[1,5]-Anion Relay via Intramolecular Proton Transfer to Generate 3,3-Bis(silyl) Allyloxy Lithium: A Useful Scaffold for Syn-Addition to Aldehydes and Ketones.

A [1,5]-anion relay has been achieved in 3,3-bis(silyl) benzyl enol ether. Deprotonation at the sterically more accessible benzyl position triggers an intramolecular proton transfer to generate the thermodynamically more stable 3,3-bis(silyl) allyloxy lithium. This endo-oriented allyl anion is stable at −78 °C and undergoes diastereoselective syn-addition at the γ-position with aldehydes and ketones to give monobenzyl-substituted 1,2-diols.