LETTER
Introduction of Highly Electronegative Groups into the Hydrazine Molecule
1941
(8) Ragnarsson, U.; Grehn, L.; Koppel, J.; Loog, O.; Tšubrik,
O.; Bredikhin, A.; Mäeorg, U.; Koppel, I. J. Org. Chem.
2005, in press.
(9) (a) Groth, R. H. J. Org. Chem. 1959, 25, 102. (b)Brown,H.
C.; Cheng, M. T.; Parcell, L. J.; Pilipovich, D. J. Org. Chem.
1961, 26, 4407.
(12) Ried, W.; Franz, G. Liebigs Ann. Chem. 1961, 644, 141.
(13) Fritz, H.; Kristinsson, H.; Mollenkopf, M.; Winkler, T.
Magn. Res. Chem. 1990, 28, 331.
(14) Compound 4a: mp 130–132 °C. 1H NMR (DMSO-d6):
d = 1.42 (s, 9 H, Boc), 9.31 (s, 1 H, NH), 11.27 (s, 1 H, NH).
13C NMR (DMSO-d6): d = 27.9 (Me, Boc), 80.1 (Cq, Boc),
115.9 (q, CF3, JCF = 287 Hz), 154.4 (CO, Boc), 156.2 (q,
CF3CO, JCF = 36 Hz). IR: 3294, 3192 (NH), 1740, 1696
(C = O) cm–1. Anal. Calcd for C7H11F3N2O3: C, 36.85; H,
4.86; N, 12.28. Found: C, 37.14; H, 4.77; N, 12.03.
Compound 4b: mp 106–108 °C. 1H NMR (CDCl3):
d = 5.150 (s, 2 H, PhCH2), 4.341 (s, 5 H, CHarom), 9.096 (s, 1
H, NH-Z), 10.926 (s, 1 H, NHCOCF3). 13C NMR (CDCl3):
d = 67.4 (PhCH2), 116.0 (q, JCF = 286 Hz, CF3), 128.1,
128.3, 128.5, 136.0 (Carom), 155.8 (CO, Z), 157.1 (q, JCF = 38
Hz, CF3CO). ESI-MS: m/z calcd for C10H8F3N2O3: 261.049;
found: 261.096 [M–].
(10) Braun, M. W.; Rudolph, W. H.; Palsherm, S. B.; Eichholz,
K. L. US Patent 5532411, 1996.
(11) An oven-dried flask was charged with 224 mg of the
compound 1 (1 mmol), then evacuated and backfilled with
argon. Then, 8 mL of Et2O was added to dissolve the solid
and the solution was cooled down to –80 °C. A 1.6 M
solution of n-BuLi in hexane (2 equiv, 1.26 mL) was added
dropwise and the obtained mixture stirred for 30 min. In the
other flask, 6 mL of trifluoroacetylanhydride was added to
the solution of pyridinium chloride (10 equiv) in minimum
quantity of TFA. The emerging gaseous CF3COCl was
passed into the solution of metallated compound 1. The
mixture was stirred for 30 min at –80 °C and then let to warm
up to r.t. LiCl was filtered off and solvents were evaporated
in vacuo, yielding 271 mg of 2 (mp 148–150 °C). The ESI
molecular ion does not exist due to the rapid decomposition
to 1. 13C NMR (DMSO-d6): d = 116.1 (q, JCF = 286 Hz,
CF3CONH), 117.1 [q, JCF = 294 Hz, (CF3CO)2N], 155.8 (q,
JCF = 37 Hz, CF3CONH), 159.2 [q, JCF = 33, (CF3CO)2N].
Compound 3 was obtained in the same way in THF using 1
equiv n-BuLi for the first deprotonation of 1. After the
reaction with CF3COCl the addition of 1 equiv n-BuLi and
CF3COCl was repeated. THF was removed using rectifi-
cation, furnishing 3 as a colorless oil. ESI-HRMS: m/z calcd
for C8HF12N2O4: 416.9739; found: 416.9745 [MH]+.
13C NMR (DMSO-d6): d = 116.9 [q, JCF = 293 Hz,
(CF3CO)2N], 160.2 [q, JCF = 34, (CF3CO)2N].
(15) Schreiber, S. L. Tetrahedron Lett. 1980, 21, 1027.
(16) Compound 4d: mp 140–141 °C. 1H NMR (DMSO-d6):
d = 5.15 (s, 2 H, PhCH2), 7.38 (s, 5 H, Ph), 10.12 (s, 1 H,
NH-Z), 11.66 (s, 1 H, NHSO2CF3). 13C NMR (DMSO-d6):
d = 66.9 (s, PhCH2), 119.2 (q, JCF = 321 Hz, CF3SO2), 127.9,
128.2, 128.4, 136.0 (Carom), 156.1 (CO). ESI-MS: m/z calcd
for C9H8F3N2O4S: 297.016; found: 297.083 [M–].
Compound 4e: mp 161–163 °C. 1H NMR (DMSO-d6):
d = 7.29 (d, JCH = 9.6 Hz, 1 H, Ar), 8.39 (m, 1 H, Ar), 8.90
(d, JCH = 2.6 Hz, 1 H, Ar), 10.41 (s, 1 H, NH). 13C NMR
(DMSO-d6): d = 115.1 (Carom), 115.9 (JCF = 286 Hz,
COCF3), 123.1, 130.5, 137.6, 147.1 (Carom), 156.4 (JCF = 36
Hz, CO). ESI-MS: m/z calcd for C8H4F3N4O5: 293.013;
found: 293.071 [M–].
(17) Hendrickson, J. B.; Sternbach, D. D. J. Org. Chem. 1975, 40,
3450.
Synlett 2005, No. 12, 1939–1941 © Thieme Stuttgart · New York