Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• reagents offer a viable alternative to traditional aryl-λ5-iodane-based oxidants, although further studies are necessary to fully understand their reaction mechanisms. Experimental General procedure for oxidation of benzylic alcohols 1a (700 µmol, 201 mg, 1.40 equiv), benzylic alcohol (3, 500 µmol, 1.00

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• to a phosphine radical cation. The proposed mechanism involves the formation of a phosphine radical cation via SET from photoexcited [Ir(III)] complex. Subsequently, the benzylic alcohol initiates a polar nucleophilic attack on the phosphine radical cation, forming a phosphoranyl radical. This

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• according to well-established protocols [71][72][73][74]. The β-ketoesters were obtained employing a sequence of two reactions, the formation of the benzylic alcohol derivative, through a Reformatsky reaction using In(0), followed by a pyridinium chlorochromate (PCC) oxidation, giving the β-ketoesters 7a–g

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• to 93% yield of the desired products (Scheme 63), whereas a secondary benzylic alcohol gave the product in 68% yield. When substituted indoles were reacted with benzyl alcohol the C-3-benzylated indole products were obtained with up to 96% yield under the same reaction conditions. After the

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• reaction is possible upon elimination of the resulting benzylic alcohol on D, allowing another arylation forming E [18]. This complex sequence of transformations is herein applied to the synthesis of 1-aryltetralines, analogues of cyclolignan natural products having important medicinal applications [19][20

Linker, loading, and reaction scale influence automated glycan assembly

• Marlene C. S. Dal Colle,
• Manuel G. Ricardo,
• Nives Hribernik,
• José Danglad-Flores,
• Peter H. Seeberger and
• Martina Delbianco

Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77

• ] and L2 [3] are based on the o-nitrobenzyl scaffold [23][24] and expose a hydroxy group that serves as glycosyl acceptor in the first AGA cycle (Figure 1B). While L1 displays a flexible aliphatic chain terminating with a primary alcohol, L2 carries a secondary benzylic alcohol. Upon irradiation with UV

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• biomimetic oxidation of benzyl alcohols was developed using o-naphthoquinone [129] (Scheme 28). The reaction shows regioselectivity toward benzylic alcohol oxidation. This process could be included in one-pot synthesis strategies. The key step of the reaction is a 1,5-hydrogen transfer (the suggested

• oxidative organocatalysis. Electrochemical DDQ-catalyzed intramolecular dehydrogenative aryl–aryl coupling. DDQ-mediated cross-dehydrogenative C–N coupling of benzylic substrates with azoles. Biomimetic o-quinone-catalyzed benzylic alcohol oxidation. Electrochemical synthesis of secondary amines by

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• the racemic naphthohydroquinone hongconin (197) starting from the ortho-allyl alcohol derivative 195. The starting material was cyclized using a Hg(II) salts to get an inseparable mixture of products 196a and 196b in the ratio of 1:5 [121]. The synthetic route proceeded by benzylic alcohol ortho

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

• benzylic alcohol selectively to the aldehyde or ketone is still desirable. Recently, cerium photocatalysis was introduced as a robust alternative to generate oxygen or carbon-centered radicals under mild reaction conditions [57][58][59][60][61][62][63][64]. CeCl3 reacts via ligand-to-metal charge transfer

• benzylic alcohols were tested and 2-fluoro (1l) and 2-chloro (1m) benzyl alcohols gave the aldehydes 2l and 2m in good yields. The o-phenyl-substituted benzylic alcohol (1n) afforded biphenyl-2-carbaldehyde (2n) in only low yield (25%) probably due to steric reasons. The o-methyl (1o) and o-methoxy (1p

• , 1s) were oxidized under our reaction conditions giving the corresponding aldehydes (2q, 2s) in good yields. Also, the meta-substituted benzylic alcohols 1t–v reacted to the corresponding benzaldehydes in good yields in our reaction conditions. Ortho/para-disubstituted benzylic alcohol 1w gave 2,4

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• benzylic alcohol byproducts (Table 1, entries 6–9). In view of these results, we decided to continue the optimization of the reaction conditions by testing other oxidizing agents and solvents but only for the CoNPs/MgO catalyst. Thus, we found that using this catalyst, in refluxing MeCN as the solvent and

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• of the benzylic cation intermediate 48f↔48f’, stabilized by the phenyl group (Scheme 12b). Substrate 51, bearing a tert-butyl group in the para-position, was also submitted to solvolysis in labeled H218O, generating the labeled benzylic alcohol 18O-52 (Scheme 13). The solvolysis of 51 was found to be

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• equiv) in dichloromethane. The reaction was slow and required heating (50–65 °C) for 26 h to reach a 75% conversion and afforded a mixture of E/Z-1a in 60% yield. However, a low E/Z selectivity (40:60) was observed (Table 1, entry 1). When using neat benzylic alcohol, completion was achieved after 20 h

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

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• and Brückner reported the synthesis of 7-hydroxy-2,3-benzotropones by ring-closing metathesis (Scheme 48) [173]. 7-Hydroxy-2,3-benzotropone (241) was synthesized in four steps starting from a Br/Li exchange reaction of o-bromostyrene (283) followed by the addition of aldehyde 284 to give the benzylic

