Alkenyl glycosides

We have found that the secret to a successful synthesis of the alkenyl glycosides 64 lies in obtaining the pure -acetate 65 [47]. Condensation of the acetate 65 with the appropriate alkenol,in the presence of a small amount (5-20 mol% depending on the scale) of trimethylsilyl triflate, gave the alkenyl glycosides 64 in excellent yield. Oxidation of the alkene 64 with dimethyldioxirane, followed by deacetylation, then gave the putative enzyme inhibitors 60. 

N.A. Triterpenoid saponins, sterins, perlolyrin, alkenyl, polysaccharides, alkenyl glycoside, tangshenoside.99-122 An adaptogen, stimulant and tonic. 

Synthesis of 2-(l-Bromoalkyl)tetrahydrofurans by Bromocyclization of 4-Alkenyl Glycosides... 

Bromoalkyl)tctrahydrofurans by Cleavage of 4-Alkenyl Glycosides General Procedure57 ... 

SCHEME 5.23 Active-latent glycosylation using alkenyl glycosides,... 

C-Glycosides. 2-(Trimethylsiloxy)alkenyl glycosides undergo rearrangement on exposure to SnCl to afford 2-(l-hydroxy-2-oxoalkyl)tetrahydropyrans. 

R. Rodebaugh, J. S. Debenham, B. Fraser-Reid, and J. P. Snyder, Bromination of alkenyl glycosides with copper (II) bromide and lithium bromide synthesis, mechanism, and DFT calculations,./. Org. Chem., 64 (1999) 1758-1761. 

Activation of alkenyl glycosides. Transglycosylation" and anomeric phosphoryla-... 

In view of the dilemma apparent in Schemes 7a and b, an alternative rationalization was required, and this emanated from our studies on the oxidative hydrolysis of co-alkenyl glycosides, 46a-d (Scheme 8) (20). We found that all of these alkenes underwent addition reactions to give bromohydrins, 47, with the spectacular exception of pentenyl, 46c, which underwent hydrolysis to give the corresponding glycose 48. 

Various 6 -octylmellblose-based aldehydes fe.q. 42) and related hemiacetals (e.q. 43) have been made by reductive ozonolysis of corresponding alkenyl glycosides for reductive coupling to amino-acid derivatives. ... 

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