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Developing (chemo)enzymatic cascades is very attractive for green synthesis, because they streamline multistep synthetic processes. In this Feature Article, we have summarized the recent advances in in vitro or whole-cell cascade reactions with a focus on the use of renewable bio-based resources as starting materials. This includes the synthesis of rare sugars (such as ketoses, L -ribulose, D -tagatose, myo-inositol or aminosugars) from readily available carbohydrate sources (cellulose, hemi-cellulose, starch), in vitro enzyme pathways to convert glucose to various biochemicals, cascades to convert 5-hydroxymethylfurfural and furfural obtained from lignin or xylose into novel precursors for polymer synthesis, the syntheses of phenolic compounds, cascade syntheses of aliphatic and highly reduced chemicals from plant oils and fatty acids, upgrading of glycerol or ethanol as well as cascades to transform natural L -amino acids into high-value (chiral) compounds. In several examples these processes have demonstrated their efficiency with respect to high space-time yields and low E-factors enabling mature green chemistry processes. Also, the strengths and limitations are discussed and an outlook is provided for improving the existing and developing new cascades. [ABSTRACT FROM AUTHOR]

Biocatalysis has found numerous applications in various fields as an alternative to chemical catalysis. The use of enzymes in organic synthesis, especially to make chiral compounds for pharmaceuticals as well for the flavors and fragrance industry, are the most prominent examples. In addition, biocatalysts are used on a large scale to make specialty and even bulk chemicals. This review intends to give illustrative examples in this field with a special focus on scalable chemical production using enzymes. It also discusses the opportunities and limitations of enzymatic syntheses using distinct examples and provides an outlook on emerging enzyme classes. [ABSTRACT FROM AUTHOR]

Die Biokatalyse hat in verschiedenen Einsatzgebieten Anwendung als Alternative zur chemischen Katalyse gefunden, wobei die herausragendsten Beispiele die Herstellung chiraler Verbindungen für Pharmazeutika und für die Riechstoff‐ und Aromen‐Industrie sind. Zunehmend werden Biokatalysatoren im großen Maßstab genutzt, um Spezial‐ und sogar Bulkchemikalien herzustellen. Dieser Aufsatz soll lehrreiche Beispiele in diesem Gebiet mit besonderem Augenmerk auf skalierbare chemische Verfahren aufzeigen. Es werden Möglichkeiten und Grenzen enzymatischer Synthesen diskutiert, und es wird ein Ausblick auf neu aufstrebende Enzymklassen gegeben. [ABSTRACT FROM AUTHOR]

2‐Phenylethanol (2‐PE) is an aroma compound with a rose‐like odors widely used as food ingredient, and natural 2‐PE is much preferred for the application with high selling price but limited availability. Bioproduction of 2‐PE from bioresources could provide a green, sustainable, and economic process to manufacture natural 2‐PE. Here we report a novel artificial cascade biotransformation to convert bioderived L‐phenylalanine (L‐Phe) to natural 2‐PE via deamination, decarboxylation, epoxidation, isomerization, and reduction in one pot. Recombinant E. coli strains co‐expressing the 5 necessary enzymes were engineered by using double plasmids, modular approach, and random combination as highly active, easily available, and recyclable biocatalysts. Two‐phase biotransformation with E. coli (RE) cells using biodiesel, a green and easily available solvent for in situ product extraction to minimize the inhibition, significantly improved product concentration and yield, converting 80 mM of L‐Phe to 71 mM (8.8 g/L, 89 % yield) of 2‐PE. The inhibition of 2‐PE was also reduced through in‐situ product adsorption using XAD4 resins. Using XAD4‐biodiesel‐aqueous buffer 3‐phase system could further enhance the concentration of 2‐PE to 85 mM (10.4 g/L, 85 % yield). The developed artificial cascade biotransformation of L‐Phe to 2‐PE is much better than other reported bioproductions of 2‐PE and provides high‐yielding, sustainable, and potentially practical synthesis of high‐value natural 2‐PE. Getting out while the going is good: A novel and high‐yielding cascade biotransformation for the synthesis of natural 2‐PE from biobased L‐Phe via artificial pathway was developed. Recombinant E. coli strains coexpressing 5 necessary enzymes were engineered for the designed cascades by a modular approach. The biocatalytic performance was significantly improved by applying in‐situ product removal system, giving 2‐PE in high concentration and high yield. [ABSTRACT FROM AUTHOR]

