Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• at the hydroxy. To prevent excessive reaction at the amine, both reactions were stopped at 2 hours. Aside from 1H NMR, the independent functionalization of KSU-1 with isocyanates was also confirmed by conducting electrospray ionization mass spectrometry (ESI–MS) on samples of the MOF products

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• reporting NMR spectral data are: bm, broad multiplet; bs, broad singlet; bt, broad triplet; d, doublet; dd, doublet of doublets; m, multiplet; q, quartet; s, singlet; and t, triplet. High-resolution (HR) electrospray ionization (ESI) mass spectra (MS) were collected using a Bruker microTOF Focus orthogonal

• ESI-TOF mass spectrometer instrument operating in either negative or positive ion mode as indicated in the experimental procedures (Chemistry Mass Spectrometry Core Facility, Dalhousie University). Melting points were recorded on Barnstead International (Model No. 1201D) melting point apparatus and

Chemical synthesis of glycan motifs from the antitumor agent PI-88 through an orthogonal one-pot glycosylation strategy

• Shaokang Yang,
• Xingchun Sun,
• Hanyingzi Fan and
• Guozhi Xiao

Beilstein J. Org. Chem. 2025, 21, 1587–1594, doi:10.3762/bjoc.21.122

• was obtained in 60% overall yield from 20 via sequential global deprotection of the Bn, Cbz, and Bz groups. The structures of the synthetic glycan motifs 1–4 were supported by their 1H and 13C NMR spectra and MALDI–TOF as well as ESI mass spectra. In particular, the anomeric proton signals of 1–4 were

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• precoated TLC plates (0.2 mm thick). The identity of all compounds was confirmed employing various spectroscopic techniques including NMR and HRMS–ESI high-resolution mass spectrometry. The 1H and 13C NMR spectra were recorded in CDCl3 or DMSO-d6 at 25 °C on a Bruker Ultrashield Plus 500 spectrometer using

• °C. The measurements were done on a Bruker MicrOTOF-QII-system coupled with an ESI source with a nebulizer: 1.2 bar, dry gas 8.0 L min−1, dry temperature 200 °C, capillary 4500 V and plate offset 500 V. Synthesis of 8-(phenyldiazenyl)quinolin-7-ol (1) A 50 mL round-bottomed flask equipped with a mini

• ), 7.73–7.33 (m, 2H), 7.02 (d, J = 9.5 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 171.3, 151.3, 148.5, 145.0, 137.7, 136.5, 131.0, 129.7, 128.8, 125.8, 123.2, 120.7, 120.0; HRMS–ESI (m/z): [M + H]+ calcd for C15H12N3O+, 250.09749; found, 250.09739. Synthesis of 8-(4-hydroxy-1,2,3,5-tetrafluorophenyldiazenyl

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates

• Alexander S. Budnikov,
• Igor B. Krylov,
• Fedor K. Monin,
• Valentina M. Merkulova,
• Alexey I. Ilovaisky,
• Liu Yan,
• Bing Yu and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96

• ). Coupling constants are reported in Hertz (Hz). FTIR spectra were recorded on a Bruker Alpha instrument. High-resolution mass spectra (HRMS) were measured on a Bruker maXis instrument using electrospray ionization (ESI). The measurements were performed in a positive ion mode (interface capillary voltage

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• RS UHPLC coupled to a Thermo Scientific ISQ™ EC single quadruple ESI mass spectrometer. HRESIMS data were acquired on a Bruker maXis II ETD ESI-qTOF. TLC was carried out on Merck (Kenilworth, NJ, USA) silica gel 60 F254 pre-coated aluminium plates and developed plates were visualised using UV light

• ) δC 147.9 (C-8), 146.8 (C-3), 139.7 (C-9), 139.5 (C-19), 135.0 (C-13), 130.3 (C-6), 129.8 (2C, C-11, C-15), 129.4 (2C, C-12, C-14), 128.7 (2C, C-20, C-24), 128.3 (2C, C-21, C-23), 126.1 (C-22), 125.1 (C-10), 106.0 (C-5), 41.6 (C-17), 34.5 (C-18); LRMS (ESI-SQ) m/z: 350 [M + H]+, 372 [M + Na]+; HRESIMS

