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.
Construction of bispirooxindoles containing three quaternary stereocentres in a cascade using a single multifunctional organocatalyst
作者:Bin Tan、Nuno R. Candeias、Carlos F. Barbas
DOI:10.1038/nchem.1039
日期:2011.6
Single-step constructions of molecules with multiple quaternary carbon stereocentres are rare. The spirooxindole structural motif is common to a range of bioactive compounds; however, asymmetric synthesis of this motif is complicated due to the presence of multiple chiral centres. The development of organocatalytic cascade reactions has proven to be valuable for the construction of several chiral centres
A copper(I)/DDQ-mediated double-dehydrogenative Diels–Alder (DDDA) reaction of simple butenes with 1,4-diketones and indolones has been established for the first time. This strategy is based on a tandem double-dehydrogenation/Diels–Alderreaction from nonprefunctionalized starting materials, in which both a diene and dienophile were in situgenerated via activation of fourfold inert C(sp3)–H bonds
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