Product ion spectra from the [M+2H]²⁺ ions of anabaenopeptin A (3) (panel a), B (4) (panel b), citrullinated-B (5) (panel c), and C (6) (panel d), acquired at a 20 eV laboratory-frame collision energy

Doubly charged ions are marked with #. The numbers in parentheses beside each dashed line are nominal masses corresponding to the side of each formal cleavage site. The italicized numbers are nominal masses of actual fragment ions that were generated with hydrogen rearrangement(s). The data were acquired by using a Synapt G2 quadrupole/time-of-flight (Q-TOF) tandem mass spectrometer (Waters Co., Manchester, UK) equipped with an Acquity UPLC system (Waters) and an ESI source. Samples were injected into a reversed-phase column (ACQUITY UPLC BEH C18 1.7 µm, 2.1×50 mm, at 25°C) and eluted with an isocratic solvent system (solvent A: 0.1% formic acid in water; Solvent B: acetonitrile; 30% B) at a flow rate of 0.2 mL/min for short LC-MS/MS runs. The ions generated at positive ESI capillary (3 kV) under atmospheric pressure went into the vacuum system through the sampling cone (15 V). The ions were transferred to the quadrupole mass analyzer for isolation of precursor ions of interests (i.e., the protonated molecules of analytes). The isolated precursor ions were subjected to low-energy CID (20 eV laboratory-frame collision energy) with Ar (99.9999%, 0.4 mL/min) at the trap collision cell (2.5×10−2 mbar). Ions went through the collision cell and the following ion optics were mass analyzed at the orthogonal TOF analyzer for the recording of a high-resolution (approx. 20,000 FWHM) externally calibrated product ion spectrum in each second. In post-run data processing, a few spectra at the retention time of each analyte were combined and converted to a centroid spectrum. The precursor ion peak in each combined spectrum was used as an internal lock mass for recalibration to ensure ppm-level mass accuracy. </div

LC-ESI mass spectra of anabaenopeptin (panel a) and anabaenopeptin B (panel b)

The externally calibrated spectra (no internal lock mass correction) were acquired with a sampling cone setting at 30 V. The data were acquired by using a Synapt G2 quadrupole/time-of-flight (Q-TOF) tandem mass spectrometer (Waters Co., Manchester, UK) equipped with an Acquity UPLC system (Waters) and an ESI source. Samples were injected into a reversed-phase column (ACQUITY UPLC BEH C18 1.7 µm, 2.1×50 mm, at 25°C) and eluted with an isocratic solvent system (solvent A: 0.1% formic acid in water; Solvent B: acetonitrile) at a flow rate of 0.2 mL/min for short gradient (30% B to 70% B in 1 to 2 min) LC-MS runs. The ions generated at positive ESI capillary (2.5 kV) under atmospheric pressure went into the vacuum system through the sampling cone (30 V). The ions went through the transfer optics were mass analyzed at the orthogonal TOF analyzer for the recording of a high-resolution (approx. 10,000 FWHM) externally calibrated product ion spectrum in each second. In post-run data processing, a few spectra at the retention time of each analyte were combined and converted to a centroid spectrum. </p

Product ion spectra from the protonated molecules of citrullinated-anabaenopeptin B (5) (panel a) and anabaenopeptin C (6) (panel b) acquired at a 40 eV laboratory-frame collision energy

The numbers in parentheses beside each dashed line are nominal masses corresponding to the side of each formal cleavage site on the chemical structures. The italicized numbers are nominal masses of actual fragment ions that were generated with hydrogen rearrangement(s). The data were acquired by using a Synapt G2 quadrupole/time-of-flight (Q-TOF) tandem mass spectrometer (Waters Co., Manchester, UK) equipped with an Acquity UPLC system (Waters) and an ESI source. Samples were injected into a reversed-phase column (ACQUITY UPLC BEH C18 1.7 µm, 2.1×50 mm, at 25°C) and eluted with an isocratic solvent system (solvent A: 0.1% formic acid in water; Solvent B: acetonitrile; 30% B) at a flow rate of 0.2 mL/min for short LC-MS/MS runs. The ions generated at positive ESI capillary (3 kV) under atmospheric pressure went into the vacuum system through the sampling cone (15 V). The ions were transferred to the quadrupole mass analyzer for isolation of precursor ions of interests (i.e., the protonated molecules of analytes). The isolated precursor ions were subjected to low-energy CID (40 eV laboratory-frame collision energy) with Ar (99.9999%, 0.4 mL/min) at the trap collision cell (2.5×10−2 mbar). Ions went through the collision cell and the following ion optics were mass analyzed at the orthogonal TOF analyzer for the recording of a high-resolution (approx. 20,000 FWHM) externally calibrated product ion spectrum in each second. In post-run data processing, a few spectra at the retention time of each analyte were combined and converted to a centroid spectrum. The precursor ion peak in each combined spectrum was used as an internal lock mass for recalibration to ensure ppm-level mass accuracy. </div

Product ion spectra from the protonated molecules of anabaenopeptin A (3) and B (4) acquired at a 40 eV laboratory-frame collision energy

