One‐Pot Synthesis of Silylated Enol Triflates from Silyl Enol Ethers for Cyclohexynes and 1,2‐Cyclohexadienes

Regiocontrolled synthesis of precursors for strained cyclohexynes and 1,2‐cyclohexadienes is described based on one‐pot rearrangement of silyl enol ether followed by formation of enol triflate. Treatment of silyl enol ether with a combination of LDA and tBuOK led to the migration of the silyl group to generate α‐silyl enolate, which was treated with Comins' reagent to provide the corresponding enol triflate. The transient α‐silylated lithium enolate was smoothly isomerized in the presence of stoichiometric amount of water within one hour at room temperature, providing precursors for cyclohexynes exclusively in one pot. Effects of silyl groups, isomerization of the lithium enolate, and regiocontrolled generation of these precursors for these strained molecules were also investigated. Regiocontrolled synthesis of precursors for strained cyclohexynes and 1,2‐cyclohexadienes is described based on one‐pot rearrangement of a silyl group followed by the formation of enol triflates. The transient α‐silylated lithium enolate was smoothly isomerized in the presence of stoichiometric amount of water within one hour at room temperature to provide precursors for cyclohexyne.