Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• than the 1CT state (2.60 eV), while 3CT remains slightly lower in energy (2.57 eV). This has some important consequences on the TADF mechanisms. Table 5 lists spin–orbit couplings matrix elements (SOCMEs) between 1CT, 3LE, and 3CT states. The SOCMEs between 1CT and 3CT are small, 0.03 cm−1 at most

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• whether 2 was generated by A. oryzae NSAR1. The result showed that the heterologous host indeed converts 1 to talaro-7,13-dien-19-ol (2, Scheme 1A; Supporting Information File 1, Figure S18). Mechanistic characterization of TadA So far, cyclization mechanisms of FC-type diterpenes afforded by PaFS [18

• monitored at 254 nm. Biosynthesis of FC-type diterpenoids. A) The biosynthetic pathway of 1, 2 and 4. B) Cyclization mechanisms of 1 and reported FC-type diterpenes. Supporting Information Supporting Information File 328: Experimental methods, nucleotide sequence, tables, and figures. Acknowledgements We

Make or break: the thermodynamic equilibrium of polyphosphate kinase-catalysed reactions

• Michael Keppler,
• Sandra Moser,
• Henning J. Jessen,
• Christoph Held and
• Jennifer N. Andexer

Beilstein J. Org. Chem. 2022, 18, 1278–1288, doi:10.3762/bjoc.18.134

• PPK2. They are structurally unrelated and use different catalytic mechanisms. PPK1 enzymes prefer the usage of adenosine 5'-triphosphate (ATP) for polyphosphate (polyP) synthesis while PPK2 enzymes favour the reverse reaction. With the emerging use of PPK enzymes in biosynthesis, a deeper understanding

• reaction where the terminal phosphate dissociates from the polyP chain before being attacked by the nucleotide [18]. Both mechanisms could proceed without a phosphate group transfer onto an amino acid side chain of the enzyme as in PPK1: here, the enzyme structure generates proximity and polarisation of

• the different reaction mechanisms. The thermodynamic equilibrium of the PPK reaction is not as close to the product side as in other ATP regenerating systems, which corresponds to the phosphate transfer potential of the different phosphate donors. This raises the question if PPK/polyP based systems

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• compared to 10ab-v2. Moreover, CH3NH2 approaches 4a/4a’ at the opposite side of the C–C6H5 sites to form IS3/IS5 and finally 10ab-v2/10ab . The reaction mechanisms in the gas phase and in the solvents model are only slightly different. Experimental General experimental methods NMR spectra were acquired on

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

• Md Azadur Rahman,
• Kana Kuroda,
• Hirofumi Endo,
• Norihiko Sasaki,
• Tomoaki Hamada,
• Hiraku Sakai and
• Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

• (T2) on the yield of oligosaccharides. Influence of temperatures of anodic oxidation (T1) and glycosylation (T2). MALDI–TOF MS spectra of oligosaccharides. Proposed structures of byproducts of electrochemical polyglycosylation. Proposed mechanisms of electrochemical polyglycosylation. Oxidative

Enzymes in biosynthesis

• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1131–1132, doi:10.3762/bjoc.18.116

• as Escherichia coli or Saccharomyces cerevisiae. Besides in vitro studies with purified enzymes, heterologous expressions of whole pathways for the production of compounds is possible [6]. Enzyme mechanisms can be addressed through structure-based site-directed mutagenesis, which may also lead to

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

• , Supporting Information File 1). Other plant polyketides, such as anthraquinones 19 and 20 and phenylpropanoids 21–24, failed to be dimerized. The reaction mechanism of P450-mediated phenol dimerization is believed to involve oxidative radical–radical coupling, though other mechanisms, such as radical

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• of their biosynthetic mechanisms. Keywords: biosynthesis; methyltransferase; natural azoxides; reactivity-based screening; Streptomyces; Introduction Azoxy natural products are a rare yet intriguing class of natural products with various beneficial biological properties, such as antibacterial

• macrozamin [4]. Although the N2H4 generation is an advantageous reactivity of an azoxy group, to the best of our knowledge, it has not been applied for the detection of azoxy bonds in the context of natural products discovery. The azoxy bond is biosynthesized by two distinct mechanisms. The first is the

• enzyme VlmA [18]. This intermediate is hypothesized to be transformed into the azoxy bond-containing intermediate via an intramolecular rearrangement accompanied by a concomitant oxidation [18]. Although the exact mechanisms of azoxy bond formation remain unclear, VlmH and VlmA cooperate to biosynthesize

