Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• solvents and with water, it has been used in a large variety of (electro)chemical reactions [53]. The hydroxy group of this alcohol has a pKa of 9.3 [54][55], so we can expect that it is a suitable proton donor for this kind of reaction. We performed the photocatalytic CO2 reduction by dissolving in 5 mL 1

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• EtOH, and NaOH in water (Scheme 1). The key intermediate of the macrocycle preparation, imidate 4, was synthesized using the reported procedure [43] by refluxing a solution of aminopyrazole 3 in triethyl orthoformate. First, we studied the reaction of imidate 4 with hydrazine hydrate in EtOH under

• under reflux for 23 h. After the reaction had completed (monitored by 1H NMR spectroscopy), the obtained solution was concentrated under water pump vacuum upon heating in a water bath at 65 °C. The product was extracted from the resulting dense brown oil by trituration 4 times with a mixture of ether

• (1.026 g) was recrystallized from boiling DMF (255 mL). After precipitation completed, the solid was filtered, washed with cold DMF (3 × 5 mL). The filter cake was suspended in water (10 mL) for 5 min followed by suction, this procedure was repeated 3 times to remove DMF from crystals. After drying in a

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• liquors and, in both cases, XRD confirmed the obtention of the (E)-isomer, in an anti-conformation. Computational calculations (gas and water phases) were performed in order to confirm some of the structural and vibrational aspects of the compounds. An important intramolecular H bond involving the

• species (ROS) in vitro, which may be another mechanism through which the compound exerts its protective effects in the brain. From a drug development perspective, however, INHHQ has some pharmacological limitations, such as low solubility and certain susceptibility to hydrolysis in a water-rich medium

• water molecules in the network (calcd.: 9.47% for C18H20O5N2·2H2O, MW = 380.39 g mol−1). On the other hand, hdz-NO2 did not show any mass loss below 250 °C, indicating the absence of solvation molecules in the sample (C17H17O7N3, MW = 375.34 g mol−1). Single crystals of both compounds, as monohydrates

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• aggregation-induced emission (AIE) luminogen. The experimental (solvatochromic and emission in THF/water mixtures studies) and theoretical investigations prove that TPECNz retains cooperative hybridized local and charge transfer (HLCT) and weak AIE features. Thanks to its D–A–D-type structure with a proper

• solution. However, the moderate PLQY in thin films still makes TPECNz suitable for the deep-red OLEDs. In addition, the AIE characteristic of TPECNz was further investigated by observing its PL emissions in water/THF mixtures with different water fractions (fw = 0–95%). In such diverse solvent mixtures

• , the molecule will demonstrate different degrees of aggregation since it can dissolve really well in THF but is insoluble in water, resulting in colloidal nanoaggregates being formed in solutions with high water contents. As shown in Figure 4a and 4b, in pure THF, TPECNz deep-red emission color with

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• chlorobenzene at 293 K in the absence of light, air, and water. In each case the reaction is apparently first order in dopant, consistent with the rate law: previously demonstrated for 1bH and VI [9]. The rate constants, k, obtained assuming this rate law are shown in Table 2 (the value for 3b being similar to

• strongly bound dimers. Figure 8b compares the evolution of one of the distinctive VII •– absorptions when doping VII with excess 12 derivatives in chlorobenzene at 293 K in the absence of light, air, and water. In the case of the Y = 4-dimethylaminophenyl dimers 1b2 and 1g2, the VII•– absorption grows in

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• commercially available. Regarding the molecular design and their properties, porphyrins and crown ethers are like water and fire – they constitute the opposite elements (Figure 1). Porphyrins are built of four pyrrole rings, two of which are considered amine-like due to the presence of NH groups, whereas the

• , interacting with the calixpyrrole macrocycle through hydrogen bonds. The water molecule was bound near the fluoride and was further stabilised through hydrogen bonding to the oxygen atoms in the central part of the receptor. This selective fluoride binding was evidenced with the help of 1H NMR spectroscopy

• axially bound H2O. The water molecule was stabilised by hydrogen bonding to the diaza-crown-6 core. Over the years, significant advancements have been made in crown ether-capped porphyrins, demonstrating their versatile applications in host–guest chemistry, multitopic receptor design, and cation sensing

