Structures and Absolute Configurations of Diketopiperazine Alkaloids Chrysopiperazines A–C from the Gorgonian-Derived Penicillium chrysogenum Fungus

Three new diketopiperazine alkaloids, including two oxepine‐containing diketopiperazines, chrysopiperazines A and B (1 and 2), and one quinazoline‐containing diketopiperazine, chrysopiperazine C (5), together with three known analogues (3, 4, and 6), were isolated from the gorgonian-derived Penicillium chrysogenum fungus. The relative and absolute configurations of C-3 and C-15 in 1 and 2, C-3 and C-14 in 5 were established by NOE modified Marfey’s analysis and electronic circular dichroism (ECD) calculations. Particularly, the absolute configurations of C-19 in 1 and 3, which was very challenging to be identified due to the flexible conformation in a short aliphatic chain, were successfully determined by the vibrational circular dichroism (VCD) method, supplying with a reliable and optional method to define the absolute configurations. Additionally, this is the first report on oxepine-containing diketopiperazines from the genus Penicillium.

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Determination of the Absolute Configuration of Perylene Quinone-Derived Mycotoxins by Measurement and Calculation of Electronic Circular Dichroism Spectra and Specific Rotations

Chemistry - A European Journal ◽

10.1002/chem.201402567 ◽

2014 ◽

Vol 20 (36) ◽

pp. 11463-11470 ◽

Cited By ~ 9

Author(s):

Joachim Podlech ◽

Stefanie C. Fleck ◽

Manfred Metzler ◽

Jochen Bürck ◽

Anne S. Ulrich

Keyword(s):

Circular Dichroism ◽

Absolute Configuration ◽

Circular Dichroism Spectra ◽

Electronic Circular Dichroism ◽

The Absolute ◽

Circular Dichroïsm

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Absolute Configuration Sensing of Chiral Aryl- and Aryloxy-Propionic Acids by Biphenyl Chiroptical Probes

Chemosensors ◽

10.3390/chemosensors9070154 ◽

2021 ◽

Vol 9 (7) ◽

pp. 154

Author(s):

Stefania Vergura ◽

Stefano Orlando ◽

Patrizia Scafato ◽

Sandra Belviso ◽

Stefano Superchi

Keyword(s):

Circular Dichroism ◽

Absolute Configuration ◽

Optical Rotation ◽

Environmental Pollutants ◽

Red Shift ◽

Electronic Circular Dichroism ◽

Configuration Assignment ◽

Clear Sign ◽

The Absolute ◽

Circular Dichroïsm

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, the 4,4′-biphenyl substitution gives rise to a red shift of the diagnostic electronic circular dichroism signal of the biphenyl A band employed for the configuration assignment, removing its overlap with other interfering dichroic bands and allowing its clear sign identification. The largest A band red shift, and thus the most reliable results, are obtained by employing as a probe the 4,4′-dinitro substituted biphenylazepine 3c. The method was applied to the absolute configuration assignment of 2-arylpropionic acids ibuprofen (1a), naproxen (1b), ketoprofen (1c) and flurbiprofen (1d), as well as to the 2-aryloxypropionic acids 2-phenoxypropionic acid (2a) and 2-naphthoxypropionic acid (2b). This approach, allowing us to reveal the sample’s absolute configuration by simple optical rotation measurements, is potentially applicable to online analyses of both the enantiomeric composition and absolute configuration of these chiral pollutants.

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