Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• steroids in plants as a starting point for future research. Keywords: biosynthesis; CYPs; cytochrome P450 monooxygenases; plants; steroid; sterol; triterpene; triterpenoid; Introduction Triterpenoids are a large class of natural products derived from precursors containing 30 carbon atoms and composed of

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

• can be embedded in complex biosynthetic networks such as in vitro S-adenosylmethionine (SAM)- or carbon dioxide fixation cycles, and de novo nucleobase synthesis [38][39][40][41]. For the biocatalytic synthesis of ATP or derivatives, up to three consecutive phosphorylation reactions are coupled in a

Ferrocenoyl-adenines: substituent effects on regioselective acylation

• Mateja Toma,
• Gabrijel Zubčić,
• Jasmina Lapić,
• Senka Djaković,
• Davor Šakić and
• Valerije Vrček

Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133

• ferrocene–nucleobase conjugates [4], which are known to exhibit anticancer [5][6][7], antibacterial [8][9][10], or antitrypanosomal activity [11], but also may serve as electrochemical biosensors [12][13], self-assembled molecular materials [14][15], decorations of carbon tubes and nanomaterials [16][17

Enantioselective total synthesis of putative dihydrorosefuran, a monoterpene with an unique 2,5-dihydrofuran structure

• Irene Torres-García,
• Josefa L. López-Martínez,
• Rocío López-Domene,
• Manuel Muñoz-Dorado,
• Ignacio Rodríguez-García and
• Miriam Álvarez-Corral

Beilstein J. Org. Chem. 2022, 18, 1264–1269, doi:10.3762/bjoc.18.132

• compound 2. The isopropenyl residue of the target compound 1 was assembled through a two-step sequence. The first one was the addition of an excess of methylmagnesium bromide to the ester 2, that completed the carbon skeleton. The second step was the pH-controlled regioselective dehydration of the tertiary

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• on the SiMe(OSiMe3)2 unit, which were readily converted through Pd- or Cu-catalyzed electrophilic substitution reactions into an array of furfurals decorated at C3 with carbon- or heteroatom-containing substituents (Scheme 1). Conversely, all of our subsequent efforts to achieve cross-coupling

• ). With the 3-silylated 2-furyl carbinol substrates at hand, we then considered C–Si bond activation strategies relying on the assistance of the oxygen atom to promote electrophilic substitution reactions with carbon electrophiles. C3–Si bond functionalization through intramolecular activation by

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

•  1b). Alternatively, the oxidation of α-C–H of active methylene ketones generate α-carbon-centered radicals, thus providing another way to obtain thiazoles. Recently, Sun et al. reported a tert-butyl hydroperoxide/azodiisobutyronitrile-mediated synthesis of 2-aminothiazoles from active methylene

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• : preussochromones E and F. Review 1. α-Ketoesters as key intermediates: (+)-Euphorikanin A In the final step of the synthesis of (+)-euphorikanin A (16), an ingenane-derived diterpenoid with a 5/6/7/3-fused tetracyclic carbon skeleton, Carreira et al. used an intramolecular nucleophilic addition of an alkenyl metal

• ). (−)-Jiadifenoxolane A The Illicium sesquiterpenes containing a seco-prezizaane carbon framework are highly oxidized, structurally complex natural products. Maimone et al. published a remarkable synthesis of the Illicium sesquiterpene (−)-jiadifenoxolane A (36), starting from the abundant sesquiterpene (+)-cedrol (31

• diesters and ester amides as key intermediates (+)-Awajanomycin Diethyl mesoxalate (90a) is a valuable building block due to the high density of carbon atoms in high oxidation states. As a vic-tricarbonyl compound, its central keto group is an especially potent electrophile. The Koert group used this

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation

• Nosheen Beig,
• Aarti Peswani and
• Raj Kumar Bansal

Beilstein J. Org. Chem. 2022, 18, 1217–1224, doi:10.3762/bjoc.18.127

• which their observed relative dienophilic reactivities could be rationalized. Besides, the Fukui functions of the carbon/nitrogen and phosphorus atoms of the >C=P– and –N=P– functionalities were also computed which revealed their hard electrophilic character and accorded well with the dienophilic

• As discussed earlier, the descriptor Fukui function was developed to determine the hard/soft character of the reactive site in a molecule [19][20][21]. The Fukui functions at the carbon/nitrogen and phosphorus atoms of the >C=P– or –N=P– functionality of 2-phosphaindolizines calculated from the

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

• Blaine G. Fiss,
• Georgia Douglas,
• Michael Ferguson,
• Jorge Becerra,
• Jesus Valdez,
• Trong-On Do,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125

• , mechanochemical synthesis of phosphorus-bridged heptazine-based carbon nitrides (g-h-PCN). The structure of these materials was determined through a combination of powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), 31P magic angle spinning nuclear magnetic resonance (MAS NMR), density

• -PCN300) show a reduction in photoluminescent recombination, as well as a nearly two-time increase in photocurrent under broad spectrum irradiation, which are appealing properties for photocatalysis. Keywords: carbon nitride; density functional theory; mechanochemistry; phosphorus; photochemistry

