Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• ). Eosin Y was inefficient under these conditions (Table 1, entry 20). Since [Ru(bpy)3]Cl2 is significantly cheaper than the iridium catalyst, the former was used in further reactions. Regarding the addition of different bases, the yield remained unchanged, when lutidine was added. Potassium carbonate and

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K₂CO₃/n-Bu₄PBr in water

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati and
• Gregor Schnakenburg

Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71

• of potassium carbonate and tetrabutylphophonium bromide, which mediate the reaction in water through the formation of the interface between organic and aqueous phases. The advantageous of this reaction include high yields, no column chromatography, broad substrate scope, multiscale synthesis, and

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• developing systems, and products were detected by inspection under UV light (254 nm) and with a solution of potassium permanganate. Merck Kieselgel 60 (0.063–0.200 μm), Merck Kieselgel 60 (0.040–0.063 μm), and Merck Kieselgel 60 (0.015–0.004 μm), were used for column chromatography. X-ray diffraction data

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• ) as atom-economical boron sources leading to the desired products 432–435 in moderate to good ees (Scheme 69) [132]. In addition, the reaction of potassium N-(4-methoxyphenyl)-3-(trifluoroborato)butanamide (436) as the nucleophilic coupling partner was investigated with heteroarylchlorides 437 leading

Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

• Zeguo Fang,
• Nawaf Al-Maharik,
• Peer Kirsch,
• Matthias Bremer,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

• to generate 13a and 13b as a mixture of regioisomers in a ratio of 4:1. There was no requirement to separate these isomers at this stage. Subsequent addition of potassium tert-butoxide into a mixture of 13a and 13b in dichloromethane (DCM) resulted in an efficient elimination to generate vinyl

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• choice in this type of coupling reaction. Potassium carbonate was chosen due to the sensitivity of the amide 3 towards harsh basic conditions. With these conditions we were able to couple (Z)-bromide 4 with amide 3 selectively to yield (Z)-enamide 16. The obtained double bond geometry was confirmed by

• the indicative NMR coupling constants of 9.6 Hz. Moreover, we observed a concentration dependent formation of the undesired desilylated (Z)-enamide 17 (Table 1). The best results were achieved using a 65 mM solution of the amide 3. Using dry potassium carbonate, purified copper(I) iodide provided the

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• potassium selenocyanate proceeded via a rearrangement with ring expansion, leading to a six-membered 2,3-dihydro-1,4-thiaselenin-2-yl selenocyanate (kinetic product) which in turn underwent rearrangement with ring contraction to a 1,3-thiaselenol-2-ylmethyl selenocyanate (thermodynamic product). These

• 1 with potassium selenocyanate was studied in detail. We found that the reaction of thiaselenole 1 with KSeCN at room temperature afforded a five-membered heterocycle, selenocyanate 4, in a quantitative yield. This result was unusual since previously studied substitution reactions of thiaselenole 1

• potassium selenocyanate led to the six-membered thiaselenine 5 (kinetic product), which underwent a rearrangement to a five-membered thiaselenole selenocyanate 4 (thermodynamic product). These rearrangements proceeded by a nucleophilic attack of the selenocyanate anion on two different carbon atoms of the

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• important role to promote this ring-opening N-alkylation, but also acts as an oxygen donor. Keywords: N-alkylation; oxazolines; potassium tert-butoxide; ring opening; thiazolidinones; Introduction 2-Oxazolines are important structural units in pharmaceutical applications and efficient ligands in

• to synthesize thiazolidinone derivatives through a Barton–McCombie pathway in 2015 [17] (Scheme 1b). Recently, potassium tert-butoxide has been shown to be an efficient promoter for C–C-bond formation reactions [18][19][20][21][22]. However, only few reports described C–N-bond cross-coupling

• reactions using potassium tert-butoxide as promoter. Wu developed an efficient protocol for the KOt-Bu-promoted synthesis of 1-aminoisoquinolines from 2-methylbenzonitriles and benzonitriles [23], and the carbonylative cyclization of propargylic amines with selenium under CO gas-free conditions [24]. Based

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• potassium 2-cyano-2-fluoroethenolate was developed. A broad substrate scope was tested and mostly excellent yields were obtained. The synthesis of fluorinated aminopyrazoles from the same fluorinated precursor could be demonstrated but proceeded with lower efficiency. Keywords: cyclization; fluorinated

• fluorinated C3 building block recently described and used by our laboratory for the synthesis of 2 [36]. Herein, we present the synthesis of fluorinated pyrimidines and pyrazoles from the same precursor. Potassium (Z)-2-cyano-2-fluoroethenolate (8) was synthesized in three steps starting from chloroacetamide

• ) of potassium formate, which could not easily be removed without risking the decomposition of the enolate salt (Scheme 1). As the fluorine atom is part of a building block, harsh conditions for a late-stage fluorination can be avoided, and even products with sensitive functionalities are accessible

