Triterpene Glycosides of Scheffleropsis angkae. IV. Structure of Glycosides L-C2 and L-I2

Two new triterpene glycosides of the -amyrin series, L-C ₂ and L-I ₂ , 27-hydroxyursolic acid 3-O--L-arabinopyranoside and its 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl ester, are isolated from leaves ofScheffleropsis angkae(Araliaceae). The structures of the glycosides are established using chemical methods and NMR techniques ( ¹ H, ¹³ C, ¹³ C-APT, COSY, TOCSY, HSQC, HMBC, and ROESY).     

Triterpene Glycosides of Tetrapanax papyriferum. I. Isolation and Structure of Glycosides St-H2 and St-I2 from Stem Bark

Stem bark ofTetrapanax papyriferumC. Koch., Araliaceae, yielded new triterpene glycosides 28-O--L-rhamnopyranosyl-(14)-O-(6-O-acetyl--D-glucopyranosyl)-(16)-O--D-glucopyranosyl esters of the 3-O-[-D-glucopyranosyl-(13)-[-D-galactopyranosyl-(12)]-O--L-arabinopyranosides of oleanolic and echinocystic acids. The structures of these substances were established using chemical and physicochemical methods     

Synthesis of methyl derivatives of uronic acids. I. Synthesis of methyl (methylα-D-galactopyranosid)uronate and its 2-, 3-, and 4-O-methyl ethers

Alternative unidirectional methods for synthesizing methyl (methyl α-D-galactopyranosid)uronate and its mono-O-methyl ethers by the oxidation (with CrO₃-H₂SO₄-acetone) of the corresponding methyl O-benzyl-O-methyl-α-D-galactopyranosides having unsubstituted 6-OH groups to the corresponding methyl O-benzyl-O-methyl-α-D-galactouronic acids followed by esterification with CH₂N₂ and the catalytic hydrogenolysis of the benzyl groups are proposed.     

Synthesis of glycosidic analogues of N-acetylneuramoyl-L-alanyl-D-isoglutamine

-Heptyl and -hexadecyl glycosides of N-acetylglucosamine have been obtained by the oxazoline method followed by deacetylation. Via a benzylidenation stage, the glycosides have been converted into the corresponding N-acetylmuramic acid derivatives and from these compounds glycosidic analogues of N-acetylmuramoyl-L-alanyl-D-isoglutamine have been synthesized.M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 714–718, September–October, 1987.     

Synthesis ofβ-glycosides of n-acetylglucosamine in the presence of HgI2

The use of HgI₂ as catalyst in the synthesis oftrans-glycosides of N-acetylglucosamine is described. Using this catalyst, -glycosides of N-acetylglucosamine with aglycons of different structures and lyophilicities have been synthesized. The possibility of performing oligosaccharide synthesis has been demonstrated.