Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• reaction. After filtration through activated aluminum, (S)-α-phellandrene (30) is obtained in a high yield of 88% over three steps on a 30 g scale corresponding to a productivity of 0.887 mol/day [36]. The smell of leaves and freshly cut green grass can mainly be traced back to (Z)-hex-3-en-1-ol (32) (so

An isoxazole strategy for the synthesis of 4-oxo-1,4-dihydropyridine-3-carboxylates

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2022, 18, 738–745, doi:10.3762/bjoc.18.74

• )-one 14 in 89% yield. The reaction of pyridone 2e with PBr3 afforded methyl 4-bromo-6-(4-fluorophenyl)-2-phenylnicotinate (15) in 80% yield. The latter was employed in the Suzuki reaction in the high-yield synthesis of 2,4,6-triaryl-substituted nicotinate 16. The nitrogen of 2,3,4,6-tetrasubstituted

• rearrangement of methyl 2-(isoxazol-5-yl)-3-oxopropanoates 1. High yield transformations of compound 2 provide easy access to 2,4,6-triaryl-substituted and 1,2,5,6-tetrasubstituted nicotinates. Approaches to the synthesis of alkyl 4-oxo-1,4-dihydropyridine-3-carboxylates. Synthesis of 4-oxo-1,4-dihydropyridine

Rapid gas–liquid reaction in flow. Continuous synthesis and production of cyclohexene oxide

• Kyoko Mandai,
• Tetsuya Yamamoto,
• Hiroki Mandai and
• Aiichiro Nagaki

Beilstein J. Org. Chem. 2022, 18, 660–668, doi:10.3762/bjoc.18.67

• with good operational stability, evaluated by a constant high yield of cyclohexene oxide, to obtain the desired product with high productivity. Keywords: air; continuous flow; cyclohexene oxide; flow epoxidation; rapid gas–liquid reaction; Introduction From the past to the present, organic synthesis

• achieved by using a flow technique (Scheme 1). Cyclohexene oxide was selectively produced with high yield in our flow oxidation system using air and within only 1.4 min. The fast epoxidation of cyclohexene without added catalyst in the solution was achieved since the solution of cyclohexene and aldehyde in

• . Conclusion In the present study, we developed the continuous flow system for the aerobic cyclohexene oxide production based on appropriate temperature and residence time control. Moreover, the production of cyclohexene oxide with high yield and selectivity was achieved under the conditions of a very short

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• (73%) and 109b (82%) in high yield (Figure 23b) [110], although the relevant distances in the pseudo-rotaxane 110a,b (prior to the second click reaction) are 14.3 and 21.1 Å. Actually, the yield with [FeCu2(104)2]4+ was far better than with a dicopper reference catalyst, where the separation of the

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• shown to strongly depend on the nature of the substituents in the diazo substrate. The new reaction provides access to dibenzoazulenodipyrrole and indenopyrrole derivatives in moderate to high yield. Dibenzoazulenodipyrroles bearing alkyl substituents at the nitrogen atom showed pronounced cytotoxocity

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

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

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• acceptors. The obtained vesicles could be utilized as a nanoreactor for photocatalyzed dehalogenation reactions in water. However, the above reported supramolecular nanosystem requires a long time to produce the dehalogenated product with high yield. Therefore, the development of a potential nanoreactor for

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• the desired product 3a in a high yield. Table 3 shows the effect of the electrode distance on the yield of the reduction products 3a and 4. From these results, the optimal electrode distance was determined to be 40 µm (Table 3, entry 2). When the electrode distance was increased to 80 µm, the yield of

• environment for the reduction of imine 1 is considered to result in the high yield of 3a. To confirm that the reaction environment of the flow system was in the steady state, the electrolyzed solution was collected from the reactor outlet at regular intervals and the yield of 3a for each fraction was

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• compatible with the catalyst and afforded the products with high yield. The efficiency of the catalyst in water was found to be increased by introducing polyethylene glycol (PEG) chains. From the mechanistic explanation, the reaction proceeds via an oxidative addition and reductive elimination route. Fe3O4

Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole

• Estelle Silm,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2022, 18, 167–173, doi:10.3762/bjoc.18.18

• oxindole and the squaramide decreasing the effective concentration of the catalyst. Taking this into consideration, 2 equiv of substituted oxindole was used and the reaction proceeded smoothly in 2 h in high enantioselectivity (90%/94% ee), in high yield (74%) but in moderate diastereoselectivity (Table 1

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• this transformation. The structure of 13 was elucidated with the help of the 2D NMR (COSY and HMQC) experiments. Finally, removal of the Boc group from 13 with HCl(g)–MeOH resulted in the formation of cyclic β-amino acid derivative 8 in high yield. Our suggested mechanism for the reaction of epoxide 7

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• also important in quantitative analytical determinations of drugs containing free primary and secondary amino groups, as they react quickly and in high yield with amines to form colored products in good yields. This review reports several examples of syntheses of functionalized 1,2-naphthoquinones

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• as solvent (Scheme 23). Both aromatic and aliphatic aldehydes performed well and gave the desired products in good yields. At the same time ketones were found less active in this strategy. The operational simplicity and high yield of products are the prominent characteristics of this reaction. In

