Abstract
Despite significant advances in organocatalysis, stereoselective polymerization reactions utilizing chiral organocatalysts
have received very little attention and much about the underlying mechanisms remaining unknown. Here, we report that both
commercially available (R,R)- and (S,S) enantiomers of chiral thiourea-amine Takemoto’s organocatalysts promote efficient control
and high isoselectivity at room temperature of the ring-opening polymerization (ROP) of racemic lactide by kinetic resolution,
yielding highly isotactic, semi-crystalline and metal-free polylactide (PLA). Kinetic investigations and combined analyses of the
resulting PLAs have allowed the stereocontrol mechanism, which eventually involves both enantiomorphic site control and chainend
control, to be determined. Moreover, epimerization of rac-LA to meso-LA is identified as being responsible for the introduction
of some stereoerrors during the ROP process.
have received very little attention and much about the underlying mechanisms remaining unknown. Here, we report that both
commercially available (R,R)- and (S,S) enantiomers of chiral thiourea-amine Takemoto’s organocatalysts promote efficient control
and high isoselectivity at room temperature of the ring-opening polymerization (ROP) of racemic lactide by kinetic resolution,
yielding highly isotactic, semi-crystalline and metal-free polylactide (PLA). Kinetic investigations and combined analyses of the
resulting PLAs have allowed the stereocontrol mechanism, which eventually involves both enantiomorphic site control and chainend
control, to be determined. Moreover, epimerization of rac-LA to meso-LA is identified as being responsible for the introduction
of some stereoerrors during the ROP process.
| Original language | English |
|---|---|
| Pages (from-to) | 1413-1419 |
| Number of pages | 7 |
| Journal | ACS Macro Letters |
| Volume | 2018 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 19 Nov 2018 |