Alkenes are excellent starting materials for organic synthesis due to the versatile reactivity of C=C bonds and the easy availability of many unfunctionalised alkenes. Direct regio- and/or enantioselective conversion of alkenes into functionalised (chiral) compounds has enormous potential for industrial applications, and thus has attracted the attention of researchers for extensive development using chemo-catalysis over the past few years. On the other hand, many enzymes have also been employed for conversion of alkenes in a highly selective and much greener manner to offer valuable products. Herein, we review recent advances in seven well-known types of biocatalytic conversion of alkenes. Remarkably, recent mechanism-guided directed evolution and enzyme cascades have enabled the development of seven novel types of single-step and one-pot multi-step functionalisation of alkenes, some of which are even unattainable via chemo-catalysis. These new reactions are particularly highlighted in this feature article. Overall, we present an ever-expanding enzyme toolbox for various alkene functionalisations inspiring further research in this fast-developing theme. [ABSTRACT FROM AUTHOR]

Performing one-pot multi-catalysis reactions is a revolutionary tool for multistep synthesis, representing a fast-developing theme in catalysis field. To develop cascade reactions, enzymes are ideal catalysts due to their compatible reaction conditions. The implementation of enzyme cascades in recombinant microbial cells provides easily available self-replicating catalysts for facile one-pot biotransformations to produce a wide range of high-value (chiral) chemicals. In this minireview, we summarize the recent development of whole-cell cascade biotransformations according to the types of substrates, ranging from petrochemicals to biochemicals. Furthermore, we provide general instructions for the establishment of in vivo enzyme cascades, discuss the encountered problems and the corresponding solutions, and highlight the promising directions for future advance. [ABSTRACT FROM AUTHOR]

Enzymatic alcohol oxidation plays an important role in chemical synthesis. In the past two years, new alcohol oxidation enzymes were developed through genome-mining and protein engineering, such as new copper radical oxidases with broad substrate scope, alcohol dehydrogenases with altered cofactor preference and a flavin-dependent alcohol oxidase with enhanced oxygen coupling. New cofactor recycling methods were reported for alcohol dehydrogenase-catalyzed oxidation with photocatalyst and coupled glutaredoxin-glutathione reductase as promising examples. Different alcohol oxidation systems were used for the oxidation of primary and secondary alcohols, especially in the cascade conversion of alcohols to lactones, lactams, chiral amines, chiral alcohols and hydroxyketones. Among them, biocatalyst with low enantioselectivity demonstrated an interesting feature for complete conversion of racemic secondary alcohols through non-enantioselective oxidation. [ABSTRACT FROM AUTHOR]

Enantiopure d-phenylglycine and its derivatives are an important group of chiral amino acids with broad applications in thepharmaceutical industry. However, the existing synthetic methods for d-phenylglycine mainly rely on toxic cyanide chemistry and multistep processes. To provide green and safe alternatives, we envisaged cascade biocatalysis for the one-pot synthesis of d-phenylglycine from racemic mandelic acid, styrene, and biobased l-phenylalanine, respectively. Recombinant Escherichia coli (LZ110) was engineered to coexpress four enzymes to catalyze a 3-step reaction in one pot, transforming mandelic acid (210 mM) to give enantiopure d-phenylglycine in 29.5 g L−1 (195 mM) with 93% conversion. Using the same whole-cell catalyst, twelve other d-phenylglycine derivatives were also produced from the corresponding mandelic acid derivatives in high conversion (58-94%) and very high ee (93-99%). E. coli (LZ116) expressing seven enzymes was constructed for the transformation of styrene to enantiopure d-phenylglycine in 80% conversion via a one-pot 6-step cascade biotransformation. Twelve substituted d-phenylglycines were also produced from the corresponding styrene derivatives in high conversion (45-90%) and very high ee (92-99%) via the same cascade reactions. A nine-enzymeexpressing E. coli (LZ143) was engineered to transform biobased l-phenylalanine to enantiopure d-phenylglycine in 83% conversion via a one-pot 8-step transformation. Preparative biotransformations were also demonstrated. The high-yielding synthetic methods use cheap and green reagents (ammonia, glucose, and/or oxygen), and E. coli whole-cell catalysts, thus providing green and useful alternative methods for manufacturing d-phenylglycine. [ABSTRACT FROM AUTHOR]

