Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• reversed selectivity, which may imply that the chiral cyclohexanediamine other than diphenylethylenediamine moiety governed the stereoselection process. Using M3 as the optimal catalyst, the reaction solvent was then screened (Table 2). Ethyl ether was found to give a better conversion, but with decreased

• selectivity (Table 2, entry 2). The reaction in 1,4-dioxane afforded the product with a moderate yield and the best selectivity so far, 62% ee (Table 2, entry 3). To our delight, among the other ether solvents screened (Table 2, entries 4–7), cyclopentyl methyl ether (CPME) gave an excellent conversion (90

• M1, M5, M7, and M8 was previously reported [30]. Substrate scope of isatin imines. Reaction conditions: 6 (0.2 mmol), 7a (0.3 mmol), and 5 mol % M3 in 2 mL of CPME (cyclopentyl methyl ether). Substrate scope of MAHTs. Reaction conditions: 6a (0.2 mmol), 7 (0.3 mmol), and 5 mol % M3 in 2 mL of CPME

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• of C-4 constructed a propenoic acid unit with a 1,1-disubstituted oxymethyl substituent at C-2. The HMBC correlations of H-4 of this unit with C-5, C-6, C-7, and C-10 as well as the chemical shifts of C-4 and C-7 established an ether bond between C-4 and C-7 and a C–C bond between C-4 and C-5 to form

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• EtOAc (3 × 10 mL). The organic layers were combined and washed with brine, then dried over anhydrous Na2SO4. After the solvent was removed under reduced pressure, the crude product was purified by column chromatography using 100–200 mesh silica gel and petroleum ether–ethyl acetate mixture as the eluent

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• donors have shown important biological activities due to their unique electronic and coordination ability [37][38], such as antitumor [39] and antiparasitic [40][41]. Previously, furoxans were synthesized via dimerization of hydroximoyl chlorides in the presence of a base, such as trimethylamine in ether

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• the addition of phenols to bromoacetylenes (K2CO3 or Cs2CO3, DMF, 110 °C), the reaction turned out to be non-selective: along with the expected bromovinyl phenyl ether 3a (3–9%) and phenoxyhydroxyketone 4a (25–39%), diphenoxyketone 5a was isolated in 9–24% yield (Table 1, entries 1–3). At 50–55 °C

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• 2002, an interesting methodology for menadione synthesis was reported by Kacan and Karabulut (Scheme 5). The authors studied a Diels–Alder reaction, using LiClO4-diethyl ether (LPDE) as a catalyst, 1-ketoxy-1,3-butadiene 28 as a diene and 2-methyl-1,4-benzoquinone (29) as dienophile. By this method

• characteristic properties, such as the biological redox cycle. The main and most common menadione reduction product is menadiol or vitamin K4, followed by its dialkyl ether and diacyl derivatives. Menadione can be easily converted to menadiol (14) by reduction with sodium dithionite, as first described by Fieser

• dithionite, Suhara and co-workers reported in their various works on the synthesis of vitamin K analogues, the use of menadione (10) to obtain 14 [113][114][115][116][117]. In these works, menadione (10) was reduced by using an aqueous 10% sodium dithionite solution in diethyl ether to furnish alcohol 14 in

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• and efficient organocatalyst. Recent promoted reactions by the resorcin[4]arene capsule include the intramolecular ether cyclization [34], the synthesis of bis(heteroaryl)methanes [35], the imine formation [36], the Michael addition reactions of N-methylpyrrole on methyl vinyl ketone [37], the

• alkene in the side chain [56] for which the reaction catalyzed by the same capsule led to the protonation of the alkene unit with an intramolecular nucleophilic attack by the alcohol moiety forming a final cyclic ether product. In the latter case the tertiary alcohol could not easily eliminate water and

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

• catalyst could be reused three times after being separated from the reaction mixture and was washed thoroughly with diethyl ether and methanol. To avoid the oxidative coupling of terminal alkynes the reaction was carried out in presence of nitrogen atmosphere. The authors also proposed a mechanism for the

