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Special Report Special Report

expression model. A whole-cell biocon- ketoreductase from Lactobacillus kefi ri. Enzyme-immobilised metal effi ciency. The biotransformation was Biocatalytic formal regio- of JMW’s contributions. This problem
version system was designed and 20.89- With improvements the conversion organic frameworks (MOFs) with recombinant Pseudomonas tai- and enantio-selective Marko- has been solved by different process
gm ALA was obtained from 42.42-gm was taken to 94.3% and the concentra- wanensis VLB120 and yield up to 61% vnikov hydroamination of methods, which are covered in this
glutamate with a conversion of 63.51%. tion of the feed could be raised from MOFs have extremely high specifi c is reported. (Green Chem., 2023; DOI: aryl alkenes to chiral amines review, with the development of enzy-
(Catalysis Sci. Technol., 2023; DOI: 5 to 85-gm per litre. The fi nal product surface area and adjustable porosity 10.1039/D3GC01105D). matic cascades. Now the new bottle-
10.1039/D2CY02172B). had an ee of 99.9%+ and 90% yield and these provide advantages to carry Q. Jin et al have referred to the impor- neck is the downstream processing and
over two steps. Scale-up was done at 30 enzymes and to protect the activity of Crystallisation-based down- tance of enantiomeric pure amines as this is the key challenge for scale-up.
Sustainable setups for the litre scale. (Org. Proc. Res. Dev., 2023; enzymes. These MOFs provide a large stream processing of omega- crucial intermediates for a wide range (ChemCatChem., 2023; DOI: 10.1002/
biocatalytic production and DOI: 10.1021/acsoprd.2c00371). space to carry enzymes and stabilise transaminase- and amine of pharmaceuticals, natural products, cctc.202300560).
scale-up of panthenyl mono- them. Further, selective mass transfer dehydrogenase-catalysed and bioactive compounds. The title
acyl esters (PMAE) under Biocatalytic and chemo-enzy- of substrates is provided to facilitate reactions process is atom-economical. The pro- Continuous fl ow-mode syn-
solvent-free conditions matic synthesis of quinolines catalytic processes. This review cess carries out sequential alkene thesis of (chiral) amines with
(Qs) and 2-quinolones (QL) by covers preparation strategies and pros- asymmetric hydration catalysed by a transaminase (T)
S. Nieto et al have reported a sustainable monoamine oxidase (MAO-N) pects and current challenges are dis- F. Belov et al have referred to the hydratase (HD), followed by in situ
scaling-up process of new title bioactive and horseradish peroxidase cussed. (Chemistry – An Asian Jl., 17, formation of co-products in the title oxidation of alcohol into ketone by two H.M. Arango et al have referred to the
provitamin-B monoacyl esters and that (HRP) biocatalysts issue 21/e202200751; DOI:10.1021/ reactions, resulting in additional effort enantio-complementary alcohol dehydro- essentiality of chiral amines as building
5
too under solvent-free conditions. This asia.202200751). during downstream processing. Thus, genases (ADHs), and fi nally, enantio- blocks for a plethora of valuable com-
is based on the formation of eutectic H. Xiang et al have reported that for the removal of the residual amine donor selective transformation of ketone into pounds, including APIs. It seems that
mixtures between neat substrates for the title group of compounds the syn- In situ product recovery of enantiomerically pure amine by an about half of the current APIs contain
highly effi cient direct esterifi cation of thetic methodologies still require toxic β-ionone (BI) from fermenta- omega-transaminase (TA). One example chiral amines. Biocatalytic routes have
free fatty acids, C-6 to C-18, with pan- and expensive reagents as well as harsh tion broth given is that of 4-hydroxystrenes.
thenol catalysed by lipase. 63% yield of conditions. Two enzymatic strategies Eventually, preparative experiments