Green and selective oxidation methods are highly desired in chemical synthesis and manufacturing. In this work, we have developed a biocatalytic method for the regio- and stereoselective oxidation of styrene derivatives into arylacetic and ( S)-2-arylpropionic acids via a one-pot epoxidation-isomerization-oxidation sequence. This was done via the engineering of Escherichia coli (StyABC-EcALDH) coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI) and aldehyde dehydrogenase (EcALDH) as an active and easily available whole-cell catalyst. Regioselective oxidation of styrene and 11 substituted styrenes using the E. coli cells was performed in a one-pot set-up, producing 12 phenylacetic acids in both high conversion and high yield. Engineering of E. coli (StyABC-ADH9v1) coexpressing SMO, SOI and ADH9v1 (a mutated alcohol dehydrogenase) led to biocatalysts capable of regio- and stereoselective oxidation of α-methylstyrene derivatives to the corresponding chiral acids. One-pot asymmetric synthesis of 4 ( S)-2-arylpropionic acids was achieved in good conversion and excellent ee with the E. coli cells. This is a new type of asymmetric alkene oxidation to give chiral acids with no chemical counterpart thus far. The cascade bio-oxidation operates under mild conditions, uses molecular oxygen, exhibits very high regio- and enantioselectivity, and gives high conversion, thus providing a green and efficient method for the synthesis of arylacetic acids and ( S)-2-arylpropionic acids directly from easily available styrenes. [ABSTRACT FROM AUTHOR]

Biotransformation is a green and useful tool for sustainable and selective chemical synthesis. However, it often suffers from the toxicity and inhibition from organic substrates or products. Here, we established a hollow fiber membrane bioreactor (HFMB)-based aqueous/organic biphasic system, for the first time, to enhance the productivity of a cascade biotransformation with strong substrate toxicity and inhibition. The enantioselective trans-dihydroxylation of styrene to ( S)-1-phenyl-1,2-ethanediol, catalyzed by Escherichia coli (SSP1) coexpressing styrene monooxygenase and an epoxide hydrolase, was performed in HFMB with organic solvent in the shell side and aqueous cell suspension in the lumen side. Various organic solvents were investigated, and n-hexadecane was found as the best for the HFMB-based biphasic system. Comparing to other reported biphasic systems assisted by HFMB, our system not only shield much of the substrate toxicity but also deflate the product recovery burden in downstream processing as the majority of styrene stayed in organic phase while the diol product mostly remained in the aqueous phase. The established HFMB-based biphasic system enhanced the production titer to 143 mM, being 16-fold higher than the aqueous system and 1.6-fold higher than the traditional dispersive partitioning biphase system. Furthermore, the combination of biphasic system with HFMB prevents the foaming and emulsification, thus reducing the burden in downstream purification. HFMB-based biphasic system could serve as a suitable platform for enhancing the productivity of single-step or cascade biotransformation with toxic substrates to produce useful and valuable chemicals. [ABSTRACT FROM AUTHOR]

Sustainable synthesis of useful and valuable chiral fine chemicals from renewable feedstocks is highly desirable but remains challenging. Reported herein is a designed and engineered set of unique non-natural biocatalytic cascades to achieve the asymmetric synthesis of chiral epoxide, diols, hydroxy acid, and amino acid in high yield and with excellent ee values from the easily available biobased l-phenylalanine. Each of the cascades was efficiently performed in one pot by using the cells of a single recombinant strain over-expressing 4-10 different enzymes. The cascade biocatalysis approach is promising for upgrading biobased bulk chemicals to high-value chiral chemicals. In addition, combining the non-natural enzyme cascades with the natural metabolic pathway of the host strain enabled the fermentative production of the chiral fine chemicals from glucose. [ABSTRACT FROM AUTHOR]

