Preparative and Stereoselective Synthesis of the Versatile Intermediate for Carbocyclic Nucleosides:  Effects of the Bulky Protecting Groups to Enforce Facial Selectivity

The preparative and stereoselective synthesis (45-50% overall yields) of the target compound 17 has been accomplished from D-ribose. The bulky protecting groups such as TBDPS and Trityl enforced the facial selectivity during Grignard reaction to give the tertiary beta-allylic alcohol 16 as the sole product, which was oxidatively rearranged to the key molecule 17 in excellent yield.