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

• the corresponding halo-substituted benzaldehydes 2a–d in good yields. The oxidation of simple benzyl alcohol (1e) under our reaction conditions gave benzaldehyde (2e) in 55% yield. A variety of electron-donating para-substituted benzyl alcohols (1f–h) gave lower isolated yields of the corresponding

• -dichlorobenzaldehyde (2w) in 70% yield. The sulfur-containing compounds 4-(phenylthio)benzyl alcohol (1r) and the heterocyclic compound thiophene-2-ylmethanol (1x) gave the corresponding aldehydes 2r and 2x in 61 and 80% yield, respectively. Finally, 2-naphthylmethanol (1y) was subjected to the reaction conditions and

• ][67][68][69]. Under aerobic conditions the catalytic CeIII(OBn)Ln species I (in situ derived by the reaction of CeCl3 (CeIIILn) with the substrate benzyl alcohol, BnOH) could be oxidized to LnCeIV–OBn complex II [67][68][69]. During this process O2 is converted into a superoxide radical anion O2

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• % from benzyl alcohol (16), alongside 50% of the trifluoroacetate 18. Carrying out the same process via a flow-based protocol allowed for the formation of benzaldehyde (17) in 91% yield with only 8% of the accompanying side product 18 [88]. Similarly, a stereoselective alkylation of an Evans’ type

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• carbocation species [52]. Thus, in contrast to the other primary alcohols, an excess of 3.0 equiv was required to provide a moderate 62% yield of mannoside 3g when benzyl alcohol (2g) was used as an acceptor. Next, the formation of tertiary carbenium ion from 3-methyl-butan-2-ol (2i) via 1,2-hydrogen shift in

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• benzyl alcohol delivering a stable aromatized product. Although the yields were comparable under reflux and microwave approach, the conventional approach provided access to the desired molecule in 24 h whereas the microwave assistance exponentially reduced the reaction time to 25 min. A possible

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

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• depsidipeptide ᴅ-Ala-ᴅ-Lac was a new antibiotic strategy. In this regard, the phosphonodepsipeptide hapten 127 was designed to induce the antibody. First, N-Boc-(S)-1-aminoethylphosphinic acid (122) was coupled with benzyl alcohol in the presence of DCC as the coupling reagent, affording the benzyl N-Boc-1

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• ). Cyclohexanol (26) was observed only once in C. marinus, and aromatic compounds included benzyl alcohol (27), benzaldehyde (28) and salicylaldehyde (29), acetophenone (30) and o-aminoacetophenone (31), 2-phenylethanol (32), and phenylacetone (33). 6-Methylhept-5-en-2-one (34) was detected in all strains, while

Coupling biocatalysis with high-energy flow reactions for the synthesis of carbamates and β-amino acid derivatives

• Alexander Leslie,
• Thomas S. Moody,
• Megan Smyth,
• Scott Wharry and
• Marcus Baumann

Beilstein J. Org. Chem. 2021, 17, 379–384, doi:10.3762/bjoc.17.33

• flow process is presented that couples a Curtius rearrangement step with a biocatalytic impurity tagging strategy to produce a series of valuable Cbz-carbamate products. Immobilized CALB was exploited as a robust hydrolase to transform residual benzyl alcohol into easily separable benzyl butyrate. The

• within continuous flow processes [17][18][19][20] to provide a greener and more chemoselective means for the synthesis of drug-like targets. Recently, we reported on an innovative telescoped process using immobilized CALB (Candida antarctica lipase B) to enable the conversion of residual benzyl alcohol

• ). Furthermore, a backpressure regulator (Upchurch, 100 psi) allowed for superheating of the reaction mixture to 120 °C whilst offering control of released nitrogen gas. As the specific target was the generation of a set of Cbz-carbamate products, benzyl alcohol was used as the nucleophile and initial studies

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• detected with hydroxynitrobenzylic alcohol (Table 1, no side product of 4 and 9 with transfer on an aromatic secondary alcohol; i.e., phenol), 2-chloro-4-nitrophenol, or 4NTC (data not shown). Additionally, the exact position of the benzyl alcohol affected the transfer, with ortho-substitutions (R1

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• photosynthetic reaction center for photosynthesis could be realized. König and co-workers demonstrated the use of a flavin–Zn(II)–cyclen assembly (Figure 4) to convert benzyl alcohol to benzaldehyde upon irradiation [20]. This reaction could be performed in both organic and aqueous phases, with a photooxidation

• explained as follows: the zinc(II)–cyclen complex can absorb light and facilitate the intramolecular electron transfer from benzyl alcohol to the excited flavin, and thus the benzaldehyde and the photoreduced flavin were produced. The study indicates the significance of connecting a photosensitizer and a

