Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• stability. Conversely, selenepine 28c and selenepine Se-oxide 29c were quantitatively converted into the seco-HBC 31 by thermal activation at 200 °C for 5 min, as evidenced by UV–visible absorption and HPLC monitoring. SO-extrusion from thiepine S-oxide 29b was also successfully triggered in the solid state

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• heating at 90 °C for 4 hours. The crude reaction mass obtained with these conditions was then purified by column chromatography (toluene). After eluting unreacted pristine C70, a dark reddish fraction was isolated and analyzed by HPLC. A major peak was observed at a retention time of 17.5 minutes, which

• was also observed in the HPLC chromatogram, whose UV–vis has a pattern that is similar to a previously reported α-adduct [49]. We reasoned that this minor compound was the cyclohexadiene-fused C70 intermediate, analogous to cyclohexadiene-fused C60 I (see Scheme 1), which had not completely evolved

• were found to be the same, showing that 90 °C is sufficient for the reaction to proceed. In contrast, on extending the reaction time to 24 hours, the minor peak in the HPLC disappeared and only the peak corresponding to the bis(fulleroid) remained. The yield of derivative 2a was 45%. Other experiments

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• isomerization and photochemical (only for 13a) isomerization [46]. Compounds 13 showed intrinsic planar chirality and their enantiomers could be separated by HPLC. Notably, upon thermal and photochemical isomerization of these compounds, no Z-isomers were detected and only the racemization took place. Such

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• Supporting Information File 1 for comprehensive information on the synthesis details of the tetrapeptide). To avoid loss of valuable material through HPLC purification, crude 7 is used directly in the next step, and purification performed after the final prenyl phosphate coupling and global deprotection

• % (from compound 7) following reversed-phase HPLC purification (Scheme 2). Similarly, farnesyl, geranylgeranyl, and solanesyl-lipid II analogues 8–10 were synthesized with overall yields of 13%, 21%, and 11%, respectively, using the corresponding prenyl phosphates (Scheme 2). Conclusion In conclusion, we

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• spectroscopy and the ee values were determined by chiral HPLC. Structures of bioactive fluorinated indole derivatives. Proposed mechanism for the transfer hydrogenation reaction. Synthesis of chiral indolines via asymmetric reduction. Substrate scope of 3,3-difluoro-3H-indoles. Experiment at 2 mmol scale

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• in TCBDs and DCNQs and their optical resolutions were first realized in 2010 through their conjugation with methylated fullerenes, as shown in Figure 2 [130]. The optical resolution was realized using a chiral high-performance liquid chromatography (HPLC) system equipped with an (S,S)-WHELK-O1 column

• when the TCBD moiety was incorporated at the axial position of the subphthalocyanine (SubPc) core (Figure 3) [131]. Axially chiral SubPc–TCBD–aniline conjugates 59 and 60 were characterized via optical-resolution analysis through chiral HPLC using a Chiralpak IC column. The researchers unequivocally

• types of subporphyrin derivatives 61 and 62, wherein the subporphyrin skeleton was functionalized at its meso or axial position with the TCBD moiety (Figure 3). Although the optical resolution of 61 failed, they succeeded in achieving the optical resolution of 62 via chiral HPLC using a Chiralpak IC

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• molecular sieves, or by drying over 3 Å molecular sieves. All remaining anhydrous solvents were obtained from a solvent drying tower (IT model PS-MD-05). HPLC grade solvents were used unless otherwise specified. Purification by chromatography was performed using silica gel (flash: 40–63 μm, Sepacore® Flash

• Cary 50 UV–vis spectrophotometer scanning between 800 and 200 nm. All spectra were recorded with baseline correction in CH2Cl2 or toluene (HPLC grades) at 25 °C in a quartz cuvette with a 10 mm path length. Electrochemistry Cyclic voltammograms (CV) and differential pulse voltammograms (DPV) were

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• a linear gradient of chloroform/methanol. Fractions containing compound 6 were concentrated by evaporation. The residual materials were desorbed in 1 mL DMSO and applied to a reversed-phase high-performance liquid chromatography (HPLC, Shimadzu Corp.) equipped with a COSMOCORE Packed column 5C18-AR

Long oligodeoxynucleotides: chemical synthesis, isolation via catching-by-polymerization, verification via sequencing, and gene expression demonstration

• Yipeng Yin,
• Reed Arneson,
• Alexander Apostle,
• Adikari M. D. N. Eriyagama,
• Komal Chillar,
• Emma Burke,
• Martina Jahfetson,
• Yinan Yuan and
• Shiyue Fang

