[C:1]([C:3]1(O[Si](C)(C)C)[CH2:8][CH2:7][CH2:6][N:5](C(OC(C)(C)C)=O)[CH2:4]1)#[N:2].COCCN(S(F)(F)[F:31])CCOC.[O-][Mn](=O)(=O)=O.[K+]>C(Cl)Cl>[F:31][C:3]1([C:1]#[N:2])[CH2:8][CH2:7][CH2:6][NH:5][CH2:4]1To a mixture of tert-butyl 3-cyano-3-(trimethylsilyloxy)piperidine-1-carboxylate (300 mg, 1.005 mmol) in DCM (10 mL) was added [bis(2-methoxyethyl)amino]sulfur trifluoride (0.222 mL, 1.206 mmol). The reaction mixture was stirred for 2 hours at room temperature. TLC (1:1 EtAOc/hexanes) shows a new higher Rf spot when stained with KMnO4 and no starting material. The reaction mixture was diluted with DCM (10 mL) and washed with H2O. The organic layer was dried with MgSO4, filtered, and concentrated. Solids were purified on a silica gel cartridge using a 0-100% gradient of EtOAc/hexanes, concentrated, and then treated with TFA/DCM for 1 hour. Solvent was removed in vacuo and the solids were dried to give 201 mg of 3-fluoropiperidine-3-carbonitrile as a TFA salt. 1H NMR (400 MHz, chloroform-d) δ ppm 3.82-4.01 (1H, m), 3.68(1H, br. s.), 3.45-3.61 (1H, m), 3.37(1H, br. s.), 2.06-2.31 (2H, m), 1.79-1.94(1H, m), 1.63-1.76 (1H, m); 19F NMR (400 MHz, chloroform-d) δ ppm −157.4 (alpha-F); −156.5 (TFA).
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