Sustainable synthesis of useful and valuable chiral fine chemicals from renewable feedstocks is highly desirable but remains challenging. Reported herein is a designed and engineered set of unique non-natural biocatalytic cascades to achieve the asymmetric synthesis of chiral epoxide, diols, hydroxy acid, and amino acid in high yield and with excellent ee values from the easily available biobased l-phenylalanine. Each of the cascades was efficiently performed in one pot by using the cells of a single recombinant strain over-expressing 4-10 different enzymes. The cascade biocatalysis approach is promising for upgrading biobased bulk chemicals to high-value chiral chemicals. In addition, combining the non-natural enzyme cascades with the natural metabolic pathway of the host strain enabled the fermentative production of the chiral fine chemicals from glucose. [ABSTRACT FROM AUTHOR]

[Display omitted] Apremilast is an important active pharmaceutical ingredient that relies on a resolution to produce the key chiral amine intermediate. To provide a new catalytic and enzymatic process for Apremilast, we performed the directed evolution of the amine transaminase from Vibrio fluvialis. Six rounds of evolution resulted in the VF-8M-E variant with > 400-fold increase specific activity over the wildtype enzyme. A homology model of VF-8M-E was built and a molecular docking study was performed to explain the increase in activity. The purified VF-8M-E was successfully applied to produce the key chiral amine intermediate in enantiopure form and 49% conversion via a kinetic resolution, representing a new enzymatic access towards Apremilast. [ABSTRACT FROM AUTHOR]

Rivastigmine is one of the several pharmaceuticals widely prescribed for the treatment of Alzheimer's disease. However, its practical synthesis still faces many issues, such as the involvement of toxic metals and harsh reaction conditions. Herein, we report a chemo‐enzymatic synthesis of Rivastigmine. The key chiral intermediate was synthesized by an engineered alcohol dehydrogenase from Lactobacillus brevis (LbADH). A semi‐rational approach was employed to improve its catalytic activity and thermal stability. Several LbADH variants were obtained with a remarkable increase in activity and melting temperature. Exploration of the substrate scope of these variants demonstrated improved activities toward various ketones, especially acetophenone analogs. To further recycle and reuse the biocatalyst, one LbADH variant and glucose dehydrogenase were co‐immobilized on nanoparticles. By integrating enzymatic and chemical steps, Rivastigmine was successfully synthesized with an overall yield of 66 %. This study offers an efficient chemo‐enzymatic route for Rivastigmine and provides several efficient LbADH variants with a broad range of potential applications. [ABSTRACT FROM AUTHOR]

The front cover picture, provided by Zhi Li, illustrates the use of enzyme cascades to provide new and green ways for the synthesis of chiral molecules. Here, the one‐pot synthesis of d‐phenylglycines from racemic mandelic acids, styrene, and biobased l‐phenylalanine was achieved by using three recombinant Escherichia coli whole‐cell catalysts, respectively. The one‐pot synthetic process afforded enantiopure d‐phenylglycines in high concentration and high yield. Details of this work can be found in the full paper on pages 4305–4316 (Y. Zhou, S. Wu, Z. Li, Adv. Synth. Catal. 2017, 359, 4305–4316; DOI: 10.1002/adsc.201700956). [ABSTRACT FROM AUTHOR]

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one‐pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non‐natural three‐enzyme cascade for one‐pot conversion of biobased l‐phenylalanine into ethylbenzene. The key rate‐limiting photodecarboxylase was subjected to structure‐guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3‐fold higher productivity. With this improved photodecarboxylase, an optimized two‐cell sequential process was developed to convert l‐phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one‐pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals. [ABSTRACT FROM AUTHOR]

