A Highly Active Chiral Indium Catalyst for Living Lactide Polymerization

Abstract

It loves LA! A unique chiral dinuclear indium complex 1 (see structure; In gray, Cl green, O red, N blue, C black) has been developed as a catalyst for the highly active, living ring‐opening polymerization of lactide (LA). The catalyst retains the same reaction rate during two consecutive additions of lactide, and there is significant site control of polymer tacticity.

Guanidine Metal Complexes for Bioinorganic Chemistry and Polymerisation Catalysis

“…These values are in good agreement with those of other single-site catalysts [174]. A polymerisation at room temperature with these catalysts is energetically hindered.…”

Effect of the phenyl ring substituent on stereoselectivity in the ring-opening polymerization of the rac-lactide initiated by salen aluminum complexes

“…The stereo-composition of the polymers affects the physical and chemical properties of themselves. Usually, PLA is prepared by the ring-opening polymerization (ROP) of lactide initiated by metal complexes, such as some alkoxides of Sn [7], Al [8][9][10][11][12], Zn [13][14][15][16], Mg [17][18][19], Fe [20], Ti [21][22][23][24][25][26], In [27], rare earth metal [28][29][30][31][32][33], organo-catalytic system [34,35], and enzyme [36]. In addition, the ring-opening copolymerization of epoxides and cyclic anhydrides has also the potential to produce a wider variety of polymer backbone structures [37,38].…”

Preparation and structure of an enantiomeric water-bridged dinuclear indium complex containing two homochiral N atoms and its performance as an initiator in polymerization of rac-lactide

“…The two indium atoms are equivalently coordinated in a molecule, which is consistent with the 1 H NMR spectrum of 1. [6,21,22].…”

“…Although indium complexes and salts have been demonstrated to be mild, efficient and tolerant catalysts and reagents with high regio-, diastereo-and chemoselectivity in various organic transformations [1][2][3][4][9][10][11][12], only three reports have appeared so far in literature on ring-opening polymerization (ROP) of lactide (LA) using structurally defined indium-based initiators [6][7][8]. Mehrkhodavandi and coworkers applied a dinuclear indium complex featuring a chiral diamine mono(phenolate) ligand of NNO-type as initiator for ROP of rac-LA and found it highly active and modestly isoselective (P m = 0.59) [6]. Very recently, Okuda et al reported the catalytic properties of mononuclear indium complexes, containing either a tetradentate OSSO-type ligand or two R 2 P = OCH 2 CHRO − ligands, in the controlled ROP of lactide [7,8].…”

“…Over the past decade, organoindium complexes are of increasing interest in organic synthesis [1][2][3][4], and more recently in polymerization reactions [5][6][7][8], for their inherent merits of good stability and unique reactivity in the presence of air, functional groups of organic compounds, and water. Organoindium complexes have homologous relation to aluminum, group 3 metals and lanthanide complexes, which are widely used as Lewis acidic catalysts in numerous organic reactions.…”