3-b]furan-4,9-diones has been developed by N-iodosuccinimide (NIS)-induced enone difunctionalization with 2-hydroxy-1,4-naphthoquinones. This reaction involved sequential Michael addition, intramolecular oxidative cyclization and dehydrogenative aromatization to form new C–C and C–O bonds at the α and β positions of the enones. Various enones survived under the reaction conditions and the corresponding products
Chiral aldehyde catalysis is uniquely suitable for the direct asymmetric α-functionalization of N-unprotected amino acids, because aldehydes can reversibly form imines. However, there have been few successful reports of these transformations. In fact, only chiral aldehyde catalyzed aldol reactions of amino acids and alkylation of 2-amino malonates have been reported with good chiral induction. Here
one-pot, two-step process was disclosed for production of chiral α,β-epoxy ketonesfrom benzaldehydes and acetophenones catalyzed by imidazolium-modified poly(l-leucine). Two effective reaction systems with complementary high enantioselectivities (up to 98% ee) or satisfactory yields (up to 89%) have been developed. Importantly, the poly(aminoacid) catalyst can be easily recovered and recycled for ten
A novel NHC-catalyzed three-component domino strategy to access high functionalized cis-ε-ketoesters with excellent yields (up to 98%) and high stereoselectivities (up to 20â:â1) is documented. The title domino reactions are atom economical and work on a broad range of substrates. The relative stereochemistry could be explained by a cascade crossed-benzoin/oxy-Cope rearrangement/esterification process. The thus-obtained products are of potential synthetic value in the drug research and combinatorial chemistry.
Organic anions. Part 1. Equilibration of 1,3-diarylpropenes
作者:Richard J. Bushby、Gerald J. Ferber
DOI:10.1039/p29760001683
日期:——
A number of 1,3-diarylpropenes, potential precursors of the allylic anions (I). have been synthesised, and the base catalysed equilibration between the double bond isomers (II) and (III) has been investigated. The equilibrium constants correlate satisfactorily with the substituent constant σ. N.m.r. shift reagents aided spectroscopic analysis of certain mixtures.