• (C-6), 129.8 (2C, C-11, C-15), 129.3 (2C, C-12, C-14), 125.2 (C-10), 105.7 (C-5), 38.4 (C-17), 37.5 (C-18), 25.4 (C-19), 22.5 (2C, C-20, C-21); LRMS (ESI-SQ) m/z: 316 [M + H]+; HRESIMS–qTOF (m/z): [M + H]+ calcd for C16H1935ClN5, 316.1329; found, 316.1323; [M + Na]+ calcd for C16H1835ClN5Na, 338.1143

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• further purification. For column chromatography, 70–230 mesh silica 60 (E. M. Merck) was used as the stationary phase. Electrospray ionization–high-resolution mass spectra (ESI–HRMS) were acquired on a SCIEX X500 QTOF instrument in the positive ion mode. A Büchi melting point B-545 apparatus was used to

• compounds 5a–e. Molecular docking results of potential drugs with enzyme iNOS. Supporting Information Supporting Information File 44: Synthetic procedures, compound characterization, X-ray crystallographic data, bioassay for NO inhibition, NMR and ESI-HRMS spectra for all reported compounds

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• internal solvent residual peaks (CDCl3, CD3OD) and given to tetramethylsilane as internal standard (δ = 0.00 ppm). High-resolution mass spectra (HRMS) of the obtained compounds were measured on an Agilent 6220 ESI-TOF MS instrument (Agilent Technologies, Santa Clara, CA, USA) using a spray voltage of 4 kV

• , CDCl3) δ −56.23 (t, J = 20.7 Hz), −140.45 (dq, J = 28.6, 11.9, 11.1 Hz); ATR-FTIR (neat): 3587, 2975, 2868, 1634, 1500, 1333, 1249, 1137, 870, 820, 709 cm−1; HRMS (ESI-TOF) m/z: [M + Na]+ calcd for C35H23Cl3F7N3NiO3, 853.9916; found, 853.9958. Ni(II)-Schiff base complex of bisTfMePhe 7: Under inert

• , 121.5, 71.2, 70.9, 63.3, 58.6, 40.7, 30.8, 23.7; 19F NMR (565 MHz, CDCl3) δ −62.57 (s); ATR-FTIR (neat): 3062, 2982, 2868, 1638, 1463, 1278, 1133, 894, 820, 705 cm−1; HRMS (ESI-TOF) m/z: [M + Na]+ calcd for C36H26Cl3F6N3NiO3, 850.0167; found, 850.0181. Ni(II)-Schiff base complexes of (2S,4R)-TfLeu 11a

Semisynthetic derivatives of massarilactone D with cytotoxic and nematicidal activities

• Rémy B. Teponno,
• Sara R. Noumeur and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 607–615, doi:10.3762/bjoc.21.48

• Anton Paar MCP-150 Polarimeter with sodium D line at 589 nm and 100 mm path length. HRESIMS mass spectra were measured with a maXis ESI TOF mass spectrometer (Bruker Daltonics) [scan range m/z 100–2500, rate 2 Hz, capillary voltage 4500 V, dry temperature 200 °C], coupled to an Agilent 1200 series HPLC

Sequential two-step, one-pot microwave-assisted Urech synthesis of 5-monosubstituted hydantoins from L-amino acids in water

• Wei-Jin Chang,
• Sook Yee Liew,
• Thomas Kurz and
• Siow-Ping Tan

Beilstein J. Org. Chem. 2025, 21, 596–600, doi:10.3762/bjoc.21.46

• ), 4.33 (td, J = 5, 1 Hz, 1H), 2.92 (m, J = 5 Hz, 2H); 13C NMR (100 MHz, DMSO-d6) δ 175.2, 157.2, 135.6, 129.8, 128.1, 126.7, 58.4, 36.4; LC–MS (ESI) m/z: 191 [M + H]+, 163, 120; HRMS (ESI) m/z: [M + H]+ calcd for C10H11N2O2 191.0815; found, 191.0815. The procedure was repeated by substituting ʟ

• ) δ 10.59 (s, 1H), 7.88 (s, 1H), 7.74 (s, 1H), 6.88 (s, 1H), 5.52 (s, 2H), 4.25 (t, J = 6 Hz, 1H), 2.95 (dd, J = 15, 4 Hz, 1H), 2.81 (dd, J = 15, 6 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) δ 175.5, 157.4, 134.6, 131.6, 117.0, 57.6, 28.8; LC–MS (ESI) m/z: 181 [M + H]+, 136. The procedure was repeated by

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• –240 mesh). Chiral HPLC analysis was performed using different chiral columns. IR spectra were recorded on an FTIR instrument. High-resolution mass spectra were performed by positive electrospray ionization using a quadrupole-time-of-flight detector (ESI+-Q-TOF) instrument. All compounds were purchased

