8112 J . Org. Chem., Vol. 62, No. 23, 1997
Kataoka et al.
coupling product and the alcohol. The ratio of the diastereo-
mers (dl:meso) of the coupling product was determined by H
coupling. It has been reported that reaction of VCl3(thf)3
with RMgBr gave the vanadium(II) and vanadium(IV)
species by disproportionation.18 Thus, in the VCl3(thf)3
system (Table 2, run 1), some vanadium(II) species would
be also produced by disproportionation of the vanadium-
(III) species, and the coupling product 1a was obtained
in 58% isolated yield.
1
NMR.
3,4-Dim eth yl-3,4-d ip h en ylh exa n e (1a ).20 A mixture of
two diastereomers (dl:meso ) 50:50); Rf ) 0.27 (hexane) mp
1
55-57 °C; H NMR (C6D6) δ 0.62 (t, J ) 7.6 Hz, 6H), 1.20 [s,
3H, (dl)], 1.23[s, 3H, (meso)], 1.30-1.48 (m, 2H), 1.47-1.58
[m, 1H, (meso)], 1.95-2.13 [m, 1H, (dl)], 2.05-2.23 (m, 1H),
6.85-7.23 (m, 10H).
TMEDA also plays an important role in the deoxygen-
ative coupling reaction. For example, when [V2-
Cl3(thf)6]2[Zn2Cl6]19 was employed as another vanadium-
(II) species instead of VCl2(tmeda)2, the coupling product
1a was not obtained and the alcohol 2a was obtained in
59% isolated yield. Of course, when only TMEDA
(without vanadium) instead of VCl2(tmeda)2 was em-
ployed, the cleavage of the C-O bond did not proceed at
all. One of the reasons for this difference could be that
VCl2(tmeda)2 is soluble in THF, whereas [V2Cl3(thf)6]2[Zn2-
Cl6] is not sufficiently soluble. Surprisingly, when a
combination of vanadium(III) complex, VCl3(thf)3, and 2.0
equiv of TMEDA was employed instead of the VCl2-
(tmeda)2/O2 system, the coupling reaction occurred
smoothly and the coupling product 1a was obtained in
96% isolated yield along with the alcohol in 4% yield,
which was a similar result to the VCl2(tmeda)2-O2
system (eq 7). The combination of a vanadium(II) species
3,4-Dieth yl-3,4-d ip h en ylh exa n e (1b):20b Rf ) 0.27 (hex-
ane); mp 42-44 °C; 1H NMR (CDCl3) δ 0.66 (t, J ) 7.2 Hz,
12H), 2.00 (q, J ) 7.2 Hz, 8H), 6.93-7.01(m, 4H), 7.03-7.14
(m, 6H).
5,6-Dieth yl-5,6-d ip h en yld eca n e (1c). A ratio of two
diastereomers (dl:meso) could not be determined due to a
poorly resolved signals of both isomers: Rf ) 0.45 (hexane);
1H NMR (CDCl3) δ 0.64 [t, J ) 7.3 Hz, 6H (dl or meso)], 0.65
[t, J ) 7.3 Hz, 6H (meso or dl)], 0.81 (t, J ) 7.3 Hz, 6H), 0.76-
0.89 (m, 2H), 0.92-1.07 (m, 2H), 1.15-1.27 (m, 4H), 1.87-
2.02 (m, 8H), 6.92-6.96 (m, 4H), 7.11-7.24 (m, 6H); MS (EI)
m/z 175 [M+ - C6H5C(C2H5)C4H9]; IR (neat) 3130, 3100, 2950,
2920, 2860, 1940, 1800, 1740, 1590, 1490, 1460, 1440, 1380,
1330, 1250, 1070, 1030, 970, 910, 840, 790, 750, 700 cm-1. Anal.
Calcd for C26H38: C, 89.07; H, 10.93. Found: C, 89.39; H,
10.96.
4,5-Dieth yl-4,5-d ip h en ylocta -1,7-d ien e (1d ). A mixture
of two diastereomers (dl:meso ) 50:50) was obtained: Rf )
1
0.24 (hexane); H NMR (CDCl3) δ 0.67 [t, J ) 7.4 Hz, 6H (dl
or meso)], 0.72 [t, J ) 7.4 Hz, 6H (meso or dl)], 1.91-2.17 [m,
3H], 2.10-2.31 (m, 1H), 2.55-2.97 (m, 4H), 4.79-4.98 [m, 4H
(dl or meso)], 4.95-5.14 [m, 4H (meso or dl)], 5.52-5.68 [m,
2H (dl or meso)], 5.68-5.84 [m, 2H (meso or dl)], 6.66-7.02
(m, 4H), 6.97-7.11 (m, 6H); MS (EI) m/z 318 (M+); IR (neat)
3070, 2975, 2940, 2890, 1640, 1600, 1500, 1460, 1440, 1420,
1400, 1390, 1080, 1040, 1000, 915, 770, 705 cm-1. Anal. Calcd
for C24H30: C, 90.51; H, 9.49. Found: C, 90.73; H, 9.25.
1,1-Dip h en ylp r op -1-en e:21 Rf ) 0.28 (hexane); 1H NMR
(CDCl3) δ 1.74 (d, J ) 7.1 Hz, 3H), 6.15 (q, J ) 7.1 Hz, 1H),
7.15-7.38 (m, 10H).
and a higher-valent vanadium species prepared by dis-
proportionation of the trivalent alkoxyvanadium species
derived from VCl3(thf)3 and the magnesium alcoholate
in the presence of TMEDA should be very effective for
the deoxygenative coupling reaction.
