Reaction of Enol Ethers with Lead Tetraacetate: An Improved Method for the Synthesis of α-Methoxy Ketones^#

^#Communication No 5664 from Central Drug Research Institute, Lucknow

Abstract

The reaction of cyclic enol ethers with lead tetraacetate in methanol in the presence of BF₃.Et₂O at 0°C gives α- methoxy cyclic ketones.

^#Communication No 5664 from Central Drug Research Institute, Lucknow

Notes

^#Communication No 5664 from Central Drug Research Institute, Lucknow

We were not able to affect the complete conversion of the intermediate acetals to the enol ethers and varying ammount of the acetal (5–15%) was always present as contaminant in the enol ethers even after careful fractional distillation.

The reported yields of the α- methoxyketones take into consideration the dimethyl acetal content of the enol ether and have been calculated on the basis of either gas chromatographic data or on the PMR basis. The reason for the low yields may be the facile conversion of I to III under acid catalysis.