butyrate ester is reported; it is 83% for for the oxidation of 1,2,3,4-tetrahydro- A.F. Arroya-Avirama et al have referred were demonstrated by using the whole-
myristate. A vacuum system was cou- quinolines (THQs) and N-cyclopro- to the production of BI through fermen- cell biocatalyst E. coli (RFM-ERR-CB)
pled to the reaction unit. The recovery pyl-N-alkylanilines into Qs and QL, tation and its recovery; genetically modi- and E. coli (RFC-ERR-CB) with some
and reuse of the immobilised enzyme is respectively are described. (ACS Catal., fi ed Saccharomyces cerevisiae is used. substrates. (Green Chem., 2023; DOI:
reported. (ACS Sustainable Chem. Eng., 2023; DOI: 10.1021/acscatal.2c05902). Since BI is toxic to the enzyme an in situ 10.1039/D3GC01030A).
2023, 11, 5737-5747; DOI: 10.1021/acs- liquid-liquid extraction was carried out. gained considerable importance (e.g.,
suschemeng.3c00266). Supramolecular ionic liquid 6012 solvents were screened and looked Scale-up of in vitro transami- for sitagliptin, atorvastatin, etc.). Batch
(SMIL) gels for enzyme for partition coeffi cients using COSMO- nase (T)-catalysed asymmetric reactors face many problems such as
Biocatalytic asymmetric entrapment RS. The best solvents were selected synthesis of chiral amines catalyst separation, recovery and reuse,
reduction of a sterically hin- taking into considered all the relevant [This column has covered many papers apart from thermodynamic restrictions.
dered α-bromo ketone for the H.T. Imam et al have reported a method aspects. Further simulation was done on based on T, which are relevant in indus- Heterogenised biocatalysts are more
synthesis of key intermediates that does not require the formation of Aspen Plus V10. Recovery was through trial practice.] versatile, more stable and amenable
of olodaterol new covalent bonds. SMIL gels are two distillation columns in series. (ACS to continuous fl ow process. Improve-
formed containing enzymes that can Sustainable Chem. Eng., 2023; DOI: J.O. Madsen and J.M. Woodley (who ments in this direction are discussed.
Y. Feng et al have reported an effi - be shaped into gel beads, which act as 10.1021/acssuschemeng.3c01739). has made many valuable contributions (Reaction Chem. Eng., 2023; DOI:
cient and selective biocatalytic process recyclable immobilised biocatalysts. in enzymatic processes) have referred 10.1039/D3RE00210A).
for the reduction of highly bulky and The formation of gel is explained. Gel Integrated electrosynthesis to the unfavourable reaction equili-
hydrophobic α-bromo ketone using entrapped lipase from Aneurinibacillus and biosynthesis for the pro- brium as the main bottleneck in one Engineering of hydroxyman-
thermoaerophilus was recycled for duction of adipic acid (AA)
10 runs without loss of activity and from lignin (L) derived phe- delate oxidase and cascade
retained for at least 150 days. (ACS nols reactions for high-yielding
Sustainable Chem. Eng., 2023; DOI: [This column has covered several conversion of racemic man-
10.1021/acssuschemeng.3c00517). papers on valorising L to give value- or unreacted substrates etc. cause pro- delic acids to phenylglyoxylic
added phenolic compounds.] blems. These authors have advocated acids and (R)- and (S)-phenyl-
selective removal of the desired pro- glycines
M.C. Morejon et al have carried out duct via salt- specifi c crystallisation
electrolytic hydrogenation to give cyclo- step and thus the product amine crystal- D-Y. Jung et al have adopted Directed
hexanols followed by biotransforma- lises as a product ammonium salt, which Evolution of hydroxymandelate
tion to give AA. 69% yield of cyclo- can be fi ltered. (Reaction Chem. Eng., oxidase (HMO) and this was used for
hexanol is reported at 69% coulombic 2023; DOI: 10.1039/D2RE00496H). the (S)-enantioselective oxidation of

178 Chemical Weekly May 14, 2024 Chemical Weekly May 14, 2024 179

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