N-Heterocyclic Carbene-Catalyzed Enantioselective Annulation of Bromoenal and 1,3-Dicarbonyl Compounds
作者:Fang-Gang Sun、Li-Hui Sun、Song Ye
DOI:10.1002/adsc.201100622
日期:2011.11
Highly enantioselective [3+3] annulation reactions of bromoenals and 1,3-dicarbonylcompounds are reported. In addition, both enantiomers of the resultant dihydropyranone could be easily obtained by choosing N-heterocyclic carbenes (NHCs) with the same stereocenter but different substituents under the optimized reaction conditions.
aerobic asymmetric cyclization reaction of cinnamaldehydes and 1,3-dicarbonylcompounds through oxidative NHC-catalysis has been developed, and it allows the synthesis of a wide range of enantiomeric enriched dihydropyranone derivatives in good yields with good to excellent enantioselectivities. Various α,β-unsaturated aldehydes with aliphatic and aromatic substitution groups and 1,3-dicarbonyl compounds
Direct β-Activation of Saturated Aldehydes to Formal Michael Acceptors through Oxidative NHC Catalysis
作者:Junming Mo、Liang Shen、Yonggui Robin Chi
DOI:10.1002/anie.201302152
日期:2013.8.12
mediated by N‐heterocyclic carbenes (NHCs) enables the direct β‐carbon functionalization of saturated aldehydes (see scheme). The reaction proceeds through two sequential oxidative steps to generate α,β‐unsaturated triazolium ester equivalents as formal Michael acceptors, which react with 1,3‐diketones and β‐ketone esters in an enantioselective manner.