Stereoselective Preparation of Bicyclic Selena and Telluraheterocycles Starting from the Chiral Pool

Abstract

The preparation of seleno- and telluroesters by way of the Mitsunobu reaction[1] is not possible since seleno- and telluroacetic acid are unsuitable reagents. However, sodium hydrogen selenide and telluride can be conveniently prepared as in situ reagents. These powerful nucleophiles readily attack methyl 2,3-anhydro-5-O-mesyl-α-D-ribo-furanoside (1) to yield in a tandem reaction the selena- (3) – (5) and tellurabicyclics (11) as pure enantiomers.