O- And S-Heteroaromatic Compounds

Higginsianins A and B, Two Diterpenoid α-Pyrones Produced by Colletotrichum higginsianum, with in Vitro Cytostatic Activity

“…Compound 1 had a molecular formula of C 27 H 38 O 4 as deduced from its HRESIMS spectrum and consistent with nine hydrogen deficiencies. The preliminary investigation of its 1 H and 13 C NMR spectra (Table ) showed signals for carbonyl, olefinic, and hydroxy groups consistent with the bands observed in the IR spectrum, while its UV spectrum showed a band typical of an extended conjugated ester . A further investigation of its 1 H NMR spectrum (Table ) showed the presence of a broad doublet ( J = 9.0 Hz, H-13) at δ 5.14 and two broad singlets (H 2 -19) at δ 4.47 and 4.22, belonging to a trisubstituted and a 1,1-disubstituted double bond.…”

“…The preliminary investigation of its 1 H and 13 C NMR spectra (Table 1) showed signals for carbonyl, olefinic, and hydroxy groups consistent with the bands observed in the IR spectrum, 14 while its UV spectrum showed a band typical of an extended conjugated ester. 15 A further investigation of its 1 H NMR spectrum (Table 1) showed the presence of a broad doublet ( J = 9.0 Hz, H-13) at δ 5.14 and two broad singlets (H 2 -19) at δ 4.47 and 4.22, belonging to a trisubstituted and a 1,1-disubstituted double bond. Further, a triplet of doublets ( J = 9.0 and 6.8 Hz, H-12) at δ 4.78 and a broad singlet (H-8) at δ 3.64 were observed and assigned to the two oxygenated methine groups.…”

Untargeted Metabolomics Approach for the Discovery of Environment-Related Pyran-2-Ones Chemodiversity in a Marine-Sourced Penicillium restrictum

“…Compound 7 had the molecular formula C 6 H 6 O 3 as indicated by the (+)-HRESIMS m / z 127.0416 [M+H] + . As for compounds 5 and 6 , the UV spectrum of compound 7 was consistent with the presence of a pyran-2-one moiety [ 42 ]. The 1 H, 13 C-NMR analysis ( Table 3 ) allowed a final identification of compound 7 as 4-methoxy-2 H -pyran-2-one.…”

“…Thus, these isobaric compounds were annotated as putative isomers of a reference compound already described from fungi. Most of the VIP compounds were found to correspond to some pyran-2-one derivatives, which could be clearly annotated due to the characteristic UV absorption of either the pyran-2-one (λ max = 280 nm) [ 42 ] or the 5,6-dihydropyran-2-one moieties (λ max = 238 nm) [ 43 ]. In SSW extracts, pestalotin and 2’-hydroxypestalotin isomers [ 44 , 45 ] were highly produced, whereas dehydropestalotin, LL-P880 γ [ 46 ], and 5,6-dihydro-4-methoxy-2 H -pyran-2-one [ 45 ] were correlated with DW culture conditions.…”

“…The (+)-HRESIMS analysis returned a molecular formula of C 11 H 16 O 5 with four degrees of unsaturation from ions m / z 229.1069 [M+H] + , 251.0896 [M+Na] + , and 211.0969 [M−H 2 O+H] + . The UV spectrum of compound 5 in MeOH showed an absorption maximum at 280 nm characteristic of an unsaturated pyran-2-one moiety [ 42 ]. The 1 H-NMR spectrum showed the presence of one methoxy group at δ H 3.83 (3H, s, 4-OCH 3 ), a pair of olefinic hydrogens at δ H 5.46 (1H, d, J = 2.0 Hz, H-3) and 6.16 (1H, d, J = 2.0 Hz, H-5), a methyl at δ H 0.93 (3H, 7.1, H-5’), four methylenes at δ H 1.43 (2H, m, H-3’), δ H 1.54 (1H, m, H-4’) and δ H 1.35 (1H, m, H-4’), and two oxygenated sp 3 methines at δ H 4.44 (1H, d, J = 4.0 Hz, H-1’) and 4.02 (1H, m, H-2’).…”