Total synthesis of syringalide B, a phenylpropanoid glycoside

Chemical compositions and biological activities of Scutellaria pinnatifida A. Hamilt aerial parts

“…1 H-NMR (200 MHz, CD3OD): δ H 7.70 (1H, d, J = 15.9, H-7’), 6.95 (1H, d, J = 2.0, H-2’), 6.83 (1H, d, J = 8.0, H6’), 6.79 (2H, d, J = 8.0, H-2, H-6), 6.62 (1H, dd, J = 8.0, 2.0, H-5’), 6.33(1H, d, , J = 15.9, H-8’), 6.33 (2H, d, J = 8.0, H-3, H-5), 4.40 (1H, d, J = 7.2, H-1’’), 3.31, 3.71 (2H, m, H-8), 3.203.90 (6H, overlapped, glucose protons), 2.82 (2H, t, J = 7.5, H-7), 13 C-NMR (50 MHz, CD3OD): δ C 162.8 (C-9’), 153.8 (C-4), 148.7 (C-3’), 148.1 (C-4’), 147.7 (C-7’), 130.94 (C- 2, C-6), 130.4 (C-1), 121.2 (C-6’), 121.1(C- 1’), 116.5 (C-5’), 116.3 (C-3, C-5), 115.1 (C- 8’), 110.9 (C-2’), 103.1 (C-1’’), 77.8 (C-3’’), 76.2 (C-5’’), 75.4 (C-2’’), 72.3 (C-8), 71.7 (C- 4’’), 62.7 (C-6’’), 36.5 (C-7), These data are in agreement with the published data (1819). …”

“…1). The chemical structures of all isolated compounds were elucidated unequivocally through UV and NMR and also all spectroscopic data were in agreement with respective published data (1415161718192021). The data of 1 H-NMR and 13 C-NMR of the compounds are given as follows:…”

“…The related anomeric carbon resonances was at δ C 103.1. Based on these results, the structure of (5) was identified as a phenylethanoid, syringalide A, whose spectral data were consistent with the literature (1819). Syringalide A was previously isolated from the leaves of Syringa species (Oleaceae family) but, to the best of our knowledge, this is the first report on the occurrence of this compound in the genus Scutellaria .…”

“…A combination of SPE and reversed-phase prep-HPLC analyses of the methanolic extract and also using Sephadex LH-20 column chromatography of the aerial parts of S. pinnatifida led to the characterization of a phenylpropanoid: 1-o-feruloyl-ß-D-glucose (1) (14), two known flavonoids: luteolin-7-o- glucoside (2) (15) and apigenin-7-o-glucoside (3) (16), three known phenylethanoid glycosides: phlomisethanoside (4) (17), syringalide A (5) (1819), and verbascoside (6) (20), and oleic acid (7) (21), respectively. The 1 H-NMR spectrum of compound (1) displayed signals for three aromatic methine protons at δ H 7.20 (1H, d, J = 2.0, H-2), 6.84 (1H, d, J = 8.0, H-5), 7.09 (1H, dd, J = 8.0, 2.0, H-6) suggesting the presence of a 1, 3, 4 tri substituted phenyl moiety, two trans-olefinic protons at δ H 7.74 (1H, d, J = 15.8, H-7), 6.44 (1H, d, J = 15.8, H-8) indicating the presence of an α, ß-unsaturated carbonyl functionality, a singlet proton resonance at 3.90 (3H, s) exhibiting the presence of a methoxy group and a doublet proton resonance at 5.60 (1H, d, J = 8.0, H-1’) was readily assigned to the anomeric proton of a glucose moiety, indicating the monoglycosidic structure in (1) .…”

Plantamajoside — A current review

“…Schilling et al (1982) reported the transformation of natural verbascoside to isoverbascoside by isomerization of the caffeoyl group using sodium hydroxide solution. In 2005, Li described complete synthesis of syringalide B, a phenylpropanoid monoglycoside (Li et al, 2005). Syringalide B was synthesized through a common intermediate, using a benzyl-moiety as a temporary protecting group following a shorter route together with another polyphenolic glycoside-grayanoside A (Das et al, 2007).…”