Lipase catalyzed regioselective

Figure 12 Lipase-catalyzed regioselective esterification of glucose in a mixed...

Tamarez, M., Morgan, B., Wong, G.S.K., Tong, W., Bennett, E., Lovey, R., McCormick, J.L. and Zaks, A., Pilot-scale lipase-catalyzed regioselective acylation of ribavirin in anhydrous media in the synthesis of a novel prodrug intermediate. Org. Proc. Res. Dev., 2003, 7, 951-953. 

Gu J, Ruppen ME, Cai P. (2005) Lipase-catalyzed regioselective esterification of rapamycin Synthesis of temsirolimus (CCl-779). Org Lett 7 3945-3948. 

Figure 6.6 Pilot-scale lipase-catalyzed regioselective acylation of ribavirin (24).

M. Ferrer, M. A. Cruces, M. Bernabe, A. Ballesteros, and F. J. Plou., Lipase-catalyzed regioselective acylation of sucrose in two-solvent mixtures, Biotechnol. Bioeng., 65 (1999) 10-16. 

Ferrer M., Cruces M.A., Bernabe M., Ballesteros A., Plou F.J., Lipase catalyzed regioselective acylation in two solvent... 

Figure 2. ESI MS analysis of the lipase-catalyzed regioselective esterification of l,3-bis(3-carboxypropyl)tetramethyldisiloxane and a,P-ethyl...

Palocci, C., M. Falconi, L. Chronopoulou, and E. Cemia. 2008. Lipase-Catalyzed Regioselective Acylation of Tritylglycosides in Supercritical Carbon Dioxide. Journal of Supercritical Fluids 45 (l) 88-93. 

Figure 25 The use of lipase-catalyzed regioselective acetylation as the key step in the synthesis...

Modified enantioselectivity was reported if the reaction was carried out in an IL solvent instead of traditional organic soivent. For instance, Kaziauskas and Kim independently reported that the regioselectivity of lipase-catalyzed reaction was enhanced if the reaction was carried out in an IL solvent system (Fig. 13). " " Recently Wu and co-workers reported another chip of iipase-catalyzed reaction a... 

Figure 13 Enhanced regioselectivity of lipase-catalyzed acylation in IL solvent...

Fig. 10. Regioselective initiation at glucopyranoside in lipase-catalyzed polymerization of...

Following the first examples of the acylation of adenosine and uridine [2], the regioselective lipase-catalyzed esterification of these important molecules has been extensively investigated by Gotor s group [21g]. Attention has been mainly focused on deoxynucleosides - compounds of special interest in medicinal chemistry because of their antiviral and antitumoral properties. Some significant examples are discussed below. 

S. Park and R. J. Kazlauskas, Improved preparation and use of room-temperature ionic liquids in lipase-catalyzed enantio-and regioselective acylations, J. Org. Chem. 2001, 66, 8395-8401. 

The latter two successful processes were combined in the solvent-free lipase-catalyzed reaction of 1-O-ethyl glucoside with trimethylene carbonate or -caprolactone to form amphiphilic oligomers and polymers [20]. The products are biodegradable polycarbonates and polyesters that are formed regioselectively by reaction with the primary hydroxyl group of the sugar moiety. 

Preparation of enantiometrically pure aldehyde substrates for DHAP-dependent aldolase reactions has been accomplished by a combination of enzymatic and chemical methods. The lipase-catalyzed resolution of racemic aldehyde precursors has been accomplished by enantioselective acetate hydrolysis, as exhibited in the preparation of enantiomerically pure R- and S -glycidaldehyde acetals (Scheme 5.10).31 Regioselective ring opening of the epoxides, followed by acetal hydrolysis, generated the aldehydes in enantiomerically pure form. 

The considerations in the previous section need to be addressed and customized for every screening project. As an example, when we set out to develop a new library of esterases for synthetic chemistry use, we first needed to determine the criteria that would be used in the screening project. Esterases and lipases catalyze the hydrolysis of ester bonds as shown in Scheme 1 and are useful for reactions requiring different regioselectivities, chemoselectivities, and stereoselectivities depending on the enzyme s substrate specificities. 

Multiarm heteroblock star-type copolymers of poly(lactic acid) (PLA) and poly(e-CL), poly(LA-co-e-CL) were prepared via a chemoenzymatic route [90]. Firstly, ROP of e-CL was initiated regioselectively from 6-OH site of ethyl glucopyrano-side (EGP) (see also above) using porcine pancreatic lipase as catalyst followed by termination of the EGP-PCL-OH terminus by lipase-catalyzed acetylated using vinyl acetate. Subsequently, Sn-catalyzed ROP of lactide was initiated from 2-, 3- and 4-OH groups of EGP to give a copolymer consisting of one poly(e-CL) arm with M = 1300 and three PLA arms so that the M of the final product was 11500 (Scheme 4.25). 

---