Low temperature equilibration of cyclopropanes by Lewis acid catalysis
作者:Hans-Ulrich Reissig、Ingrid Böhm
DOI:10.1016/s0040-4039(00)81506-3
日期:1983.1
Under the influence of Lewis acids the cis/trans-equilibration of methyl 2-trimethyl-siloxy cyclopropanecarboxylates occurs even at −78°C. It involves the heterolytic cleavage of a CC bond and seems to be governed by steric effects.
Starting from methyl 2-siloxycyclopropanecarboxylates simple and efficient one-pot procedures are described that lead to beta-cyanoesters and methoxycarbonyl-substituted terminal alkynes. The prepared functionalized alkynes were subjected to typical transformations such as [3+2] cycloaddition providing triazole derivatives, Sonogashira coupling, Au-catalyzed hydrophosphorylation or a copper-catalyzed coupling of methyl diazoacetate furnishing alkyne 14 and allene derivative 15. The Pauson-Khand reaction of the enyne 4c afforded a diastereomeric mixture of methyl 5-oxohexahydropentalen-2-carboxylate 16 in moderate yield.
KUNKEL, E.;REICHELT, I.;REISSIG, H. -U., LIEBIGS ANN. CHEM., 1984, N 4, 802-819