Rh(II) and Chiral Phosphoric Acid Co-catalyzed Selective O–H Insertions for Stereodivergent O-Alkylation of Glycosides

Abstract

Carbohydrates are synthetically challenging molecules with essential biological functions in all living systems. The selective synthesis and modification of carbohydrates are crucial for investigating their biological functions. Controlling chemo-, regio-, and stereoselectivity is a central theme in carbohydrate synthesis. Achieving the full set of stereoisomers of carbohydrate derivatives would significantly enhance the efficiency of building compound libraries for biological studies and drug discovery. However, the selective functionalization of seemingly identical hydroxyl groups in carbohydrates remains a long-standing challenge in organic chemistry. In carbohydrate synthesis, achieving precise control of both relative configurations in catalyst-controlled reactions that create a new stereocenter presents a significant synthetic challenge. Herein, we developed an efficient method for the stereodivergent O-alkylation of carbohydrate hydroxyl groups via Rh(II)/chiral phosphoric acid-cocatalyzed insertion of metal carbenoids. This system is mild and robust, offering excellent selectivity across a broad range of substrates with high regio- and stereoselectivity. Furthermore, this strategy opens up vast opportunities for stereodivergent synthesis.