Cationic gold(I)-catalyzed glycosylation with glycosyl S-3-butynyl thiocarbonate donors

Efficient and versatile formation of glycosidic bonds via catalytic strain-release glycosylation with glycosyl ortho−2,2-dimethoxycarbonylcyclopropylbenzoate donors

“…Yu’s reaction activates the donor through a weak interaction between the metal catalyst and the alkyne leaving group and suppresses the aglycone transfer side reactions which plague the traditional glycosylation reactions with covalent activation modes. Inspired by this elegant activation mode, a series of catalytic glycosylation reactions have been developed recently for efficient construction of O - 32 – 35 and N -glycosidic linkages 36 – 38 . The glycosylation reactions employing glycosyl alkynes catalyzed by expensive gold, silver or highly toxic mercury catalysts thus remain the prevailing strategy for catalytic glycosylation with weak-interaction-mediated activation 39 – 41 .…”

Cationic gold(i)-catalyzed glycosylation with glycosyl N-1,1-dimethylpropargyl carbamate donors

“…5 b ,6,7 In addition, Hotha's group disclosed an interesting cationic gold( i )-catalyzed glycosylation involving glycosyl ethynylcyclohexyl carbonate donors 3 (b, Scheme 1). 8 Recently, our group reported a cationic gold( i )-catalyzed glycosylation using bench-stable glycosyl S -3-butynyl thiocarbonate donors, 9 based on our previous discovery of glycosyl S -3-butynyl thioglycosides in gold-catalyzed glycosylation. 10 However, fully substituted sugar-derived glycosyl donors bearing these sulfur-containing leaving groups 9,10 were found to be less reactive than those glycosyl o -alkynylbenzoates 5 b or ethynylcyclohexyl carbonate donors 8 towards cationic gold( i ) catalysis.…”