5078
T. Hirao et al. / Tetrahedron 57 -2001) 5073±5079
4. Experimental
1.42 ,m, 6H), 2.34 ,s, 2H), 7.01 ,d, 2H, J8.1 Hz), 7.42
,d, 2H, J8.1 Hz); 13C NMR d9.68, 13.75, 19.93, 27.33,
28.98, 105.82, 119.64, 127.11, 131.92, 150.71; IR ,neat)
3030, 2956, 2926, 2851, 2224, 1601, 1500, 1464, 1077,
837 cm21. Anal. Calcd for C20H33NSn: C, 59.14; H, 8.19;
N, 3.45. Found: C, 59.07; H, 7.96; N, 3.45. 1-Tributylstannyl-
4.1. General
1H ,300 MHz) and 13C ,75 MHz) NMR spectra were
measured on a Varian Mercury 300 spectrometer. CDCl3
1
methylnaphthalene ꢀ7g) [113688-53-2]: H NMR d0.75±
was used as
a
solvent and residual chloroform
,d7.24 ppm; 13C, 77.0 ppm) or Me4Si was used as an
internal standard. Infrared spectra were recorded on
Perkin±Elmer Model 1600 Series FT-IR. Mass spectra
were measured on a JEOL JMS-DX-303 spectrometer
using either electron impact ,EI) or chemical ionization
,CI) modes. Elemental analyses were carried out at the
Analytical Center, Faculty of Engineering, Osaka
University. Column chromatography was conducted on
silica gel ,Wakogel C-200). GPC was performed with
Japan Analytical Industry LC-908 using chloroform as a
solvent. t-BuOH was distilled from sodium t-butoxide and
0.93 ,m, 15H), 1.17±1.30 ,m, 6H), 1.32±1.45 ,m, 6H), 2.73 ,s,
2H), 7.14 ,d, 1H, J6.6 Hz), 7.28 ,dd, 1H, J8.2 Hz, 6.6 Hz),
7.4±7.5 ,m, 2H), 7.50 ,d, 1H, J8.2 Hz), 7.77±7.80 ,m, 1H),
7.86±7.89 ,m, 1H), 13C NMR d10.08, 13.72, 15.94, 27.37,
29.03, 123.56, 123.58, 123.91, 124.82, 125.18, 125.58, 128.58,
130.83, 133.76, 140.19; IR ,neat) 3058, 1577, 1508, 1394, 793,
774 cm21. Anal. Calcd for C23H36Sn: C, 64.06; H, 8.41.
Found: C, 64.19; H, 8.13.
VOCl3, VO,acac)2, and VO,OEt)3 are commercially
available. VO,OPri)3 was supplied from Nichia Chemical
Industries Ltd.
Ê
dried over 4 A Molecular Sieves. Hexane was freshly
distilled from CaH2. THF was purchased from Kanto
Chemical Co., Inc. as dehydrated stabilizer free grade, and
was collected with argon stream introduced directly into the
apparatus.
4.2. Preparation of other oxovanadiumꢀV) compounds31
To a well-dried 200 mL round-bottomed ¯ask equipped
with a condenser, magnetic stirring bar, and septum, hexane
,120 mL) was added followed by trichlorooxovanadium,V)
,1.73 g, 9.4 mL, 0.01 mol) under a stream of argon. The
mixture was stirred at room temperature while the dry
corresponding alcohol ,1.1 or 2.2 molar amounts) was
added dropwise via syringe with a constant ¯ow of argon
to remove HCl evolved from the reaction. Upon completion
of the addition, the mixture was stirred for 1 h at room
temperature. For dichloro,2,2,2-tri¯uoroethoxy)oxovana-
dium,V), the mixture was required to be heated to re¯ux
for 30 min. The re¯ux condenser was then quickly replaced
with a distillation head and the solvent was removed at
atmospheric pressure. The product was distilled at reduced
pressure to give the corresponding oxovanadium ,V)
compound as a yellow/orange liquid, which was stored
under an inert atmosphere.
Benzylsilanes 1a±d and benzyltins 7a±g were prepared
using a modi®ed procedure for the reaction of the
corresponding benzyl chlorides, Mg, and Me3SiCl/
Bu3SnCl.29 7h,30 7i,22 and 7j23 were synthesized according
to the literature methods.
