Highly Stereoselective Synthesis of Lamivudine (3TC)and Emtricitabine (FTC) by a Novel N-GlycosidationProcedure.

The combined use of silanes (Et3SiH or PMHS) and I2as novel N-glycosidation reagents for thesynthesis of bioactive oxathiolane nucleosides 3TC and FTC is reported.Both systems (working as anhydrous HI sources) were devised to actas substrate activators and N-glycosidation promoters.Excellent results in terms of chemical efficiency and stereoselectivityof the reactions were obtained; surprisingly, the nature of the protectivegroup at the N4 position of (fluoro)cytosine additionally influencedthe stereochemical reaction outcome. [ABSTRACT FROM AUTHOR]