Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• glycoprotein (≈1–2%), laccase (≈0.2%), and stellacyanin (≈0.02%) [6][7]. Urushiol is the main active coating-forming ingredient of the resin. A typical urushiol is shown in Scheme 2. In a humid and warm environment, urushiol absorbs oxygen from air and is oxidized to a phenolic oxygen free radical under the

• action of laccase enzymes [5]. The radical then rearranges to form a semiquinone radical and reacts rapidly with a neighboring urushiol molecule to produce a biphenyl dimer. The dimers further polymerize to form the polymer [8]. Radical processes also occur in oceans. The mussel attachment system

• , such as organic peroxides, hydrogen peroxide, persulfates undergo homolysis of O–O bonds generating radicals that can break C–H bonds followed by a hydrogen abstraction reaction. Phenolic compounds can be oxidized by molecular oxygen in the presence of laccase, and the resulting phenolic radical reacts

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• in a freely rotating state (Supporting Information File 1). Discovery of the P450 enzyme responsible for dimerization We next investigated which enzyme in S. cattleya is responsible for dimerization of 4. The genome of S. cattleya (GCF_000237305.1) did not encode any laccase homologs but encoded 41

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• to 1,8-dihydroxynaphthalene (1,8-DHN) (10) by Abr1, a multi-copper reductase. In a last step polymerization of 1,8-DHN monomers is facilitated by the laccase Abr2 [45][149][150][151][152]. Knock out mutants of either ayg1, arp2, or abr2 lead to different coloured conidia while loss of pksP aborts DHN

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• with shikimic acid, feature the dimerization of monomeric phenolic precursors by a laccase enzyme, a single-electron enzyme complex within macro-organisms which facilitates oxidative dimerization through phenolic coupling [19]. In the case of balsaminone A (4), lawsone (6) is methylated to ether 7

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• synthesis of UDCA. For example the 3α-HSDHs [51][99] catalyze the oxidoreduction of the 3α-OH groups to the corresponding ketones and the well-known laccase-TEMPO system [100] can be used for the unselective oxidation of CA to dehydrocholic acid (DHCA). Solvent and substrate loading considerations in

Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• .10.246 Abstract The oxidative oligomerization of a chiral mandelamide derivative (N-(4-hydroxyphenyl)mandelamide, 1) was performed in the presence of horseradish peroxidase, laccase and N,N'-bis(salicylidene)ethylenediamine-iron(II) to obtain chiral oligophenols 2. The low enantioselectivity of the

• The chiral N-(4-hydroxyphenyl)mandelamide (1) was synthesized through condensation of p-aminophenol with (R)- or (S)-mandelic acid, respectively in presence of dicyclohexylcarbodiimide as condensing agent. For oligomerization of 1 via oxidative coupling laccase from Pleurotus ostreatus, peroxidase

• time was limited to one minute at 0 °C. In the presence of the lower active laccase–O2 system, the reaction was carried out for 4 h at room temperature. In the absence of RAMEB-CD it is apparent that laccase shows no enantioselectivity. However it can be established that during the oligomerization with

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• the role of classical radical initiators obtained by thermal decomposition, we will focus on some intriguing redox systems, including nitric oxides, laccase, quinones and aldehydes, which allow operation under very mild conditions, offering efficient alternative solutions to the classical autoxidation

• yields. Enzyme laccase Enzyme laccase is a family of “blue-copper” oxidase proteins, containing four copper ions in the active site, which cooperates in the degradation of the biopolymer lignin in woody tissues. With respect to other powerful oxidant enzymes, laccase has a lower redox potential. For this

• oxidation of a wider range of nonphenolic substrates. Among the huge number of mediators, N-hydroxy derivatives (NHDs) turned out to be particularly valuable and have been widely investigated. The role of NHDs-mediators in the laccase oxidation is outlined in Scheme 11. They act as electron carriers that

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• ]. Several oxido-reductases and their catalytic mechanisms are well-studied; the most common are soybean peroxidase, bilirubin peroxidase, laccase and horse radish peroxidase (HRP) [8][9][10][11][12]. Taking the latter case, horse radish peroxidase catalyzes the oxidative polycondensation of electron-rich

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

• Kengo Akagawa,
• Ryota Umezawa and
• Kazuaki Kudo

Beilstein J. Org. Chem. 2012, 8, 1333–1337, doi:10.3762/bjoc.8.152

• Kengo Akagawa Ryota Umezawa Kazuaki Kudo Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan 10.3762/bjoc.8.152 Abstract In the presence of a peptide catalyst and the oxidative enzyme laccase, a one-pot sequential reaction including a Friedel

• -functionalized indole or pyrrole derivatives in a highly enantioselective manner. Keywords: Friedel–Crafts-type alkylation; laccase; one-pot reaction; organocatalysis; α-oxyamination; resin-supported peptide catalyst; Findings Indole derivatives represent a class of biologically active compounds [1][2][3], and

• -oxyamination of aldehydes catalyzed by a peptide and an oxidizing enzyme, laccase [36][38]. Because the reaction conditions for that system are mild without employing a strong oxidant, we envisaged that the sequential FCAA/α-oxygenation could be attained by adopting the peptide-and-laccase-cocatalyzed

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

• both in discontinuous- and continuous-operation modes (Scheme 5) [26]. Cellobiose dehydrogenase was applied to catalyze the oxidation of 12, while laccase was used as a regenerating enzyme coupled by the redox mediator 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). In continuous-flow

• reactor equipped with a nanofiltration membrane. E1: Leucine dehydrogenase; E2: Formate dehydrogenase [25]. Continuous oxidation of lactose (12) to lactobionic acid (13) in a dynamic membrane-aerated reactor (DMAR) catalyzed by cellobiose dehydrogenase (D) and laccase (L) [26]. Production of N