Figure 2
Synthesis scheme to obtain the fluorinated cis-enantiomers (±) 6. Reagents and conditions: (a) absolute THF, DMAP, di-tert-butyl dicarbonate, r.t., 24 h; (b) absolute THF, LiHMDS, NFSI, 201 K–r.t., 42 h; (c) CH3CN, 85% (w/w) H3PO4, 323 K, 4 d. |