Simple Synthesis of Dialkyl 2-(3-Oxo-3H-indol-2-yl)-but-2-enedioates

摘要

Triphenylphosphine undergoes a smooth addition reaction with dialkyl acetylenedi-carboxylates in the presence of isatin or 5-bromoisatin to produce stable crystalline phosphorus ylides.These products exist as a mixture of two geometrical isomers.Dynamic NMR effects have been observed in the H NMR spectra of dimethyl 2-(2,3-dioxo-2,3-dihydro- 1H-indol-1 -yl)-3-( 1,1,1 -triphenyl-gamma~5-phosphanylidene)-suc-cinate.These ylides are converted to dialkyl 2-(3-oxo-3H-indol-2-yl)-but-2-enedioates in boiling toluene.