Quaternary onium tribromide catalyzed cyclic carbonate synthesis from carbon dioxide and epoxides

Bifunctional Chiral Catalyst for the Synthesis of Chiral Cyclic Carbonates from Carbon Dioxide and Epoxides

“…The cobalt complexes 2 Eb and 2 Fb, which contain a quaternary ammonium group, were fabricated first and used in the asymmetric cycloaddition reaction of CO 2 to PO. The enantioselectivities of the reactions are at the same level as those previously reported [4,8] (Table 1, entries 6 and7). A quaternary phosphonium group was then introduced into the salen-type ligands to prepare the relevant complexes 2 Aa-2 Dd.…”

“…[1] Besides the asymmetric epoxidation of olefins, [2] the resolution of racemic epoxides by a nucleophilic ring-opening reaction is an efficient method for obtaining enantiopure epoxides. [3] Recently, the kinetic resolution of racemic epoxides, especially propylene oxide (PO), with carbon dioxide as a reagent presents an attractive method [4][5][6][7][8][9] in respect to yielding both an enantiopure epoxide and cyclic carbonate, which are usually prepared by the cyclization of chiral diols with triphosgene or by the enzyme-mediated hydrolysis of racemic epoxides. [10] Cyclic carbonates are also widely used in organic synthesis and as pharmaceutical intermediates, aprotic solvents, and raw materials for plastics and other such materials.…”

“…[4][5][6][7][8][9][12][13][14][15] Meanwhile, a quaternary ammonium group was recently introduced into the frame of the salen ligand, thus leading to a novel bifunctional catalyst in one molecule. [16,17] This type of compound would be a good class of catalyst for the kinetic resolution of racemic epoxides.…”

Chiral metal-containing ionic liquid: Synthesis and applications in the enantioselective cycloaddition of carbon dioxide to epoxides

“…That is to say the conversion of PO equals to the yield of propylene carbonate (PC). According to our previous study [32], the salts that consist of two parts: cation (Lewis acid, electrophile) and anion (Lewis base, nucleophile), have catalytic activity under a generally harsh condition. The metal-containing ionic liquid (MIL) is a good catalyst since its cation can act as a Lewis acid center and its amino acid anion can acts as a Lewis base center In the catalyst systems, salenCo(OOCCCl 3 ), which gives the chiral Lewis acid center and works as the main catalyst, activates the epoxides, while the chiral anion of CMILs which supplies the chiral Lewis base center for the coupling reaction and functions as the co-catalyst, attacks the activated epoxides to produce intermediates for the insertion of CO 2 to lead to cyclic carbonates…”

Synthesis of Chiral Cyclic Carbonates via Kinetic Resolution of Racemic Epoxides and Carbon Dioxide

“…The utility of the catalyst system containing cobalt(III) complex 7 was demonstrated for the conversion of other epoxides such as butylene oxide into its corresponding chiral cyclic carbonate with a s value of 31.5 and 88.5% ee. Since the initial report, a number of modifications to the cobalt(III) salen catalyst system have been reported, all of which demonstrated some degrees of success [13][14][15][16][17][18][19][20][21][22]. Jing and co-workers reported a chiral polymer based on BINOL cobalt(III) salen complex 6 for the asymmetric addition of carbon dioxide to racemic propylene oxide 2a [23].…”