Unique features of chiral palladium enolates derived from β-ketoamide: structure and catalytic asymmetric Michael and fluorination reactions
摘要:
We have previously reported enantioselective reactions of 1,3 -diketones and beta-ketoesters with various electrophiles catalyzed by chiral Pd complex, in which chiral Pd enolates play a key role. Here, we present a detailed examination of Pd-catalyzed enantioselective Michael addition and fluorination reactions of beta-ketoamides. beta-Ketoamide showed higher reactivity than 1,3-diketone and beta-ketoester, though its alpha-proton is likely to be least acidic. Pd enolate formation of beta-ketoamide was much faster than that of beta-ketoester. The crystal structures of (R)-BINAP-Pd-diketone and ketoamide complexes were found to be quite distinct. Pd-diketone complex has bidentate square-planar geometry as have been predicted before, whereas Pd-ketoamide complex was greatly distorted, probably due to steric constraints of the amide bond. (C) 2015 Elsevier Ltd. All rights reserved.
α-Oxo-Ketenimines from Isocyanides and α-Haloketones: Synthesis and Divergent Reactivity
作者:Mathias Mamboury、Qian Wang、Jieping Zhu
DOI:10.1002/chem.201703458
日期:2017.9.18
β-Hydride elimination at will: Reaction of α-haloketones with isocyanides in the presence of a catalytic amount of Pd(OAc)2 afforded α-oxo-ketenimines that can be further converted to 5-aminopyrazoles, tetrazole, β-keto amidines and enaminone in good to excellent yields.
Highly efficient asymmetric intermolecular radical-polarcrossoverreactions were realized by combining a chiral N,N'-dioxide/NiII complex catalyst with Ag2 O under mild reaction conditions. Various terminal alkenes and indanonecarboxamides/esters underwent radical addition/cyclization reactions to afford spiro-iminolactones and spirolactones with good to excellent yields (up to 99 %) and enantioselectivities