Lewis Acid Monoarylation

Several different catalyst systems, anomeric activators, and applications of Lewis acid catalyzed reactions for aryl C-glycoside synthesis have been published over recent years and a few are presented in Scheme 86. Inazu et al. used the dimethyl-phosphinothioate groups [151], while Satoh et al. introduced the use of AgOTfa/ SnCl4 as a novel catalyst system [152]. Schmidt et al. continued the use of the trichloroacetimidate group, this time directed at the preparation of bis(C-glycosyl) flavanoid precursors [153]. Sato's group has also used glycosyl fluorides to prepare precursors for C-glycosyl flavanoids (Scheme 86) [154]. Mallareddy and Rao prepared analogs of monocerin via intramolecular aryl C-glycosidation, (Scheme 86)

Scheme 85

507 508

TMS0Tf-AgCI04 50 mol % hi

MeCN

TMS0Tf-AgCI04 50 mol % hi

507 508

510 508

TMS0Tf-AgCI04

TMS0Tf-AgCI04

511,72%

MeCN

oh montmorillonite K-10

510 508

511,72%

montmorillonite K-10

0 0

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