The current greening of chemical production processes going along with a rising interest for the utilization of biogenic feedstocks recently revived the research to find new ways for the degradation of the complex lignin-backbone by means of biocatalysis and combined chemo-enzymatic catalysis. Lignin, which accumulates in 50 million t/a, is regarded as a potential substitute for phenolic and other aromatic, oil-based chemicals in the upcoming post oil age. The cleavage of the β-O-4-aryl ether linkage is the most favoured, since it accounts for approximately 50% of all ether linkages in lignin. This enzymatic cleavage was proposed to be a part of the lignin catabolism in the proteobacterium Sphingobium sp. SYK6.Three enzymes, LigD, a Cα-dehydrogenase, LigF, a β-etherase and LigG, a glutathione lyase, are supposed to be involved in lignin degradation. We cloned and recombinantly expressed these genes in E. coli and determined their pH and temperature optima on the lignin model substrate 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol 1. Using an NAD + dependent glutathione reductase from Allochromatium vinosum (AVR) we established an efficient way to regenerate the co-substrates NAD + and glutathione allowing for a self-sufficient balanced enzymatic cascade with net internal hydrogen transfer (hydrogen borrowing). We showed the capability of this enzyme system to release lignin monomers from complex lignin structures coming from differently prepared real lignin substrates. This novel enzyme system could become a useful tool to release lignin monomers from complex lignin structures. † Electronic supplementary information (ESI) available. See

Teicoplanin 1,2 is a complex of five antibiotics isolated from Actinoplanes teichomyceticus that are related to vancomycin [3][4][5][6][7][8] which is enlisted as the drug of last resort for treatment of resistant bacterial infections or for patients allergic to -lactam antibiotics. 6 It is 2-8-fold more potent, possesses a lower toxicity, exhibits a longer half-life in man (40 vs 6 h), and is easier to administer and monitor than vancomycin.Herein we describe the first total synthesis of the teicoplanin aglycon (1). 9-12 Although teicoplanin bears the identical ABCD ring system and the same CDE atropisomer stereochemistry as vancomycin, it contains a DE ring system that lacks the -hydroxy group of the vancomycin E-ring substituted phenylalanine (C 2 residue) and incorporates an especially racemization prone substituted phenylglycine C 3 residue. 13 Most significantly, it contains the additional 14-membered FG ring system not found in vancomycin. Key elements of the approach include sequential DE and FG ring system introductions onto the common vancomycin/teicoplanin ABCD ring system providing a late stage divergent total synthesis of the two classes of glycopeptide antibiotics. The ring systems were introduced enlisting a nucleophilic aromatic substitution reaction of an o-fluoronitroaromatic for macrocyclization and formation of the 16-membered DE diaryl ether and a macrolactamization 14 of the N-terminus amide for closure of the 14-membered FG ring system. With the respective order of closures, the choice of substrates, and the conditions enlisted, no epimerization of the sensitive C 2 3 center was observed.Because of the facile C 2 3 epimerization observed within the confines of the teicoplanin FG ring system, 13 the FG diaryl ether was formed using an intermolecular nucleophilic aromatic substitution reaction with acyclic phenylglycinol substrates incapable of epimerization. Thus, coupling of 2 15 and 3 16 (6 equiv of K 2 CO 3 , 5 equiv of 18-c-6, 0.1 M DMSO, 14 h, 25°C) provided 4 (70%), Scheme 1. Reactions conducted in DMSO were substantially faster than those conducted in DMF and the (1) Parenti, F.; Beretta, G.; Berti, M.; Arioli, V. J. Antibiot. 1978, 31, 276. (2) Hunt, A. H.; Molloy, R. M.; Occolowitz, J. L.; Marconi, G. G.; Debono, M. J. Am. Chem. Soc. 1984, 106, 4891. Barna, J. C. J.; Williams, D. H.; Stone, D. J. M.; Leung, T.-W. C.; Doddrell, D. M. J. Am. Chem. Soc. 1984, 106, 4895. (3) McCormick, M. H.; Stark, W. M.; Pittenger, G. E.; Pittenger, R. C.; McGuire, J. M. Antibiot. Annu. 1955-1956, 606. (4) Harris, C. M.; Kopecka, H.; Harris, T. M. J. Am. Chem. Soc. 1983, 105, 6915. Williamson, M. P.; Williams, D. H. (10) Nicolaou, K. C.; Li, H.; Boddy, C. N. C.; Ramanjulu, J. M.; Yue, T.-Y.; Natarajan, S.; Chu, X.-J.; Bräse, S.; Rübsam, F. Chem. Eur. J. 1999, 5, 2584. Nicolaou, K. C.; Boddy, C. N. C.; Li, H.; Koumbis, A. E.; Hughes, R.; Natarajan, S.; Jain, N. F.; Ramanjulu, J. M.; Bräse, S.; Solomon, M. E. Chem. Eur. J. 1999, 5, 2602. Nicolaou, K. C.; Koumbis, A. E.; Takayanagi, M.; Natarajan, S.; Ja...

The use of renewable feedstock is one of the twelve key principles of sustainable chemistry. Unfortunately, bio-based compounds often suffer from high production cost and low performance. To fully tap the potential of natural compounds it is important to utilize their functionalities that could make them superior compared to fossil-based resources. Here we show the conversion of (+)-3-carene, a by-product of the cellulose industry into ε-lactams from which polyamides. The lactams are selectively prepared in two diastereomeric configurations, leading to semi-crystalline or amorphous, transparent polymers that can compete with the thermal properties of commercial high-performance polyamides. Copolyamides with caprolactam and laurolactam exhibit an increased glass transition and amorphicity compared to the homopolyamides, potentially broadening the scope of standard polyamides. A fourstep one-vessel monomer synthesis, applying chemo-enzymatic catalysis for the initial oxidation step, is established. The great potential of the polyamides is outlined.

The reaction of hydrated electrons (e(-)(aq) with 8-bromoadenosine 7 has been investigated by radiolytic methods coupled with product studies. Pulse radiolysis revealed that one-electron reductive cleavage of the C-Br bond gives the C8 radical 8 followed by a fast radical translocation to the sugar moiety. The reaction is partitioned between C5' and C2' positions in a 60:40 ratio leading to 5'-adenosinyl radical 9 and 2'-adenosinyl radical 11. This radical translocation from C8 to different sites of the sugar moiety has also been addressed computationally by means of DFT B3LYP calculations. In addition, ketone 21 was prepared and photolyzed providing an independent generation of C2' radical 11. Both C5' and C2' radicals undergo unimolecular reactions. Radical 9 attacks adenine with a rate constant of 1.0 x 10(4) s(-1) and gives the aromatic aminyl radical 10, whereas C2' radical 11 liberates adenine with a rate constant of 1.1 x 10(5) s(-1).

The synthesis and polymerization of two β‐lactams and two ε‐lactams derived from the terpenes α‐pinene and (+)‐3‐carene are reported. The new biopolymers can be considered as polyamide 2 (PA2) and polyamide 6 (PA6)‐types with aliphatic stereoregular side chains, which lead to remarkable new properties. The macromolecules are investigated by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and infrared (IR). The (+)‐3‐carene‐derived PA6‐type is of particular interest, since it reaches a molecular weight of over 30 kDa, which is the highest value for lactam‐based polyamides derived from terpenes reported to date. Additionally, a glass transition temperature (Tg) of 120 °C is observed, surpassing the glass transition temperature of PA6 by 60 °C. The absence of a melting point (Tm) indicates high amorphicity, another novelty for terpene‐based polyamides, which might give transparent bio‐polyamides access to new fields of application.