Recyclable Poly-Zn3(OAc)4-3,3′-Bis(aminoimino)binaphthoxide Catalyst for Asymmetric Iodolactonization

On the basis of the structure of the unimolecular Zn-3(OAc)(4)-3,3-bis(aminoimino)binaphthoxide complex, a poly-Zn-3(OAc)(4)-3,3-bis(aminoimino)binaphthoxide (poly-Zn) complex was prepared from 3,3-diformylbinaphthol, tetramine, and Zn(OAc)(2). The first-generation poly-Zn catalyst (poly-Zn1) was prepared from poly(aminoiminobinaphthol) and Zn(OAc)(2). Although poly-Zn1 showed high catalytic activity for iodolactonization, the catalyst could not be reused. The second-generation poly-Zn catalyst (poly-Zn2) was prepared by the self-organization of 3,3-diformylbinaphthol, tetramine, and Zn(OAc)(2). This produced a stable and active poly-Zn2 catalyst for asymmetric iodolactonization that was reused over five cycles.