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• achieved by solid-state synthesis. Our synthetic strategy could synthesize the target peptide in high yield with good purity Keywords: antimalarial; highly methylated polypeptides; hoshinoamides; total synthesis; Introduction Malaria is an insect-borne infectious disease caused by parasites of the genus

• synthesized in high efficiency. After systematic screening of the coupling reagents in liquid phase, the key intermediate tripeptide 7 was obtained in high yield. The solid-phase synthesis improves the entire efficiency of the synthetic route. This strategy could be applied to the stereoselective synthesis of

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• co-workers established a Heck/Kumada cross-coupling cascade to construct nitrogen and oxygen-containing cis-heterospirocycles 40 in high yield and diastereoselectivity with inexpensive Fe(acac)3 as the precatalyst (Scheme 8) [73]. Interestingly, this protocol was applicable to substrates bearing

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• ]. Zhou and co-workers published an excellent paper in 2019 on the conversion of central to axial chirality in an enantioselective [3 + 2] annulation of 1-styrylnaphthols 32 with azonaphthalenes 33. Under defined conditions, the cycloaddition product 34 was prepared in high yield (99%) with exclusive

• -axial chirality conversion by oxidative aromatization. With excellent diastereoselectivities (all >20:1) and enantioselectivities (87–99% ee), the target products 35 containing different groups were obtained in high yield (up to 94%) (Scheme 12). In this transformation, electron-donating and withdrawing

• chiral arylquinazolinones 76 were obtained in high yield (up to 99%) with high enantioselectivity (83–97% ee, Scheme 25). Both the position and the electronic properties of the substituents on the aromatic ring had a minor influence on the reaction efficiency and enantioselectivity of this transformation

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• reaction of benzoyl chloride in pyridine to protect the hydroxy group, which results in a high yield. The isopropylidene group was selectively deprotected using 10% HCl, followed by oxidative breakage of the carbon–carbon bond of the resulting diol using sodium periodate. Further reduction of the aldehyde

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• (7a) using sulfinylurea catalyst (S,R)-C2. A relatively high yield (81%) of Michael adduct 8a was formed in 3 hours of milling, with triethylamine as the base (Table 3, entry 1). The diastereoselectivity and enantioselectivity reached comparable values as in the solvent conditions. The chemical yield

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• (quinidinethiourea + ᴅ-proline), instead of the expected domino Mannich/Michael product, the bridged tetrahydroisoquinoline product 25a was obtained in high yield (90%) and excellent dr (94:6) and ee value (99%) (Table 5). The controlled reactions using 23 and 24 as the catalyst gave the product in very poor yield

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• esterified pyridines 29 in moderate to high yield. It is worth noting that 1,3-enynes 28 bearing internal alkyne moieties were not tolerated as substrates. In 2016, Aïssa and co-workers reported a nickel-catalyzed [4 + 2]-cycloaddition of 3-azetidinones 30 with 1,3-enynes 31 for the synthesis of 3‑hydroxy

Enantioselective PCCP Brønsted acid-catalyzed aminalization of aldehydes

• Martin Kamlar,
• Robert Reiberger,
• Martin Nigríni,
• Ivana Císařová and
• Jan Veselý

Beilstein J. Org. Chem. 2021, 17, 2433–2440, doi:10.3762/bjoc.17.160

• dramatically improved the enantioselectivity (Table 1, entries 9–11). In particular, when the aminalization reaction between 1a and 2a was carried out in the presence of 5 Å molecular sieves, the corresponding product 3a was delivered in high yield (96%) and with enantiomeric purity 80% ee (Table 1, entry 11

• averaged only around 50%. In addition, the role of an electron-donating methyl group on the aromatic ring was investigated. When p-tolualdehyde (1f) was used in the cyclization reaction with anthranilamide (1a), the corresponding aminal 3f was obtained in high yield (83%) and with good enantiomeric excess

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• group. The first step was initiated by the protection of the primary hydroxy group of metronidazole (1) with p-toluenesulfonyl chloride in dry DCM in the presence of triethylamine at 0 °C to room temperature. The reaction afforded the desired metronidazole tosylate 2 in high yield (96%) [17]. In the

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

• undergo an effective cyclization reaction to synthesize 2-methylfuran derivatives 167 with high yield in the presence of Hg(OTf)2 as the catalyst under very mild reaction conditions (Scheme 48) [108]. Cyclization of 6-aminohex-1-yne 168 was performed by catalytic amounts of Hg(NO3)2 and generated 2

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• , and acetonitrile (Table 1, entries 2–9). The results indicated that the solvent has a meaningful impact on the efficiency of the reaction. Among the tested solvents, CH3CN was the best choice for the process (Table 1, entry 9). In this instance, a high yield (89%) was achieved. Then, in the presence

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• high yield by refluxing the reactants in the presence of K2CO3 in DMF. 2-Phenoxybenzaldehyde (1a) was converted into secondary alcohol derivative 2a by adding a phenyl group using a Grignard reaction. This reaction was carried out with high yield by adding the freshly prepared Grignard compound of

• phenyl bromide to 2-phenoxybenzaldehyde. As a result, phenoxy secondary alcohol 2a containing three aromatic rings was obtained. In the third step, 2a was oxidized and the ketone derivative 3a was obtained in high yield. The oxidation reaction was carried out using PCC in DCM at room temperature. In the

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129