Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• [47]. Hence, we screened different lipases for the trans-acetylation of (±)-4 for its effective resolution and the results are summarized in Table 1. Based on our past experience in lipase-catalyzed resolution of homoallylic alcohols [38], initially a Novozym 435®-catalyzed acetylation of (±)-4 with

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• activity (89–99% conversion) was found for Candida antarctica lipase B (CAL-B, Novozym® 435) in all tested conditions (Table 1, entry 2). For porcine pancreas lipase (PPL), a different scenario was found, since conversion was strongly influenced by buffer composition and, to a lesser extent, the cosolvent

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• , 480 mg weight) using water (3.6 μL, 0.5 equiv), 0.2 mL of 2-methyl-2-butanol (2M2B) as a LAG additive (η = 1.63) and 40 mg of CALB (Novozym 435, Novozymes, recombinant, expressed in Aspergillus niger, immobilized in acrylic resin, >10000 U/g) at 25 Hz during 30 min. Gratifyingly, 55% conversion to the

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• chemoenzymatic route. The central chiral building block, 1-(10H-phenothiazin-10-yl)propan-2-ol, was obtained via a lipase-mediated kinetic resolution protocol, which furnished both enantiomeric forms, with superb enantioselectivity (up to E = 844), from the racemate. Novozym 435 and Lipozyme TL IM have been

• representative set of 14 different lipases isolated from various microorganisms (see Supporting Information File 1 for details). Among the broad panel of investigated commercially available preparations, immobilized lipases of a fungal origin such as Novozym 435, Chirazyme L-2, C2, Chirazyme L-2, C3, and

• that generated ester (R)-(−)-6a was enantiomerically pure (>99% ee) regardless of the time and the conversion. In turn, the reaction rate was considerably improved in Novozym 435-catalyzed analytical scale acetylation. This revealed that Candida antarctica lipase B (CAL-B) immobilized on acrylic resin

cis–trans Isomerization of silybins A and B

• Michaela Novotná,
• Radek Gažák,
• David Biedermann,
• Florent Di Meo,
• Petr Marhol,
• Marek Kuzma,
• Lucie Bednárová,
• Kateřina Fuksová,
• Patrick Trouillas and
• Vladimír Křen

Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105

• novel compounds with UV spectra similar to that of silybin. Enzymatic alcoholysis (n-butanol) of this mixture by Novozym 435 led, after a prolonged reaction time, to the removal of the acetyl groups from trans-isomers 2a and 2b to give 1a and 1b (Figure 1), while the two minor isomers remained

• ], and at the preparatory scale by lipase-catalyzed discrimination [4][5]. However, chromatographic separation of 2,3-cis- and 2,3-trans-silybins is feasible after their C-23 O-acetylation, which can be accomplished with Novozym 435 in an acetone/vinyl acetate mixture, giving a nearly quantitative yield

• in decomposition or reversed isomerization to the original trans-isomers. We eventually had to use enzymatic alcoholysis with a large excess of Novozym 435 and a longer reaction time (5:1, wt. enzyme/substrate, 3–5 d, 45 °C) compared to the alcoholysis of the respective acetates of the trans-silybins

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• /transition metal-catalysed approach was investigated [48][49]. In this regard, the combination of Ru complexes such as Shvo’s catalyst (C) [50], the amino-Cp catalyst D [51], or [Ru(CO)2Cl(η5C5Ph5)] [52], and the lipase novozym 435 has emerged as particularly useful [53][54]. We tested Ru catalysts C and D

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• immobilized Candida antarctica lipase B (Novozym 435) was used as a heterogeneous catalyst in the kinetic resolution of the alcohol 22 [30]. Racemization of the unreacted (S)-22 was achieved with acidic zeolite catalysts. Both heterogenous catalysts were coated with ionic liquids for improved stability of the

• and solvent-free environment [38]. In the first noncatalyzed thermal aza-Michael addition performed at 80 °C, the racemic ester rac-46 is formed from cheap starting materials benzylamine (44) and trans-ethylcrotonate (45) (Scheme 14). Subsequently, Novozym 435 is applied for the kinetic resolution of

