13C nmr study of α- and β-anomeric pairs of d-mannopyranosides and l-rhamnopyranosides

Isolation of a novel macrocyclic dilactone—JBIR-101—from Promicromonospora sp. RL26

“…Coupling constants among these protons revealed that the sugar moiety is an a-glucopyranoside. The direct 13 C-1 H coupling constant at C-1¢ ( 1 J CÀH ¼170.2 Hz) 13 also supported the identification of an a-glucopyranoside moiety. The 1 H-13 C long-range couplings from oxymethine proton 2¢-H to the carbonyl carbon C-1 and from the oxymethylene protons 6¢-H to the carbonyl carbon C-4, in addition to the acylated shifts at 2¢-H and 6¢-H, proved that two succinic acid moieties and two glucopyranoside moieties are connected through ester bonds.…”

“…The structure of 1 was determined by NMR spectral analyses. The direct connectivity of protons and carbons were established by heteronuclear single quantum coherence spectrum, and the tabulated 13 C and 1 H NMR spectral data for 1 is shown in Table 1. The structure of 1 was elucidated in a series of DQF-COSY and constant time (CT)-HMBC 12 as follows.…”

Cardiac glycosides from Cryptostegia grandiflora

“…The downfield shift of C-4 of the rhamnopyranosyl unit ( c 85.1) indicated its substitution at this position. The b configuration of the glucopyranosyl unit was deduced from the doublet signal of its anomeric proton at H 5.20 with J constant 7.7 Hz in the 1 H NMR spectrum while the configuration of the rhamnopyranosyl unit was established from the upfield shift of its C-5 ( c 68.3) in the 13 C NMR spectrum (Kasai et al, 1979). The structural assignment was confirmed by carrying out 2D NMR techniques such as HMQC and H-H COSY.…”

Sesquiterpenes from the Roots of Cichorium endivia

“…12) Cichorioside D (6) was suggested to have the molecular formula C 27 H 38 O 13 based on high resolution (HR)-FAB-MS [m/z: 593.2203 [MϩNa] ϩ ]. In the 1 H-and 13 C-NMR spectra of 6, two anomeric proton and carbon signals were observed at d 4.89, 5.49 and d 104.3, 102.6, in addition to signals due to the aglycone, and this aglycone was identified as 4, according to the similarity of the 13 C-NMR spectral data. The acid hydrolysis of 6 and the J value and/or chemical shifts of each anomeric proton signal showed that the sugar moiety consisted of b-D-glucopyranose and a-L-rhamnopyranose.…”

“…The acid hydrolysis of 6 and the J value and/or chemical shifts of each anomeric proton signal showed that the sugar moiety consisted of b-D-glucopyranose and a-L-rhamnopyranose. 13) Comparison of the 13 HR-FAB-MS showed the molecular formula of cichorioside E (7) to be C 27 H 38 O 14 . The 1 H-and 13 C-NMR spectra indicated that 7 was also jacquinelin 15-O-diglycoside.…”