Glycosides of the

Indolocarbazole glycosides have attracted considerable interest over the years, as most indolo[2,3-fl]pyrrolo[3,4-c]carbazole alkaloids possess this structural feature. These systems are beyond the scope of this review however, there are several studies where glycosides of the parent system 1 have been investigated, in some... 

Although trityl perchlorate is used to accomplish the glycosidation of the C-8 hydroxyl in 44 with acetoxy glycoside 49, control experiments have demonstrated that no reaction takes place in the presence of 4 A molecular sieves or 2,6-di-terf-butylpyridine. This observation suggests that the actual catalyst is not trityl perchlorate, but perchloric acid. Consistent with this conclusion is the observation that catalytic amounts of a strong Brpnsted acid such as triflic or perchloric acid can catalyze the glycosidation of 44 with 49 in the absence of trityl perchlorate. 

Flavonoids glycosides of the genus were also studied in detail and again L. tridentata, with 17 of the 18 identified compounds, exhibited the most complex array. The close relationship between L. tridentata and L. divaricata was again... 

These contain C-NO2 bonds in contrast to the nitrate esters of, for example, glycerol and pentae-rythritol with O-NO2 bonds. Nitroalkanes have been used as solvents, and there are a few naturally occurring nitroalkanes such as the glycoside of the toxic 3-nitropropionic acid and the 0-methyl... 

Anthocyanins are the deeply colored glycosides of the aglycone anthocyanidins. Only the six aglycones shown in Figure 13.6 are common, although others occur sporadically [11,12]. 

XVIII has now been excluded,42 since the methyl glycoside of the sugar reacts rather rapidly with one mole of periodate per mole furthermore, in contrast to the behavior of mycaminose (XXI), no moiety with one carbon atom less has been isolated from the products of periodate oxidation. Oxidation of mycarose with hypoiodite affords a crystalline lactone with the empirical formula C7H12O4 this observation eliminates the possibility of the keto structure XX. Thus, mycarose appears to be a 2,6-dideoxy-3-C -methylhexose (XIX). In the original compound, the isovaleryl group must be esterified to the alcohol function at C4, since the methyl glycoside isovalerate obtained from carbomycin is only attacked by periodate after alkaline hydrolysis. 

Wagner H (1973) The Chemistry of Resin Glycosides of the Convolvulaceae Family. In Bendz G, Santensson J (eds) Medicine and Natural Sciences. Chemistry in Botanical Classification. Academic Press, New York, p 235 12. Mannich C, Schumann P (1938) Uber Jalapenharz und dessen Hauptbestandteil, das Con-volvulin. Arch Pharm Ber Dtsch Pharm Ges 276 211... 

The treatment of free sugars with alcohols in the presence of acid catalysts is the procedure most commonly used to prepare simple alkyl glycosides of the type frequently used in synthetic work. Although this is one of the oldest and most widely used reactions of carbohydrates it has not, until recently, been investigated in any detail on account of the variety of competing processes involved and the complexities of the products. Alternatively, the reverse reaction, the acid catalysed hydrolysis of glycosides, which is appreciably easier to study because of the single products obtained, has been the subject of many detailed studies and is now well documented and understood. 

The stereoselective glycosidation of the secoaglycon 1338 was achieved by reaction of the sodium salt of 1338 with the a-l,2-anhydrosugar 1339 to give the p-glucopyranoside 1340 in 48% yield. After the removal of the SEM protecting group with TBAF, the photocyclization of compound 1341 afforded the indolocarbazole... 

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