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

• different chemoselectivity: secondary and benzyl alcohols are more easily oxidized. The great diversity of catalytic systems based on amine-N-oxyl radicals for alcohol oxidation was proposed [74][76][77][95]. Amine-N-oxyl organocatalysts with enhanced catalytic activity were developed by the modification of

• 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

• (hydroxylation, hydroperoxidation, halogenation, etc.), cross-dehydrogenative coupling and oxidative cyclization, alcohol oxidation, and the oxidation of other functional groups. Compared to other types of organocatalysis (type I and type II in Scheme 1) reversible bonding and non-covalent interactions of redox

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

• ]. Kim et al. reported the formation of vic-1,2-diols in the sacrificial anode-free electrocarboxylation of 1-phenylethanol and benzyl alcohol which involves tetramethylpiperidine-1-oxyl-mediated alcohol oxidation as an anodic event [46]. However, vic-1,2-diols were obtained only as minor products and

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

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

• catalytic oxidation of alcohols into aldehydes, thus mimicking the reactivity of galactose oxidase. Complexes 1 and 2, exhibiting a twisted tetracoordinated geometry, and a distorted square pyramidal geometry, respectively, were used in alcohol oxidation on a wide variety of mostly aromatic alcohols in the

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• -assisted oxidation of alcohols in a) basic or b) acidic reaction conditions. TEMPO-assisted oxidation of 3-pheny-1-propanol (1a) under mechanical activation conditions. aPercentages of conversion were calculated by GC–MS using an internal reference standard. Scope of primary alcohol oxidation under

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation

• Takayuki Yakura,
• Tomoya Fujiwara,
• Akihiro Yamada and
• Hisanori Nambu

Beilstein J. Org. Chem. 2018, 14, 971–978, doi:10.3762/bjoc.14.82

• -iodoxybenzoic acid (IBX, 2) [11] are well known as representative environmentally benign oxidants for alcohol oxidation (Figure 1). However, despite the utility and versatility of these oxidants, they still have several drawbacks: both are potentially explosive, DMP is moisture-sensitive, and IBX is insoluble

• room temperature, appears to be a promising catalyst for efficient and environmentally benign alcohol oxidation reactions [67]. Herein, we report our efforts on improving the reactivity of 2-iodobenzamide catalysts. Results and Discussion We evaluated several 2-iodobenzoic acid derivatives including

• esters and amides as catalysts for alcohol oxidation in the presence of Oxone®, and we found that the simply modified derivative, N-isopropylamide 13, exhibited excellent catalytic properties at room temperature [67]. Interestingly, the reactivity of 13 was much higher than that of 3 at room temperature

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• ; alcohol oxidation; aldehyde; flow chemistry; Introduction trans-2-Hexenal is well-known as a major component of the Green Notes of fruits and vegetables such as apples, strawberries, cherries and more. It is widely used in the flavour and fragrance industry as fresh flavour ingredient in foods and

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

• Andrea Porcheddu,
• Evelina Colacino,
• Giancarlo Cravotto,
• Francesco Delogu and
• Lidia De Luca

Beilstein J. Org. Chem. 2017, 13, 2049–2055, doi:10.3762/bjoc.13.202

• choice of solvent for TEMPO-based oxidative procedures remains a crucial issue in the development of greener alternatives to traditional alcohol oxidation reactions [32][33][34]. In particular, the lack of a green option significantly decreases the attractiveness of the proposed synthetic routes, as the

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

• 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

• photographs (middle and right). 1H NMR (crude) of 4-methoxyacetophenone 6b. Oxidation of 4,4’-dimethoxybenzhydrol (1a) to 4,4’-dimethoxybenzophenone (1b). Scope for benzylic alcohol oxidation and obtained yields. Oxidation of 4-methoxyphenyl methyl carbinol (6a) to 4-methoxyacetophenone (6b). Conditions and

A protecting group-free synthesis of the Colorado potato beetle pheromone

• Zhongtao Wu,
• Manuel Jäger,
• Jeffrey Buter and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2013, 9, 2374–2377, doi:10.3762/bjoc.9.273

• decemlineata, has been developed based on a Sharpless asymmetric epoxidation in combination with a chemoselective alcohol oxidation using catalytic [(neocuproine)PdOAc]2OTf2. Employing this approach, the pheromone was synthesized in 3 steps, 80% yield and 86% ee from geraniol. Keywords: aggregation pheromone

• efficient synthesis of the aggregation pheromone of the Colorado potato beetle (S)-1,3-dihydroxy-3,7-dimethyl-6-octen-2-one (1). Combining Sharpless asymmetric epoxidation, stereoselective epoxide ring-opening and catalytic chemoselective alcohol oxidation with [(neocuproine)PdOAc]2OTf2 (2), (S)-1 was

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• benzyl alcohol oxidation [27], the esterification of benzoic acid in a microwave tubular flow reactor [28], a continuous flow recycle microwave reactor for homogeneous and heterogeneous processes [29], a mesoscale flow reactor utilizing Fe3O4 as a microwave absorbing packed reactor bed with internal

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: a fast and efficient protocol for alcohol oxidation

• Nida Ambreen,
• Ravi Kumar and
• Thomas Wirth

Beilstein J. Org. Chem. 2013, 9, 1437–1442, doi:10.3762/bjoc.9.162

• were used without further purification. General procedure for the alcohol oxidation in flow Solutions of (diacetoxyiodo)benzene (1.1 equiv) and the alcohol (50 mg) in CH2Cl2 (1.5 mL) and 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) (5–10 mg, 10–20 mol %) in CH2Cl2 (1.5 mL) were loaded in two syringes

Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine

• Jessica Baiget,
• Sabin Llona-Minguez,
• Stuart Lang,
• Simon P. MacKay,
• Colin J. Suckling and
• Oliver B. Sutcliffe

Beilstein J. Org. Chem. 2011, 7, 1407–1411, doi:10.3762/bjoc.7.164

• analogues containing the carboline heterocyclic moiety. A manganese dioxide mediated one-pot method starting with an activated alcohol and consisting of alcohol oxidation, Pictet–Spengler cyclisation, and oxidative aromatisation, offers a convenient process that allows access to β-carbolines. This one-pot

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed- bed microreactor

• Andrew Bogdan and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2009, 5, No. 17, doi:10.3762/bjoc.5.17

• 100 trials without showing any loss of catalytic activity. Keywords: alcohol oxidation; flow chemistry; heterogeneous catalysis; microreactors; TEMPO; Introduction Microreactors have gained attention because they can help run chemical transformations more efficiently, more selectively, and with a

• flow conditions for the benzyl alcohol oxidation, a number of different substrates were examined to test the generality of the AO-TEMPO packed-bed microreactor. High conversions were achieved when using both aromatic and aliphatic alcohols (Table 1, Entries 1–6). Secondary alcohols, which are known to

• . Preparation of AO-TEMPO 6. The AO-TEMPO-catalyzed oxidation of benzyl alcohol. Oxidation of alcohols using AO-TEMPO packed-bed microreactor. Supporting Information Supporting Information File 28: Experimental methods and spectral data Acknowledgements We thank NSF SGER, ARO (Grant No. W911NF-06-1-0315), NSF