Asymmetric allylboration of acyl imines catalyzed by chiral diols.
Chiral BINOL-derived diols catalyze the enantioselective asymmetric allylboration of acyl imines. The reaction requires 15 mol % (S)-3,3'-Ph2-BINOL as the catalyst and allyldiisopropoxyborane as the nucleophile. The reaction products are obtained in good yields (75-94%) and high enantiomeric ratios (95:5-99.5:0.5) for aromatic and aliphatic imines. High diastereoselectivities (diastereomeric ratio > 98:2) and enantioselectivities (enantiomeric ratio > 98:2) are obtained in the reactions of acyl imines with crotyldiisopropoxyboranes. This asymmetric transformation is directly applied to the synthesis of Maraviroc, the selective CCR5 antagonist with potent activity against HIV-1 infection. Mechanistic investigations of the allylboration reaction including IR, NMR, and mass spectrometry studies indicate that acyclic boronates are activated by chiral diols via exchange of one of the boronate alkoxy groups with activation of the acyl imine via hydrogen bonding.
Lou
Sha
S
Department of Chemistry and Center for Chemical Methodology and Library Development, Life Science and Engineering Building, Boston University, 24 Cummington Street, Boston, Massachusetts 02215, USA.
Moquist
Philip N
PN
Schaus
Scott E
SE
D000498:Allyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D019380:Anti-HIV Agents / Q000138:chemical synthesis*; D001880:Boranes / Q000138:chemical synthesis* / Q000737:chemistry; D001897:Boronic Acids / Q000737:chemistry; D003510:Cyclohexanes / Q000138:chemical synthesis*; D007097:Imines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D000077592:Maraviroc; D009284:Naphthols / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D014230:Triazoles / Q000138:chemical synthesis*
D000498:Allyl Compounds; D019380:Anti-HIV Agents; C406944:BINOL, naphthol; D001880:Boranes; D001897:Boronic Acids; D003510:Cyclohexanes; D007097:Imines; D009284:Naphthols; D014230:Triazoles; D000077592:Maraviroc