A general and efficient method for the preparation of 2-diethoxyphosphoryl-6-oxohexanoates
is presented. This approach is based on the Michael addition of [2-(1,3-dioxolan-2-yl)ethyl]magnesium
bromide to various 3-substituted tert-butyl
(E)-2-(diethoxyphosphoryl)alk-2-enoates
as a key step. Application of the 2-diethoxyphosphoryl-6-oxohexanoates
obtained in the intramolecular Horner-Wadsworth-Emmons
reaction for the preparation of 5-substituted tert-butyl
cyclopent-1-enecarboxylates is also reported.
Michael reaction - intramolecular Horner-Wadsworth-Emmons
reaction - cyclopent-1-enecarboxylates - phosphonates - 6-oxoalkanoates