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• adding a methanol/water mixture; thus, no lengthy purification steps were required for any of the syntheses. Yields of 52.4%, 80.2%, 58.1%, and 68.3% were obtained for PDIN-FB, PDIN-B, CN-PDIN-FB, and CN-PDIN-B, respectively. All compounds were structurally characterized using 1H NMR spectroscopy, 13C

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• ), and the extract suspended in water was sequentially partitioned with ethyl acetate and n-butanol. Breynin J (1), epibreynin J (2), and probreynin I (4) together with known compounds 6 and 7 were isolated from the n-butanol fraction (Figure 1). Probreynogenin (3) and known compound 5 were obtained from

• the solution was evaporated in vacuo to afford a MeOH extract (47.2 g). The MeOH extract was partitioned three times with 1.6 L of ethyl acetate and water 1:1 (v/v), and the water-soluble fraction was further partitioned three times with 800 mL of n-butanol. The ethyl acetate and n-butanol solutions

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• lacquerwares several thousand years ago [5]. The surface coating of lacquerwares was made up of a sap from a lacquer tree growing in Asia. The lacquer sap obtained from Rhus vernicifera lacquer tree mainly consists of urushiol (60–65%), water (20–30%), lacquer polysaccharide (3–7%), water-insoluble

• water phase and oil phase into an emulsion phase. The simultaneous presence of a hydrophobic head and a hydrophilic tail on emulsifiers provides the ability to combine water and oil phase into an emulsion. In emulsion polymerization, high molecular weights can be achieved at fast polymerization rates

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• internal cavity and a hydrophilic outer surface [1]. The common CDs are the native α-CD, β-CD, and γ-CD consisting of 6, 7, and 8 ᴅ-glucopyranose units, respectively. Due to their limited water solubility (especially β-CD), native CDs can be chemically or enzymatically modified (by e.g., alkylation

• , arylation, hydroxypropylation, amination, etherification, etc.) giving rise to synthetic CD derivatives with greater water solubility [2]. Thanks to their unique structure, CDs can offer exclusive advantages by allowing the entrapment of lipophilic molecules inside their inner cavities. This inclusion

• improves the chemical stability and aqueous solubility of the guest molecule and results in most of the cases in the formation of a water-soluble CD–guest complex [3]. Being recognized as non-toxic, biodegradable, and sustainable carriers, CDs have attracted wide interest as potential carriers in different

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• × 50 mm, Phenomenex), and Nucleosil 120 OH Diol (7 µm, 250 × 21 mm, Machery-Nagel, Düren, Germany) columns maintained at room temperature. Normal phase p-HPLC equipped with DAD detector (Agilent 1100 Series, Santa Clara, USA) was connected to a Nucleosil 120 OH Diol column. Deionized water used for RP

• p-HPLC was obtained from a Milli-Q water purification system (Millipore, Schwalbach, Germany) and all organic solvents and reagents were of analytical grade. Evaporation of solvents from fractions was performed using rotary evaporators equipped with a vacuum controller and diaphragm pump vacuum (Hei

• Erlenmeyer flasks of 500 mL, each containing 80 g of rice and 100 mL distilled water and incubated at 25 °C. After 28 days, the cultures were harvested. The fungal mycelia were further extracted with ethyl acetate and the solution was concentrated under reduced pressure to yield 12.2 g of crude extract. 12 g

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• potential environmental impacts [14]. For a synthetic purpose, the melting point of the DES and its viscosity are key parameters for the convenience of their use. Indeed, DES viscosities are generally higher than those of water and other common organic solvents and a too high viscosity can act as an

• proline/lactic acid/water (1:2:2.5). The authors studied their use in the synthesis of aurones via a Knoevenagel condensation and compared them to the classical choline-based DES, ChCl/Gly (1:2). They demonstrated that the ʟ-proline-based DES were superior to ChCl/Gly and obtained aurones from the

• aldehydes to study the scope of this reaction (Scheme 1). It must be noted that in most of the cases, the reaction mixture changed its appearance from colorless to yellow or orange and that some solid precipitate formed during the reaction. The addition of water at the end of the reaction clearly led to the

