Lipases Pseudomonas fluorescens

Various cyclic esters have been subjected to hpase-catalyzed ring-opening polymerization. Lipase catalyzed the ring-opening polymerization of 4- to 17-membered non-substituted lactones.In 1993, it was first demonstrated that medium-size lactones, 8-valerolactone (8-VL, six-membered) and e-caprolactone (e-CL, seven-membered), were polymerized by lipases derived from Candida cylindracea, Burkholderia cepacia (lipase BC), Pseudomonas fluorescens (lipase PF), and porcine pancreas (PPL). °... 

PPL catalyzed polycondensation of bis(2,2,2-trichloroethyl) alkanediaoates with glycols in anhydrous solvents of low polarity to produce the polyesters [34, 35]. In the polymerization of bis(2-chloroethyl) succinate and 1,4-butanediol using Pseudomonas fluorescens lipase (lipase PF) as catalyst, the polyester with low molecular weight was formed [36]. This may be due to the low enzymatic reactivity of the succinate substrate. 

Xie, Z. F. Pseudomonas fluorescens lipase in asymmetric synthesis. Tetrahedron Asymmetry 1991, 2, 733-750. 

The first enzymatic polymerizations of substituted lactones were performed by Kobayashi and coworkers using Pseudomonas fluorescens lipase or CALB as the biocatalyst [90-92]. A clear enantiopreference was observed for different lactone monomers, resulting in the formation of optically active polymers. More recently, a systematic study was performed by Al-Azemi et al. [93] and Peelers et al. [83] on the ROP of 4-alkyl-substituted CLs using Novozym 435. Peelers et al. studied the selectivity and the rates as a function of the substituent size with the aim of elucidating the mechanism and the rate-determining step in these polymerizations. Enantio-enriched polymers were obtained, but the selectivity decreased drastically with the increase in substituent size [83]. Remarkably for 4-propyl-e-caprolactone, the selectivity was for the (R)-enantiomer in a polymerization, whereas it was S)-selective in the hydrolysis reaction. Comparison of the selectivity in the hydrolysis reaction (Fig. 10b) with that of the polymerization reaction (Scheme 8a) revealed that the more bulky the alkyl substituent, the more important the deacylation step becomes as the rate-determining step. 

Other similar lipase/esterase resolution processes have been developed such as the use of Bacillus that esterase to produce the substituted propanoic acids that are precursors of non-steroidal anti-inflammatory drags, snch as naproxen and ibuprofen etc., and the formation of chiral amines by Celgene. Other methods start from prochiral precursors and have the advantage that enantioselective synthesis allows the production of particular isomers in yields approaching 100%, rather than the 50% yields characteristic of resolution processes. For instance Hoechst have patented the production of enantiomers using Pseudomonas fluorescens lipase to either acylate diols or hydrolyse diacetate esters. 

In September 1989 Amano announced that Pseudomonas fluorescens lipase from Amano did not belong to the subspecies fluorescens but to the subspecies cepacia see D. L. Hughes, J. J. Bergan, J. S. Amato, M. Bhupathy, J. L. Leazer, J. M. McNamara. D. R. Sidler, P. J. Reider, E. J. J. Grabowski, J. Org. Chem. 55. 6252 (1990). Thus a review on Pseudomonas fluorescens lipase [Z.-F. Xie, Tetrahedron Asymmetry 2, 733 (1991)] may well be a review on Pseudomonas cepacia lipase. 

Lipases from Pseudomonas sp. [Amano PS and Pseudomonas fluorescens lipase (PFL)] are useful. Provided that the conversion is high enough, the remaining (R)-2-methylalkanols R-2 can be obtained almost enantiomerically pure. The (S)-... 

Two 2-hydroxyaldehydes protected as acetals (63) have been resolved by lipase-catalyzed acylation with vinyl acetate as reagent and solvent (Scheme 4.24) [84]. For the vinyl derivative (n = 0) Chirazyme L2 (CALB) gives the best E, whereas Pseudomonas fluorescens lipase (PFL) provides the best E for n = 1 [84]. 