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• computed with the ESI-3D program using AIM partition of space [75][76]. The anisotropy of the induced current density (AICD) plots have been computed at the same level of theory [77]. Current density maps have been computed by means of the SYSMOIC package [78][79][80], at the same level of theory. Finally

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• using a Gallenkamp melting point apparatus. For FTIR spectra, a Bruker Alpha spectrometer (model 200262) was used. NMR spectra were obtained using a Bruker Avance spectrometer operating at 300 and 75 MHz for 1H and 13C, respectively. HRMS analysis was performed using an Agilent 6546 LC/Q-TOF for ESI

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• ) were acquired using a Thermo-Fischer Scientific UltiMate 3000 Series UPLC (Waltham, MA, USA) equipped with a C18 column (Acquity UPLC BEH 50 × 2.1 mm, 1.7 µm; Waters, Milford, MA, USA) and an amaZon speed ESI-Ion trap-MS (Bruker) with a sample injection volume of 2 µL and a flow rate of 0.6 mL/min. A

• ) connected to a maXis® Electrospray Time-Of-Flight mass spectrometer (ESI-TOF-MS; Bruker). The experimental conditions for acquiring the HRESIMS data were identical to those used for ESIMS. Fungal strain The ex-holotype strain of Samsoniella aurantia BCC 55782 (corresponding type specimen BBH 33739) was

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• ) 200.0, 197.0, 140.1, 137.5, 136.6, 133.1, 133.0, 132.7, 129.9 (2C), 129.2 (2C), 128.6 (2C), 128.5 (2C), 71.9, 51.6, 49.3, 43.0, 36.9; HRMS–ESI+ (m/z): [M + H]+ calcd for C21H19O2, 303.1380; found, 303.1382. Minor isomer 9 1H NMR (400 MHz, CDCl3, δ) 7.55–7.49 (m, 2H), 7.22–7.15 (m, 3H), 7.11–6.99 (m, 5H

• ), 115.0, 85.6, 39.3, 37.8, 27.4; HRMS–ESI+ (m/z): [M + H]+ calcd for C21H19O2, 303.1380; found, 303.1383. Equipment for carrying out reactions by the diffusion mixing method. Knoevenagel and Diels–Alder reactions in the multicomponent synthesis of substituted cyclohexadienes under formaldehyde

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• supramolecular dimerization was triggered by observations in mass spectrometry experiments when exploring host–guest interactions. Positive-ion electrospray ionization mass spectrometry (ESI(+)MS) of a sample solution of cyclo[6]aramide H1 and a pyridinium derivative G1 in CHCl3/CH3CN (1:1, v/v) showed a

• molar ratio observed in ESI experiments. These inspiring results prompted us to further examine the interaction between host H1 and G1 by 1H NMR spectroscopy. Our prior experience with cyclo[6]aramide has confirmed binding to the cationic guest [49]. Indeed, addition of compound H1 to the guest solution

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• ). UPLC-MS analyses were performed on a Waters Acquity H-class UPLC with a Sample Manager FTN and a TUV dual wavelength detector coupled to a QDa single quadrupole analyzer using electrospray ionization (ESI). UPLC separation was achieved with a C18 reversed-phase column (Acquity UPLC BEH C18, 2.1 mm × 50

• hydrochloride (1b): The product was isolated by use of (II) as an amorphous white solid (83%). 1H NMR (600 MHz, CD3OD) δ 2.97 (m, J = 5.18 Hz, 2H), 3.18 (m, J = 5.24 Hz, 2H), 7.28 (m, J = 5.0 Hz, 3H), 7.35 (m, J = 7.6 Hz, 2H); 13C NMR (151 MHz, CD3OD) δ 34.55, 41.98, 128.26, 129.77, 129.99, 137.92; ESI-MS m/z

• , J = 8.4, 2.5, 0.2 Hz, 2H); 13C NMR (151 MHz, CD3OD) δ 33.75, 42.14, 55.71, 115.42, 129.60, 130.78, 160.47; ESI-MS m/z: [M + 1]+ 151.1; found, 152.1; mp 214–216 °C. 1-(2,5-Dimethoxyphenyl)propan-2-amine hydrochloride (3b): The product was isolated by use of (II) as a white solid (62%). 1H NMR (600