• yield of 1 kg L−1 day−1 was achieved. Apart from the difference in operation temperatures, separation of the two steps of this reaction sequence into individual reactors was also necessary as Novozym 435 is also able to catalyze the unwanted aminolysis of 45. Baxendale et al. [39] established a

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

• . Different examples can be found, in this regard, in the literature. The most common transformations are the kinetic resolution (KR) of secondary alcohols. For example, Matsuda has reported the use of the commercially available supported lipase Novozym 435 for the kinetic resolution of aromatic and

• 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

• combination of a supported enzyme (Novozym 435) and a supported acid catalyst, both covered by a thin layer of an IL. This has allowed the development of the continuous chemoenzymatic dynamic kinetic resolution of the corresponding racemic alcohols with yields of up to 80% and enantioselectivities of about 91

Development of dynamic kinetic resolution on large scale for (±)-1-phenylethylamine

• Lisa K. Thalén and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2010, 6, 823–829, doi:10.3762/bjoc.6.97

• )acetamide, 3. A flame dried 1 L two-necked round-bottomed flask was charged with Novozym 435 (340 mg), Na2CO3 (900 mg, 8.5 mmol), and Ru-complex 4 (745 mg, 0.56 mmol). The vessel was evacuated and backfilled with argon three times. Toluene (225 mL), (±)-1-phenylethylamine (1, 5.8 mL, 45 mmol), 2,4-dimethyl

• -3-pentanol (8 mL, 57 mmol), and methyl methoxyacetate (3.4 mL, 34 mmol) were added subsequently via syringe. The mixture was stirred at 100 °C. After 24 h the reaction vessel was allowed to cool for 10 min at rt. Methyl methoxyacetate (15.8 mmol, 1.6 mL) and Novozym 435 (110 mg) were added. The

• Novozym 435 (100 mg), Na2CO3 (200 mg), and Ru-complex 4 (166 mg, 0.125 mmol). The vessel was evacuated and backfilled with argon three times. Toluene (50 mL), (±)-1-phenylethylamine (1, 1.3 mL, 10 mmol), 2,4-dimethyl-3-pentanol (3.5 mL, 25 mmol), and ethyl methoxyacetate (1.6 mL, 7.5 mmol) were added

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

• lipase B, Novozym® 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity, utilising the commercially available oxidant hydrogen peroxide (100 volumes). Initial investigations focussed

• ; hydrogen peroxide; lipase; micro reactor; Novozym® 435; peracids; Introduction In addition to their synthetic value as intermediates in the preparation of diols, alcohols, hydroxyesters and alkenes, epoxides are a key raw material in many industrial processes, finding application in adhesives, polymers

• alkene epoxidation via the chemo-enzymatic perhydrolysis of ethyl acetate using Novozym® 435 (4), immobilised Candida antarctica lipase B, and UHP (3). They utilised the high specificity of Candida antarctica lipase B towards ester hydrolysis to generate acetic acid (1) in situ and subsequently

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• have been developed recently, including processes using alternative solvents such as ionic liquids and/or scCO2 [56][57][58][59][60][61]. The kinetic resolution of racemic 1-phenylethanol 54 was performed continuously in scCO2, using an immobilized lipase (Candida antarctica, Novozym 435) and vinyl

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

• lipase (Novozym® 435) are described and optimum conditions for selective N-acylation rather than O-acylation are also discussed. Microwave assisted solution phase, solid supported and conventional methods were investigated and results were compared. There is a synergy between the enzyme catalysis and

• lipase (CAL B Novozym® 435) with fatty acids or esters 1a–h and ethanolamine (2) under simultaneous microwave irradiation. Results and Discussion In the reaction of fatty acids 1a–d or esters of fatty acids 1e–h with ethanolamine (2), two types of acylated products are possible. Out of two possible

• 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