• alcohol 285. Oxidation with Dess–Martin periodinane of the alcohol 285 followed by ring-closing metatheses in the presence of 1 mol % of the second generation Grubbs catalyst (287) gave the 5H-benzo[7]annulene-5,6(7H)-dione monoketal 288 in nearly quantitative yield. The hydrolysis of 288 with excess p

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• with the synthesis. Compound 28b was treated with DeoxoFluor at low temperature, in order to affect a deoxyfluorination of the benzylic alcohol. This reaction gave the product 31 in high yield, but unfortunately with poor stereoselectivity, presumably due to a competing SN1-type reaction mechanism [36

Selective enzymatic esterification of lignin model compounds in the ball mill

• Ulla Weißbach,
• Saumya Dabral,
• Laure Konnert,
• Carsten Bolm and
• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1788–1795, doi:10.3762/bjoc.13.173

• monoacetylated derivatives, and the reactions occurred regioselectively at the primary hydroxy group of the model compounds. The regioselectivity of the reaction was further confirmed after the milling of isopropenyl acetate (2a) and the monolignol 1i, only containing a benzylic alcohol. After the standard

• addressing the centrally-located primary aliphatic hydroxyl content of lignins is still highly possible. This strategy is expected to allow the preservation of the phenolic and benzylic alcohol contents in modified lignins, in order to keep the antibacterial and antioxidant activities of this biopolymer

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• reaction mixture. The corresponding carbonyl compounds were obtained in moderate to good yields. Keywords: benzylic alcohol; oxidation; photocatalysis; solvent free; visible light; Introduction According to a classification made by Wilhelm Ostwald, one of the pioneers in the field of physical chemistry

• as photocatalyst under blue light irradiation was performed. Furthermore, the oxidation of a liquid benzylic alcohol is presented as well. Results and Discussion For our investigations on solvent-free photocatalytic conversions, we chose riboflavin tetraacetate (RFTA) as photocatalyst. RFTA and

• mechanical but by electromagnetic energy input, realized by blue light irradiation. Furthermore, the heat input is not the primary cause for the reaction, but its prerequisite. Subsequently, the scope of the benzylic alcohol oxidation was investigated, applying 5% of RFTA. Four solid alcohols were oxidized

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• of 11 to 12 in excellent yield was catalysed by Hg(II), instead of Au(I). With furan 12 in hand, it was then transformed into the furan analogue 17 of ThDP by the same route as previously used for the synthesis of deazaThDP 2 [9][10], Scheme 4. Thus selective oxidation of the benzylic alcohol with

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• . With the newly optimized reaction conditions at hand different benzylic alcohol derivatives were investigated (Table 3). Uniformly very good isolated yields after short reaction times were achieved in case of dibenzylic alcohol derivatives. Steric bulk (Table 3, entry 2), as well as a broad range of

• observed. Moving to monobenzyl alcohols, e.g., replacement of one aromatic group with an alkyl chain resulted in prolonged reaction times but nevertheless acceptable yields of the deoxygenated products (Table 3, entries 8 and 9). With α-carbonyl-substituted benzylic alcohol derivatives irradiation times

Homochiral BINOL-based macrocycles with π-electron-rich, electron-withdrawing or extended spacing units as receptors for C₆₀

• Marco Caricato,
• Silvia Díez González,
• Idoia Arandia Ariño and
• Dario Pasini

Beilstein J. Org. Chem. 2014, 10, 1308–1316, doi:10.3762/bjoc.10.132

• with a BINOL derivative with masked phenol functionalities in the 2,2’-positions and benzylic alcohol functionalities in the 3,3’-positions (diol 1 in Scheme 1). The incorporation of sp3 methylene carbon atoms in the cyclic structure adds a certain degree of conformational freedom to the covalent

A unified approach to the important protein kinase inhibitor balanol and a proposed analogue

• Tapan Saha,
• Ratnava Maitra and
• Shital K. Chattopadhyay

Beilstein J. Org. Chem. 2013, 9, 2910–2915, doi:10.3762/bjoc.9.327

• effected a smooth conversion to the new benzylic alcohol 10. The latter was oxidized with tetrapropylammonium perruthenate to provide the benzophenone derivative 11 in good yield. Subsequent cleavage of the 1,3-dioxane unit followed by oxidation of the resulting aldehyde 12 furnished carboxylic acid 13 in

Synthesis of the spiroketal core of integramycin

• Evgeny. V. Prusov

Beilstein J. Org. Chem. 2013, 9, 2446–2450, doi:10.3762/bjoc.9.282

• NOE-correlation for H-18 and H-22 protons in the NOESY spectrum of 4 (see Supporting Information File 2). In the case of the ketone with the TES-protected benzylic alcohol, exposure to 2 N HCl in THF resulted in formation of numerous products, including the spiroketal 4, thus demanding further

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• strong P1 base polymer-supported BEMP gave the corresponding ether adduct which was then converted to the desired secondary amine 1.64 via direct amidation and borane-mediated reduction. Next an SNAr reaction on 2-fluoropyridine (1.66) followed by oxidation of the benzylic alcohol using immobilised

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• benzylic alcohol 20 [28]. Protection as the THP acetal 21 was essential before preparing the boronic acid 22. Previously (see [15]), we reported on a synthesis of 22 starting with the bromination of 3-methoxybenzyl alcohol to 4-bromo-3-methoxybenzyl alcohol. In contrast to the original contribution [29