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

• Shani Zev,
• Marion Ringel,
• Ronja Driller,
• Bernhard Loll,
• Thomas Brück and
• Dan T. Major

Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97

• reference environment for terpene synthases [10][11][12][15][16][21][22][23][24][25]. The proposed reaction mechanisms yielding HP and IE and are presented in Scheme 1, while the reaction free energy profile is presented in Figure 2. Here, we modeled the transformations A→I (HP) and A’→E’ (IE). The gas

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• attracting much attention, since bioactive compounds possessing these structures are known. This method has the potential to be applied to synthesize bioactive 2-cyanonaphthalen-1-ols [8][9] and 3-substituted phthalides [12][13][14][15][16]. The reaction mechanisms of the electroreductive coupling of 1 with

• by cyclic voltammetry (Table 3) and acceptors 2 revealed no reduction peaks from 0 to −2.00 V vs SCE [5][6]. Therefore, this electroreductive coupling is initiated by the reduction of compounds 1. There are two possible reaction mechanisms for the reductive coupling of 1 with 2a as illustrated in

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• [1][2][3]. In OLEDs photons are mainly generated by radiative recombination in the emitting layer [4]. Therefore, the development of efficient luminescent materials and the exploration of new luminescent mechanisms are one of the core tasks in academic research. The most common luminescent materials

• ) [6][7]. In 2012, Adachi et al. first reported purely organic thermally activated delayed fluorescent (TADF) materials, which achieved nearly 100% exciton utilization via reverse intersystem crossing (RISC) [8]. Meanwhile, novel materials based on new luminescence mechanisms such as hybridized local

• brand new luminescent properties. In this mini-review, we summarize unique electron donor and acceptor materials which regulate luminescent properties via Lewis acid–base interactions and briefly explain the exploration of their chemical nature and interaction mechanisms. Review Lewis acids as electron

The stereochemical course of 2-methylisoborneol biosynthesis

• Binbin Gu,
• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82

• 2-methylisoborneol from (S)-2-Me-LPP may be explained by isomerization to 2-Me-GPP and then to (R)-2-Me-LPP. Keywords: biosynthesis; enantioselective synthesis; enzyme mechanisms; gas chromatography; terpenoids; Introduction After its first discovery from Streptomyces [1][2], it has been

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• attention in the field of natural products and organic synthesis. In this review, we summarize the structural analyses, mechanistic investigations, and proposed reaction mechanisms of endoperoxide-forming oxygenases, including cyclooxygenase, fumitremorgin B endoperoxidase (FtmOx1), and the asnovolin A

• reduced to produce PGH2. PGH2 is metabolized by downstream enzymes to yield a series of prostaglandins, which play important roles in inflammatory responses [35][36][37]. Although the active site architectures of COX-1 and COX-2 are not completely identical, the reaction mechanisms and catalytic residues

• enzymes, COX, FtmOx1, and NvfI, indicated that these enzymes employ distinct reaction mechanisms, suggesting that the enzymatic endoperoxide formation reactions individually evolve in a substrate-dependent manner. This fact makes it difficult to identify the endoperoxide-forming enzymes by a sequence

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• Theoretical background of electromagnetic induction To better understand the mechanisms of inductive heating, some basic physical principles are first explained. This type of heating depends on various structural, morphological, chemical, and physical properties of the materials to be heated. When a suitable

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• to give selectively spiro[indoline-3,2'-furan-3',3''-indolines] in satisfactory yields. The relative configuration of the complex spirooxindoles was confirmed by determination of several single crystal structures. Also, plausible reaction mechanisms have been proposed. This reaction has the

Rapid gas–liquid reaction in flow. Continuous synthesis and production of cyclohexene oxide

• Kyoko Mandai,
• Tetsuya Yamamoto,
• Hiroki Mandai and
• Aiichiro Nagaki

Beilstein J. Org. Chem. 2022, 18, 660–668, doi:10.3762/bjoc.18.67

• operation of the gas–liquid oxidation even with air in the flow reactor definitely paved the way for a green and fast oxidation process. Based on the mechanisms reported in the literature [11][31], we hypothesized the plausible reaction mechanism in our flow system as shown in Scheme 2. Firstly, the peracid

Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• quenched due to aggregation-caused quenching (ACQ) [10]. Generally, the restriction of intermolecular π–π interactions in highly planar compounds plays a key role in aggregate structures exhibiting fluorescence [5][6][10]. In addition, intramolecular mechanisms, such as intramolecular rotation (RIR

• ), intramolecular charge transfer, and twisted intramolecular charge transfer (TICT) are involved in AIEE [20][21][22]. Various AIEE-based luminogens have been developed based on these mechanisms; however, many of them are high-molecular-weight compounds (MW > 500) with bulky substituents, which limits their

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• was kept around 10%, whereas in the case of doubly donor-substituted compound POZ-DBPHZ, the EQE dropped below 10% [17]. Theoretical calculations We performed electronic structure calculations on both the D–A (1) and D–A–D (POZ-DBPHZ) compounds to understand better their respective TADF mechanisms and

• ) luminance–current density characteristics. Schematics of the TADF mechanisms along with NTOs for the relevant electronic states for a) D–A compound 1 and b) D–A–D compound POZ-DBPHZ. Synthesis of compound 1. Summary of steady-state photophysical data of diluted solutions of 1.a Summary of the general

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• leading to intermediate A, nucleophilic attack of phenolate at the less sterically hindered carbon of the above zwitterion A and subsequent protonation of anion B (Scheme 8). Based on these plausible mechanisms for the formation of phenoxyketones, it can be assumed that a decline of the Cs+ concentration

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• reaction mechanisms: free radical autoxidation, cation radical autoxidation, and thermal intersystem crossing (ISC), using 18O2 labeling, spin-trapping, spectroscopic, mass spectrometric, kinetic, and computational techniques. After several experiments, the obtained results have demonstrated that the 2

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• several studies on the solvolysis mechanisms for alkanesulfonyl chlorides (RSO2Cl) and arenesulfonyl chlorides (ArSO2Cl). The earlier of these studies were reviewed a little over thirty years ago by Gordon, Maskill and Ruasse (Chem. Soc. Rev. 1989, 18, 123–151) in a contribution entitled “Sulfonyl

• of the review, the study is of solvolysis mechanisms and the reactions involve the solvolyses of a series of para and meta-ring-substituted substrates. Applying the Hammett equation to the rate measurements of Berger and Oliver [4], we arrive, in 50% water/50% acetone (v/v) at a reaction constant ρ

• defining mechanisms of nucleophilic substitution at sulphur are known to the writer...”. Examination of this section of the text shows, however, that it is limited to a consideration of substitution at the sulfur of sulfinates and reactions of the general type illustrated in Equation 3 and reactions

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• 1.44 ppm. ORTEP diagram of the asymmetric unit consisting of two cations 6b(A) and 6b(B) and triflate anions. Conversion of cyclic amino acids to 1,2-oxazole derivatives. Plausible mechanisms for the formation of 1,2-oxazoles 4a–h and VII from β-enamino ketoesters 3a–h with hydroxylamine. Synthesis of

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• % ee) could still be maintained (Scheme 6b). This one-pot three-component reaction would be more convenient for potential industrial applications. Finally, in order to understand the enantioselective formation process of product 3, we proposed the possible mechanisms for the [3 + 2] cyclization

The enzyme mechanism of patchoulol synthase

• Houchao Xu,
• Bernd Goldfuss,
• Gregor Schnakenburg and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 13–24, doi:10.3762/bjoc.18.2

• Chemistry, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany 10.3762/bjoc.18.2 Abstract Different mechanisms for the cyclisation of farnesyl pyrophosphate to patchoulol by the patchoulol synthase are discussed in the literature. They are based on isotopic labelling experiments, but the

• calculations; enzyme mechanisms; isotopes; terpenes; Introduction Patchouli oil, the essential oil of the shrub Pogostemon cablin, has a pleasant woody odour and is of high economic value for the perfumery and cosmetics industries. It is mainly composed of sesquiterpenes with patchoulol as the main compound

• sesquiterpene (2-2H)-16 that may take up the deuteron released in the formation of 5 (and similar compounds) to give (2,15-2H2)-H (Scheme 3C). Notably, none of the proposed mechanisms in Schemes 1–3 can explain the reported results from all labelling experiments and some of the reported findings are even

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• arylative spirocyclization reaction delivered product 40a in comparable yield, suggesting an initial in situ reduction of the Fe(III) precatalyst occurs in the early stages of the catalytic cycle. Although the mechanisms of Fe-catalyzed cross-coupling reactions are often complex [74][75] (Scheme 8), the