Die Herstellung von chemischen Grundstoffen wie Benzol, Toluol, Ethylbenzol und Xylol (BTEX) aus erneuerbaren Ressourcen ist der Schlüssel zu einer nachhaltigen Gesellschaft. Die Biokatalyse ermöglicht die Ein‐Topf‐Mehrschritt‐Transformation von Bioressourcen unter milden Bedingungen, ist jedoch oft auf Biochemikalien beschränkt. Wir haben eine nicht‐natürliche Drei‐Enzym‐Kaskade für die Ein‐Topf‐Umwandlung von biobasiertem l‐Phenylalanin in Ethylbenzol entwickelt. Die geschwindigkeitsbestimmende Photodecarboxylase als Schlüsselenzym wurde einem strukturbasierten semi‐rationalem Engineering unterzogen und es wurde eine Dreifachmutante CvFAP(Y466T/P460A/G462I) mit einer 6.3‐fach höheren Produktivität erhalten. Mit dieser verbesserten Photodecarboxylase wurde ein optimiertes sequentielles E. coli Zwei‐Zellsystem‐Verfahren zur Umwandlung von l‐Phenylalanin in Ethylbenzol mit 82 % Umsatz entwickelt. Die Kaskadenreaktion wurde in die Fermentation integriert, um eine Ein‐Topf‐Bioproduktion von Ethylbenzol aus biobasiertem Glycerin zu erreichen. Dies zeigt das Potenzial der Kaskaden‐Biokatalyse in Kombination mit einem Enzym‐Engineering für die Produktion von biobasierten chemischen Grundstoffen auf. [ABSTRACT FROM AUTHOR]

(S)‐Mandelic acid is a useful and high value chemical with many synthetic applications, but its synthesis often requires the use of toxic cyanide. Here, we report the development of several cyanide‐free methods to prepare (S)‐mandelic acid via cascade biotransformation. Enhanced production of (S)‐mandelic acid from styrene via 4‐step enzyme cascades was achieved with Escherichia coli (A‐M1_R‐M2) cells, giving 118–144 mM (18–21.9 g/L, 72–79% yield) product. The process was scaled up to 1.5 L to produce 140 mM (21.3 g/L) of (S)‐mandelic acid in 70% yield. A strategy with the recycling and reuse of Escherichia coli cells, unreacted substrate, and organic solvent was developed to enhance the productivity of (S)‐mandelic acid through repeated batches, affording 190 mM (95% yield) and 328 mM (82% yield) product in two and four batches, respectively. (S)‐mandelic acid was also produced from bio‐derived L‐phenylalanine via 6‐step enzyme cascades. Biotransformation of L‐phenylalanine with Escherichia coli (LZ37) cells expressing all enzymes for the reactions gave 160 mM (S)‐mandelic acid in 80% yield. Moreover, (S)‐mandelic acid were synthesized from glycerol or glucose via L‐phenylalanine biosynthesis pathway and the 6‐step enzyme cascade. Coupling of Escherichia coli (NST74‐Phe) with Escherichia coli (LZ37) enabled the sustainable production of 63 mM (10 g/L) or 52 mM (8 g/L) (S)‐mandelic acid from renewable feedstocks glycerol and glucose, respectively. [ABSTRACT FROM AUTHOR]

Biocatalysis has undergone revolutionary progress in the past century. Benefited by the integration of multidisciplinary technologies, natural enzymatic reactions are constantly being explored. Protein engineering gives birth to robust biocatalysts that are widely used in industrial production. These research achievements have gradually constructed a network containing natural enzymatic synthesis pathways and artificially designed enzymatic cascades. Nowadays, the development of artificial intelligence, automation, and ultra-high-throughput technology provides infinite possibilities for the discovery of novel enzymes, enzymatic mechanisms and enzymatic cascades, and gradually complements the lack of remaining key steps in the pathway design of enzymatic total synthesis. Therefore, the research of biocatalysis is gradually moving towards the era of novel technology integration, intelligent manufacturing and enzymatic total synthesis. [ABSTRACT FROM AUTHOR]

