A Diastereoselective Method for the Construction of syn-2'-Deoxy-2'-fluoronucleosides

A general and diastereoselective fluorination/glycosylation strategy for the synthesis of 2 '-fluorinated nucleosides has been developed. Electrophilic fluorination of a glycal with NFSI provided the 1 ',2 '-difunctionalized furanoside intermediate with high diastereoselectivity. The TBS-protected 2 '-deoxyfluorosulfonimide sugar was prepared on an 80 g scale and isolated as a crystalline, bench-stable single diastereomer. This intermediate was found to undergo a subsequent glycosylation reaction with a variety of heteroaryl nucleophiles with generally good diastereoselectivities.