• of the reactant of 300 mM, ≥93% selectivity), with H2 liberation being achieved by visible-light irradiation in an aqueous solution. In comparison, CdS–CD was a highly efficient photocatalyst for benzyl alcohol dehydrogenation (77 µmol H2 in 180 h) compared to the CD-free CdS (5.4 µmol H2 in 30 h

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• interaction greatly affected the chemical properties. They also reported that complexes that had higher oxidation potential and went through irreversible oxidation were not good catalysts for the oxidation of benzyl alcohol to benzaldehyde (0–30% yields, e.g., PhPhCuO.S.2, O.S.x signifies oxidation state and

• x increases with the removal of electrons). On the other hand, complex t-BuPhCuO.S.2, showing a reversible oxidation behavior very efficiently performs dehydrogenation of benzyl alcohol with low catalyst loading (0.1 mol %) and high turnover numbers (TONs up to 184). Besides the oxidation of benzyl

• reaction of CuII complex 6A with dioxygen to generate a CuII superoxide intermediate 6B. The electron needed to reduce O2 to superoxide is provided by the redox-active ligand. Subsequent coordination of benzyl alcohol results in the formation of species 6C, which undergoes a H-atom abstraction step to form

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• spirothiazolidinediones via a [2 + 2 + 2] cyclotrimerization reaction and the derivatives were further functionalized through DA chemistry and click reaction. Using flow cytometry, it was shown for the first time that the new benzyl alcohol derivatives of thiazolidine-2,4-dione generated here are efficient apoptosis

• strategy with propargyl halides. We have also shown the synthesis of linearly fused spirocyclic alcohol derivatives of thiazolidinedione using Wilkinson’s catalyst and these compounds were tested for their anticancer activity. We have shown for the first time that the new benzyl alcohol derivatives of

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• corresponding carboxylic acid followed by hydrogenolysis with H2/Pd-C led in spontaneous lactonization to give the key butenolide 66. Oxidation of 66 with CrO3/AcOH–H2O, followed by saponification and reduction afforded known benzyl alcohol 46 (19% from 66). Then, phenol 46 was converted to the corresponding

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• synthesis. Comparison of our work with previous studies. Scope of pyridinium salts and benzylamine substrates. Reaction conditions: 1 (1 mmol), 2 (1 mmol), base (2.5 mmol), solvent (5 mL), 80 °C, 8 h. Isolated yields are given in parentheses. Scope of pyridinium salts and benzyl alcohol substrates. Reaction

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• the reaction of 3,4,6-tri-O-acetyl-D-glucal (1a) with benzyl alcohol (2) in the presence of 20 mol % of arylboronic acids in different solvents (Table 1, entries 1–6). Phenylboronic acid failed to promote the reaction in several solvents and the starting glucal 1a was recovered unchanged (Table 1

• blocks especially for natural product synthesis [36][37][38][39][40]. Therefore, we used the perfluorophenyl boronic acid catalyst in the reaction between 2,3,4,6-tetra-O-acetyl-D-glucal (1a) and benzyl alcohol, n-butyl alcohol, cyclohexyl alcohol and p-toluenethiol (Figure 2). Gratifyingly, the reaction

• -acetyl-D-glucal (1a) with benzyl alcohol (2). Supporting Information Supporting Information File 276: Experimental data and copies of 1H and 13C NMR spectra of glycosides 3a–u, 5a–d and 7a–h are provided. Acknowledgements We thank Nanyang Technological University, Singapore for financial help (RG 13/18).

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• ). Representative procedure for mechanochemical solvent-free poly(trimethylene carbonate) synthesis (Table 1, entry 11). Three 7 mm stainless-steel milling balls were placed in a 10 mL stainless-steel milling container and trimethylene carbonate (0.100 g), benzyl alcohol (1.02 µL), and DBU (1.46 µL) were added. The

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• achieved from benzyl alcohol using a Br+ source as the catalyst (Figure 16). In the reaction pot subcomponents such as benzaldehydes and H+ were formed which further participated in a cascade transformation to give dihydropyrimidones 29. Dynamic combinatorial chemistry and mechano-milling Dynamic

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• , reaction with pyrrolidine, imidazole, methanol, allyl alcohol, benzyl alcohol and 9-fluorenemethanol (FmOH) provided the corresponding urea 30, N-carbamoyl imidazole 31 and carbamates 32–35, respectively, in good yields (69–80%). The reaction of isocyanate 28 with tert-butanol was sluggish even by heating

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• trifluoride etherate-catalyzed reaction of 95 with benzyl alcohol induces first opening of the 5-membered ring to form a benzyl ester and later the cleavage of the 3-membered ring to give a vicinal N-Cbz aminoalcohol with inversion of configuration. However, the reaction mixture (1:1) consists of the

