Trifluoroethyl enol ethers, dienol ethers, and acetals: an investigation of their preparations, reactivities, and synthetic applications

Abstract

The major portion of this work details our investigation of trifluoroethoxy (TFE) substituted compounds with particular emphasis given to their preparation and possible applications. The three types of compounds studied were trifluoroethoxy substituted ketals, enol ethers, and dienol ethers.

The ketal and enol ether work involved developing methodology for the large scale preparation of these structures as well as studies detailing their behavior. For the TFE ketals, preparation involved an acid-catalyzed alcohol exchange reaction. Applications included their use as non-complexing/acid-stable carbonyl protecting groups.

The TFE enol ether work also involved preparation and applications studies. These structures were synthesized from propargyl ketones via a conjugate addition reaction. The applications were synthetic in nature mainly involving utilization of these compounds in cycloaddition and conjugate addition reactions.

The last portion of this work involved our investigation into behavior of trifluoroethoxy substituted dienol ethers (substituted 1-trifIuoroethoxy-3-trialkylsiloxy-1,3- butadienes). Their preparation was accomplished by a method similar to that used by Danishefsky in his synthesis of the 1-methoxy analogs. The applications portion of this study focused on the use of these compounds as 4 carbon synthons in [4+2] cyclcoaddition reactions. Information gained from these studies provided insight into the effect the electron-withdrawing trifluoroethoxy group has on the reactivities of structures into which in has been incorporated.