Département de chimie moléculaire

Quaternary ammoniums assocd. with bis(trifluoromethane)sulfonimide (NTf2) or tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF) counterions were readily prepd. from com. available tertiary amine, amidine, guanidine and pyridine. As predicted by mol. modeling, these ammonium salts proved to be efficient multiple H-bond donor catalysts in the ring-opening polymn. of cyclic esters (lactide, $δ$-valerolactone and ϵ-caprolactone). In addn., a sodium(i) complex of [15-c-5] crown-ether paired with NTf2 or BARF was shown to activate the cyclic monomers through a cation-dipole interaction. These simple and non-protonated ionic structures appeared as attractive alternative organocatalysts to classical H-bond donors for the activation of carbonyl bonds. [on SciFinder(R)]