Conformation and absolute configuration of 2‐naphthylalkylsulfoxides by combined use of dynamic NMR, ECD spectroscopy, DFT computations, and X‐ray diffraction

Casarini, Daniele; Lunazzi, Lodovico; Mancinelli, Michele; Mazzanti, Andrea; Scafato, Patrizia

doi:10.1002/chir.20587

Cited by 9 publications

(6 citation statements)

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“…The most important result from our investigation is that TDDFT calculations, run with hybrid functionals such as BH&HLYP and B3LYP and a moderately large basis set (TZVP) on DFT-computed geometries, are able to fully reproduce CD spectra of aryl benzyl sulfoxides. Therefore, as noted by other authors, TDDFT//DFT calculations lend themselves as a reliable tool for interpreting the CD spectra of these and other related compounds and for determining their absolute stereochemistry.…”

Section: Discussionmentioning

confidence: 65%

“…Rather surprisingly, no other systematic discussion of CD spectra of sulfoxides has been reported since then in the literature. In particular, time-dependent density functional theory (TDDFT) calculations, which currently represent the most popular approach to quantitative predictions of chiroptical properties, were applied only to a few specific cases and were found to correctly reproduce experimental CD spectra or optical rotations and to allow safe configurational assignments to be established. − …”

Section: Introductionmentioning

confidence: 99%

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Systematic Investigation of CD Spectra of Aryl Benzyl Sulfoxides Interpreted by Means of TDDFT Calculations

et al. 2010

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The CD spectra of 13 crystalline aryl benzyl sulfoxides 1a-m with various substituents on the two aromatic rings were recorded in solution and in the solid state. Solution CD spectra were very homogeneous along the series, consisting in most cases of a couplet-like feature in the 200-300 nm region. The red-shifted component of the couplet, corresponding to the sulfoxide-centered n-pi* transition, is always positive for (R) absolute configuration in accordance with Mislow's rule. The presence of a strong electron-withdrawing substituent on the phenyl ring (nitro or ester group) alters the shape of the CD spectrum. CD calculations using the TDDFT method were run for eight representative compounds using DFT-optimized geometries. In all cases, calculated spectra were in very good agreement with experimental ones and allowed for rationalization of the diverse spectral behaviors. It is demonstrated that TDDFT//DFT calculations represent a reliable option for assigning the absolute configuration of this class of compounds whenever crystals suitable for X-ray are not available. Solid-state CD spectra recorded with the KCl pellet technique were in some cases in agreement with those in solution. However, in other cases new and strong CD signals appeared which were interpreted as being due to intermolecular couplings in the crystals.

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Section: Discussionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Systematic Investigation of CD Spectra of Aryl Benzyl Sulfoxides Interpreted by Means of TDDFT Calculations

et al. 2010

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“…As shown above, DNMR and NOE spectra can give detailed information on the ratio of populated conformers and on their three‐dimensional structures. This approach has been used for the AC assignment of some 2‐naphthylalkylsulfoxides 192. These compounds exist as syn ‐ and anti ‐periplanar conformers depending on the orientation of the S=O group with respect to the naphthalene ring.…”

Section: Application Of Conformational Analysis To the Determination mentioning

confidence: 99%

Recent trends in conformational analysis

Mazzanti

Casarini

2011

WIREs Comput Mol Sci

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An outlook of the various research fields of organic chemistry where conformational analysis plays a fundamental role is presented. The section Methodologies for Conformational Analysis is focused on the information that can be obtained by various spectroscopic techniques such as nuclear magnetic resonance and optical methods such as electronic circular dichroism and vibrational circular dichroism. A comprehensive screening of the more recent ab initio and density functional theory theoretical approaches to conformational analysis is presented in the section Theoretical Conformational Analysis. The section Application of Conformational Analysis to the Determination of the AC of Organic Molecules shows how the synergic use of experimental and theoretical methods can solve challenging conformational tasks arising from modern organic chemistry. © 2011 John Wiley & Sons, Ltd. This article is categorized under: Electronic Structure Theory > Density Functional Theory

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“…14,15) As shown in Fig. 3, the calculations of the ECD spectra for these structures and their arithmetical averaging provided the overall theoretical ECD spectrum.…”

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confidence: 97%

Three New Oligostilbenes from the Seeds of Paeonia suffruticosa

Peng

et al. 2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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NotePaeonia suffruticosa ANDR. (Paeoniaceae) is found extensively in China. It is an important Chinese medicinal plant from the section Moutan of the genus Paeonia. This genus consists of ca. 35 species placed in three sections: Moutan, Oneapia, and Paeonia.1) The root cortex of this plant (Chinese name: mudanpi) is a well-known Chinese herbal medicine widely used as an analgesic, anaphylactic, antioxidative, and antiinflammatory agent. Numerous studies on the chemistry and pharmacology of this species have been performed.2) Previous phytochemical studies indicated that stilbenes were the primary bioactivity constituents of peony seeds. These stilbenes exhibit potent biological activities such as cytotoxic, antimutagenic, ecdysteroid antagonist, antioxidant, hyperpigmentation, antitumor, and anti-inflammatory activity and can improve bone disease. [3][4][5][6][7][8] In the course of searching for new bioactive natural products from the seeds of this plant, 11 stilbenes, trans-(1) and cis-suffruticosol D (2), trans-resveratrol (3), 9) trans-e-viniferin (4), 7)cis-e-viniferin (5), 7) gnetin H (6), 7) cis-gnetin H (7), suffruticosol A (8),3) suffruticosol B (9), 3) suffruticosol C (10), 3) and cis-ampelopsin E (11), 10) were isolated from the ethyl acetate extract of the seeds of P. suffruticosa. Among them, 1, 2, and 7 were new compounds. Here, we report the isolation and extensive structural elucidation of the new compounds. Results and Discussiontrans-Suffruticosol D (1) Three new oligostilbenes, trans-suffruticosol D (1), cis-suffruticosol D (2), and cis-gnetin H (7), were isolated along with the eight known stilbenes, trans-resveratrol (3), trans-e e-viniferin (4), cis-e e-viniferin (5), gnetin H (6), suffruticosol A (8), suffruticosol B (9), suffruticosol C (10), and cis-ampelopsin E (11) from the seeds of Paeonia suffruticosa. Compounds 3-6 were isolated for the first time from this plant species, and compound 11 was isolated for the first time from the genus Paeonia. The structures of the new compounds were elucidated based on spectral analyses, including 1D and 2D NMR experiments. The absolute configuration of compound 1 was determined by quantum chemical calculation of the electronic circular dichroism and comparison with the experimental circular dichroism spectrum.

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Conformation and absolute configuration of 2‐naphthylalkylsulfoxides by combined use of dynamic NMR, ECD spectroscopy, DFT computations, and X‐ray diffraction

Cited by 9 publications

References 40 publications

Systematic Investigation of CD Spectra of Aryl Benzyl Sulfoxides Interpreted by Means of TDDFT Calculations

Systematic Investigation of CD Spectra of Aryl Benzyl Sulfoxides Interpreted by Means of TDDFT Calculations

Recent trends in conformational analysis

Three New Oligostilbenes from the Seeds of Paeonia suffruticosa

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