1874
S.-H. Hsieh, H.-M. Gau
LETTER
127.43, 127.01, 126.77, 126.67, 126.05, 125.95, 124.98,
119.78, 119.51, 118.84, 93.35, 90.92, 87.19, 86.39, 84.50,
79.54, 79.07, 78.62, 42.02, 36.23, 36.11, 25.58, 19.13,
17.97, 17.74. Anal. Calcd for C24H24NO4V (%): C, 65.31; H,
5.48; N, 3.17. Found: C, 65.66; H, 5.08; N, 3.57.
(14) General Procedures for Synthesis of Oxovanadium(V)
Complexes 3a–h.
To a solution of a Schiff base (1.00 mmol) in 10 mL
appropriate alcohol, VO(Oi-Pr)3 (0.24 mL, 1.0 mmol) was
added at r.t. The mixture was stirred for 1 h and the solvent
was removed under reduced pressure to give a quantitative
yield of the product. All compounds were characterized by
1H NMR and 13C NMR spectroscopy and by elemental
analyses. Two sets of NMR resonances are observed for
each complex due to the presence of two isomers in solution.
Spectroscopic data of complexes 3c and 3g as examples are
listed in the following. The two isomers are designated as
major and minor based on relative intensities of resonances.
1H NMR spectra for the two isomers in the phenyl region are
overlapped and resonances of the minor are included in data
of the major.
Complex 3g: brown solid. 1H NMR (400 MHz, CDCl3): d
(major, 71%) = 7.45–6.77 (m, CH=N, Ph), 4.89 (d, J = 4.0
Hz, 1 H, CHN), 4.85 (ddd, J = 6.8, 11.4, 28.0 Hz, 2 H,
OCH2), 4.05 (d, J = 12.0 Hz, 1 H, CHO), 3.83 (dd, J = 12.4,
12.4 Hz, 1 H, CHAHBPh), 3.43 (d, J = 13.2 Hz, 1 H,
CHAHBPh), 2.16–2.06 (m, 1 H, CH2CH), 1.18 (s, 9 H, t-Bu),
1.03 [d, J = 6.8 Hz, 6H, CH(CH3)2] ppm; d (minor, 29%) =
5.24 (d, J = 4.0 Hz, 1 H, CHN), 5.05 (ddd, J = 6.8, 11.0, 30.8
Hz, 2 H, OCH2), 4.32 (d, J = 11.6 Hz, 1 H, CHO), 3.28 (d,
J = 14.0 Hz, 1 H, CHAHBPh), 2.62 (dd, J = 12.4, 12.4 Hz, 1
H, CHAHBPh), 2.40–2.22 (m, 1 H, CH2CH), 1.21 (s, 9 H, t-
Bu), 1.12 [d, J = 6.8 Hz, 6 H, CH(CH3)2] ppm. 13C{1H}
NMR (100 MHz, CDCl3): d = 165.18, 163.73, 161.93,
161.78, 137.98, 137.17, 135.37, 135.08, 132.25, 132.15,
130.20, 130.03, 128.44, 128.38, 126.67, 126.60, 120.01,
119.34, 119.04, 118.97, 118.64, 118.57, 98.05, 94.60, 89.84,
88.71, 83.31, 78.13, 36.77, 36.31, 35.81, 31.91, 31.60,
27.55, 27.12, 19.47, 19.41, 18.79. Anal. Calcd for
C24H32NO4V (%): C, 64.13; H, 7.18; N, 3.12. Found: C,
63.72; H, 7.42; N, 3.59.
Complex 3c: dark green solid. 1H NMR (400 MHz, CDCl3):
d (major, 69%) = 7.56 (s, 1 H, CH=N), 7.50–6.76 (m, Ph),
6.43 (d, J = 3.2 Hz, 1 H, CHO), 5.34–5.26 (m, 2 H, OCH2),
4.20 (d, J = 6.0 Hz, 1 H, CHN), 3.61 (dd, J = 7.6, 9.2 Hz, 1
H, CHAHBPh), 2.62 (dd, J = 2.0, 9.0 Hz, 1 H, CHAHBPh),
1.59 (t, J = 5.2 Hz, 3 H, CH3) ppm; d (minor, 31%) = 7.57 (s,
1 H, CH=N), 6.65 (d, J = 3.6 Hz, 1 H, CHO), 5.40–5.36 (m,
2 H, OCH2), 4.53 (d, J = 7.2 Hz, 1 H, CHN), 2.57 (dd,
J = 2.4, 9.2 Hz, 1 H, CHAHBPh), 2.47 (dd, J = 7.6, 9.2 Hz, 1
H, CHAHBPh), 1.69 (t, J = 4.8 Hz, 3 H, CH3) ppm. 13C{1H}
NMR (100 MHz, CDCl3): d = 163.26, 162.86, 162.71,
140.50, 137.86, 137.11, 135.82, 135.57, 132.45, 132.35,
130.19, 130.14, 128.70, 128.60, 128.55, 128.47, 127.62,
(15) (a) Hartung, J.; Drees, S.; Greb, M.; Schimdt, P.; Svoboda,
I.; Fuess, B.; Murso, A.; Stalke, D. Eur. J. Org. Chem. 2003,
2388. (b) Blum, S. A.; Bergman, R. C.; Ellman, J. A. J. Org.
Chem. 2003, 68, 150.
Synlett 2006, No. 12, 1871–1874 © Thieme Stuttgart · New York