Glycosylated coumarins, flavonoids, lignans and phenylpropanoids from Wikstroemia nutans and their biological activities

• Meifang Wu,
• Xiangdong Su,
• Yichuang Wu,
• Yuanjing Luo,
• Ying Guo and
• Yongbo Xue

Beilstein J. Org. Chem. 2022, 18, 200–207, doi:10.3762/bjoc.18.23

• -d6) established the C(6)–O–C(7') ether linkage. Therefore, a bis-coumarin-based aglycone was determined as shown (Figure 1), which is identical with that of daphnogitin [10]. In addition, two sugar units in substructure C (Figure 2 and Figure 3), including a β-glucopyranosyl and a β-xylopyranosyl

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• hampered this transformation [24]. Therefore, the same synthetic way was repeated with ethoxymethyl ether as the protecting group to give 17. The ESI mass spectrum provided evidence that cyclization occurred with formation of 18. However, protection with chloromethyl ethyl ether was achieved only in 18

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• and purification of the residue via silica gel (100–200 mesh) column chromatography using ethyl acetate/petroleum ether (bp 60–80 °C) as eluent. FTIR spectra of (a) the Ni–chitosan NPs and (b) bare chitosan. PXRD data for the Ni–chitosan NPs. TEM (a and b) and SEM images (c and d) of the Ni–chitosan

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• ] arenesulfonyl chlorides. Böhme and Schurhoff [8] similarly found that the solvolyses, in several homogeneous mixtures of an ether and water, were relatively slow. They found that the overall reaction rate could be considerably increased by the addition of reasonably powerful anionic nucleophiles. Indeed, Swain

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

• material in the synthesis of the other isomer of β-amino acid 6. The ring-opening reaction of 7 with HCl(g) in MeOH resulted in a mixture of products 8 and 9 in a 9:1 ratio (1H NMR). The product 8 in the reaction mixture was purified by recrystallization from ethanol/ether, but all attempts to purify the

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• ether (PE) used for column chromatography was the 60–90 °C fraction, and the removal of residual solvent was accomplished under rotovap. Reactions were monitored by thin-layer chromatography on silica gel GF254 coated 0.2 mm plates from Institute of Yantai Chemical Industry. Microwave-assisted reactions

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• dry DCM (45 mL) at room temperature. After stirring at room temperature for 39 h, the reaction mixture was concentrated, and directly purified by silica gel column chromatography (dichloromethane/ethyl acetate/petroleum ether 1:1:5) to afford the desired product 3ah as white solid (1.976 g, 94% yield

• . Then m-CPBA (≈85%, 60.9 mg, 0.30 mmol, 3.0 equiv) was added to the reaction mixture at 0 °C. After completion of the addition, the reaction mixture was slowly warmed to room temperature and allowed to stir overnight. The residue was purified by silica gel column chromatography (petroleum ether/ethyl

• residue was purified by flash column chromatography on silica gel (petroleum ether/ethyl acetate 4:1) to give pure compound 5 as white solid (44.0 mg, 95% yield). 6. One-pot three-component reaction for the synthesis of 3aa 1,3-Dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (15.6 mg, 0.10 mmol) and

Stepwise PEG synthesis featuring deprotection and coupling in one pot

• Logan Mikesell,
• Dhananjani N. A. M. Eriyagama,
• Yipeng Yin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2021, 17, 2976–2982, doi:10.3762/bjoc.17.207

• synthesis of monodisperse polyethylene glycols (PEGs) and their derivatives usually involves using an acid-labile protecting group such as DMTr and coupling the two PEG moieties together under basic Williamson ether formation conditions. Using this approach, each elongation of PEG is achieved in three steps

• reaction to carry out the deprotonation and Williamson ether formation reactions under basic conditions (Scheme 1) [15][16][18][23][25]. It is remarkable that the method has evolved to such a sophistication that the synthesis of (PEG)16 was achieved in nine steps without any chromatography [18][27

• under basic conditions. (2) The protecting group is stable under the basic Williamson ether formation conditions. For this reason, we screened several potentially useful protecting groups against these two criteria using compounds 3a–l (Scheme 2). For criterion (1), we subjected the compounds into basic

