The chemoenzymatic synthesis of clofarabine and related 2′-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases

• Ilja V. Fateev,
• Konstantin V. Antonov,
• Irina D. Konstantinova,
• Tatyana I. Muravyova,
• Frank Seela,
• Roman S. Esipov,
• Anatoly I. Miroshnikov and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2014, 10, 1657–1669, doi:10.3762/bjoc.10.173

• -ribofuranoside by using 2-deoxy-α-D-ribofuranose-1-phosphate as a co-substrate and PNP from bovine spleen as a biocatalyst [34]. Recently, an efficient transformation of 8-aza-7-deazahypoxanthine (allopurinol) into its N9-2′-deoxy-β-D-ribofuranoside has also been demonstrated in the transglycosylation reaction

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• type activity [20]. Conclusion Finally, in this study we investigated the application of CYP154E1 as regio- and chemoselective biocatalyst for the synthesis of allylic alcohols of acyclic terpenoids. Highest regioselectivity towards geraniol (1) and nerol (2) was observed with the wild type enzyme

C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• catalyst during the reaction. The continuing loss of TBAB during the work-up after each cycle was quantified by 1H NMR analysis of the reaction crude. Very interestingly, we found that the direct use of the precursor collagen as biocatalyst also afforded the desired product in very good yields. In this

• the biocatalyst used. In the case of biopolymers in powder form, first-order rate constants increased in the order chitosan < gelatin < BSA < collagen, whereas the same concentration of gelatin in hydrogel form showed slower kinetics. These results suggest a detrimental decrease of accessibility to

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• -catalyzed reactions such as the type and quantity of the biocatalyst and solvent on the enantiomers resolution was investigated. The aim was to achieve a conversion close to 50% and 99% ee for the slow-reacting substrates and product enantiomers. Four different lipases, i.e., two native (Amano PS, Amano AK

• separation of 1-(1H-imidazol-1-yl)propan-2-ol (±)-3a proceeded with excellent enantioselectivity, exceeding E = 500, in a short reaction time (5 h), by using a native enzymatic preparation from Pseudomonas fluorescens (Amano AK) as biocatalyst. In turn, after many trials we found that the kinetic separation

Regio- and stereoselective oxidation of unactivated C–H bonds with Rhodococcus rhodochrous

• Elaine O’Reilly,
• Suzanne J. Aitken,
• Gideon Grogan,
• Paul P. Kelly,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2012, 8, 496–500, doi:10.3762/bjoc.8.56

• dioxygenases has made them the focus of research into bioremediation and biocatalyst development [12]. The soil bacterium Rhodococcus rhodochrous (also referred to as Corynebacterium sp. 7E1C, Rhodococcus rhodochrous ATCC 19067 and Gordonia rubripertinctus 7E1C) is known to oxidise a wide variety of aliphatic

Chimeric self-sufficient P450cam-RhFRed biocatalysts with broad substrate scope

• Aélig Robin,
• Valentin Köhler,
• Alison Jones,
• Afruja Ali,
• Paul P. Kelly,
• Elaine O'Reilly,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2011, 7, 1494–1498, doi:10.3762/bjoc.7.173

• , often with high regio- and stereoselectivity [1], and are therefore attractive candidates for biocatalyst development. However, the need for reconstitution of protein redox partners, the necessary use of expensive NAD(P)H, and the lack of widely applicable high-throughput screening protocols render the

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• mL·min–1, H2:substrate ratio = 4). The racemic alcohol (75% conversion for the first step) was directly fed to a second catalytic reactor containing the supported biocatalyst to carry out the kinetic resolution (40–50 °C, Novozym 435 or CLEAS as the immobilized enzyme). Although only moderate conversions

• [88]. The combination of supporting the biocatalyst in an IL (either dissolved or suspended) with the use of a scF for delivering the substrates to the IL phase and to extract the final products from there, allows one to take full advantage of the above mentioned benefits and to develop continuous

• Antarctica lipase B (CALB) as the biocatalyst (Scheme 9). In the case of the work by Leitner and Reetz, the CALB enzyme was suspended in a bulk IL phase. At 45 °C and 10.5 MPa and using a substrate:donor ratio of 0.5 they achieved conversions of 43–50% with 99% ee values for the acetate. In a further

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• , nanoparticulate biocatalysts that can easily be separated magnetically. The enzymatic activity of the obtained biocatalyst system can be influenced by outer stimuli, such as temperature and external magnetic fields, by utilizing the LCST of the copolymer shell. Keywords: biocatalysis; biolabelling; core–shell

