MONO AND DIFUNCTIONALISATION OF CHIRAL FERROCENYL BIS-ACETALS - X-RAYCRYSTAL-STRUCTURE OF BIS-1,1'-[(2S, 4S)-(HYDROXYMETHYL)-2-DIOXANE1,3]-FERROCENE

The chiral 1,1'-bis-acetals, bis-1,1'-[(2S, 4S)-(hydroxymethyl)-2-diox anel,3]-ferrocene (3) and 1,1'-bis-1,1'-[(2S, 4S)-(methoxymethyl)-2-di oxanel,3]-ferrocene (4) were synthesized. (3) was crystallographically characterised. The ortholithiation of (4) was studied in various cond itions. Fair yields of monosubstituted compounds could be obtained wit h a complete regioselectivity in favor of the 2 position but the diast ereoselectivities were moderate (up to 35%). Some disubstituted compou nds can be isolated but in low yields (up to 8%). The regioselectivity is complete in favor of the 2,2'-disubstituted isomer. Only the diast ereoisomer with two opposite planar chiralities is observed. (C) 1998 Elsevier Science S.A. All rights reserved.