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• tested alkenyl ether 6 as a model of C–O-bond cleavage. Photoirradiation of the ether 6 similarly provided a mixture of C9-containing products 3, 4, and 5. Under these reaction conditions, the C–X cleavage products (MeOH or 2) were observed, but no formyl products were formed. The C9 byproducts – the

• nitroso 3, and related compounds 4 and 5 are all consistent with the classical C–X cleavage mechanism and with hydrolysis of the presumed oxonium intermediate 6’, but are inconsistent with the production of formyl products. In contrast, photoirradiation of the same alkenyl ether 6 under acidic conditions

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

• evaporated in vacuo and the residue was triturated with ether (10 mL), the crude amine was washed with ether (quintic, 10 mL each time) and dried in vacuo. The crude amine and Fmoc-Val-OH (71 mg, 0.20 mmol) were dissolved in 10 mL anhydrous DMF. The coupling reagent was added to the solution and the mixture

A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

• Yuki Yamamoto,
• Akihiro Tabuchi,
• Kazumi Hosono,
• Takanori Ochi,
• Kento Yamazaki,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 2906–2914, doi:10.3762/bjoc.17.198

• -valerolactone (1a), has been limited. The main process for the bromination of δ-valerolactone (1a) was treating the lactone with lithium diisopropylamide (LDA) at −78 °C to first generate the corresponding enolate, trapping it with trimethylsilyl chloride (TMSCl) to form the enol silyl ether, followed by

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

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• appeared to be stable towards heating and underwent intramolecular cyclocondensation performed in diphenyl ether at 230 °C giving target products 7 in good to high yields (see Table 1). Since it was not possible to predict a priori which of the nitrogen atoms of 7 would participate in PIFA-promoted

• diphenyl ether (10 mL) was heated at 230 °C for 4 h, then cooled to rt, and diluted with hexanes (20 mL). The precipitate was filtered, washed with t-BuOMe/hexanes (1:3), and dried to give product 7. An analytical sample was obtained by recrystallization from t-BuOMe. 2-(But-3-en-1-yl)quinazolin-4(3H)-one

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

• treated with acetic anhydride at room temperature. After workup by adding water and diethyl ether, the reaction mass was filtered and distilled until a residue was obtained. The colorless liquid compound 8 was obtained in 64% yield (as 6:1 mixture of anomers) after flash chromatography with 20% ethyl

• diastereomers by silica gel column chromatography and reaction with lead tetraacetate provided the key oxathiolane derivative 31. In 1995, Jin et al. [46] carried out the reaction of 1,4-dithiane-2,5-diol (3q) with glyoxylic acid (3g) hydrate at reflux temperature in tert-butyl methyl ether, which provided the

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• expected, the TBS ether was cleaved under the Suzuki conditions and had to be reapplied [63] to give bis-TBS-protected cyanobiaryl 22 in 85% yield. Next, the nitrile group was reduced to the corresponding primary amine 23 in 80% yield, using LAH and AlCl3 [60]. The target compound nobilone (1d) was

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

• 104 to Bz-protected (E)-4-hydroxybut-2-enal 105 in the presence of (S)-α,α-bis[3,5-bis(trifluoromethyl)phenyl]-2-pyrrolidinemethanol trimethylsilyl ether as the organocatalyst (cat. 106) and using PhCO2H as the acid additive. Desired products were obtained in good yields ≈78% with excellent

• of prolinol silyl ether (cat. 120) and benzoic acid (A1) catalysts to bring about reaction between 3-formyl-substituted indoles or pyrroles 118 and diverse electrophiles, including carbonyls, imines and other Michael acceptors (Scheme 5) [69]. The reaction with secondary amines occurred via the

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• and 4-nitro congeners in acetonitrile, followed by sulfide contraction of the resulting thioiminium ether salts with triethylamine and triethyl phosphite, afforded the (E)-enaminones 25a–c in yields of 86–89%. The E-geometry of 25a was again confirmed by NOESY NMR spectroscopy, which showed an