Redesigning the mechanism of the lipase-catalysed aminolysis of esters

Enantioselective Addition of Diethyl Zinc to Benzaldehyde Catalyzed by Ti(iv) and Glucose Derivatives

“…With the Ti(IV)/carbohydrate ratio of 10, the maximum enantioselectivity was obtained in all the reactions examined (Table1). These results are consistent with those in the literature, 9,10 and existence of the Ti(IV)-carbohydrate 2 dinuclear catalytic species (Scheme 1).…”

“…[7][8][9][10][11][12][13][14] We have recently catalyzed the homogeneous selective addition of diethylzinc to benzaldehyde 15 . The catalyst was the mixture of 10% mol of a diol derivative of D-xylose (3) relative to the aldehyde with 1 equivalent of Ti(O i Pr) 4 .…”

Reactions of Carboxylic, Phosphoric and Sulfonic Acids and their Derivatives

“…The results suggested as the most plausible intermediate for the CAL-B-catalysed aminolysis a zwitterionic TI resulting from the direct His-assisted attack of the amine on to a C=O group of the acyl-enzyme. 80 Native chemical ligation of unprotected peptide segments involves reaction between a peptide-α-thioester and an N-terminal cysteine-peptide to yield a product with a (55) native amide bond at the ligation site. Peptide-α-thioalkyl esters, used because of their ease of preparation, are rather unreactive so the ligation reaction is catalysed by in situ transthioesterification with thiol additives.…”

Enantioselective ethylation of aldehydes with 1,3-N-donor ligands derived from (+)-camphoric acid

“…1,7,21,22 Urabe et al 23 reported the use of a dialkylated diamine, a diamide and some dialkylaminoamides derived from (+)-camphoric acid in the reaction of benzaldehyde with several organometallic reagents, including diethylzinc. The best result (81% yield, 93% ee) was obtained with ligand 9, in the alkylation of benzaldehyde with diethylzinc, at 0°C, using toluene as a solvent.…”