Oh

523 524

Scheme 89

AcO

Scheme 90

in a sequential process to deliver 522 [153]. Kumazawa et al. employed anomeric fluorides under boron trifluoride catalysis to give the corresponding bis-C-glycosyl flavanoid precursor 526 [162].

Satoh, using his SnCl4/AgOTfa catalyst system, was able to introduce a second sugar unit onto an existing aryl C-glycoside (Scheme 90) [163].

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