Absolute stereochemistry of altersolanol a and alterporriols

Abstract

The absolute stereochemistry of altersolanol A (1) was established by observing a positive exciton couplet in the circular dichroism (CD) spectrum of the C3,C4-O-bis(2-naphthoyl) derivative 10 and by chemical correlations with known compound 8. Before the discussion, the relative stereochemistry of 1 was confirmed by X-ray crystallographic analysis. The shielding effect at C7'-OMe group by C1-O-benzoylation established the relative stereochemical relationship between the C8-C8' axial bonding and the C1-C4/C1'-C4' polyol moieties of alterporriols E (3), an atropisomer of the C8-C8' dimer of 1. As 3 could be obtained by dimerization of 1 in vitro, the absolute configuration of its central chirality elements (C1-C4) must be identical to those of 1. Spectral comparison between the experimental and theoretical CD spectra supported the above conclusion. Axial stereochemistry of novel C4-O-deoxy dimeric derivatives, alterporriols F (4) and G (5), were also revealed by comparison of their CD spectra to those of 2 and 3.

Absolute Stereochemistry of Novel Isochromanone Derivatives fromLeptosphaeriasp. KTC 727

“…The profile for the theoretical spectrum thus obtained showed good agreement with the experimental spectrum of 1, affirming the foregoing discussions. 10,11) The molecular formula of 2 was determined to be C 13 H 16 O 6 based on the ESI mass spectrum (m=z 269.1023 ½M þ H þ calcd. 269.1025).…”

The Anthraquinone Derivatives from the Fungus Alternaria sp. XZSBG-1 from the Saline Lake in Bange, Tibet, China

“…Comparing the CD spectra ( Figure 6) with that of the the known compound alterporriol N, because the CD spectra were less sensitive to the configuration of the four chiral centres [10,16], according to the trends of CD between compound 3 and alternporriol N, we suggest that the absolute configuration of the chirality axis for compound 3 can be assigned as aS.…”

“…Anthraquinones and tetrahydroanthraquinones are widely distributed as secondary metabolites in natural biosources, and show important biological activities [2][3][4][5]. So far, 18 compounds of alterporriol family [6][7][8][9][10][11][12] and 14 compounds of altersolanol family [9,[13][14][15][16] have been reported. Herein, we report that the isolation, elucidation and biological activities of the anthraquinone and tetrahydroanthraquinone derivatives from Alternaria sp.…”

Current Knowledge on Pathogenicity and Management of Stemphylium botryosum in Lentils (Lens culinaris ssp. culinaris Medik)

“…Two endophytic strains of S. globuliferum also produced alterporriols H and K, altersolanol L, stemphypyrone [43], alterporriols D and E, altersolanol A, altersolanols B and C, and macrosporin [44], while an another endophytic strain of S. botryosum produced altersolanol A, curvularin, dehydrocurvularin, macrosporin, and stemphyperylenol [45]. A strain of S. herbarum produced alterporriols D-G and altersolanol A [46]. Recently, it has also been shown that Stemphylium metabolites have biological activities, such as cytotoxic and antibacterial effects [43,44] that may be of interest to the pharmaceutical industry.…”