Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

• Matthew J. Fleming and
• David M. Hodgson

Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155

• alkoxide. Keywords: alkenes; aziridines; epoxides; lithiation; synthetic methods; Introduction Methods for the convergent generation of alkenes can be of significant utility in organic synthesis [1]. A relatively under-examined approach is through the interaction of two carbenoids [2]. Dimerisation of

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• catalyst-bound alkoxide species (3·OEt) that is then able to attack the benzaldehyde for product 2 formation. However, it took some time until the scientific community started considering and taken cognizance of the potential of this type of activation mode in catalysis. In this regard, Jacobsen and co

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• catalysts (Scheme 11) [63]. Here, the use of a zinc-based Lewis acid (LA) was found to activate α-hydroxy C‒H bonds by forming alkoxide (O‒LA) and suppressing the C‒O bond formation by inhibiting the formation of a nickel alkoxide species. The authors also claimed that the use of the zinc-based LA also

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• , 26, and 28. The materials were prepared by the Pd(0)-mediated coupling of lithium N-arylindole-3-alkoxide 21 with 3-bromo-N-arylindole 22, followed by a further C-2 bromination (24) and subsequent Suzuki reaction with boronic acids 27 or 25 (Scheme 4) [42]. A similar class of molecules have found

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• -bifunctional organomagnesium alkoxide reagent 107, which converted esters into di- and monofunctionalized anthracenes (Scheme 25) [59]. They prepared this reagent by deprotonation–magnesiation of compound 106. Then, the treatment of aromatic esters with 107 produced dialkoxide 108, which could be easily

• anthracenes from a bifunctional organomagnesium alkoxide. Palladium-catalyzed tandem C–H activation/bis-cyclization of propargylic carbonates. Ruthenium-catalyzed C–H arylation of acetophenone derivatives with arenediboronates. Pd-catalyzed intramolecular cyclization of (Z,Z)-p-styrylstilbene derivatives

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• ) positively influenced the regioselectivity, albeit with poor conversion (59–72%) when compared with other inorganic carbonate bases (vide supra). Despite poor conversion (30%), the use of the strong alkoxide base, potassium tert-butoxide, in tetrahydrofuran (THF) gave an appreciably higher degree of N-1

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• mixing the (n-Bu4N)2CeIVCl6 complex with BnOH under basic conditions. The UV–vis spectra of the CeIV(OBn)Cln complex displayed a band resembling the LMCT band of known cerium–alkoxide complexes, showing considerable overlap with the blue LED region, thus suggesting that the CeIV(OBn)Cln species could be

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• formed by the conjugate addition of the phosphine to the Michael acceptor, is believed to be protonated by the alcohol forming the actual catalytically active species namely ion pair ii, consisting of a phosphonium cation and an alkoxide. The alkoxide in ii then reacts with another electrophile

• alkoxide to yield the product iv and the phosphine. Our results disclosed in the following contribute to the rational selection of proper (pre-)catalysts for this and similar reactions also considering the oxygen sensitivity of the nucleophiles. Results and Discussion To compare the activity of the

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• could be conducted in an air atmosphere, and the reaction times were shorter using a combination of Fe(acac)3 and PhSiH3 as the reductor (Mukaiyama-like conditions) in the presence of an alkoxide source (Scheme 21) [79]. Under these conditions, the radical formed after the HAT with unactivated olefins

Synthesis of functionalized imidazo[4,5-e]thiazolo[3,2-b]triazines by condensation of imidazo[4,5-e]triazinethiones with DMAD or DEAD and rearrangement to imidazo[4,5-e]thiazolo[2,3-c]triazines

• Alexei N. Izmest’ev,
• Dmitry B. Vinogradov,
• Natalya G. Kolotyrkina,
• Angelina N. Kravchenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2021, 17, 1141–1148, doi:10.3762/bjoc.17.87

• is, probably, a result of a transamidation reaction upon the treatment with a base, for example, alkoxide anion. The nucleophilic attack of the alkoxide anion leads to the cleavage of the C(7)–N(8) bond to form intermediates B and C followed by the recyclization of the thiazolidine ring involving the

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

•  18). A sequence of reactions involving elimination of a proton from 83, treatment of 84 with an alkoxide, and protonation of the resulting enolate delivered thermodynamically favored equatorial ester 80 and 81. The highly diastereoselective Brønsted superacid-catalyzed Prins cyclization of

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• -allylic 2-silylacetamides would provide an intermediate alkoxide from which the Brook rearrangement and subsequent oxygenation could proceed (Scheme 1C). This represents in the event a geminal C–C/C–O difunctionalization of amide 8 and results in the α,γ-dioxygenated N-allylic amides 9. Thermal radical

