title: Diastereo- and Enantioselective Iridium Catalyzed Coupling of Vinyl Aziridines with Alcohols: Site-Selective Modification of Unprotected Diols and Synthesis of Substituted Piperidines.
abstract: The chiral cyclometalated π-allyliridium ortho-C,O-benzoate complex (R)-Ir-VIb derived from [Ir(cod)Cl]2, allyl acetate, 4-cyano-3-nitro-benzoic acid, and (R)-MeO-BIPHEP catalyzes the coupling of N-(p-nitrophenylsulfonyl) protected vinyl aziridine 3a with primary alcohols 1a-1l to furnish branched products of C-C bond formation 4a-4l with good levels of anti-diastereo- and enantioselectivity. In the presence of 2-propanol, but under otherwise identical conditions, vinyl aziridine 3a and aldehydes 2a-2l engage in reductive coupling to furnish an equivalent set of adducts 4a-4l with roughly equivalent levels of anti-diastereo- and enantioselectivity. Using enantiomeric iridium catalysts, vinyl aziridine 3a reacts with unprotected chiral 1,3-diols 1m-1o in a site-selective manner to deliver the diastereomeric products of C-allylation syn-4m, -4n, -4o and anti-4m, -4n, -4o, respectively, with good isolated yields and excellent levels of catalyst-directed diastereoselectivity. These adducts were directly converted to the diastereomeric 2,4,5-trisubstituted piperidines syn-5m, -5n, -5o and anti-5m, -5n, -5o.
authors.affiliation: University of Texas at Austin, Department of Chemistry, Austin, Texas 78712, United States.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.affiliation: University of Texas at Austin, Department of Chemistry, Austin, Texas 78712, United States.
authors.forename: Jana
authors.initials: J
authors.lastname: Franke
authors.affiliation: University of Texas at Austin, Department of Chemistry, Austin, Texas 78712, United States.
authors.forename: Chinh Q
authors.initials: CQ
authors.lastname: Ngo
authors.affiliation: University of Texas at Austin, Department of Chemistry, Austin, Texas 78712, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Krische
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000085:Acetates / Q000737:chemistry; D000438:Alcohols / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry; D001388:Aziridines / Q000737:chemistry*; D002384:Catalysis; D007495:Iridium / Q000737:chemistry*; D010084:Oxidation-Reduction; D010880:Piperidines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D000085:Acetates; D000438:Alcohols; D000447:Aldehydes; D000498:Allyl Compounds; D001388:Aziridines; D010880:Piperidines; D014753:Vinyl Compounds; D007495:Iridium; C498551:allyl acetate; D019840:2-Propanol