SYNTHESIS OF CHIRAL STARBURST DENDRIMERS FROM PHB-DERIVED TRIOLS AS CENTRAL CORES

Chiral triols 1-3('tris(hydroxymelhyl)methane' derivatives), prepared from (R)-3-hydroxybutanoic acid and aldehydes, are used as center piec es of dendrimers. The triols may be employed as such or after attachme nt of spacers containing alkyl or aryl moieties (see 5 and 7). The bra nches combined with the original or elongated triols are those first r eported by Frechet (9-12, benzyl ethers of 3,5-dihydroxybenzyl alcohol and bromide). In this way, 1st-, 2nd-, and 3rd-generation chiral dend rimers without (13-15), or with aliphatic (16-18) or aromatic (19-21) spacers are prepared. The molecular weights range from 447 to 2716 Dal ton. Two of the chiral triols, i.e., 2 and 3, are used as center piece s for chiral dendrimers containing 6 NH2, or 6 and 12 NO2 groups on th e periphery (22-27), with 3,5-dinitrobenzoyl chloride as the branching unit. All compounds thus synthesized are of course monodisperse and a re fully characterized. In some cases, the optical activity of the den drimers indicates that conformationally chiral substructures might be present. The NH2 and NO2-substituted compounds avidly clathrate smalle r molecules; they are sorbents exchanging host molecules through the g as phase.