Development of chiral dinitrones as modular Lewis base catalysts: asymmetric allylation of aldehydes with allyltrichlorosilanes
摘要:
Chiral dinitrones were synthesized by the condensation of a C-2-symmetrical chiral dihydroxylamine with various aldehydes. The electronic and steric properties of the dinitrones can be modified by changing the aldehyde component. The activity of dinitrones as Lewis base catalysts was examined for the asymmetric allylation of aldehydes with allyltrichlorosilanes. Using DMPU as an additive in chloroform, the reaction proceeded at room temperature to afford allylated products in good yields and good enantioselectivities. (C) 2010 Elsevier Ltd. All rights reserved.
Ti-Catalyzed Barbier-Type Allylations and Related Reactions
作者:Rosa E. Estévez、José Justicia、Btissam Bazdi、Noelia Fuentes、Miguel Paradas、Duane Choquesillo-Lazarte、Juan M. García-Ruiz、Rafael Robles、Andreas Gansäuer、Juan M. Cuerva、J. Enrique Oltra
DOI:10.1002/chem.200802180
日期:2009.3.9
Versatility of titanium: Titanocene(III) complexes catalyze Barbier‐type allylations, intramolecular crotylations (cyclizations), and prenylations of a wide range of aldehydes and ketones. These reactions take place at RT under mild conditions compatible with many functional groups; provide good yields of open‐chain and cyclic homoallylic alcohols, including heterocyclic derivatives; and can be conducted