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(ppm) 131.5 (Carom. quat.), 127.7, 127.5, 125.6 (Carom), 44.6
(CH2), 44.3(NMe2); IR/FT (nujol) n (cm21) 3152 (n NH); 895
(n N–N); 782 (g CHarom.); 693 (d CHarom.).
borane: 0.356 g, 4.9 mmol, 1 equiv.; toluene: 6 mL; 1.01 g
of hydrazine hydrochloride 2j was obtained; yield 91%.
Data for 2j white solid; mp:30 2458C (EtOH). Anal. Calcd
for C11H17ClN2O: C, 57.76; H, 7.49; N, 12.25. Found: C,
57.42; H, 7.34; N, 11.92. 1H NMR (D2O, 300 MHz) d (ppm)
7.7–7.4 (5H, m, Harom), 4.38 (2H, s, CH2Ph), 4.1–3.7 (4H,
m, OCH2), 3.4–3.1 (4H, m, NCH2); 13C NMR DEPT (D2O,
75 MHz) d (ppm) 130.3 (Carom. quat.), 130.1, 129.5, 129.1
(Carom), 65.1 (CH2Ph), 52.6 (OCH2), 49.4 (NCH2); IR/FT
(nujol) n(cm21) 3166(n NH); 1499(n ArC–C);859 (n N–N);
745 (g CHarom.); 694 (d CHarom.).
4.5.6. N,N-Dimethyl-N0-pyridin-3-ylmethyl-hydrazine
dihydrochloride (2f). Hydrazone 1f: 1.73 g, 11.6 mmol,
1 equiv.; trimethylamine-borane: 0.827 g, 11.3 mmol,
1 equiv.; toluene: 16 mL; 2.55 g of hydrazine dihydro-
chloride 2f was obtained; yield 98%. Data for 2f white solid;
mp: 158–1618C (EtOH). Anal. Calcd for C8H15Cl2N3: C,
42.87; H, 6.75; N, 18.75. Found: C, 42.49; H, 6.94; N, 18.39.
1H NMR (D2O, 300 MHz) d (ppm) 8.73 (1H, s, Harom.2),
8.63 (1H, d, J¼5.8 Hz, Harom.6), 8.54 (1H, d, J¼8.2 Hz,
Harom.4), 7.96 (1H, dd, J¼5.8 Hz, J¼8.2 Hz, Harom.5), 4.33
(2H, s, CH2), 3.02 (6H, s, NMe2); 13C NMR DEPT (D2O,
75 MHz) d (ppm) 154.0 (Carom. quat.), 149.6, 143.4, 130.1
(Carom), 48.7 (CH2), 47.4 (NMe2).
4.5.11. N-benzyl-N0-(1-phenyl-ethyl)-hydrazine hydro-
chloride (2l). Hydrazone 1l: 1.73 g, 7.7 mmol, 1 equiv.;
trimethylamine-borane: 0.567 g, 7.7 mmol, 1 equiv.; tolu-
ene: 16 mL; 1.65 g of hydrazine hydrochloride 2l was
obtained; yield 81%. Data for 2l: white solid; mp: 1678C
(MeOH/Et2O). Anal. Calcd for C15H19ClN2: C, 68.50; H,
7.30; N, 10.70. Found: C, 68.40; H, 6.99; N, 10.34.
4.5.7. N,N-Dimethyl-N0-naphthalen-1-ylmethyl-hydra-
zine hydrochloride (2g). Hydrazone 1g: 1.08 g,
5.4 mmol, 1 equiv.; trimethylamine-borane: 0.410 g,
5.6 mmol, 1 equiv.; toluene: 8 mL; 1.18 g of hydrazine
hydrochloride 2f was obtained; yield 92%. Data for 2g
white solid; mp: 173–1748C (EtOH). Anal. Calcd for
C13H17ClN2: C, 65.95; H, 7.24; N, 11.83. Found: C, 65.57;
H, 7.14; N, 11.51. 1H NMR (D2O, 300 MHz) d (ppm) 8.2–
7.2 (7H, m, Harom), 4.48 (2H, s, CH2), 2.99 (6H, s, NMe2);
13C NMR DEPT (D2O, 75 MHz) d (ppm) 151.4, 135.8,
133.3 (Carom. quat.), 131.0, 130.6, 129.1, 128.6, 127.9, 125.5
1
(a(2D5¼252.7 (c¼2 g/100 mL CHCl3). H NMR (CDCl3,
300 MHz) d (ppm) 7.60–7.50 (2H, s broad, NH2), 7.45–
7.20 (11H, m, NHþHarom.), 4.30 (1H, q, J¼6.7 Hz, CHPh),
4.12 (1H, d, J¼12.4 Hz, CH2Ph), 4.14 (1H, d, J¼12.4 Hz,
CH2Ph), 1.55 (3H, d, J¼6.7 Hz, CH3).
4.5.12. (1-Phenyl-ethyl)-hydrazine hydrochloride (2k).