Beilstein J. Org. Chem. 2023, 19, 1957–1965, doi:10.3762/bjoc.19.146

• -length sequence 3 contains a polymerizable methacrylamide group at its 5'-end; the failure sequences 4 and many other impurities do not. In principle, due to the large relatively hydrophobic tag introduced by 2, the full-length sequence could be isolated by RP HPLC. However, we found that this is

• impossible [20]. Once the length of ODNs reaches about 100-mer, RP HPLC could not resolve the full-length and failure sequences. Therefore, to isolate the full-length sequence, the catching-by-polymerization (CBP) method was employed (step 2, Figure 1, and Scheme 1). To the crude ODN, the polymerization

•  1). Because depurination is less likely for deprotected ODNs, and the conditions are widely used for detritylation after RP HPLC, ODN damage in this step is unlikely or negligible. The purified ODNs, 399 and 401 nt, were each extracted from their gel. To remove residual acetic acid, the ODNs were

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• OEEFs (Figure 9B). To elaborate on these great expectations, pristine MWCNTs 3 were drop casted on the graphite anodes of electrochemical microfluidic reactors [44]. The substrate was injected by a syringe pump, the product was collected at the other end of the microflow channel and analyzed by HPLC

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• °C for 2 h (Scheme 1). Figure 1 depicts the changes in the visible–near infrared (vis–NIR) absorption spectra during the reaction, showing gradual changes with isosbestic points. Since the electrolyte interferes with the high-performance liquid chromatography (HPLC) separation and anionic species may

• not be eluted under typical fullerene HPLC separation conditions, trifluoroacetic acid was added to the reaction mixture. Notably, La@C2v-C82 is produced after the addition of trifluoroacetic acid to the La@C2v-C82 anion [20]. After removing the solvent under vacuum, the electrolyte was removed by

• adding CS2 and then filtering. Subsequent HPLC separation of the reaction mixture with 1a afforded products 2a, 3a, 4a, and 5a in yields of 40, 37, 9, and 1%, respectively, based on the consumption of La@C2v-C82 (Figure 2a and Supporting Information File 1, Figure S1). The yield was estimated from the

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• ), dimesitylboronfluoride (90%, Sigma-Aldrich), 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Sigma-Aldrich), tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4, 99%, Sigma-Aldrich), were used as received. Diethyl ether and THF were dried over metallic sodium. Dimethylformamide (HPLC grade) was stored over activated molecular

GlAIcomics: a deep neural network classifier for spectroscopy-augmented mass spectrometric glycans data

• Thomas Barillot,
• Baptiste Schindler,
• Baptiste Moge,
• Elisa Fadda,
• Franck Lépine and
• Isabelle Compagnon

Beilstein J. Org. Chem. 2023, 19, 1825–1831, doi:10.3762/bjoc.19.134

• spectroscopic fingerprints database. In MS–IR experiments, the IR data as well as the mass of the molecule are simultaneously acquired, therefore the mass could readily be used as a prefilter. More generally, all experimental data obtained in a glycomics workflow – such as MS/MS; HPLC; ion mobility; … – could

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• and high-performance liquid chromatography–mass spectrometry (HPLC–MS). The solvent ratios of the eluents are given in volume units (mL mL−1). Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker DRX-500 Avance spectrometer (at 500 and 126 MHz for the 1H and 13C spectra, respectively) or

• ionization. HPLC–MS was performed on an HPLC system using a Shimadzu LCMS-2020 (Shimadzu Corp., Japan) device equipped with a Reprospher (Altmann Analytik Corp., Germany) 100 Å C18 (5 µm; 100 × 3 mm) column and a positive/negative double ion source with a quadrupole MS analyzer in the range of 50–1000 m/z

• . Further details are available in Supporting Information File 1. The enantiomeric ratios of the samples were determined by chiral high-performance liquid chromatography (HPLC) measurements. The exact conditions of chiral HPLC are indicated in the experimental section of the corresponding compound

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

• electrospray ionization HRESIMS analysis, and quantum chemical electronic CD calculations. Furthermore, the absolute configurations of sugar residues were determined by derivatization of the hydrolysates with ʟ-cysteine methyl ester and o-tolyl isothiocyanate followed by HPLC analysis. The anti-inflammatory

• by acid hydrolysis of 1 using the method developed by Tanaka et al. [16], in which the hydrolysates are derivatized with ʟ-cysteine methyl ester and o-tolyl isothiocyanate followed by HPLC analysis. For compound 1, peaks were observed at retention times of 13.96, 20.83, and 22.16 min. The peaks at