4-Methoxybenzyltrimethylsilane ꢀ1a) [17988-20-4]: 1H
NMR d20.01 ,s, 9H), 2.01 ,s, 2H), 3.78 ,s, 3H), 6.79
,d, 2H, J8.8 Hz), 6.92 ,d, 2H, J8.8 Hz). 4-Methyl-
benzyltrimethylsilane ꢀ1b) [7450-04-6]: 1H NMR
d0.01 ,s, 9H), 2.05 ,s, 2H), 2.31 ,s, 3H), 6.91 ,d, 2H,
J8.3 Hz), 7.04 ,d, 2H, J8.3 Hz). Benzyltrimethylsilane
1
ꢀ1c) [770-09-2]: H NMR d20.03 ,s, 9H), 2.06 ,s, 2H),
6.97±7.23 ,m, 5H). 1-Trimethylsilylmethylnaphthalene
1
ꢀ1d) [18410-58-7]: H NMR d0.03 ,s, 9H), 2.61 ,s, 2H),
7.19 ,d, 1H, J6.9 Hz), 7.39 ,dd, 1H, J8.2, 6.9 Hz), 7.40±
7.60 ,m, 2H), 7.64 ,d, 1H, J8.2 Hz), 7.80±8.00 ,m, 2H).
4-Tributyl-ꢀ4-methoxybenzyl)tin ꢀ7a) [74260-40-5]: 1H
NMR d0.74±0.82 ,m, 15H), 1.20±1.27 ,m, 6H), 1.37±
1.43 ,m, 6H), 2.22 ,s, 2H), 3.74 ,s, 3H), 6.72 ,d, 2H,
J8.1 Hz), 6.88 ,d, 2H, J8.1 Hz). Tributyl-ꢀ4-methyl-
Dichloroꢀethoxy)oxovanadiumꢀV) [1801-77-0]: ,78%, bp
55±608C/5 mmHg). Dichloroꢀisopropoxy)oxovanadiumꢀV)
[1636-01-7]: ,75%, bp 59±628C/3 mmHg). Chloroꢀdiiso-
propoxy)oxovanadiumꢀV) [1636-00-6]: ,83%, bp 55±
588C/1 mmHg). Dichloroꢀ2,2,2-tri¯uoroethoxy)oxovana-
diumꢀV): ,82%, bp 808C/115 mmHg).21
1
benzyl)tin ꢀ7b) [74260-32-5]: H NMR d0.76±0.89 ,m,
15H), 1.22±1.29 ,m, 6H), 1.39±1.41 ,m, 6H), 2.24 ,s, 2H),
2.25 ,s, 3H), 6.85 ,d, 2H, J7.9 Hz), 6.95 ,d, 2H,
4.3. Oxidation of 4-methoxybenzyltrimethylsilane ꢀ1a)
by VOꢀOCH2CF3)Cl2 under an oxygen atmosphere
1
J7.9 Hz). Benzyltributyltin ꢀ7c) [28493-54-1]: H NMR
d0.75±0.93 ,m, 15H), 1.17±1.30 ,m, 6H), 1.34±1.45 ,m,
6H), 2.28 ,s, 2H), 6.95±6.97 ,m, 3H), 7.12±7.16 ,m, 2H).
Tributyl-ꢀ2-methylbenzyl)tin ꢀ7d) [174473-23-5]: 1H
NMR d0.74±0.86 ,m, 15H), 1.19±1.26 ,m, 6H), 1.36±
1.53 ,m, 6H), 2.17 ,s, 3H), 2.26 ,s, 2H), 6.85±7.05 ,m,
4H); 13C NMR d9.82, 13.77, 16.20, 20.31, 27.42, 29.07,
123.01, 125.76, 127.27, 129.67, 133.15, 141.95; IR ,neat)
3009, 2956, 2924, 1601, 1487, 1460, 756, 743 cm21. Anal.
Calcd for C20H36Sn: C, 60.78; H, 9.18. Found: C, 60.78; H,
To a 20 mL two-necked round-bottomed ¯ask equipped
with a re¯ux condenser, magnetic stirring bar, septum,
and a balloon charged with O2 were added t-BuOH
,2 mL), VO,OCH2CF3)Cl2 ,355.3 mg, 1.5 mmol), and then
4-methoxybenzylsilane 1a ,97.2 mg, 0.5 mmol), and the
mixture was stirred at 508C for 20 h. The reaction was
quenched with 1 M HCl solution, and the mixture was
extracted with Et2O. The combined organic layer was
washed with brine and was dried over MgSO4. The organic
solvent was evaporated and the resulting crude product
was puri®ed by silica gel column chromatography to give
4-methoxybenzaldehyde ,3a, 88%) and 1-t-butoxymethyl-
4-methoxybenzene ,2a, 4%).32
1
8.99. Tributyl-ꢀ4-chlorobenzyl)tin ꢀ7e) [74260-39-2]: H
NMR d0.77±0.89 ,m, 15H), 1.22±1.29 ,m, 6H), 1.37±
1.43 ,m, 6H), 2.26 ,s, 2H), 6.90 ,d, 2H, J8.4 Hz), 7.12
1
,d, 2H, J8.4 Hz). Tributyl-ꢀ4-cyanobenzyl)tin ꢀ7f): H
NMR d0.77±0.86 ,m, 15H), 1.21±1.26 ,m, 6H), 1.36±