1,1-Dip h en ylp r op a n e:22 Rf ) 0.22 (hexane); 1H NMR
(CDCl3) δ 0.89 (t, J ) 7.3 Hz, 3H), 2.06 (dt, J ) 7.8, 7.3 Hz,
2H), 3.77 (t, J ) 7.8 Hz, 1H), 7.10-7.28 (m, 10H).
2,3-Dim eth yl-2,3-d ip h en ylbu ta n e (1f):23 Rf ) 0.36 (hex-
ane); mp 115-116 °C (lit.23 mp 118-119 °C); 1H NMR (CDCl3)
δ 1.31 (s, 12H), 7.04-7.18 (m, 10H).
Exp er im en ta l Section
All manipulations were conducted under argon atmosphere
with standard Schlenk methods. Unless otherwise noted,
materials were obtained from commercial suppliers and were
used after distillation. THF was distilled from sodium ben-
zophenone ketyl under argon prior to use. TMEDA was
distilled from calcium hydride under argon prior to use.
3,4-Dim eth yl-1,3,4,6-tetr a p h en ylh exa n e (1h ). A mix-
ture of two diastereomers (dl:meso ) 50:50); Rf ) 0.13
1
(hexane); mp 47-48 °C; H NMR (CDCl3) δ 1.34 [s, 6H (dl or
meso)], 1.41 [s, 6H (meso or dl)], 1.79-1.99 (m, 2H), 2.05-
2.21 (m, 2H), 2.27-2.48 (m, 4H), 6.95-7.24 (m, 20H); MS (EI)
m/z 209 [M+ - C6H5(CH2)2CCH3C6H5]; IR (neat) 3087, 3059,
3024, 2960, 2880, 1945, 1870, 1802, 1654, 1602, 1541, 1496,
1453, 1442, 1375, 1270, 1156, 1117, 1065, 1030, 909, 844, 789,
766, 752, 727, 700, 669, 637, 563, 527, 498 cm-1. Anal. Calcd
for C32H34: C, 91.81; H, 8.19. Found: C, 91.69; H, 8.09.
1,3-Dim eth yl-3-(1,3-d im eth yl-2-cycloh exen -1-yl)cyclo-
h ex-1-en e (3).24 The ratio of the diastereomers (dl:meso )
60:40 or vice versa) was determined by 1H NMR: Rf ) 0.71
(hexane); 1H NMR (CDCl3) δ 0.89 [s, 6H (dl or meso)], 0.89 [s,
6H (meso or dl)], 1.20-1.88 (m, 12H), 1.65 (s, 6H), 5.26 [bs,
2H (dl or meso)], 5.29 [bs, 2H (meso or dl)].
12
VCl2(tmeda)2,8 [V2Cl3(thf)6]2[Zn2Cl6],19 and VCl3(thf)3 were
prepared according to published procedures. VCl4 was ob-
tained from a commercial supplier (Aldrich) and was used
without further purification. The melting points are uncor-
rected.
Gen er a l P r oced u r e for th e Red u ctive Cou p lin g Rea c-
tion . To a solution of propiophenone (1.0 mmol) in THF (5.0
mL) was added a THF solution of MeMgBr (1 mol/L, 1.2 mmol)
at 0 °C. After the reaction mixture was stirred for 1 h at 20
°C, a blue solution of VCl2(tmeda)2 (1.0 mmol) in THF (10 mL)
was added at 20 °C, and then O2 gas (5.0 mL) was introduced
into the reaction mixture by syringe. The resulting dark
purple solution was refluxed for 15 h. Aqueous NaOH solution
(1 mol/L, 3 mL) was added, and the mixture was stirred at 20
°C for an additional 1 h. The precipitated brown solid was
removed by filtration and washed with ethyl acetate. The
combined filtrate and washings were dried over MgSO4 and
concentrated in vacuo. The residual oily materials were
purified by column chromatography on silica gel to afford the
3,3,4,4-Tet r a m et h yl-1,6-d ip h en ylh exa -1,5-d ien e (6a ),
3,3,6-Tr im eth yl-1,4-diph en ylh epta-1,5-dien e (6b), an d 2,7-
Dim eth yl-4,5-d ip h en ylocta -2,6-d ien e (6c). The isomers
1
could not be separated, and their ratio was determined by H
NMR analysis (6a :6b:6c ) 5:53:42). A ratio of the two
diastereomers of 6c could not be determined: Rf ) 0.46
1
(hexane:AcOEt ) 10:1); H NMR (CDCl3) δ 1.09 (s, 3H, 6b),
(20) (a) Huang, R. L.; Kum-Tatt, L. J . Chem. Soc., 1954, 2570-2577.
(b) Beckhaus, H.-D.; Ru¨chardt, C. Chem. Ber. 1977, 110, 878-895.
(21) Simes, B. E.; Rickborn, B. J . Org. Chem. 1988, 53, 4613-4616.
(22) Bonner, W. A.; Mango, F. D. J . Org. Chem. 1964, 29, 430-435.
(23) Bors, D. A.; Kaufman, M. J .; Streitweser, A., J r. J . Am. Chem.
Soc. 1985, 107, 6975-6982.
(19) (a) Cotton, F. A.; Duraj, S. A.; Extine, M. W.; Lewis, G. E.; Roth,
W. J .; Schmulbach, C. D.; Schwotzer, W. J . Chem. Soc., Chem.
Commun. 1983, 1377-1378. (b) Bouma, R. J .; Teuben, J . H.; Beukema,
W. R.; Bansemer, R. L.; Huffman, J . C.; Caulton, K. G. Inorg. Chem.
1984, 23, 2715-2718. (c) Cotton, F. A.; Duraj, S. A.; Roth, W. J . Inorg.
Chem. 1985, 24, 913-917.
(24) Corbally, R. P.; Perkins, M. J .; Elnitski, A. P. J . Chem. Soc.,
Perkin Trans. 1 1979, 793-798.