325811-01-6

Upstream product

• 104-88-1 4-chlorobenzaldehyde 
• 97-72-3 2-Methylpropionic anhydride 
• 37580-81-7 (syn)-1,2-bis(4-chlorophenyl)ethane-1,2-diol 
• 3457-46-3 4,4'-dichlorobenzil 
• 2510-74-9 (E)-1,2-di(4-chlorophenyl)ethene 
• 329-15-7 4-trifluoromethyl-phenyl acetyl chloride 

Downstream Products

• 14365-73-2 2,3,4-tri-O-acetyl-β-D-glucopyranosylamine uronic acid methyl ester 

Relevant academic research and scientific papers

Horeau amplification in the sequential acylative kinetic resolution of (±)-1,2-diols and (±)-1,3-diols in flow

The sequential acylative kinetic resolution (KR) of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols using a packed bed microreactor loaded with the polystyrene-supported isothiourea, HyperBTM, is demonstrated in flow. The sequential KRs of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols exploits Horeau amplification, with each composed of two successive KR processes, with each substrate class significantly differing in the relative rate constants for each KR process. Optimisation of the continuous flow set-up for both C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diol substrate classes allowed isolation of reaction products in both high enantiopurity and yield. In addition to the successful KR of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols, the application of this process to the more conceptually-complex scenario involving the sequential KR of C1-symmetric (±)-1,3-anti-diols was demonstrated, which involves eight independent rate constants. This journal is

Biocatalyzed asymmetric reduction of benzils to either benzoins or hydrobenzoins: pH dependent switch

Enantiopure benzoins and hydrobenzoins are precursors of various pharmaceuticals and biologically active compounds. In addition, hydrobenzoins are precursors of chiral ligands and auxiliaries in stereoselective organic synthesis. Biocatalytic reduction of benzils is a straightforward approach to prepare these molecules. However, known methods are not selective and lead to formation of a mixture of benzoin and hydrobenzoin, requiring expensive separation procedures. Here, we describe an enzyme system Talaromyces flavus, which exhibited excellent pH dependent selectivity for the conversion of benzil to either benzoin or hydrobenzion in high ee. Thus, (S)-benzoin was the exclusive product at pH 5.0 (ee >99%), whereas at pH 7.0, (S,S)-hydrobenzoin (ee >99%, dl/meso 97 : 3) was the exclusive product. The observed pH dependent selectivity was shown to be due to the presence of multiple enzymes in Talaromyces flavus, which specifically accepted either benzil or benzoin as a substrate and exhibited different pH profiles of their activity. The biocatalyst efficiently reduced a variety of symmetrical and unsymmetrical benzils. Moreover, a 36.4 kDa benzoin reductase was purified, the N-terminal sequence of which did not show a significant similarity to any of the known reductase/dehydrogenase in the database. The protein therefore appears to be a novel reductase.

Enantioselective pinacol coupling reaction of aromatic aldehydes catalyzed by chiral vanadium complexes

The asymmetric pinacol coupling of aromatic aldehydes by chiral salan-vanadium complexes as effective catalysts is reported. Chiral 1,2-diols were obtained with high diastereoselectivities (up to 90/10) and moderate to high enantioselectivities (up to 82%

Catalytic asymmetric dihydroxylation of substituted trans-stilbene derivatives: implications of the variation of enantioselectivities on the mechanism of OsO4 addition to olefins

The OsO4 catalyzed asymmetric dihydroxylation of substituted trans-stilbene derivatives using 9-O-acetyldihydrocinchonidine as chiral ligand gives the corresponding diols with lower enantioselectivity in the case of substrates containing electr

Kinetic resolution of d,l-1,2-diols catalyzed by amine-phosphinite bifunctional organocatalysis derived from quinidine

Racemic C2-symmetric 1,2-diols were kinetically resolved by the acylation reaction catalyzed by the phosphinite derivative of quinidine to afford the corresponding monoacylated product with good to high enantioselectivities.

Asymmetric pinacol coupling of aromatic aldehydes catalyzed by a new titanium-Schiff base complex

A new Schiff-base with two stereogenic centers has been prepared and its titanium complex applied to catalyze the pinacol coupling of aldehydes, which afforded pinacols in high yield, excellent diastereoselectivities, and high enantioselectivities.

Truly catalytic and enantioselective pinacol coupling of aryl aldehydes mediated by chiral Ti(III) complexes

A variety of chiral Ti(IV) complexes were reduced in situ with zinc in acetonitrile. The resulting chiral Ti(III) complexes were found to catalyze the pinacol coupling reaction stereoselectively. The best results were obtained from the Ti-SALEN complex, which was found to be an efficient catalyst at 10 mol % concentration. Various aromatic aldehydes were coupled to obtain chiral hydrobenzoin derivatives with high diastereoselectivity and enantioselectivity. A plausible mechanism is proposed that rationalizes the stereochemical outcome of the reaction.