New strategies for protecting group chemistry: synthesis, reactivity, and indirect oxidative cleavage of para-siletanylbenzyl ethers.

Reported herein is a new entry in the growing arsenal of arylmethyl ether protecting groups. The para-siletanylbenzyl (PSB) ether is electronically similar to the benzyl ether. Cleavage of the PSB ether is accomplished under mild conditions--involving alkaline hydrogen peroxide--that are unique among cleavage protocols for arylmethyl ethers. Furthermore, the PSB group affords the user new flexibility in the implementation of protecting group strategies that revolve around multiple arylmethyl ether protecting groups. In addition to hydrogen peroxide-based cleavage protocols, conversion of a PSB ether into a para-methoxybenzyl (PMB) ether and assembly of a PSB ether from a pre-existing para-bromobenzyl (PBB) ether are described. Finally, a new reagent for installing PSB ethers under neutral "mix and heat" conditions is reported.

p-Siletanylbenzylidene acetal: oxidizable protecting group for diols.

[reactions: see text] Hydrogen peroxide oxidation of benzylidene acetals (and derivative benzyl ethers) that incorporate a siletane ring at the para position creates a deprotection pathway without affecting other important chemical properties of the benzylidene acetal, such as regioselective reductive ring opening.