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A novel unsymmetrical (S,S,S)-salen ligand bearing a derived chiral-BINOL was synthesized by the reaction of the condensation product of (1S,2S)-1,2-diaminocyclohexane mono(hydrogen chloride) with 3-adamanyl-5-tert-butyl-2-hydroxybenzalde-hyde and 3-formoyl-2-hydroxy-2’-alkyloxy-1,1’-binaphthyl,which originated from (S)-1,1’-bi-2-naphthol via a four-step reaction.The cobalt complexes of this ligand,in conjunction with a nucleophilic cocatalyst,exhibited excellent activity in catalyzing asymmetric,regio-and stereo-selective copolymerization of CO2 and racemic propylene oxide.The highest record of kinetic resolution coefficient (Krel) was obtained with the use of binary catalyst system consisting of (S,S,S)-salenCo(III) complex 1c and bulky bis(triphenylphosphine)-iminium chloride (PPNCl).The resulting poly(propylene carbonate)s have more than 99% carbonate linkages and more than 98% head-to-tail content.
A novel unsymmetrical (S, S, S) -salen ligand bearing a derived chiral-BINOL was synthesized by the reaction of the condensation product of (1S, 2S) -1,2- diaminocyclohexane mono (hydrogen chloride) with 3-adamanyl- 5-tert-butyl-2-hydroxybenzalde-hyde and 3-formoyl-2-hydroxy-2’-alkyloxy-1,1’-binaphthyl, which originated from (S) -1,1’-bi-2-naphthol via a four-step reaction. The cobalt complexes of this ligand, in conjunction with a nucleophilic cocatalyst, shows excellent activity in catalyzing asymmetric, regio-and stereo-selective copolymerization of CO2 and racemic propylene oxide. the highest record of kinetic resolution coefficient (Krel ) was obtained with the use of a binary catalyst system consisting of (S, S, S) -salenCo (III) complex 1c and bulky bis (triphenylphosphine) -iminium chloride (PPNCl) 99% carbonate linkages and more than 98% head-to-tail content.