An N-heterocycliccarbene (NHC)-catalysed retro-aldol/aldol cascadereaction of spirooxindole-based β-hydroxyaldehyde has been developed. The ring opening-closure process enables the diastereodivergent synthesis of spirocyclopentaneoxindole products with four consecutive stereocenters by simply changing the reaction solvents (THF or DCE). The Michael/aldol/retro-aldol/aldol sequential protocol allows
N-heterocyclic carbene-catalyzed synthesis of spirocyclopentene-oxindoles from bromoenals
作者:Zhao-Fei Zhang、Kun-Quan Chen、Chun-Lin Zhang、Song Ye
DOI:10.1039/c6cc10304a
日期:——
Spirocyclopentene-oxindoles were synthesized in good yields with good diastereo- and enantioselectivities via the N-heterocycliccarbene-catalyzed reaction of bromoenals and oxindoles.
BF<sub>3</sub>·OEt<sub>2</sub> catalyzed chemoselective CC bond cleavage of α,β-enones: an unexpected synthesis of 3-alkylated oxindoles and spiro-indolooxiranes
作者:Sengodagounder Muthusamy、Ammasi Prabu
DOI:10.1039/d1ob02002a
日期:——
of α,β-enones with diazoamides for the synthesis of 3-alkylated oxindoles is developed. Borontrifluoride etherate is found to be an effectivecatalyst for the chemoselective Cα–Cβ cleavage of enones to obtain 3-alkylated oxindoles. The product formation indicates a selective β-carbon elimination pathway of α,β-enones using the inexpensive BF3·OEt2 as a catalyst, transition metal-free conditions, an
Chemoselective Reduction of Isatin-Derived Electron-Deficient Alkenes Using Alkylphosphanes as Reduction Reagents
作者:Shu-Hua Cao、Xiu-Chun Zhang、Yin Wei、Min Shi
DOI:10.1002/ejoc.201100017
日期:2011.5
Under mild reaction conditions, the C=C double bond in isatin-derivedelectron-deficientalkenes has been exclusively reduced in the presence of alkylphosphanes and water to afford the corresponding reduction products in good to excellent yields. A plausible mechanism is proposed on the basis of deuterium-labeling experiments.
Diastereoselective tandem oxidation/Michael/aldol reaction: unprecedented formation of dispirocyclopentanebisoxindoles and dispiro[acenaphthylene-1,1′-cyclopentane-3′,1′′-acenaphthylene]-2,2′′diones
An unprecedented tandem oxidation/Michael/aldolreaction is reported. The diastereoselective formation of only a single isomer of dispirocyclopentanebisoxindole and dispiro[acenaphthylene-1,1′-cyclopentane-3′,1′′-acenaphthylene]-2,2′′dione is presented. The reaction generates two new C–C bonds and two all-carbon quaternary chiral stereocenters in a single step.