Glycones Glycosides

Particularly in naturally occurring glycosides, the compound ROH from which the carbohydrate residue has been removed is often termed the aglycone, and the carbohydrate residue itself is sometimes referred to as the glycone . 

It is well-known that in plant tissues certain amounts of flavour compounds are bound as non-volatile sugar conjugates. Most of these glycosides are jS-glu-cosides, but there are other glycones like pentoses, hexoses, disaccharides and trisaccharides too [46]. Acylated glycosides and phosphate esters have also been reported [47, 48]. Information about the analysis of glycosides can be found in the work of Herderich et al. [49]. 

N.A. Aloin isobarbaloin, aloeresin A, B, aloesin glycone, aloesone, emodin, chrysophanic acid, 1,8-dihydroxy-anthracene derivatives, barbaloin, anthaquinone glycosides.99-100 108 109 510-511 Purgative, eupeptic, and cholagogue effect. It is a laxative and cathartic. Juice from leaves used for cuts and other skin problems. 

The synthesis of 4 and 5 provided an opportunity to evaluate the scope of a new C-glycosidation methodology that was used for 3 (28-34). Accordingly, esterification (step A) of the glycone component, l-thio-l,2-0-isopropylidene acetal (TIA) 16 and one or the other aglycone segments, C-branched saccharide acids 14 or 15, furnishes ester 12 or 13, respectively (Scheme 1). Tebbe methylenation (step B) of the latter provides enol ethers 10 or 11. Thiol... 

The aglycone segments 14 and 15 were next individually partnered with glycone 16 for the four step C-glycosidation sequence (Scheme 4). DCC mediated esterification (36) of 16 with 14 and 15 followed by treatment of the resulting esters with the Tebbe reagent (37) gave enol ethers 23 and 25 respectively, in 61 and 65% yields from 16. The key cyclization reactions on 23... 

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