Stereoelective polymerization of d,l-lactide using N-heterocyclic carbene based compounds

Abstract

A new Zn alkoxide catalyst supported by an N-heterocyclic carbene rapidly polymerizes D,L-lactide (D,L-LA) to heterotactic enriched poly(lactide)(PLA), while the free carbene and analogs instead yield highly isotactic enriched PLA.

Development of Amino–Oxazoline and Amino–Thiazoline Organic Catalysts for the Ring‐Opening Polymerisation of Lactide

“…[27][28][29][30] These reports have led to the discovery of some of the most highly active catalysts reported to date, which display high selectivities for ROP over trans-esterification and the ability to control the tacticity of the polymer chains at low temperatures. [29,31,32] However, many of these catalyst systems do not offer a great deal of flexibility within their design to enable structure-property relationships to be obtained and thus further enable understanding and optimisation of their behaviour. Herein, we report a modular synthesis for amino-oxazoline and amino-thiazoline species and detail their application as catalysts in a mechanistic study of the organocatalytic ROP of lactide.…”

Zinc N-heterocyclic carbene complexes and their polymerization of d,l-lactide

“…In our continuing studies of N-heterocyclic carbene zinc complexes and LA polymerization [13] we have pursued a number of different avenues designed to address issues of catalyst stability and selectivity. We report herein the development of synthetic routes to a series of such complexes and studies of their LA polymerization behavior.…”

Silver alkoxide and amino N-heterocyclic carbenes; syntheses and crystal structures

“…N-heterocyclic carbenes (NHCs) are widely used as replacements for phosphines as supporting r-bases in homogeneous late metal catalyst systems, and as rate accelerating additives in organic reactions catalysed by Lewis acidic metal cations [1][2][3][4][5][6][7][8][9][10][11][12][13]. Whilst almost all isolated NHCs are thermally stable indefinitely at room temperature, the strongly basic carbenes decompose in air, often rapidly.…”