Abstract:

Two mild, efficient and practical methods to synthesize O-chloro- benzoquinonyl C-glycopyranosides are reported. At first, using NH4NO3 as a catalyst, aryl C-glycosides 1a and 1b were chlorinated by N-chlorosuccinimide to afford O-chlorinated compounds 2a and 2b in high regioselectivity. The corresponding benzoquinonyl C-glycosides 3a and 3b were obtained after oxidization with cerium ammonium nitrate (CAN) in an overall yield of 88% and 84% respectively. On the other hand, with the catalysis of BF3?Et2O, O-chloro-hydroquinonyl C-glycosides 5a and 5b can also be obtained through addition reaction and hydrolyzation involving benzoquinonyl C-glycosides and Me3SiCl in an overall yield of 82% and 76% respectively. Additional, Corresponding hydroquinone and benzoquinone compounds can be transformed each other through oxidation and reduction.

Key words: Chlorination, Benzoquinone, Hydroquinone, Aryl C-glycoside