• ; Introduction The development of heteroatom-doped graphitic carbon nitrides (g-CN) has been a rapidly growing area of research since their first report towards water splitting in 2009 [1]. Since that time, the addition of elements such as boron [2], phosphorus [3][4][5], sulfur and oxygen [6] have shown to help

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• ][26]. Donor–acceptor cyclopropanes constitute an easily available equivalent of all-carbon 1,3-zwitter-ions used in targeted synthesis of various alicyclic as well as carbo- or heterocyclic compounds [27][28][29][30]. The reactive synergy of the three-membered ring and the C–C bond polarization due to

• well as ring-opened fluorinated products [46]. Thus, recent publications on the topic concern only anodic opening of a cyclopropane ring followed by further functionalization of the carbon skeleton, demonstrating great synthetic potential of the process. Electrochemical cyclopropane opening followed by

• almost independent on the substituent at the α-carbon atom in the amino acid fragment. Electrochemical reduction of complexes containing an unsubstituted cyclopropane ring (1) or bearing Me (2) substituents is similar to that for α-alkyl derivatives: they exhibit reversible one-electron reduction (the

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

• Mana Kitano,
• Tsuyoshi Saitoh,
• Shigeru Nishiyama,
• Yasuaki Einaga and
• Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

• of cumene hydroperoxide as a starting material afforded acetophenone [18]. It should be noted that the tertiary carbon at the benzyl position is a key for the present molecular transformation, since acetophenone was yielded in 19% as the main product by the electrolysis of sec-butylbenzene as a

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

• . Keywords: 4-acetyl-3-hydroxy-3-pyrroline-2-ones; 1,5-dihydro-2H-pyrrol-2-ones; pyrrolidine-2,3-dione; 2-pyrrolidinone derivative; 3-pyrroline-2-one; Introduction 2-Pyrrolidone, also known as γ-lactam, is a five-membered heterocyclic ring containing four carbon and one nitrogen atoms [1]. This γ-lactam

• NMR spectrum of 4c in CDCl3 showed sharp peaks at 29.21 ppm and 194.61 ppm representing the two carbon atoms of the acetyl group attached to the 4-postion of the heterocyclic five-membered ring. Therefore, the broadening of peaks observed in the 13C NMR spectra is due to the tautomerism of compounds

• between the amino proton and the carbon of the methyl group separated by three σ-bonds. Thus, the reaction between 2-pyrrolidinone derivatives 4a–c and nucleophilic amines 9a–d is confirmed to occur at the carbonyl group of the acetyl moiety to achieve 1,4,5-trisubstituted pyrrolidine-2,3-dione

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

• glassy carbon (Figure 8). The oxidation potential of oligosaccharides 2a and 3a (Eox = 1.76 and 1.74 V vs SCE) was higher than that of monosaccharide 1a (Eox = 1.70 V vs SCE). We also examined electrochemical activation of tetrasaccharide 4a to obtain octasaccharide 8a through the dimerization of 4a

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• light-mediated carbon–heteroatom cross-couplings of sodium sulfinates, carboxylic acids and sulphonamides with aryl halides (Figure 2) [28]. Although recyclable, batch reactions are characterized by long reaction times (24 h). Here, we present a detailed investigation of a continuous-flow strategy for

• micro-batch reactors (SMBR), b) rotor-stator spinning disk reactors, c) slurry with pulsator, d) packed bed. Light-mediated carbon–heteroatom cross-couplings. The yields reported are the NMR yields obtained in flow with the optimized conditions described later. DMAc = dimethylacetamide, DMSO = dimethyl

Electrogenerated base-promoted cyclopropanation using alkyl 2-chloroacetates

• Kouichi Matsumoto,
• Yuta Hayashi,
• Kengo Hamasaki,
• Mizuki Matsuse,
• Hiyono Suzuki,
• Keiji Nishiwaki and
• Norihito Kawashita

Beilstein J. Org. Chem. 2022, 18, 1116–1122, doi:10.3762/bjoc.18.114

• ). Various parameters were varied to increase the chemical yield, as shown in Table 1. For example, the use of carbon felt as the cathode produced 2 in ≪25% yield (Table 1, entry 2). The small influence of the anodic electrode material was confirmed in the reaction using carbon felt as the anode. In this

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

• migrates to the π-system and is stabilized in the ortho- and para-positions, generating diverse carbon radical intermediates. As a result, various dimers are formed via promiscuous coupling of these radical intermediates. Although we cannot exclude the possibility that other P450 enzymes in S. cattleya may

Radical cation Diels–Alder reactions of arylidene cycloalkanes

• Kaii Nakayama,
• Hidehiro Kamiya and
• Yohei Okada

Beilstein J. Org. Chem. 2022, 18, 1100–1106, doi:10.3762/bjoc.18.112

• electrolyzed at 1.3–1.5 V vs Ag/AgCl using carbon felt electrodes (10 mm × 10 mm) in an undivided cell with stirring. Then, the solution was diluted with water and extracted with EtOAc. The combined organic layers were dried over Na2SO4, filtered, and concentrated in vacuo. Yields were determined by 1H NMR