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• the red phosphorus with 2-bromopyridine in potassium hydroxide/dimethyl sulfoxide emulsion, pyridylphosphine was obtained in moderate yields. Traces of phosphine oxide were present as evidenced by the observation of two phosphorus peaks in the 15P NMR spectrum. An optimized method via Grignard

• chiral acetal ligands have been reported by Lyle et al. where the fluorine–metal exchange was achieved by treatment with potassium tert-butoxide for a relatively long period (24 h) (Scheme 4) [65]. Acid-catalyzed condensation of compound 20 with enantiomerically pure C2-symmetric 1,2-tosylate analogs 21

• phosphorylation with diphenylphosphine in the presence of potassium tert-butoxide and 18-crown-6. The use of silyl and dialkylamine as reagents Organosilyl, silylphosphine derivatives, along with dialkylamines can also be used as alternative substrates to halogen-based reagents. These compounds are more stable

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• uncorrected. FTIR spectra were obtained in a Perkin–Elmer 1310 spectrometer using potassium bromide pellets. NMR spectra were recorded on an Agilent 500/54 (500 MHz and 125 MHz for 1H and 13C, respectively) spectrometer using CDCl3, and/or DMSO-d6 as solvent. Chemical shifts are given in ppm and J values in

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• form C(sp)–SeCF3 bonds (Scheme 3) [18]. Therein, Dess–Martin periodinane (DMP) was used as the oxidant and potassium fluoride as the base, and the reactions were performed at room temperature in DMF as the solvent. The desired compounds were obtained in moderate to very good yields. Both electron

• tandem formation of C–Se and Se–fluoroalkyl bonds have emerged in the last five years. In 2014, Hor and Weng reported the trifluoromethylselenolation of (hetero)aryl iodides and alkyl bromides with the Ruppert–Prakash reagent, TMSCF3, elemental selenium, potassium fluoride, and silver carbonate under

Synthesis and herbicidal activities of aryloxyacetic acid derivatives as HPPD inhibitors

• Man-Man Wang,
• Hao Huang,
• Lei Shu,
• Jian-Min Liu,
• Jian-Qiu Zhang,
• Yi-Le Yan and
• Da-Yong Zhang

Beilstein J. Org. Chem. 2020, 16, 233–247, doi:10.3762/bjoc.16.25

• shown in Scheme 2, Scheme 3 and Scheme 4. The synthesis of compounds I and III was depicted in Scheme 2 and Scheme 3. The commercially available starting materials reacted with methyl chloroacetate in CH3CN and anhydrous potassium carbonate (K2CO3) as the base, and the corresponding products C and K

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material

• between the acyl isothiocyanate 16 and amines 3, 4, 8, 9, 12 and 13 yielded the title compounds 17a–c and 18a–c in 56–62% yields (17a 57%; 17b 56%; 17c 58%; 18a 61%; 18b 60%; 18c 62%). In an attempt to improve the structural diversity of thioureas, potassium cyanate was used as a nucleophile instead of

• and the amine 4 (Scheme 3, part B). Attempts to improve the reactivity of potassium cyanate by adding crown ethers did not result in the formation of ureas as expected. Thus, five new amides 19–22 and 24 were obtained in yield range of 42–71% (19 42%; 20 53%; 21 58%; 22 53%; 24 71%). Mesomorphic

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

• Jucleiton J. R. Freitas,
• Queila P. S. B. Freitas,
• Silvia R. C. P. Andrade,
• Juliano C. R. Freitas,
• Roberta A. Oliveira and
• Paulo H. Menezes

Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

• were obtained in short reaction time, high yield and purity without the need of any solvent when allenylboronic acid pinacol ester was used, or using a minimal amount of acetone when potassium allenyltrifluoroborate was used. Keywords: boron compounds; microwave; propargylation; regioselectivity

• small proportion of the corresponding regioisomer in some cases, in the development of new synthetic methods, it is desirable that it gives the corresponding product as a single compound. Our group described the synthesis of homopropargylic alcohols using potassium allenyltrifluoroborate as the

• NMR [39] (Scheme 2). Potassium allenyltrifluoroborate (4) is a crystalline solid and despite several microwave promoted reactions can be conducted without the use of solvents, the propargylation reaction using 2-naphthaldehyde and 4 under the previously optimized conditions gave the desired product in

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• of xanthate esters with amines [18]. Furthermore, many methods have also been reported for the synthesis of cyclic thiocarbamates, and these include reactions of isothiocyanates with aldehydes in the presence of organocatalysts [19][20], reactions of vicinal diols with potassium thiocyanate [21

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• -unsubstituted triazolium salt with one equivalent I2 in the presence of two equivalents of potassium tert-butoxide [43]. When 4,5-unsubstituted triazolium salt 1 was treated with two equivalents I2 and two equivalents of potassium tert-butoxide, 4,5-diiodo-1,3-dimesityl-1,2,3-triazolium 2-I was synthesized in a