• ], these differences indicate that the sulfoxide moieties in the aglycone of 1 and 2 are isomers. The remaining NMR resonances (Table 2) and 2D NMR spectroscopic data (Figure 2) showed that the glycosyl group of 2 was the same as that of 1. This assignment was further supported by HPLC-based monosaccharide

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

• cameroonensis, isolated from the root of Trema guineensis, a Cameroonian medicinal plant from the family Ulmaceae [11]. Results Structural elucidation Diaporthe cameroonensis, which showed an interesting high-performance liquid chromatography–diode array detector–high-resolution mass spectrometry (HPLC–DAD–HRMS

• ) profile, was scale up fermented to give 12 g of culture extract. This extract was subjected to a silica gel column chromatography to give several fractions, which were further purified over normal and reversed-phase HPLC to yield 2-ethyl-2,6-dihydroxy-5,7-dimethylbenzofuran-3-one (1), 3,9

• . Key COSY and HMBC correlations for 2 are illustrated in Figure 2 and the complete assignment for all protons and carbons is tabulated in Table 1. As we have been able to detect the compound by HPLC–MS in methanolic crude extracts of the fungus that did not come into contact with ethyl acetate or

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

• %) were added to a solution of 1 (10 mol %) in 2 mL of solvent (0.25 M) and allowed to stir for 48 hours at room temperature. Yields of isolated compounds are given. Diastereomeric ratio (dr) determined by 1H NMR analysis. Enatiomeric excess (ee) determined by chiral HPLC analysis. Original triple

• : Experimental part, NMR and HPLC spectra. Funding Fabio Pesciaioli thanks the Ministero dell'Università e della Ricerca (PON-AIM1842894, CUPE18D19000560001) for funding this research. Maria Edith Casacchia thanks the support of the Italian national inter-university Ph.D. course in Sustainable Development and

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• speed ETD ion trap mass spectrometer (Bruker Daltonics, Bremen, Germany) for HPLC-DAD/MS in positive and negative ionization modes. The HPLC (Dionex UltiMate 3000 UHPLC, Thermo Fisher Scientific Inc., Waltham, MA, USA) system’s stationary phase was composed of a C18 Acquity UPLC BEH column (Waters

• at 0.6 mL/min and the UV–vis detection made at 210 nm and 190–600 nm. The isolates were analyzed on a MaXis ESI-TOF (time-of-flight) mass spectrometer (Bruker Daltonics) for the HRESIMS data, in the positive ionization mode. This was coupled to an Agilent 1260 series HPLC–UV system (Agilent

• Technologies, Santa Clara, CA, USA). The HPLC system’s stationary phase was composed of a C18 Acquity UPLC BEH column (Waters). The mobile phase employed was as follows; deionized H2O + 0.1% FA (v/v) (solvent A) and ACN + 0.1% FA (v/v) (solvent B). The separation gradient was operated as follows; 5% B for 0.5

Linker, loading, and reaction scale influence automated glycan assembly

• Marlene C. S. Dal Colle,
• Manuel G. Ricardo,
• Nives Hribernik,
• José Danglad-Flores,
• Peter H. Seeberger and
• Martina Delbianco

Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77

• ] as well as technological improvements [8][9] permitted access to highly complex carbohydrates [10]. Still, variations in yields are not always ascribable to the AGA process [11][12][13][14][15][16]. Dissimilar structures are assembled in high purity as indicated by HPLC analysis of the crude products

• Information File 1, section 2.3, module C). The outcome of each AGA experiment was analyzed in terms of: i) HPLC purity based on the chromatogram of the crude sample after AGA and UV cleavage, ii) isolated yield of the target compound after photocleavage and HPLC purification (path A). The syntheses of the α

• better purities obtained for AGA performed on L2 (to note: for experiments on L2 no capped linker was detectable by HPLC; see Supporting Information File 1). Isolated yields were relatively low for all experiments (14–32% on L1 and 29–44% on L2, Figure 2D). These values are quite low even considering the

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• methods were used to purify the extract, such as MCI gel CHP 20, silica gel column, vacuum liquid chromatography, and semi-preparative HPLC purification, to obtain pure compounds. A total of ten compounds, including five new eudesmane-type sesquiterpenoids (1–5), and five known compounds were identified

• were obtained on a Jasco J−815 circular dichroism spectrometer (JASCO, Tokyo, Japan). Semi-preparative HPLC was carried out using an Agilent 1260 chromatograph with a 250 mm × 10 mm column, i.d., 5 μm, SEP Basic 120 C18. HRESIMS were measured on a SCIEX X500R QTOF MS spectrometer (Shimadzu Corporation