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• . Cyclic voltammetry traces for rhenium complexes 27a–d, 29 and 30: 0.5 mM in MeCN solution with 0.1 M Bu4NPF6 under nitrogen at 25 °C, recorded at 0.1 V/s at a glassy carbon electrode and referenced to the saturated calomel electrode (SCE) using Fc/Fc+ as an internal standard (0.46 V vs SCE [12

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• electrolysis; Introduction Carbon–carbon bond formation is one of the most fundamental and important reactions in synthetic organic chemistry. Reductive coupling of carbonyl compounds known as pinacol coupling would be a powerful method to construct vic-1,2-diol scaffolds through C–C bond formation [1][2

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• plate cathode and a Pt wire anode (a quasi-divided cell) [24][25][26][27][28] in the presence of carbon dioxide resulted in reductive carboxylation at the cathode and selective formation of N-acyliminium ions of DMF at the anode to produce coupling products, N-phenylacetoxymethyl-N-methylformamides, in

A versatile way for the synthesis of monomethylamines by reduction of N-substituted carbonylimidazoles with the NaBH₄/I₂ system

• Lin Chen,
• Xuan Zhou,
• Zhiyong Chen,
• Changxu Wang,
• Shunjie Wang and
• Hanbing Teng

Beilstein J. Org. Chem. 2022, 18, 1032–1039, doi:10.3762/bjoc.18.104

• ][31] and carbon dioxide (CO2) [32][33][34][35][36][37][38][39] have been developed for the N-methylation of amines. However, these N-alkylation methods often require the employment of expensive catalysts, and the N-alkylation of primary amines generally does not stop with monomethylation as expected

• suitable stability for isolation or storage, and various good methods for their perparation have been developed by employing different starting materials such as amines [56][57][58], isocyanates [59][60][61] and carboxylic acids [62]. Since the carbonyl carbon atom of the carbonylimidazole moiety is easily

• acted as a nucleophile to attack the carbonyl carbon to cause the imidazolium ion to leave without reducing the carbonyl group. Although this work expands the application of N-substituted carbonylimidazoles, the reaction can still be regarded as a substitution reaction, which is attributed to the weak

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• (Ecell = 2.3 V, carbon cloth anode, and Pt cathode) of 1-phenylvinyl acetate (1) with azidotrimethylsilane was performed and the desired α-azidoketone (2) was obtained in 68% yield (Table 1, entry 1, for details of the reaction optimization see Supporting Information File 1). The cyclic voltammetry

• relevant heterocycles. From vinyl acetates to α-azidoketones. Substrate scope. Reaction conditions: α-arylvinyl acetate (0.5 mmol), TMSN3 (1.0 mmol), n-Bu4NPF6 (0.5 mmol), H2O (2.5 mmol), MeCN (5 mL), carbon cloth anode, platinum cathode, undivided cell, Ecell = 2.3 V, room temperature, 6 h. a2 h

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• -4 to C-1, C-2, C-3, C-5, and C-6, from 6-OCH3 to C-6 established a central five-membered carbon ring. Meanwhile, the correlations from H-4 to C-1’, C-1’’, from H-2’ and H-6’ to C-5, and from H-2’’ and H-6’’ to C-3 showed that two benzene rings were conjugated to the central ring at the C-3 and C-5

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

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

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• in the reaction. Because there is only one chiral carbon atom in the molecule, there are no diastereoisomers in the obtained products 3a–l. The chemical structures of compounds 3a–l were fully characterized by IR, HRMS, 1H and 13C NMR spectra. As for an example, the 1H NMR spectrum of compound 3i

• dialkyl but-2-ynedioate. Thus, a quasi-four-component reaction led to the final product. There are two chiral carbon atoms in the molecules, thus two diastereoisomers would be formed in the reaction. However, the 1H and 13C NMR spectra gave only one set of resonances for the characteristic groups, which

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• conversion to the corresponding thione (Scheme 2) [12]. NHCs are used as organocatalysts in many reactions of aldehydes (mainly aromatic) [13][14]. In fact, the reaction of NHCs with aldehydes can lead to the formation of the “Breslow intermediate” [15], in which the reactive character of the carbonyl carbon

• and a carbon-filled polyvinylidene fluoride (C/PVDF) plate as anode. BMImBF4 0.1 M in acetonitrile was the catholyte, while the anolyte was a solution of tetraethylammonium tetrafluoroborate (Et4NBF4) in acetonitrile; after only 12 minutes of electrolysis the current flow stopped. Moreover, a

• carbon-filled polyvinylidene fluoride (C/PVDF) and the cathode material is described in Table 1. Electrolyzes were carried out at room temperature, under nitrogen atmosphere, using a solution of 0.1 M of BMImBF4 in acetonitrile as catholyte. Anolyte solution is given in Table 1. Electrolyte solutions