Hydrazone 1k: 2.53 g, 18.8 mmol, 1 equiv.; trimethyl-
amine-borane: 1.38 g, 18.8 mmol, 1 equiv.; toluene: 25 mL;
3.06 g of hydrazine hydrochloride 2k was obtained; yield
94%. Data for 2k: colourless vitreous oil. 1H NMR26 (D2O,
300 MHz) d (ppm) 7.48 (5H, m, Harom.), 4.39 (1H, q,
J¼6.86 Hz, CH), 1.60 (3H, d, J¼6.86 Hz, CH3); IR/FT
(neat) n (cm21) 3285, 3171 (n NH); 2055, 1947, 1816
(overtones of g CHarom.); 1571 (n CvC); 848 (n N–N); 764
(g CHarom.); 699 (d CHarom.).
(Carom), 49.8 (CH2), 46.6 (NMe2); IR/FT (nujol) n (cm21
3199 (n NH); 888 (n N–N).
)
4.5.8. N,N-Dimethyl-N0-propyl-hydrazine hydrochloride
(2h). Hydrazone 1h: 1.03 g, 10.2 mmol, 1 equiv.; trimethyl-
amine-borane: 0.748 g, 10.2 mmol, 1 equiv.; toluene:
15 mL; 1.36 g of hydrazine hydrochloride 2h was obtained;
yield 96%. Data for 2h white solid; mp: 66–688C (toluene).
Anal. Calcd for C5H15ClN2: C, 43.32; H, 10.91; N, 20.21.
Found: C, 43.51; H, 10.58; N, 19.96. 1H NMR (D2O,
300 MHz) d (ppm) 3.05 (2H, t, J¼7.45, NCH2), 2.95 (6H, s,
NMe2), 1.59 (2H, sest, J¼7.45, NCH2CH2), 0.97 (3H, t,
J¼7.45, CH2CH3); 13C NMR DEPT (D2O, 75 MHz) d
(ppm) 50.4 (NCH2), 46.5 (NMe2), 21.7 (NCH2CH2), 13.2
(CH2CH3); IR/FT (nujol) n (cm21) 3161(nNH); 866 (n N–N).
4.6. First attempts to synthesise hydrazide 3a
4.6.1. Reduction of hydrazone 1a with BH3·THF. Under a
nitrogen atmosphere, a 1 M solution of complex BH3·THF
in THF (22 mL, 22 mmol, 2.5 equiv.) was dropped in a
solution of hydrazone 1a (1.30 g, 8.7 mmol, 1 equiv.) in
50 mL of dry THF. After 10 min, the reaction was quenched
with 1 mL of acetic acid, and Ac2O (4 mL, 40 mmol,
4.6 equiv.) was added. The reaction mixture was heated
under reflux for 30 min. The organic solution was washed
with a saturated solution of sodium bicarbonate, and the
aqueous solution extracted with CH2Cl2 (3£20 mL). The
organic layers were collected and dried over Na2SO4, and
the solvent was removed in vacuo. The crude product was
purified by means of flash chromatography over silica gel
(30 g); eluent: Et2O/ETP¼3/7; 0.446 g of hydrazide 3a was
obtained; yield 26.5%.
4.5.9. N,N-Dimethyl-N0-(1-methyl-3-phenyl-propyl)-
hydrazine hydrochloride (2i). Hydrazone 1i: 0.81 g,
4.2 mmol, 1 equiv.; trimethylamine-borane: 0.306 g,
4.2 mmol, 1 equiv.; toluene: 6 mL; 0.789 g of hydrazine
hydrochloride 2i was obtained; yield 82%. Data for 2i white
solid; mp: 122–1248C (toluene/pentane). Anal. Calcd for
C12H21ClN2: C, 63.00; H, 9.25; N, 12.25. Found: C, 62.65;
H, 9.49; N, 12.22. 1H NMR (D2O, 300 MHz) d (ppm) 7.4–
7.2 (5H, m, Harom), 1.8–1.6 (1H, m, NCH), 2.79 (6H, s,
NMe2), 3.0–2.5 (8H, m, PhCH2 and NMe2), 2.1–1.6 (2H,
m, CHCH2), 1.26 (3H, d, J¼6.3 Hz, CH3); 13C NMR DEPT
(D2O, 75 MHz) d (ppm) 141.2 (Carom. quat.), 128.7, 128.4,
126.3 (Carom), 51.5 (NCH), 44.2 (NMe2), 33.9, 30.7
(CH2CH2), 15.8 (CH3); IR/FT (nujol) n (cm21) 3192
(n NH); 739 (g CHarom.); 700 (d CHarom.).
4.6.2. Reduction of hydrazone 1a with Et3SiH/CF3-
COOH. Under a nitrogen atmosphere, Et3SiH (2.66 mL,
17 mmol, 2 equiv.) was added to a solution of hydrazone 1a
(1.24 g, 8.4 mmol, 1 equiv.) in 13 mL of CF3COOH: the
reaction mixture was heated under reflux for 4 h. The
solvent was removed in vacuo; 10 mL of dry Et3N, 20 mg of
DMAP and 5 mL of Ac2O were added, and the solution was
stirred overnight. The solvent was removed in vacuo and
the crude product diluted with 50 mL of CH2Cl2; the
4.5.10. Benzyl-morpholin-4-yl-amine hydrochloride (2j).
Hydrazone 1j: 0.93 g, 4.9 mmol, 1 equiv.; trimethylamine-