Stereospecific synthesis of 1-fluoro olefins via (fluoro-vinyl)stannanes and an unequivocal NMR method for the assignment of fluoro olefin geometry

Article abstract of DOI:10.1016/0040-4020(95)00911-Q

(E)- and (Z)-Fluorovinyl sulfones (II) form (fluorovinyl)stannanes (III) on treatment with two equivalents of tributyltin hydride and a catalytic amount of AIBN; the free radical catalyzed reaction proceeds with retention of configuration for 2,2-disubstituted fluorovinyl sulfones (IIa and IIb). Conversion of III to 1-fluoro olefins (IV) is a stereospecific reaction and provides a general method to (E) and (Z) fluoro olefins. The utility of this method is exemplified by the synthesis of the deutero fluoro olefins 27, nucleosides 32 and 34, and the amino acids 43 and 47. Proton observe, ¹⁹F irradiated (¹H-{¹⁹F}) NOE difference spectroscopy was used for the first time as an unequivocal method for the assignment of olefin geometry for fluorovinyl sulfones, (fluorovinyl)stannanes and fluoro olefins.