• protected 3,4-dihydroxy-L-glutamic acid 96 and the respective γ-lactone 97 formed from 96 in the presence of acids. Benzyl alcohol was selected to refrain from decomposition of the final amino acids during the acid hydrolysis of, e.g., methyl esters [99] since for a mixture of 96 and 97 hydrogenolysis

• give dimethyl ester 98 (Scheme 25). Silver oxide-promoted methylation introduces a MeO-C4 unit. Regioselective aziridine ring opening in 99 was then carried out in the known way with benzyl alcohol or methanol to produce substituted dimethyl L-glutamates 100 and 101. To ensure clean deprotection in the

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

• Rudolf Knorr and
• Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

• comparison with 7 and benzyl alcohol; IR (KBr): 3404 (O–H), 2971, 2228 (C≡N), 1487, 1458, 1368, 1052, 751, 716 cm−1; anal. calcd for C22H23NO (317.4): C, 83.24; H, 7.30; N, 4.41; found: C, 83.39; H, 7.33; N, 4.48. 3´-Cyclopropyl-3´-hydroxy-2´-(1,1,3,3-tetramethylindan-2-ylidene)propionitrile (9). Using the

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• functionalized with a carboxylic acid 4 or a benzyl alcohol 5 could not be obtained using the reductive azo coupling. For the benzyl alcohol 5 a variety of different, unidentified byproducts formed and in case of the carboxylic acid 4 only the starting material was retrieved. We now present a reliable one-pot

• hydroxylamine and subsequently in situ oxidized to the nitroso compound using iron(III) chloride. After addition of acetic acid the reaction was allowed to proceed for several hours at room temperature to form the azo bond. For the benzyl alcohol-functionalized S-diazocine 5, the carboxylic acid of the

• precursors for the incorporation in photopharmacophores using cross-coupling, peptide coupling or further functionalization methods such as nucleophilic substitution reaction of the benzyl alcohol 5. The yield determining steps prior to the Baeyer–Mills reaction are the formation of the hydroxylamine with

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• in 91% yield. The ethyl ester was then smoothly reduced with DIBAL to the benzyl alcohol. While the in-process analysis (TLC and HPLC) indicated quantitative reduction, the isolated yields from the reductions were only poor to modest despite utilizing standard workup conditions with sodium potassium

Synthesis of a leopolic acid-inspired tetramic acid with antimicrobial activity against multidrug-resistant bacteria

• Luce Mattio,
• Loana Musso,
• Leonardo Scaglioni,
• Andrea Pinto,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2018, 14, 2482–2487, doi:10.3762/bjoc.14.224

• tosylate in the presence of 18-crown-6 ether [15]. The synthesis of benzyl tosylate was accomplished using benzyl alcohol and freshly recrystallized p-toluenesulfonyl chloride in the presence of anhydrous trimethylamine and DMAP, in anhydrous dichloromethane [25]. At this stage, all attempts to obtain the

• , afforded the desired O-alkyltetramic acid 13 in 30% yield. The synthesis of the activated ureido fragment was achieved in four steps from suitably protected L-valine and L-phenylalanine. The benzyl protection of L-phenylalanine (14) was carried out with PTSA and benzyl alcohol in toluene and the ester 15

• tosylate, KHMDS 0.5 M in toluene, crown ether 18-crown-6, THF, 0 °C to rt, 2.5 h, 30% over two steps. Synthesis of dipeptide L-Phe-L-Val intermediate 20. Reagents and conditions: a) PTSA·H2O, benzyl alcohol, toluene, reflux, 10 h, 70%; b) HClO4, tert-butyl acetate, 0 °C, 1 h, then rt, 20 h, 75%; c

One-pot synthesis of epoxides from benzyl alcohols and aldehydes

• Edwin Alfonzo,
• Jesse W. L. Mendoza and
• Aaron B. Beeler

Beilstein J. Org. Chem. 2018, 14, 2308–2312, doi:10.3762/bjoc.14.205

• benzyl alcohol (1) in the presence of slight excess of tetrafluoroboric acid in diethyl ether (HBF4·Et2O) and tetrahydrothiophene (THT). Notably, the use of acetonitrile (MeCN) as a solvent was critical for maintaining a homogeneous reaction and a successful outcome. We also observed that sodium hydride

• -rich alcohol 4 showed faster reaction rates and yields, presumably due to faster and more efficient formation of the sulfonium salt through a para-quinonemethide (p-QM) intermediate. Furthermore, the lower diastereomeric ratios (dr) observed for benzyl alcohol 4 may be due to competing p-QM formation