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• -catalyzed sulfenylation by N-(sulfenyl)succinimides/phthalimides In 2012, Chen and co-workers found that in the reaction of N-(organothio)succinimides 1 and sodium sulfinates 2 using a Lewis acid in ionic liquids (ILs) and water as a green solvent system leads to the formation of thiosulfonates 3 (Scheme 2

• by Guo and Wu et al. (Scheme 19) [56]. Employment of a reusable heterogeneous nanomaterial, mild reaction conditions, avoiding the use of any additive, or base, and water/EtOH as a green solvent system were the advantages of this new method. N-Sulfenyl sulfoximines 45 were synthesized as coupling

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• higher concentrations (10 μg L−1) [15]. The compound has received considerable attention because of its potential to cause odour episodes in water supply systems [16][17]. The production of 1 by Penicillium can add to the flavour of cheese [18], while its occurrence in fish and coffee leads to an

• by two sequential cyclisation reactions to A and B, and terminal quenching with water. This hypothesis was confirmed by the discovery of the biosynthetic genes coding for a GPP methyltransferase (GPPMT) and a type I terpene synthase termed 2-methylisoborneol synthase (2MIBS) [23][24]. Interestingly

• , 0 °C) solution of (E)-2,3,7-trimethylocta-2,6-dien-1-ol [22] (500 mg, 2.97 mmol, 1.0 equiv) was added PBr3 (322 mg, 1.19 mmol, 0.4 equiv) dropwise. The mixture was stirred at 0 °C for 45 min, and then quenched by pouring onto ice-water (20 mL). The aqueous phase was extracted with Et2O (3 × 20 mL

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• yields of the products were poor. Then, a non-chlorinated solvent such as toluene was used which furnished the complexes in moderate to excellent yields (Scheme 20). The use of water as solvent was found to be viable in the case of the NHCs bearing aryl substituent groups. However, the reaction of alkyl

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• presence of sodium ascorbate as reducing agent and sodium carbonate as base as well as ʟ-proline as ligand in a DMF/water mixture at 60 °C provided this promising result. These conditions applied are similar to those described by Fokin et al. [24], which had also been employed by other groups [37][38]. The

• acetonitrile/water as solvent furnished the exclusively isolated bis(1,2,3-triazole) derivative 12 in excellent 94% yield. These conditions of the one-pot nucleophilic substitution double-click reaction became the standard reaction conditions and were applied in most of the following experiments. When the

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• 26 can be well understood from the cyclisation mechanism towards 23 (Scheme 1B). After substrate ionisation to A a 1,10-cyclisation leads to the (E,E)-germacradienyl cation (B) that can either be deprotonated to 24 or captured with water to yield 26. Both compounds are important neutral intermediates

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• was stirred at room temperature for 0.1 to 2 h (monitored by TLC). Deionized water (20 mL) was added to the reaction mixture and the aqueous phase was extracted with dichloromethane (3 × 20 mL). The combined organic phases were dried (anhydrous sodium sulfate), filtered, and the solvent was then

• temperature, NIS (338 mg, 1.50 mmol) and 1.00 mL DMSO were added. After complete conversion (via TLC control), methyl iodide (639 mg, 4.50 mmol) was added and also stirred at room temperature for 5 min. Water was added to the mixture and the aqueous phase was extracted with dichloromethane. The combined

• stirring bar under nitrogen. Under nitrogen DMSO (5.00 mL) and deionized water (0.80 mL) were added and the reaction mixture was heated to 85 °C (oil bath) for 2 h. Then, deionized water (20 mL) was added to the reaction mixture and the aqueous phase was extracted with dichloromethane (3 × 20 mL). The

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• of H2O were added to the reaction mixture [40] (Table 1, entry 6), but the addition of more water did not improve the reaction efficiency further (Table 1, entry 7). The structure of nickel catalysts played a significant role in the reaction efficiency. Switching the Ni catalyst to NiCl2(dtbbpy

• LEDs (λmax = 399 nm) for 7 h. After the reaction was complete, the reaction mixture was poured into water and extracted with EtOAc. The combined organic phase was separated and washed with brine, dried over Na2SO4, and concentrated under vacuum. The resulting residue was purified by silica gel flash

