PHOSPHONIUM YLIDE-CATALYZED CYCLOTRIMERIZATION OF ETHYL PROPYNOATE

ABSTRACT

The cyclotrimerization of ethyl propynoate (2) to yield aromatic triesters is shown to proceed via consecutive [2 + 2] cycloadditions of ethoxycarbonylmethylenetriphenylphosphonium ylide (1) to three moles of (2), followed by cyclization and elimination of (1).

ACKNOWLEDGMENTS

We thank Mr HSC Spies for the NMR spectra and many helpful discussions and Ms V Truter for the mass spectra. Technical assistance by Mr MC de Jongh and his staff is gratefully acknowledged.