Modified synthesis of 3'-O-TBDPS-protected furanoid glycal.

Thermolytic cleavage of 3'-OH protected thymidine is the most common method of preparing furanoid glycals. We have observed that glycosidic bond cleavage is more facile when the 5'-OH of thymidine was also protected with a silyl group. Addition of trimethylsilyl chloride facilitated cleavage of the glycosidic bond; thus, both modifications are required for the formation of the furanoid glycal. Investigations into the selective deprotection of 5'-silyl versus 3'-silyl and subsequent glycosidic bond cleavage are reported herein.