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• alcohol functions of 4.5 were deprotected in acidic media to produce 3-O-octadecyl-sn-glycerol (4.6). The enantiomer of 4.6 was obtained from 4.4 by protecting the primary alcohol with a benzyl group to give 4.7. Then, the deprotection of the two alcohol functions with H2SO4 in water followed by the

• followed by the benzylation of the sodium alcoholate produced 21.2 in 95% yield. The deprotection of the acetal was achieved with acetic acid in a mixture of isopropanol and water to give 21.3. Then, a critical step is the alkylation of the primary alcohol in the presence of the unprotected secondary

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• %; GoodFellow, Cambridge, U.K.). The GCE was polished between experiments using alumina slurry (0.3 μm), rinsed in distilled water and subjected to brief sonication to remove any adhering alumina microparticles. The metal electrodes were then dried in an oven at 100 °C to remove residual traces of water, the

• GCE was left to air dry and residual traces of water were removed under vacuum. The Ag wire pseudoreference electrodes were calibrated to the ferrocene/ferrocenium couple in THF at the end of each run to allow for any drift in potential, following IUPAC recommendations [16]. All electrochemical

• reaction mixture was dried under vacuum to remove DMF. The crude product was extracted with DCM and washed with water. The organic phase was collected and dried with MgSO4, filtered and concentrated under vacuo. The product was further purified by column chromatography (ethyl acetate/hexane 1:4) to give

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• methodologies involving ether α-C(sp3)–H and aromatic C(sp2)–H bonds were investigated and these are shown in Scheme 43. Shah et al. reported a catalyst-free CDC method using only 2 equivalents of K2S2O8 in H2O under irradiation with a 27 W CFL (Scheme 43a) [123]. In this reaction, both water and the light

• source played a key role, with lower yields or no product obtained when the reaction was performed without water or under other light source conditions such as 19 W CFL or irradiation with blue or green LEDs. This method is applicable to various heteroatom-containing compounds such as quinolines

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• these substrates and the formation of water as the sole non-toxic byproduct in the reaction [11]. In general, the previous methods for the amination of MBH alcohols needed catalysts or additives such as FeCl3 [12][13], In(OTf)3 [14], MoCl5 [15], AuCl3 [16], and I2 [17] as Lewis acids. Alternatively

• derivatives in Et3N/THF mixtures [20] (Scheme 1, reaction 1, i) and acetates in THF/water [21] (Scheme 1, reaction 1, ii), or MBH alcohols in the presence of CDI (1,1’-carbonyldiimidazole) in acetonitrile (Scheme 1, reaction 1, iii) [22]. In the last case, as the hydroxy moiety is not a good leaving group

• removal of water formed from the direct amination of alcohol 4a by azeotropic distillation shifted the position of the equilibrium in direction to the formation of the allylated imidazole 6a which was obtained in good 88% yield (Table 1, entry 6). The protocol was also successfully extended to the

Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• condensation coproducts, such as water, hydrogen chloride or other small molecules [1][2][3]. MCRs have a great advantage over the classical two-component reactions; they allow the construction of complex molecular motifs in only one synthetic operational step starting from simpler building blocks. For this

• developed in our previous work [17], we tried to introduce 6 as an acetaldehyde equivalent, adding water in the reaction system and Amberlyst-15 as a catalyst to accelerate the hydrolysis process (Scheme 2). To our delight, 6 as an acetaldehyde surrogate allows a slightly better yield with doubled

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• , the nucleophilic addition of the amino anion to the carbonyl group in the of 1,3-cyclohexanedione scaffold resulted in cyclic intermediate C. Thirdly, the elimination of water from intermediate C gave the isolated product 3. In the case of the intermediate B2 with a benzoyl group, there are two kinds

• -cyclohexanedione moiety remained unreacted. Then, the final product 4 was formed by elimination of water. Thus, the spiro compounds 3 and 4 were selectively produced due to the different reaction process. Thus, the 3-isatyl-1,4-dicarbonyl compounds derived from 3-ethoxycarbonylmethyloxindoles and 3