A Convenient Method for Converting Hydroxyacetophenones into Their Ethylene or Trimethylene Acetals

Abstract

Various types of hydroxyacetophenones are efficiently converted into the corresponding ethylene acetals in the presence of ethane-1,2-diol, triisopropyl orthoformate, and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild reaction conditions. The homologous trimethylene acetals can be also prepared in the same way.

acetal - cerium(III) trifluoromethanesulfonate - hydroxyacetophenone - Lewis acid - protecting group

References

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<A NAME="RF23108SS-8">8</A>

No reaction took place when the reaction was carried out in the absence of ethane-1,2-diol.

<A NAME="RF23108SS-9">9</A>

Cyclic acetalization of normal ketones such as octan-2-one and acetophenone proceeded smoothly under similar reaction conditions.