Biocatalytic alkylations are important reactions to obtain chemo‐, regio‐ and stereoselectively alkylated compounds. This can be achieved using S‐adenosyl‐l‐methionine (SAM)‐dependent methyltransferases and SAM analogs. It was recently shown that a halide methyltransferase (HMT) from Chloracidobacterium thermophilum can synthesize SAM from SAH and methyl iodide. We developed an iodide‐based assay for the directed evolution of an HMT from Arabidopsis thaliana and used it to identify a V140T variant that can also accept ethyl‐, propyl‐, and allyl iodide to produce the corresponding SAM analogs (90, 50, and 70 % conversion of 15 mg SAH). The V140T AtHMT was used in one‐pot cascades with O‐methyltransferases (IeOMT or COMT) to achieve the regioselective ethylation of luteolin and allylation of 3,4‐dihydroxybenzaldehyde. While a cascade for the propylation of 3,4‐dihydroxybenzaldehyde gave low conversion, the propyl‐SAH intermediate could be confirmed by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Biokatalytische Alkylierungen sind wichtige Reaktionen, um chemo‐, regio‐ und stereoselektiv alkylierte Verbindungen zu erhalten. Dies kann mit S‐Adenosyl‐l‐methionin (SAM)‐abhängigen Methyltransferasen und SAM‐Analoga erreicht werden. Kürzlich wurde gezeigt, dass eine Halogenid‐Methyltransferase (HMT) aus Chloracidobacterium thermophilum SAM ausgehend von SAH und Methyliodid herstellen kann. Wir entwickelten einen Iodid‐basierten Assay für die gerichtete Evolution einer HMT aus Arabidopsis thaliana und nutzten diesen, um eine V140T‐Variante zu identifizieren, die auch Ethyl‐, Propyl‐, und Allyliodid akzeptiert, um die entsprechenden SAM‐Analoga herzustellen (90, 50 und 70 % Umsatz ausgehend von 15 mg SAH). Die V140T‐AtHMT wurde in einer Eintopfkaskade mit O‐Methyltransferasen (IeOMT und COMT) eingesetzt, um die regioselektive Alkylierung von Luteolin und 3,4‐Dihydroxybenzaldehyd zu erzielen. Obwohl eine Kaskade zur Propylierung von 3,4‐Dihydroxybenzaldehyd niedrige Umsätze ergab, konnte das Propyl‐SAH‐Intermediat durch NMR‐Spektroskopie bestätigt werden. [ABSTRACT FROM AUTHOR]

We engineered the cytochrome P450 monooxygenase CYP107D1 (OleP) from Streptomyces antibioticus for the stereo‐ and regioselective 7β‐hydroxylation of lithocholic acid (LCA) to yield ursodeoxycholic acid (UDCA). OleP was previously shown to hydroxylate testosterone at the 7β‐position but LCA is exclusively hydroxylated at the 6β‐position, forming murideoxycholic acid (MDCA). Structural and 3DM analysis, and molecular docking were used to identify amino acid residues F84, S240, and V291 as specificity‐determining residues. Alanine scanning identified S240A as a UDCA‐producing variant. A synthetic "small but smart" library based on these positions was screened using a colorimetric assay for UDCA. We identified a nearly perfectly regio‐ and stereoselective triple mutant (F84Q/S240A/V291G) that produces 10‐fold higher levels of UDCA than the S240A variant. This biocatalyst opens up new possibilities for the environmentally friendly synthesis of UDCA from the biological waste product LCA. [ABSTRACT FROM AUTHOR]

Wir haben die P450‐Monooxygenase CYP107D1 (OleP) aus Streptomyces antibioticus für die stereo‐ und regioselektive 7β‐Hydroxylierung von Lithocholsäure (LCS) zur Herstellung von Ursodeoxycholsäure (UDCS) durch "Protein‐Engineering" angepasst. OleP wurde zuvor für die Hydroxylierung von Testosteron an der 7β‐Position beschrieben, hydroxyliert jedoch LCS ausschließlich an der 6β‐Position, wodurch Murideoxycholsäure (MDCS) gebildet wird. Struktur‐ und 3DM‐Analysen, sowie molekulare Modellierungen wurden verwendet, um die Aminosäurereste F84, S240 und V291 als spezifitätsbestimmend zu identifizieren. Durch einen Alaninscan wurde S240A als UDCS‐produzierende Variante identifiziert. Basierend auf den identifizierten Positionen wurde eine synthetische "small but smart" Bibliothek durch die Verwendung eines farbbasierten Assays auf UDCS Produktion getestet. Hier konnte eine beinahe perfekte regio‐ und stereoselektive Dreifachvariante (F84Q/S240A/V291G) identifiziert werden, die UDCS in einer 10‐fach höheren Menge produziert als die S240A Variante. Der hergestellte Biokatalysator eröffnet neue Möglichkeiten zur umweltfreundlichen Synthese von UDCS aus dem Abfallprodukt LCS. [ABSTRACT FROM AUTHOR]