The numbers in parentheses beside each dashed line are nominal masses corresponding to the side of each formal cleavage site on the chemical structure for anabaenopeptin A. The italicized numbers are nominal masses of actual fragment ions that were generated with hydrogen rearrangement(s). The data were acquired by using a Synapt G2 quadrupole/time-of-flight (Q-TOF) tandem mass spectrometer (Waters Co., Manchester, UK) equipped with an Acquity UPLC system (Waters) and an ESI source. Samples were injected into a reversed-phase column (ACQUITY UPLC BEH C18 1.7 µm, 2.1×50 mm, at 25°C) and eluted with an isocratic solvent system (solvent A: 0.1% formic acid in water; Solvent B: acetonitrile; 30% B) at a flow rate of 0.2 mL/min for short LC-MS/MS runs. The ions generated at positive ESI capillary (3 kV) under atmospheric pressure went into the vacuum system through the sampling cone (15 V). The ions were transferred to the quadrupole mass analyzer for isolation of precursor ions of interests (i.e., the protonated molecules of analytes). The isolated precursor ions were subjected to low-energy CID (40 eV laboratory-frame collision energy) with Ar (99.9999%, 0.4 mL/min) at the trap collision cell (2.5×10−2 mbar). Ions went through the collision cell and the following ion optics were mass analyzed at the orthogonal TOF analyzer for the recording of a high-resolution (approx. 20,000 FWHM) externally calibrated product ion spectrum in each second. In post-run data processing, a few spectra at the retention time of each analyte were combined and converted to a centroid spectrum. The precursor ion peak in each combined spectrum was used as an internal lock mass for recalibration to ensure ppm-level mass accuracy. </div

Total Synthesis of Kehokorins A–E, Cytotoxic <i>p</i>‑Terphenyls

This paper describes a general method for the synthesis of kehokorins A–E, novel cytotoxic <i>p</i>-terphenyls. 2,4,6-Trihydroxybenzaldehyde served as a common building block for preparation of the central aromatic ring. Construction of their <i>p</i>-terphenyl skeletons was achieved by a stepwise Suzuki–Miyaura coupling, whereas the phenyldibenzofuran moiety was built up by an intramolecular Ullmann reaction. Introduction of an l-rhamnose residue into partly protected kehokorin B was performed by the trichloroacetimidate method

Synthesis of 3-phenyldibenzo[<i>b,d</i>]furan-type bioprobes utilizing vialinin B as a structural motif

<p>Vialinin B is a natural 3-phenyldibenzo[<i>b,d</i>]furan product with a powerful inhibitory activity against tumor necrosis factor (TNF)–α production. This article describes the synthesis of three types of biotinylated <i>p</i>-terphenyls designed for clarifying the target molecule of vialinin B. Construction of the carbon backbone of the core was accomplished by stepwise Suzuki–Miyaura coupling while the phenyl dibenzofuran moiety was built up by the Ullmann reaction. The biotinyl unit was attached through click chemistry.</p

Synthesis and Structural Revision of a Brominated Sesquiterpenoid, Aldingenin C

This paper describes a short step synthesis of the proposed structure for aldingenin C from <i>trans</i>-limonene oxide. The tetrahydropyran-fused 2-oxabicyclo[3.2.2]­nonane skeleton as the structural feature was constructed by an intramolecular epoxide-opening reaction and a brominative cyclization. The spectral data of the synthetic compound did not match those of the natural product reported. Re-examination of the reported NMR data using new CAST/CNMR Structure Elucidator suggests that the structure of aldingenin C should be revised to that of known caespitol

Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision

This paper describes the first total synthesis of the proposed structure for aromin, an annonaceous acetogenin possessing an unusual bis-THF ring system, and its 4<i>S</i>,7<i>R</i>-isomer. The key steps involve an oxidative cyclization of a couple of terminal-diene alcohols and an intermolecular metathesis of an alkenyl tetrahydrofuran with an enone carrying a tetrahydrofuranyl lactone. The spectral data of both samples did not match those of aromin. Re-examination of the NMR data using the CAST/CNMR Structure Elucidator and chemical derivations suggested that the real structure of aromin should be revised to be a tetrahydropyran acetogenin, montanacin D. Cytotoxicities in human solid tumor cell lines for synthetic samples were also evaluated

Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision

This paper describes the first total synthesis of the proposed structure for aromin, an annonaceous acetogenin possessing an unusual bis-THF ring system, and its 4<i>S</i>,7<i>R</i>-isomer. The key steps involve an oxidative cyclization of a couple of terminal-diene alcohols and an intermolecular metathesis of an alkenyl tetrahydrofuran with an enone carrying a tetrahydrofuranyl lactone. The spectral data of both samples did not match those of aromin. Re-examination of the NMR data using the CAST/CNMR Structure Elucidator and chemical derivations suggested that the real structure of aromin should be revised to be a tetrahydropyran acetogenin, montanacin D. Cytotoxicities in human solid tumor cell lines for synthetic samples were also evaluated