O-Glycosides Isolated from Natural Products

The absolute configuration of compounds 25, 26 was determined by the bichromophoric exciton chirality method, and the interesting observation has been made that irradiation of Scots pine seedlings with ultraviolet B radiation induces the production of sunscreen pigments 27 and 28.  

O-Glycosides Isolated from Natural Products. — As usual, this Section is highly selective many examples with simple and complex glycosyl substituents have been reported. 

The triterpene jS-altropyranosides virescenoside A and B give broad-line spectra because of intermolecular association through hydrogen bonding. Addition of methanol results in normal line widths Ti and Tj values were measured as a function of methanol concentrations.  

Some further features of the biosynthesis of iridoid glycosides 

In the area of disaccharide natural products, 2-0-[5-0-(trans-feruloyl)-B-L-arabinofuranosyl]-D-xylose (30) was formed by enzymic 

Cell suspension cultures of Syringa vulgaris accumulate up to 16  

3 O-Glycosldes Isolated from Natural Products.- As usual, this section is highly selective many examples of simple and complex glycosides have been reported which contain unremarkable sugars and are here disregarded. 

D-Allose Is proving to be widespread in plants. -Hydroxy-phenyl 3-D-allopyranoside was Isolated from a Viburnum species, 

Thallctrum thumbergli. The same sugar, its 6-deoxy derivative. 

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Disregarding nonoxygen functional groups (amino, dimethylamino, and so on) only the 2,3,6-trideoxyhexoses were isolated from natural products. However, some of the isomeric trideoxyhexoses were chemically synthesized. Thus, the methyl a-glycosides of 3,4,6 - tr i de o xy - d - erj> f/ ro - he x o p y r a n o s e, 3,4,6-tri-deoxy-D-t/zreo-hexopyranose and 2,4,6-trideoxy-D-eryt/iro-hexopyranose were synthesized from methyl 4,6-dideoxy-a-D-xy/o-hexopyranoside via selective sub-... 

Pentosyl disaccharides continue to be of interest - largely because of their occurrence in natural products. The cyclic 6-0- 3-/)-arabinopyranosyl- -D-glucopyanose compound (123) heis been isolated from Lonicera nitida, and 6-0-/3-D-xylopyranosyl-(3-l>-glucose has been obtained as the hexa-O-acetyl benzyl glycoside from the acetylated aqueous extracts of green fruit of Prunus laurocerasus ... 

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