Fries-type Reactions for the C-Glycosylation of Phenols

C-Glycosylphenols and -polyphenols occur widely in nature and present a variety of biological properties, namely antitumor, antibacterial and antidiabetic activities. Synthetic access to such structures relies mainly on efficient methodologies for phenols C-glycosylation. In the past few years major advances have been described addressing the use of Fries rearrangement to obtain a diversity of C-glycosyl compounds. Herein we survey the glycosyl donors and the activators used for this reaction, covering both early work and recent developments in the area. Reaction mechanism and reaction outcome control, aiming at regio- and stereoselectivity are also discussed.