PREPARATION OF CHIRAL BUILDING-BLOCKS FOR STARBURST DENDRIMER SYNTHESIS

Double aldols, formally derived from acetic acid and two different ald ehydes, as obtained by addition of the enolate of (R,R)-2-(tert-butyl) -6-methyl-1,3-dioxan-4-one (A) to various aldehydes, are reduced to tr iols which are actually substituted chiral 'tris(hydroxymethyl)methane s' (see B and 3-8). Etherifications of the three OH groups of these tr iols with functionalized halides (allyl, 4-(silyloxy)but-2-en-1-yl, 4- substituted benzyl) and esterifications with pent-4-enoic and 3,5-dini trobenzyl chlorides, followed by functional group manipulations, lead to the potential center pieces 14-30 for the construction of chiral de ndrimers: the building blocks prepared contain the required 'spacers' between the core unit, as well as three vinyl groups, three aryl bromi de groups, three alcoholic or phenolic OH groups, three mesylate group s, three ester groups, or six arylamino groups at the terminus of thei r branches. The new compounds are all obtained on a preparative scale and are fully characterized (including elemental analysis),