Sialylation reactions: Expanding the C-5 effect to phosphate leaving groups

Area of Science:

• Carbohydrate Chemistry
• Organic Synthesis
• Glycosylation Chemistry

Background:

• Phosphates are increasingly utilized as effective leaving groups in sialylation reactions.
• The influence of the C-5 substituent on the reactivity and stereoselectivity of sialyl phosphate donors remains poorly understood.
• Understanding these effects is crucial for optimizing sialylation strategies.

Purpose of the Study:

• To compare the performance of sialyl phosphate donors with N-acetyloxazolidinone and trifluoroacetamido functionalities at the C-5 position.
• To investigate the impact of various solvents and glycosyl acceptors on sialylation outcomes.
• To elucidate the C-5 effect on reactivity and stereoselectivity in sialylations.

Main Methods:

• Synthesis of sialyl phosphate donors with distinct C-5 functionalities (N-acetyloxazolidinone and trifluoroacetamido).
• Performance evaluation of these donors in sialylation reactions with a range of acceptors.
• Systematic variation of reaction solvents to assess their influence on the outcomes.

Main Results:

• Excellent yields and complete stereoselectivity were achieved in several sialylation reactions using the tested donors.
• The choice of solvent significantly influenced the reaction's efficiency and stereochemical control.
• The nature of the glycosyl acceptor also played a critical role in determining the reaction's outcome.

Conclusions:

• Sialyl phosphate donors with specific C-5 functionalities offer high reactivity and stereoselectivity in sialylations.
• Solvent and acceptor selection are critical parameters for optimizing sialylation reactions.
• This study provides valuable insights for the rational design of sialylation strategies.