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