Direct formation of λ5-phospholes from trialkyl phosphites and dimethyl acetylenedicarboxylate. Alkoxyphosphonium ylides as reactive intermediates and stable products
- 1 January 1984
- journal article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 1627-1629
- https://doi.org/10.1039/p19840001627
Abstract
Trialkyl phosphites and dimethyl acetylenedicarboxylate react in toluene below –10 °C to form high yields of tetramethyl 1,1,1-trialkoxy-1λ5-phosphole-2,3,4,5-tetracarboxylates (3). These phospholes can either rearrange thermally to stable dialkoxyphosphonium ylides (4) or be converted by addition of hydrogen bromide to give stable tetramethyl 1-alkoxy-1-oxo-1H-1λ5-phosphole-2,3,4,5-tetra-carboxylates (5). The unstable trialkoxy [methoxycarbonyl-(1,2,3-trismethoxycarbonylcyclopropenyl)-methylene]phosphorane precursors of (3) can be formed almost quantitatively by carrying out the reaction in toluene below –50 °C.Keywords
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