title: Diastereoselective synthesis of beta-substituted-alpha,gamma-diaminobutyric acids and pyrrolidines containing multichiral centers.
abstract: A convenient and efficient way for the highly diastereoselective synthesis of beta-substituted-alpha,gamma-diaminobutyric acids and pyrrolidines containing multichiral centers has been well-developed. Michael addition of chiral tricyclic iminolactones 1 and 2 to nitroalkenes afforded the adducts in good yields (up to 95%) and excellent diastereoselectivities (up to dr > 99:1) when titanium(IV) isopropoxide was used. Configuration of the second new stereocenter was decided by the substitution of nitroalkene. Selective reduction and hydrolysis of the Michael adducts furnished the desired beta-substituted-alpha,gamma-diaminobutyric acids in good yields and high enantiomeric excesses (>99% ee). Synthesis of pyrrolidines containing multichiral centers has also been accomplished in good to excellent yields and diastereoselectivities under mild conditions via Michael-Mannich tandem reactions using Cu(OTf)(2) or AgOTf as an activating reagent for aliphatic nitroalkenes.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.forename: Qiong
authors.initials: Q
authors.lastname: Li
authors.forename: Tian-Liang
authors.initials: TL
authors.lastname: Liu
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Xu
mesh_terms: D000613:Aminobutyrates / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D007783:Lactones / Q000138:chemical synthesis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011759:Pyrrolidines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013343:Styrenes / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D000613:Aminobutyrates; D007783:Lactones; D011759:Pyrrolidines; D013343:Styrenes; C011955:beta-nitrostyrene