Preparation and Characterization of Aluminum Alkoxides Coordinated on salen-Type Ligands: Highly Stereoselective Ring-Opening Polymerization of <i>rac</i>-Lactide
作者:Hsiao-Li Chen、Saikat Dutta、Pei-Ying Huang、Chu-Chieh Lin
DOI:10.1021/om201281w
日期:2012.3.12
A series of salen-type ligands ((LH2)-H-1-(LH2)-H-6) with sterically bulky cumyl groups have been synthesized. Reaction of these ligands with AlMe3 yields the mononuclear aluminum complexes [LAlMe] (1-3) or dinuclear species [L2Al2Me4] (4-6), respectively. Further reaction of [LAlMe] (1-3) with benzyl alcohol produces [LAl(OBn)] (1a-3a), respectively. Solid-state structural studies reveal that complexes la and 2a are mononuclear; however, complex 6 is a d.inuclear species. Aluminum alkoxides 1a-3a are highly stereoselective in the ROP of rac-lactide, producing polylactide (PLA) with 94-97% enantiomeric selectivity (P-m) at high conversion. Their high enantioselectivity leads to PLA with high T-m (205 degrees C). The polymerization of L-lactide by these complexes also shows good living features with narrow PDI values (M-w/M-n = 1.06-1.25) signaling less or no transesterification, which can be further verified by MALDI-TOF mass spectrometric analysis.
RUTHENIUM-DIPHOSPHINE COMPLEXES AND THEIR USE AS CATALYSTS
申请人:Chirotech Technology Limited
公开号:EP1276745B1
公开(公告)日:2011-01-12
CATALYSTS CONTAINING N-HETEROCYCLIC CARBENES FOR ENANTIOSELECTIVE SYNTHESIS
申请人:Veige Adam Steven
公开号:US20100292465A1
公开(公告)日:2010-11-18
Novel N-heterocyclic carbene ligand precursors, N-heterocyclic carbene ligands and N-heterocyclic metal-carbene complexes are provided. Metal-carbene complexes comprising N-heterocyclic carbene ligands can be chiral, which are useful for catalyzing enantioselective synthesis. Methods for the preparation of the N-heterocyclic carbene ligands and N-heterocyclic metal-carbene complexes are given.