Synthesis, Structure of Zinc Complexes Containing Sulfonylated Binaphtholate Ligands and Their Catalytic Activities towards Ring‐Opening Polymerization of Lactide and ε ‐Caprolactone

Reaction of sulfonylated binaphthol [2‐hydroxy‐2′‐tosyloxy‐1,1‐binaphthyl ( 1a , Ts‐Binol) or 2‐hydroxy‐2′‐(phenylsulfonyloxy)‐1,1‐binaphthyl ( 1b , Ps‐Binol)] with 1 equiv. of ZnEt 2 afforded zinc complexes [(Ts‐Binol)ZnEt] 2 ( 2a ) and [(Ps‐Binol)ZnEt] 2 ( 2b ). Further reaction of zinc complexes 2a and 2b with benzyl alcohol (BnOH) gave the zinc benzyloxide [(Ts‐Binol) 2 Zn 2 (OBn) 2 ] 2 ( 3a ) and [(Ps‐Binol) 2 Zn 2 (OBn)2] 2 ( 3b ). Alternatively, the zinc benzyloxides 3a and 3b could also be obtained by reaction of compound 1a or 1b with Zn(OBn) 2 ( in situ reaction of ZnEt 2 and BnOH). The complexes were fully characterized by elemental analyses and spectroscopic analyses, and complexes 2a , 2b and 3a were further characterized by single‐crystal X‐ray analyses. The catalytic activities of these zinc complexes towards ring‐opening polymerization of ε ‐caprolactone and D , L ‐lactide were studied.