Williams employed complexes of Al, Rh, or Ir in combination with PFL (Pseudomonas fluorescens lipase) for the DKR of 1-phenylethanol. The best results were obtained using Rh2(OAc)4 as the catalyst for the racemization which gave 60% conversion of the alcohol to 1-phenylethyl acetate in 98% (Scheme 5.22) [43]. 

Pseudomonas fluorescens lipase AK (Amano Pharmaceutical Co. Ltd., Nagoya, Japan)... 

Pseudomonas K-10 (enantioselective) Pseudomonas cepacia (enantioselective) Pseudomonas fluorescens lipase (enantioselective)... 

Figure 18 Gas-chromatographic separation of the enantiomer of both substrate (30) (as carbamate) and product (31) on heptakis-(2,3-di-6>-methyl-6-6>-tert-butyldimethylsilyl)-/J-cyclodextrin of the Pseudomonas fluorescens lipase (PFL) catalyzed transesterification of (30) in toluene att=9 hrs, ees =99.9%, eep=92.2%, conv. =52%, E...

Chiral diols have also been prepared starting from meso-compounds [68-71]. Since meso-compounds are, in essence, symmetric molecules, the same applies as for the other symmetric starting materials. Indeed, this is exactly what was found Even though the stereocenters of the protected heptane tetrol are far away from the ester groups that are to be hydrolysed stereoselectively, this is what happens [69, 70]. The high selectivity is partly due to the fact that the secondary alcohol groups are protected as a cyclic acetal, giving additional structural information to the enzyme (Scheme 6.20 A). A cyclic acetal also provides additional structural information in the enantioselective hydrolysis of a pentane tetrol derivative (Scheme 6.20 B) [71]. In both cases Pseudomonas fluorescens lipase (PFL) proved to be the enzyme of choice. 

The synthesis of )-A -BOC-2-hydroxymethyl-2,5-dihydropyrrole )-923 with ee up to 98% was achieved by its irreversible acetylation catalyzed by Pseudomonas fluorescens lipase (Scheme 179) <1998TA403>. Precursor ( )-922 for compound 923 can be easily prepared from commercially available pyrrole-2-carboxylic acid 921 by Birch reduction, followed by esterification and reduction according to literature procedure <1996JOC7664>. 

As for the enzymatic ring-opening polymerization of e-CL, various commercially available lipases have been tested as a catalyst. Several crude lipases (PPL, lipases CR, PC, and Pseudomonas fluorescens lipase (lipase PF)) induced the polymerization however, a... 

Resolution might have been possible either by asymmetric reduction at the penultimate step, or by classical methods on the final product. However, the overall yield for the eight-step synthesis was still only 2%. Nevertheless, resolution was indeed accomplished at the penultimate stage using enantioselective transesterification and hydrolysis, both catalyzed by Pseudomonas fluorescens lipase, as shown in Scheme 7. 

The application of ionic liquids in lipase biocatalysis has not remained entirely restricted to CaLB, PcL or CrL. Other lipases have been used in ionic liquids for ester synthesis such as Candida antarctica lipase A (CaLA) [15,16], Thermomyces lanuginosus lipase [17] (TLL), Rhizomucor miehei lipase (PmL), Pseudomonas fluorescens lipase (PJL) [18], Pig pancreas lipase (PpL) [17] and Alcaligenes sp. lipase (A5 L) [16]. 

Lipase (PsL)-mediated acylation reaction of a-methyl benzyl alcohol by vinyl acetate (Scheme 10.5) gives high enantioselectivity (E value 200) in [BMIM][Tf2N] than in methyl t r-butyl ether (MTBE) (E=4) at 55°C. At the boiling point of vinyl acetate, the E value was reduced to 150 from 200 [86, 87]. Similarly, lipase from Pseudomonas fluorescens (Lipase AK)-catalyzed enantioselective acylation of phosphate substituted primary alcohols in [BMIM][PF ] with enantioselectivity comparable to DIPE, though no selectivity was obtained in [BMIM][BF ] [87]. 

Pseudomonas fluorescens lipase, vinyl acetate, cyclohexane, 20 °C 60% convn... 

Scheme 4.27 Pseudomonas fluorescens lipase-catalyzed synthesis of poly (MBC-co-TMC).

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