The first alpha-fluoroallenylphosphonate, the synthesis of conjugated fluoroenynes, and the stereoselective synthesis of vinylfluorophosphonates using a new multifunctional fluorine-containing building block

Limitations on current methodologies for the introduction of CF2 and CFH in complex alpha-fluorophosphonates led to the synthesis of a fluorine-contai ning building block TIPS-C drop CCFXP(O)(OEt)(2), where X = H or F. This mu ltifunctional fluorine synthon reacts with carbonyl compounds under WHE con ditions to give high yields of fluorinated conjugated enynes and enediyne. When X = F, trapping of the desilylated anion with an electrophile after TI PS removal provided exclusive access to gamma-substituted derivatives of al pha-fluorophosphonates. When X = H, TBAF deprotection of the silyl group yi elds H2C=C=CFP(O)(OEt)2 through an allenyl-propargyl resonance Stabilized a nion. The allene moiety has been used as template in the stereoselective Sy nthesis of alpha-fluoro-beta-gamma-diiodopropenyl phosphonate, via electrop hilic iodination, and alpha-fluoro-gamma-amino-alpha,beta-unsaturated phosp honates, including unsaturated phosphononucleosides, by nucleophilic displa cement of an allylic iodide. Hydroamination of H2C=C=CFP(O)(OEt)(2) using s econdary amines produced (Z)-alpha-fluoroenaminophosphonates, whereas Diels -Alder cycloaddition with cyclopentadiene provides the corresponding exocyc lic vinylfluorophosphonate.