• purified by preparative HPLC on YMC-Pack-ODS-A with aqueous MeCN (63%), and then purified by semi-preparative HPLC on YMC-Pack-ODS-A with aqueous MeOH (82%) to afford 7 (36.1 mg, tR = 21.3 min; flow rate: 3 mL/min). Fr.6.5 (9.3 g) was further fractionated into ten parts (Fr.6.5.1–Fr.6.5.10) by a silica gel

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• molecules only in the organic phase but not in the aqueous phase. Therefore, the organic phase was concentrated under reduced pressure and the resulting residue was subjected to reversed-phase HPLC. Those fractions that showed a color change from blue to pink in the CAS assay were collected and purified in

• a second reversed-phase HPLC run. This led to the isolation of six compounds (1–6, Figure 2). The NMR spectroscopic data of compound 1 (brownish oil, 1.7 mg) were found to be very similar to those of the previously reported massiliachelin [18], suggesting a structural relatedness. The empirical

• represent intermediates or shunt products in massiliachelin biosynthesis. A model for their formation is presented. Experimental Analytical methods Preparative HPLC was conducted on a Shimadzu LC-20A system equipped with two pumps (LC-20AD), a photo-diode array detector (SPD-M20A), a degasser unit (DGU-20A

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• Co., Japan), Sephadex LH-20 (Amersham Biosciences), and YMC gel ODS-A-HG (particle size 40–60 μm; YMC Co. Japan). A Saipuruisi chromatograph with a semi-preparative high-pressure infusion pump (SP-5030) and a semi-preparative UV–vis dual wavelength detector (UV200) were utilized for RP–HPLC. A YMC

• -Pack ODS-A column (250 mm × 20 mm, i.d., S-5 μm) was employed for preparative HPLC, while three columns (a YMC-Pack ODS-A column (250 mm × 10 mm, i.d., 5 μm), a Stabllity 100 C30 column (25 mm × 10 mm, i.d., 5 μm), and an Inetex-Biphenyl 100A column (250 mm × 10 mm, i.d., 5 μm)) were used for semi

• -preparative HPLC. Arthropod material The dried arthropod bodies of Kronopolites svenhedini (Verhoeff) were purchased from Qunkang Pharmaceutical Co. in Anhui Province, PR China, in July 2021. The voucher specimen of this material (CHYX-0674) has been deposited at the School of Pharmaceutical Sciences, Health

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• temperature derived from the heat of reaction accelerated the reaction. The quantitative yield by HPLC was 98.3% and the byproduct carboxylic acid 3a was 1.3%. 3a was easily purged by extraction with a weak base such as NaHCO3. From the above discussion, the throughput was improved to 1.4 kg/day (= 57 g/h

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• octagon-containing carbo[5]helicene was isolated in a 61% yield, which can be further transformed into other chiral hydrocarbon analogues 12 and 13 [35]. Chiral resolution of these helicenes was accomplished by chiral high-performance liquid chromatography (HPLC) and the isomerization barriers were

• determined for the enantiopure helicenes. For compound 12, the racemization barrier was 24.8 kcal mol−1 at 298 K, which provides a racemization half-life (t1/2) of 24.4 h. For compounds 11 and 13, neither racemization nor decomposition was observed by chiral HPLC after heating hexadecane solutions of each

• through oxidative cyclodehydrogenation and imine formation in a 72% yield. It was noted that no other regioisomer was detected for the asymmetrical precursor 30. The pair of enantiomers was confirmed by the racemic structure's single-crystal X-ray diffractometry and separated by chiral HPLC, and no

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• HPLC-UV yield of compound 3aa. These conditions were taken as a standard for further reactions. Noteworthy, we had to derivatize product 3aa to detect it by HPLC–UV during the optimization studies. For these purposes, compound 3aa was converted to compound 4 by an earlier procedure developed by us

• (Scheme 7) [51]. Without this derivatization procedure, we could not accurately detect compound 3aa by HPLC–UV, since the chromatographic signals of untreated compound 3aa were broad and blurry. Next, the reactant scope of the reaction was explored by involving to the reaction APBTTs 1a–h, bearing various

• (Scheme 12) by an earlier procedure developed by us [51] in order to investigate the reaction optimization by HPLC–UV. Then, the reactant scope of the reaction was explored by involving to the reaction APBTTs 1a–h, bearing various aroyl substituents, and benzylamine (Scheme 13) [55]. As a result, we found