Derivatives of 1-fluoroaziridine-2,2-dicarboxylic acid

Methyl 2-trifluoromethylaziridine-2-carboxylate: stereodirected N-halogenation from the sterically more hindered side

“…5, yield 69.5%, bp74-76°C (50Torr); 5s, 1 HNMR (CDCl 3 ) d: 3.1 (ddq, H a , 2 J ab -5.8Hz, 3 J aNF 28.7Hz, 4 J aCCF 2.4Hz), 3.29 (dd, H b , 3 J bNF 40.6Hz), 3.87 (s, MeO); 1 HNMR ([ 2 H 8 ]toluene) d: 2.34 (ddq, H a , 3 J aNF 27.9), 2.49 (dd, H b , 3 J bNF 41.5Hz), 3.09 (s, MeO); 13 CNMR (CDCl 3 ) d: 41.50 (dd, 3-C, 1 J Ca 172.1Hz, 1 J Cb 171.8Hz), 47.91 (qdt, 2-C, 2 J CCF 35.4Hz, 2 J CNF 7.0Hz, 2 J CCH 3.5Hz), 53.87 (q, MeO, 1 J CH 149.2Hz), 120.84 (q, CF 3 , 1 J CF 277.4Hz), 162.21 (dq, CO, 3 The long-range spin-spin coupling constant 4 J HCF 3 trans for the H a proton with a cis-orientation with respect to the LEP of the ring nitrogen atom is always greater. 8,9 The spin-spin coupling constant 4 J H a CF 3 trans (2.4Hz) for 6s is greater than 4 J H a CF 3 trans (1.5Hz)for 6a; hence, the chlorine atom in the aziridine 6s has a syn-arrangement relative to the CF 3 group, whereas in the aziridine 6a, this atom has the anti-orientation. In addition, greater ASIS effects for the H b protons in 6a and forH c in8a areobserved(Table2).…”

N-Fluorination of aziridinecarboxylates via fluorolysis of their N-aminomethyl derivatives

“…2,3 Later, 1-fluoro-2,2-bis(trifluoromethyl)aziridine was obtained by direct fluorination of 2,2-bis(trifluoromethyl)aziridine (F 2 /NaF) in 50% yield and its NMR parameters were refined. 4 Also, 1-fluoro-2-aryl(alkyl)aziridines were detected spectroscopically (NMR, IR) following the interaction of 2-aryl(alkyl)aziridines with CF 3 OF. 5 Recently, by direct fluorination of NH-aziridines, some stable N-fluoroaziridinecarboxylates A-E were synthesised and isolated in pure form (Scheme 1).…”

“…5 Recently, by direct fluorination of NH-aziridines, some stable N-fluoroaziridinecarboxylates A-E were synthesised and isolated in pure form (Scheme 1). 4,6,7 N-Fluorination in the presence of NaF proceeds trans-stereospecifically due to the fixed orientation of the nitrogen lone pair through the intramolecular H-bond. When this H-bond is broken in the presence of Et 3 N both isomers A and B are formed.…”

“…So, fluorine attack occurs from the more hindered side too. The configuration of 2d (Scheme 2) was assigned on the basis of the NMR data, † based on the presence of 4 J HCCF for H a and its value (1.5 Hz). 2,15 1-Fluoroaziridine 3c was obtained in an optically active form from optically active aminomethylaziridine (2S,3S)-2c.…”

“…1 H NMR (CDCl 3 ) d: 3.10 (ddq, 1H, H a , 2 J ab = -5.8 Hz, 3 J aNF = 28.7 Hz, 4 J aCCF = 2.4 Hz), 3.29 (dd, 1H, H b , 2 J ab = -5.8 Hz, 3 J bNF = 41.5 Hz), 3.87 (s, 3H, MeO). 19 F NMR (CDCl 3 ) d: 14.13 (dd, CF 3 , 4 J FCCa = 2.4 Hz, 4 J FCCNF = 22.4 Hz). 13 C NMR (CDCl 3 ) d: 41.50 (dd, 3-C, 1 J Ca = 172.1 Hz, 1 J Cb = 171.8 Hz), 47.91 (qdt, 2-C, 2 J CCF = 35.4 Hz, 2 J CNF = 7.0 Hz, 2 J CCH = 3.5 Hz), 53.87 (q, MeO, 1 J CH = = 149.2 Hz), 120.84 (q, CF 3 , 1 J CF = 277.4 Hz), 162.21 (dq, CO, 3 J = = 5.1 Hz).…”