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• . The 1H and 13C chemical shifts were referenced to solvent peaks for DMSO-d6 at δH 2.50 and δC 39.52, respectively. LRESIMS data was recorded on an Ultimate 3000 RS UHPLC coupled to a Thermo Fisher Scientific ISQEC single quadruple ESI mass spectrometer. HRESIMS data was acquired on a Bruker maXis II

• ETD ESI-qTOF. Alltech Davisil (30–40 µm, 60 Å) C8-bonded silica and Alltech Davisil (30–40 µm, 60 Å) diol-bonded silica were used for pre-adsorption work before RP- or NP-HPLC, respectively. The pre-adsorbed material was subsequently packed into an Alltech stainless steel guard cartridge (10 × 30 mm

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• undesired unknown aggregates. On the other hand, the 1H NMR spectrum does not match the one of the free ligand which shows that neither full metal extrusion took place as a result of the competitive nature of oxalate. Negative ESI-MS of a host–guest mixture with 5 equiv of oxalate gave the final proof that

• which is observed for acetate, benzoate, and oxalate. a) 1H NMR titration (500 MHz, 500 µM, DMSO-d6, 25 °C) of [L2Zn2] with oxalate showing intermediate-like exchange. b) Negative ESI-MS spectrum of [L2Zn2] with 5 equiv oxalate showing the formation of [(C2)@L2Zn2]2− as host–guest complex. a) Optimized

Structure and thermal stability of phosphorus-iodonium ylids

• Andrew Greener,
• Stephen P. Argent,
• Coby J. Clarke and
• Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

• on ex situ analysis (1H, 31P NMR, ESI-MS) following aborted TGA experiments. (b–c) TGA and derivative plots for 1e and commercial samples of decomposition products 6 (Br− salt), 8 (Br− salt) and PPh3. (d–g) TGA thermograms replotted to show the molecular weight as a function of temperature assuming

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• magnetic resonance (1H NMR) spectra was recorded on a Bruker DRX400 spectrometer operating at 400 MHz. High-resolution mass spectrometry (HRMS) was performed using a Bruker BioApex 47e FTMS with an analytical electrospray source employing NaI for accurate mass calibration (ESI). UV–vis absorption spectra

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• analyses were performed by using the ionization method ESI+ with a 6230 TOF LC/MS, Agilent Technologies. Unless otherwise noted, analytical grade solvents and commercially available reactants were used without further purification. Common reagents were purchased from commercial sources and were used

• ), 103.5 (CH Ar), 75.9 (Cq spiro), 55.4 (OCH3), 52.1 (Cq t-Bu), 47.9 (CH2), 30.9 (CH2), 28.5 (3 CH3 of t-Bu); HRMS (ESI+) (m/z) [M + H]+: calcd for C27H30N3O, 412.238; found, 412.2395. Selected natural products containing spiro-indolenines. Time profile of the reaction of N-Ph-THIQ, 3,5-dimethoxyaniline

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• preceding gas chromatograph (GC) or liquid chromatograph (LC). Samples were ionised by electron impact ionisation (EI) on an Agilent 6890/5973 or Agilent 7890/5977 GC–MS equipped with an HP-5 capillary column using helium carrier gas or by electron spray ionisation (ESI) on an Agilent 1200/6210 Time-of

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• solvent signals (DMSO-d6: 2.50 ppm (1H NMR) and 39.52 ppm (13C NMR)). High-resolution mass spectra (HRMS) were obtained on a Bruker micrOTOF II instrument using electrospray ionization (ESI). The melting points were determined on a Kofler hot stage apparatus. A magnetic stirrer IKA C-MAG HS 7 was used for

• (75 MHz, DMSO-d6) δ 178.2, 175.5, 164.8, 138.1, 128.9, 128.3, 126.4, 98.7, 44.3, 44.0, 39.4, 32.6, 32.1, 24.7, 23.9, 21.9; HRMS (ESI-TOF) m/z: [M + H]+ calcld for C23H26NO5, 396.1805; found, 396.1801. Analytical data of further synthesized compounds can be found in Supporting Information File 2

• Hz, 2H), 1.63–1.53 (m, 2H), 1.40–1.11 (m, 5H); 13C NMR (75 MHz, DMSO-d6) δ 179.8, 175.3, 164.8, 140.4, 138.4, 129.0, 128.4, 128.3, 126.3, 88.98, 43.7, 43.5, 39.7, 32.8, 32.3, 24.9, 22.0, 12.8; HRMS (ESI-TOF) m/z: [M + H]+ calcld for C23H28N3O4, 410.2074; found, 410.2092. Experimental procedure for