Candida antarctica lipase B CAL

Aqueous solutions are not suitable solvents for esterifications and transesterifications, and these reactions are carried out in organic solvents of low polarity [9-12]. However, enzymes are surrounded by a hydration shell or bound water that is required for the retention of structure and catalytic activity [13]. Polar hydrophilic solvents such as DMF, DMSO, acetone, and alcohols (log P<0, where P is the partition coefficient between octanol and water) are incompatible and lead to rapid denaturation. Common solvents for esterifications and transesterifications include alkanes (hexane/log P=3.5), aromatics (toluene/2.5, benzene/2), haloalkanes (CHCI3/2, CH2CI2/I.4), and ethers (diisopropyl ether/1.9, terf-butylmethyl ether/ 0.94, diethyl ether/0.85). Exceptionally stable enzymes such as Candida antarctica lipase B (CAL-B) have been used in more polar solvents (tetrahydrofuran/0.49, acetonitrile/—0.33). Room-temperature ionic liquids [14—17] and supercritical fluids [18] are also good media for a wide range of biotransformations. 

Candida antarctica lipase B (CAL-B), Novozyme 435 (from Sigma) (2 g) vinylbutyrate (630 p, 4.96 mmol) diisopropylether (DIPE) (30 mL)... 

Primary alcohols have been successfully used as substrates for lipases. Monterde et. Al60 reported the resolution of the chiral auxiliary 2-methoxy-2-phenylethanol 1 via Candida antarctica lipase B (CAL-B)-catalyzed acylation using either vinyl acetate (R=H) or isopropenyl acetate (R= CH3) as acyl donor (cf. fig. 8) and the alkoxycarbonylation using diallyl carbonate as the alkoxycarbonylation agent in THF at 30 °C (cf. fig. 9). 

Adsorption of enzymes to various polymeric resins is a straightforward means for immobilization. Zwitterionic molecules such as proteins can bind to both anionic and cationic ion exchange resins. Hydrophobic macroporous resins are also useful for immobilizing many enzymes, particularly lipases. For example, an immobilized form of Candida antarctica lipase B (CAL-B) on acrylic resin has been sold for many years under the name, Novozym 435 (N435). The enzyme is produced in a modified Aspergillus organism by submerged fermentation and is subsequently adsorbed onto a macroporous... 

This methodology was employed to prepare many heterocyclic cyanohydrin acetates in high yields and with excellent enantioselectivities, Candida antarctica lipase A (CAL-A) being the lipase of choice (Scheme 5.7) [23]. A recent detailed study of the reaction conditions revealed that the carrier on which the lipase is immobilised is important generally Celite should be used for aromatic substrates. With Celite R-633 as support for Candida antarctica lipase B (CAL-B)... 

Sinha et al. [7] for the first time reported a highly efficient and recyclable combination of Candida antarctica lipase B (CAL-B) and nentral ionic liqnid [hmim] [Br] for metal-free activation in the chemoselective oxidation of aryl alcohols. Initial study was carried out using 4-methoxyphenyl propanol, as substrate, and HjOj at 40°C in the presence of CAL-B/[hmim][Br], thereby providing aldehyde in 90% yield after 16 h. Increasing the reaction temperature to 60°C significantly brought down the reaction time from 16 to 8 h (Scheme 14.7). 

Novozym 435 is already a famous biocomposite containing Candida antarctica lipase B (CAL-B) as the bioactive part. Novozym 435 is commercially available immobilized enzyme with CAL-B physically adsorbed on a macroporous resin of poly(methylmethacrylate) [82]. The enzyme versatility and the substrate affinity recommended Novozym 435 for many applications, including the biomass valorization. An example is the production of the fatty acid esters used as emollient in the cosmetic industry (ex. myristyl myristate) [83,84],... 

In a further example, a biocatalytic route for the production of optically pure 3-substituted cyclohexylamine derivatives from prochiral bicychc P-diketones was established by employing three biocatalytic reaction steps (Scheme 4.16) [53]. The sequence combined the stereoselective hydrolysis of a C-C bond catalyzed by a P-diketone hydrolase [54] (6-oxocamphor hydrolase (OCH) from Rhodococcus sp. [55]), followed by an Upase-catalyzed esterification [Candida antarctica lipase B (CAL-B), Novozyme 435], and a subsequent asymmetric amination by either an (S)-or (1 )-selective m-TA [V.fluvialis [27] or a variant of the Arthrobacter sp. TA [16a] (ArRmutll)]. 

Obtained by direct acylation of quinacetophenone with vinyl propionate in the presence of Candida antarctica lipase B (CAL-B) in diisopropyl ether at 45° for 1 day (73%) [4268]. 

A total synthesis of the dipyrrolidine alkaloid (—)-trans-dendrochrysine (22), isolated from the orchid endemic Dendrohium chrysanthum, was achieved by Blechert and coworkers utilizing RRM [21]. The asymmetric synthesis commenced with preparation of diolefin 20 from commercially available tropone (19, Scheme 2.6) in 11 steps involving a solid-phase supported Candida antarctica lipase B (Cal-B)-mediated desymmetrization. 

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