Whitehorne Todd J J, Vabre Boris, Schaper Frank
Centre in Green Chemistry and Catalysis (CGCC), Département de chimie, Université de Montréal, 2900 Boul. E.-Montpetit, Montréal, QC, H3T 1J4, Canada.
Dalton Trans. 2014 May 7;43(17):6339-52. doi: 10.1039/c3dt53278j.
Diketimine ligands bearing N-benzyl, N-9-anthrylmethyl and N-mesitylmethyl substituents (nacnac(Bn)H, nacnac(An)H, and nacnac(Mes)H) were prepared from condensation of the amine with either acetyl acetone or its ethylene glycol monoketal. Chlorination with N-chlorosuccinimide in the 3-position yielded Clnacnac(Bn)H and Clnacnac(An)H. The ligands were reacted with Zn(TMSA)2 (TMSA = N(SiMe3)2) to yield nacnac(An)Zn(TMSA) and Clnacnac(Bn)Zn(TMSA). Protonation with isopropanol afforded nacnac(An)ZnOiPr and Clnacnac(Bn)ZnOiPr. Reaction of the diketimines with Mg(TMSA)2 afforded nacnac(An)Mg(TMSA), nacnac(Mes)Mg(TMSA), Clnacnac(Bn)Mg(TMSA) and Clnacnac(An)Mg(TMSA). Subsequent protonation with tert-butanol produced nacnac(Mes)MgOtBu and Clnacnac(Bn)MgOtBu, but only decomposition was observed with N-anthrylmethyl substituents. Most complexes were characterized by X-ray diffraction studies. TMSA complexes were monomeric and alkoxide complexes dimeric in the solid state. All alkoxide complexes, as well as nacnac(An)Mg(TMSA)/BnOH and Clnacnac(An)Mg(TMSA)/BnOH were moderately to highly active in rac-lactide polymerization (90% conversion in 30 s to 3 h). nacnac(An)ZnOiPr produced highly heterotactic polymers (P(r) = 0.90), Clnacnac(Bn)MgOtBu/BnOH produced slightly isotactic polymers at -30 °C (P(r) = 0.43), and all other catalysts produced atactic polymers with a slight heterotactic bias.
带有N-苄基、N-9-蒽甲基和N-均三甲苯基取代基的二酮亚胺配体（nacnac(Bn)H、nacnac(An)H和nacnac(Mes)H）由胺与乙酰丙酮或其乙二醇单缩酮缩合制备而成。在3-位用N-氯代琥珀酰亚胺氯化得到Clnacnac(Bn)H和Clnacnac(An)H。这些配体与Zn(TMSA)2（TMSA = N(SiMe3)2）反应得到nacnac(An)Zn(TMSA)和Clnacnac(Bn)Zn(TMSA)。用异丙醇质子化得到nacnac(An)ZnOiPr和Clnacnac(Bn)ZnOiPr。二酮亚胺与Mg(TMSA)2反应得到nacnac(An)Mg(TMSA)、nacnac(Mes)Mg(TMSA)、Clnacnac(Bn)Mg(TMSA)和Clnacnac(An)Mg(TMSA)。随后用叔丁醇质子化产生nacnac(Mes)MgOtBu和Clnacnac(Bn)MgOtBu，但对于N-蒽甲基取代基仅观察到分解。大多数配合物通过X射线衍射研究进行表征。TMSA配合物在固态下为单体，醇盐配合物为二聚体。所有醇盐配合物以及nacnac(An)Mg(TMSA)/BnOH和Clnacnac(An)Mg(TMSA)/BnOH在rac-丙交酯聚合中具有中度至高度活性（30秒至3小时内转化率达90%）。nacnac(An)ZnOiPr产生高度全同立构规整聚合物（P(r)=0.90），Clnacnac(Bn)MgOtBu/BnOH在-30°C下产生轻度全同立构聚合物（P(r)=0.43），所有其他催化剂产生具有轻微全同立构偏向的无规聚合物。