• kinetic data of trypsin activity, and b) Eadie–Hofstee diagram for the temperature-dependent kinetic data of nanocarrier activity. a) Turnover number kcat and b) Michaelis constant Km of particle- immobilized trypsin vs free trypsin. Synthesis of magnetic biocatalyst particles. Reaction scheme of the

• enzymatic digestion of BAPNA catalyzed by magnetically labeled trypsin (). Proposed mechanism of catalytic activity after heating magnetic biocatalyst particles above Tc. Physical and chemical composition of investigated multifunctional core–shell nanoparticles. Acknowledgements Thanks to Prof. T. J. J

The development and evaluation of a continuous flow process for the lipase- mediated oxidation of alkenes

• Charlotte Wiles,
• Marcus J. Hammond and
• Paul Watts

Beilstein J. Org. Chem. 2009, 5, No. 27, doi:10.3762/bjoc.5.27

• activity, again illustrating that careful dosage of H2O2 (2) increased the operational lifetime of the biocatalyst. The authors also noted that the presence of EtOH and urea resulted in moderate deactivation of the enzyme. In 2006, Olivo and co-workers [21] reported an environmentally benign method for

• biocatalyst with respect to peracid formation, facilitating a series of oxidations including alkenes [21] and ketones via the Baeyer–Villiger reaction [22] and retaining the broad substrate specificity of Candida antarctica lipase B. In the past decade micro reactors, and more generically continuous flow

• increasing productivity, biocatalyst lifetimes and exploring the potential of employing immobilised enzymes in industrial processes. Recent examples include the continuous flow enantioselective acetylation of a series of racemic secondary alcohols [27] and the continuous flow synthesis of alkyl esters [28

N-acylation of ethanolamine using lipase: a chemoselective catalyst

• Mazaahir Kidwai,
• Roona Poddar and
• Poonam Mothsra

Beilstein J. Org. Chem. 2009, 5, No. 10, doi:10.3762/bjoc.5.10

• effective [23]. Further, a control set with no Novozym® 435 was also irradiated under microwave irradiation, but no reaction occurred (Table 1 and Table 2). There is remarkable enhancement in reusability of biocatalyst. Conventionally there is a decrease in enzyme activity after run III while in solution

• high and low pH) and the reactivity of the amino residue [25] (Table 4). Effect of amount of biocatalyst Varying the amount of enzyme showed an effect on the rate of the reaction. Initially, 10 mg of enzyme was checked for sufficient catalytic activity. The second set of results, employing 20 mg of

• influence of temperature on enzymatic activity was studied by varying the temperature of the reaction from 50–90 °C (method A was employed): further increase in temperature (above 90 °C) leads to deactivation of enzyme (Figure 2). Reusability of biocatalyst Any reusable biocatalyst obviously impacts upon an

Large- scale ruthenium- and enzyme- catalyzed dynamic kinetic resolution of (rac)-1-phenylethanol

• Krisztián Bogár,
• Belén Martín-Matute and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2007, 3, No. 50, doi:10.1186/1860-5397-3-50

• 159 g of enantiomerically pure 3. Finally, to prove the high efficiency of the racemization catalyst 1, DKR was carried out on a 10 mol-scale employing lower amount of metal- and biocatalyst in a more concentrated reaction mixture. After 21 days, enantiomerically enriched acetate 3 (97% ee) was

• . Under optimized reaction conditions, DKR of 1-phenylethanol (2) was performed delivering 159 g (97% yield) of enantiomerically pure (R)-1-phenylethanol acetate (3) in a short reaction time (20 h) using 0.05 mol% of Ru-catalyst 1, and small amounts of enzyme. The employed heterogeneous biocatalyst

Towards practical biocatalytic Baeyer- Villiger reactions: applying a thermostable enzyme in the gram- scale synthesis of optically- active lactones in a two-liquid- phase system

• Frank Schulz,
• François Leca,
• Frank Hollmann and
• Manfred T. Reetz

Beilstein J. Org. Chem. 2005, 1, No. 10, doi:10.1186/1860-5397-1-10

• with environmentally benign reaction conditions. The first BVMO to be identified was cyclohexanone monooxygenase (CHMO).[10] Following the pioneer work of Taschner regarding the application of CHMO as a stereoselective biocatalyst in organic synthesis,[23] this BVMO is still the most commonly used

• enzyme and cofactor. In particular the solubility of the hydrophobic substrate needs to be increased while preserving activity and stability of the biocatalyst under the unnatural reaction conditions. Moreover, BVMOs as isolated enzymes are very unstable and require special care in production and