Gruppi protettori di alcoli rimovibili in condizioni di trasferimento elettronico

The generation of a series of alfa-methoxymethoxy-substituents arylmethyllithiums was achieved by direct metalation of the corresponding arylmethyl methoxymethyl ethers. While the effect of substituents at the benzyl position is straightforward, substituents located on the aromatic ring promote the set up of a competition between lateral and aromatic metalation, strongly affected by the position and relativeorthodirecting properties of the new substituent. The proposed methodology allows a simple approach to the generation of a wide array of functionalized organolithium reagents.Following our studies on lateral metalation of protected benzylic alcohols, we investigated their protection as aryl benzyl ethers. The deprotection step was attempted under single electron transfer reaction conditions from alkali metals, but this procedure led to the regioselective cleavage of the Cbenzylic-O bond.Following our investigation on the development of new hydroxyl protective groups, we investigated the reactivity towards alkali metals of severalm-terphenyl ando-biphenyl alkyl ethers. The regioselective deprotection of these ethers was successfully realized under reductive SET reaction conditions even in the presence of a variety of functional groups. Finally, we investigated the stereochemistry of the protection/deprotection sequence of different chiral secondary alcohols, affording very interesting results.