Determination of the Absolute Stereochemistry of Two New Aristophyllene Sesquiterpenes: A Combined Theoretical and Experimental Investigation

Abstract

Aristoyunnolins G (1) and H (2), two new diastereoisomeric sesquiterpenes featuring a rare aristophyllene skeleton, were isolated from the traditional Chinese medicine Aristolochia yunnanensis. Their absolute stereochemistry involving three chiral centers was determined by combined chemical, spectral, and Density Functional Theory (DFT) calculation methods.

Natural nitric oxide (NO) inhibitors from Aristolochia mollissima

“…The known compounds madolin W (7), 20 madolin H (8), 21 aristoyunnolin G (9), 18 aristoyunnolin H (10), 18 aristoyunnolin E (11), 22 madolin F (12), 21 aristolactone (13), 19 versicolactone B (14), 23 madolin U (15), 22 aristoyunnolin B (16), 22 (+)-isobicyclogermacrenal (17), 24 madolin K (18), 19 madolin T (19), 25 spathulenol (20), 26 15-hydroxyspathulenol (21), 27 aromadendrane-4b,10b-diol (22), 19 (À)-alloaromadendrane-4b,10b-diol (23), 28 versicolactone C (24), 23 manshurolide (25), 29 aristoyunnolin F (26), 22 versicolactone D (27), 30 aristophyllide A (28), 31 aristophyllide B (29), 31 and aristoloterpenate-I (30) 32 were identied by comparison of their NMR data with those in the literature.…”

“…The AC of 4 was assigned to be the same as that of 9 based on the chemical transformation of 9 to 4 by acetylation.The molecular formula of aristomollin E (5) was deduced as C 15 H 24 O 2 by HRESIMS data. Its 1D NMR spectra bore a resemblance to those of aristoyunolin H (10)18 except for the absence of signals for the formyl group and the presence of a hydroxymethyl group [d H 4.13 (1H, d, J ¼ 13.7 Hz, H-14a) and 4.06 (1H, d, J ¼ 13.7 Hz, H-14b); d C 67.8], indicating 5 was a formylreduced derivative of 10. This was supported by the HMBC correlations of H-14/C-3, C-4, and C-5, H-3/C-14, and H-5/C-14.…”

Alkaloids from an algicolous strain of Talaromyces sp.

“…Several chiroptical techniques, such as electronic circular dichroism (ECD) (Stephens et al, 2008b;Batishta Jr et al, 2011;Miao et al, 2012;Mazzeo et al, 2013;Santoro et al, 2013;Wu et al, 2014), vibrational circular dichroism (Stephens et al, 2008b;Batishta Jr et al, 2011;Mazzeo et al, 2013), optical rotatory dispersion (Mazzeo et al, 2013;, and specifi c optical rotation ([α] D ) (Stephens et al, 2008a, b;Miao et al, 2012), have often been used to establish the absolute confi gurations of chiral compounds. Quantum chemical calculations greatly expand the application of these techniques.…”

Enantiomeric Neolignans and a Sesquiterpene from Solanum erianthum and Their Absolute Configuration Assignment

“…Therefore, for a complete structural characterization of such chiral natural compounds the assignment of their absolute configuration is mandatory, especially when the biological activity of the molecules is investigated. Although there are many different approaches that can be used to determine the ACs of chiral compounds, electronic circular dichroism (ECD) may be regarded as one of the most powerful techniques, specifically, methods based on the helicity rule for the specific functional groups including the exciton chirality method, the ketone octant rule, the in situ dimolybdenum CD method (Snatzke's method), and the allylic axial chirality rule for conjugated dienes and α,β‐unsaturated ketones, and quantum chemical ECD calculations have been widely used …”

“…Although there are many different approaches that can be used to determine the ACs of chiral compounds, electronic circular dichroism (ECD) may be regarded as one of the most powerful techniques, specifically, methods based on the helicity rule for the specific functional groups including the exciton chirality method, the ketone octant rule, the in situ dimolybdenum CD method (Snatzke's method), and the allylic axial chirality rule for conjugated dienes and α,β-unsaturated ketones, and quantum chemical ECD calculations have been widely used. [4][5][6][7] Lignans, widely distributed in the plant kingdom, are a family of secondary metabolites produced by oxidative dimerization of two phenylpropanoid units. Although their molecular scaffold consists only of two phenylpropane (C 6 -C 3 ) units, lignans exhibit an enormous structural diversity originating from various linkage patterns of these phenylpropane units.…”