Efficient synthesis of an unprecedented enantiopure hybrid scorpionate/cyclopentadienyl by diastereoselective nucleophilic addition to a fulvene

摘要

The work described here represents the first example of an enantiopure hybrid scorpionate/cyclopentadiene ligand. The ligand was obtained in a one-pot synthetic procedure by an efficient and highly diastereoselective nucleophilic addition of an organolithium reagent to an electrophilically activated olefin in a new fulvene with a chiral substrate to control the stereochemistry of a newly created asymmetric center. We verified the potential utility of this ligand as a valuable scaffold that is able to induce chirality in organometallic/ coordination chemistry. This was achieved through the preparation of a new enantiomerically pure zinc complex in which the ligand behaves in a tridentate manner with a κ~2NN-η~1(π)-Cp coordination mode. This alkylzinc complex constitutes the first example of an organozinc derivative which behaves as an efficient initiator for the ROP of rac-LA in the production of isotactic-enriched poly(lactides) with P_i = 0.77.