• dichloromethane solution (Scheme 2). 2-Br and 2-Cl were synthesized by ion exchange between 2-BF4 and the respective potassium halide in acetonitrile. A single crystal of 2-Br was obtained by slow diffusion of n-pentane into a dichloromethane solution. While the single crystal of 2-Cl was obtained by slow

• electrospray ionization mode (ESI). Elemental analyses (C, H, N) were performed on Flash EA 1112 Analyzer. Synthesis 2-I: 4,5-Unsubstituted triazolium salt 1 (450 mg, 1 mmol), potassium tert-butoxide (250 mg, 2.2 mmol) and I2 (510 mg, 2 mmol) were added in a Schlenk tube under nitrogen, then THF (20 mL) was

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• hydroxy ester 4 followed by reaction with acetonitrile (CH3CN), a multistep approach would be less economical in industry (Scheme 1). Results and Discussion To date, the most economically appealing conditions from an environmentally friendly perspective entail relatively mild base-promoted (potassium tert

• -pentoxide or potassium tert-butoxide) acylation of substituted nitrile anions with esters under ambient conditions, as published by Ji et al. (2006) [9] and Kim et al. (2013) [10]. The large excess of ester and expensive base (potassium tert-pentoxide) required in the former method, in our opinion rendered

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

• Hoang Huy Do,
• Saif Ullah,
• Alexander Villinger,
• Joanna Lecka,
• Jean Sévigny,
• Peter Ehlers,
• Jamshed Iqbal and
• Peter Langer

Beilstein J. Org. Chem. 2019, 15, 2830–2839, doi:10.3762/bjoc.15.276

• reported to show potent antiallergic [1][2][3][4], anticancer [5][6], analgesic and anti-inflammatory activity [7] (Figure 1). Similarly, benzofuroindol has been studied intensively as a pharmacophore of calcium-activated potassium channel (BKCa) opening activity [8][9][10][11][12][13]. Hence

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• . Patch pipettes were filled with an internal solution containing (in mM): 135 potassium gluconate, 4 MgCl2, 10 HEPES, 4 Na2-ATP, 0.4 Na2-GTP, 10 Na2-phosphocreatine, pH 7.35. Good recordings were identified only when resting membrane potential (Rp) < −20 mV, holding current < 200 pA at −40 mV, and Rs 10

• an internal solution containing (in mM): 135 potassium gluconate, 4 MgCl2, 10 HEPES, 4 Na2-ATP, 0.4 Na2-GTP, 10 Na2-phosphocreatine, pH 7.35. The red fluorescent dye Alexa 594 (0.05 mM, ThermoFisher Scientific, Waltham, MA, USA) was added to visualize the morphology of the neurons. Normal ACSF was

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• spectrofluorometer fitted with a PMT detector and exciting with a 450 W Xe lamp across a double monochromator, and were corrected for instrumental response. Photoreaction quantum yields were determined upon excitation at 365 nm using the couple potassium ferrioxalate–phenanthroline as a chemical actinometer on an

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• investigated the asymmetric electrodihydroxylation of olefins 69 in an undivided cell under constant current using potassium osmate as a catalyst in presence of Sharpless ligand and using iodine as the oxidizing mediator (Scheme 27). Two sets of conditions were developed, and they differ in the inorganic bases

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• of 5- or 4-aryl-3-chlorothiophene-2-carboxylates, respectively, with methyl thioglycolate in the presence of potassium tert-butoxide. The saponification of the resulting esters, with decarboxylation of the intermediating acids, gave the corresponding thieno[3,2-b]thiophen-3(2H)-ones. The latter

• Fiesselmann reaction with methyl thioglycolate in the presence of potassium tert-butoxide in THF, which afforded aryl-substituted methyl 3-hydroxythieno[3,2-b]thiophene-2-carboxylates 3a–k in 41–78% yields (Scheme 1). Compounds 3 were obtained in analytically pure form after single recrystallization from a

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• carbonate resulted in no reaction at all (Table 1, entry 5). Whereby usage of potassium phenyltrifluoroborate (19) resulted in a yield comparable to boroxine 18b (Table 1, entry 6), usage of pinacol ester 20 showed no reaction in the cross-coupling reaction (Table 1, entry 7). Although described

• were a suitable source, but also potassium trifluoroborates can be taken into consideration for the reaction design, whereas pinacol esters didn’t show any reactivity. While PdCl2(PPh3)2 was a sufficient catalyst for the cross coupling, application of PdCl2(dppf) led to clearly enhanced yields: overall

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• advanced intermediate 28b (Scheme 3), which was subjected to an aromatic nucleophilic substitution with potassium phthalimide prepared in situ from 29 and K2CO3. Presumably due to the alkaline medium, the phthalimide ring was partially opened as detected by HPLC–MS. Upon attempted re-closing under reflux