ISOPROPOXY)TITANIUM) OXIDE; Chemical rearrangement; Catalytic reaction; Transition element complexes; Enantioselectivity; Furan derivatives; Iridium complex; Transition metal; Modified catalyst; Propanol; Aldehyde; Pyranone derivatives; Oxygen heterocycle; Ketone; Hydrogenation; Allylic compound; Allylation; Furfural derivatives; Chlorides; Enantiomeric excess; Methyl acetate; Platinoid; Methanol
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/jo902697g

5-Substituted-2-furan methanols 1a−c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, α-methyl allyl acetate, or 1,1-dimethylallene in the presence of an ortho-cyclometalated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3-TUNEPHOS, and (R)-C3-SEGPHOS, respectively. In the presence of 2-propanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a−c are converted to identical products of allylation, crotylation, and tert-prenylation. Optically enriched products of carbonyl allylation, crotylation, and reverse prenylation 3b, 4b, and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding γ-hydroxy-β-pyrones 6a−c, respectively, with negligible erosion of enantiomeric excess.