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• and cleaning agents [272][273]. It should be finally mentioned that during the alcoholysis reaction of PLA using alkoxide catalysts, alkaline earth metal adducts (typically of Ca2+) were isolated, and thus suggesting a potential involvement of the metal centre in the depolymerisation mechanism [274

The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst

• Deniz Tözendemir and
• Cihangir Tanyeli

Beilstein J. Org. Chem. 2021, 17, 494–503, doi:10.3762/bjoc.17.43

• Houk’s mode of activation was of lower energy than Wynberg’s activation mode, in which the activation and orientation of the nucleophile is done by the quinuclidine core [43]. According to our proposed model, the protonated quinuclidinium ion stabilizes the newly forming alkoxide on the electrophile

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• halodifluoromethanes and alkenes (Scheme 2). The elimination of hydrogen halide from the halodifluoromethane under basic conditions (metal alkoxide or alkyllithium) generated difluorocarbene [14][15]. The low yields of the product have been attributed to the facile addition of the strong bases to difluorocarbene. The

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

• Takashi Yamazaki,
• Yoh Nakajima,
• Minato Iida and
• Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

• the isolated product 4aa was subjected to the conditions shown in Table 3, entry 4, no reaction was observed at all, with recovery of 4aa, which clearly demonstrated that the deacetylation step had occurred before the conversion to 4aa. In the present cyclization, the ionic character of the alkoxide

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• . While the deprotonation/protonation equilibrium preferentially takes place at the 2- and 6-positions of the β-CD [29], the alkoxide located on the primary face at the 6-position is more inclined to react with the bulky mesitylenesulfonate group than the alkoxide on the secondary face at the 2-position

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• insertion into the formyl moiety to afford the corresponding cobalt alkoxide Int-3a, (4) protonation of Int-3a with HX (X = acac, OiPr, or OH), giving rise to the desired 2-fluoroalkylated indenol 3. The formation of the 3-fluoroalkylated indanones as a side product may be explained based on the previous

• literature [20][40]. The reaction of Int-1 with the alkynes 1 also gives Int-2b as a regioisomeric intermediate of Int-2a, leading to the 3-fluoroalkylated cobalt alkoxide Int-3b. Subsequently, the proton shift of the cobalt alkoxide Int-3b provides the allylcobalt species Int-4b because the acidity of the

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• h, providing a 10-fold increment in throughput and space–time yield (Table 5). We also found that LiBr could be used. The reaction was carried out under the same conditions. The high solubility of LiBr provided solutions that remained clear for days (TMPMgCl⋅LiBr 0.84 M, 84%, Scheme 2). 5 Alkoxide

• bases via stratified packed-bed columns containing magnesium and LiCl Objective: To generate magnesium alkoxide–lithium chloride complexes by telescoped reactions of turbo Grignards with tert-amyl alcohol using stratified bicomponent packed-bed columns composed of magnesium metal and lithium chloride, a

• T-mixer, and a coil reactor. Challenges: Alcohol incompatibility with the activating solution and alkoxide solubility. System setup: The same flow system was used as for the generation of turbo Grignard reagents. Extra feed was added between the packed-bed column and the coil (V = 10 mL, ID = 0.03

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

• achiral copper for similar purposes. In general, the pathway for introducing boron into unsaturated compounds (C–B coupling) mediated by a copper catalyst relies on the reaction of a Cu(I) salt with an alkoxide (M–OR) which then undergoes transmetallation with an organoborane to form, e.g., L-Cu-Bpin (306

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• from the oxidation of the amine with the formed [Cu(II)] complex, followed by a deprotonation by DABCO. The resulting alkoxide is finally converted into the alcohol by the protonated DABCO. During this study, the authors found that replacement of the base by the Brønsted acid (R)-1,1-binaphtyl-2,2-diyl

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• ) species B. The 1,2-addition of silylcopper(I) B to the aromatic aldehyde 1 [15][16][17][18][19] and the subsequent [1,2]-Brook rearrangement from the obtained α-silyl-substituted copper(I) alkoxide C forms the key intermediate, an α-silyloxybenzylcopper(I) species D. The transmetallation between D and an

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

• alkoxide anions. This reduces the occurrence of undesirable side-reactions, e.g., intermolecular aldol reaction, lactone/ketonitrile product dimerization and ring-opening polymerization. The application of this method to produce the analogous hemiketal 6 from γ-butyrolactone was not as efficient. Although