Untitled

Dimethyl sulfoxide as a co-solvent dramatically enhances the enantioselectivity in lipase-catalysed resolutions of 2-phenoxypropionic acyl derivatives

“…Thus, the high DMSO-induced enantioselectivity is useful for the enantioselective improvement of substrates bearing different substituents, although the enantioselectivity for lipase MY-catalysed esterification of acids 2 in organic solvents was affected by the nature of the substituents, such as their steric and/or electronic effects. 16 Indeed, the effects of DMSO on the enantioselectivity enhancement of lipase MY are consistent with results obtained for subtilisin-catalyzed hydrolysis in aqueous buffer containing DMSO, although the reaction rate as a measure of the enzymatic activity for lipase MY-catalysed hydrolysis of the substrates 1a-c decreased dramatically with an increase in the amount of DMSO added to the medium (55-65 vol%) (Table 1). This observation concerning the enzymatic activity of lipase MY can explain a decrease in the enzymatic activity of the incorrectly binding S enantiomer (see also below, for a discussion on the basis of the results of the initial rates for each enantiomer).…”

Quantitative structure–activity relationship correlation between molecular structure and the Rayleigh enantiomeric enrichment factor

“…These different relationships were reported previously when studying the effect of substituents on the enantioselectivity of lipase catalyzed reactions (these reports used values that are conversion dependent (ER) whereas we use 3 ER that is a more general value). On the other hand Ueji et al 40 reported the absence of Hammet correlation between the enantioselectivity and the electronic effect in CRL as in our case. On the other hand Ueji et al 40 reported the absence of Hammet correlation between the enantioselectivity and the electronic effect in CRL as in our case.…”

“…Y. Kawanami et al 39 showed that the electronwithdrawing character might be the main factor to enhance the enantioselectivity in PCL. On the other hand Ueji et al 40 reported the absence of Hammet correlation between the enantioselectivity and the electronic effect in CRL as in our case. Table 2 details the statistical results obtained for the three QSAR model equations.…”

Evaluation of Pseudoenantiomeric Mixed Carbonates as Efficient Fluorogenic Probes for Enantioselectivity Screening

“…[27] Acommonly used method to avoid the problem of competitive binding at the active site is the addition of ar eference compound. Initially, the fluorescencem easurements were conducted fore ach enantiomer separately (initialr eaction rates in Ta ble 1): 1 and 2 exhibitedh igh specific reactivity with enzymes and acceptable stabilitya gainst autohydrolysis.…”

“…The resultsi mply that these enzymes are very specific,a nd that achange in substrate structure affects the reaction rate. [27] Acommonly used method to avoid the problem of competitive binding at the active site is the addition of ar eference compound. But as tructurally different achiral substrate does not really mimic the conditions of the kinetic resolution process.…”