S. Ficht et al. / Tetrahedron 57 /2001) 4863±4866
4865
Table 2. Spirocyclizations
Substrate
Product
R1
Yield #%) with resin 4a
Yield #%) with resin 4b
9
10a
10b
10c
H
82
25
24
80
26
25
Cbz-NH
Boc-NH
from other commercially available functionalized polymers
and trisubstituted iodophenyl derivatives.
thoroughly with methanol. After washing, the resins 4a,b
were dried in vacuo to a constant weight. Their activity was
determined by dissolving 20 mg of hydroquinone in metha-
nol and adding 200 mg of the resin 4a or 4b. This suspen-
sion was stirred for 4 h at room temperature. The resin was
®ltered with a glass funnel and washed well with methanol.
The combined organic layers were evaporated in vacuo.
1. Experimental
1H NMR #and 13C NMR) spectra were recorded on a Bruker
AC-250 #DRX-500) spectrometer with the solvent residual
peak as internal standard. The GCMS spectra were recorded
on a HP 5890 Series II Gas Chromatograph coupled with HP
5972 Series Mass Selective Detector #speci®cations of the
column: Macherey Nagel Optima 1/20 mm, 25 m£0.2 mm
ID). Iodometric analysis was performed in the Institut fuÈr
1
From the residue a H NMR spectrum was taken. The
activity of the resin was determined by comparison of the
integrals of the singlets at 6.5 ppm #hydroquinone) and
6.7 ppm #p-benzoquinone).
1.3. General procedure for the oxidation of hydro-
quinones 5a±f
È
Anorganische Chemie, Universitat Karlsruhe, Germany.
Merck silica gel 60 for column chromatography and
Merck precoated TLC plates, silica gel F254 for TLC were
used. Compounds 1, 2, 5, 7 and 9 are commercially
available and were used without further puri®cation. All
solvents were puri®ed and, when necessary, dried in the
usual way.
Hydroquinones 5a±f #0.15 mmol) were dissolved in metha-
nol #5 mL). To this solution 2 equiv. of the resin were added
and the resulting mixture was stirred for 4 h at room
temperature. Thereafter, the suspension was ®ltered and
the resin was thoroughly washed with methanol. The
combined organic layers were evaporated in vacuo to afford
the pure benzoquinones 6a±e; compound 6f was obtained
after column chromatography #silica gel, hexane/ethyl
acetate 6:1). For yields see Table 1.
1.1. General preparation of the aminomethylpolystyrene
derivatives 3a,b
Aminomethylpolystyrene
1
#5.0 g, loading at least
1.3.1. p-Benzoquinone -6a). 1H NMR #250 MHz, CD3OD):
d #ppm)6.7 #s, 4H); GCMS: calcd m/z 108; found m/z 108.
0.78 mmol/g) was suspended in dry DMF #50 mL). Subse-
quently, 2 equiv. #relative to the loading of the resin) of
either 4-iodobenzoic acid #2a) or #4-iodophenyl)-acetic
acid #2b) as well as 2.1 equiv. of HOBt were added to the
mixture above. After addition of 2 equiv. of diisopropylcar-
bodiimide the suspension was stirred overnight at room
temperature. Thereafter, 0.5 equiv. of pyridine and
0.5 equiv. of acetic anhydride were added, and the suspen-
sion was stirred for 2 h. The resin was ®ltered in a glass
funnel, washed thoroughly with DMF and methanol and
then dried.
1
1.3.2. Chloro-p-benzoquinone -6b). H NMR #250 MHz,
CD3OD): d #ppm)7.1 #m, 1H); 6.9 #m, 1H); 6.7 #m, 1H);
GCMS: calcd m/z 142; found m/z 142.
1
1.3.3. Methyl-p-benzoquinone -6c). H NMR #250 MHz,
CD3OD): d #ppm)6.9 #s, 1H); 6.7 #m, 2H); 2.2 #s, 3H);
GCMS: calcd m/z 122; found m/z 122.
1
1.3.4. 2,3 Dimethyl-p-benzoquinone -6d). H NMR #250
MHz, CD3OD): d #ppm)6.6 #s, 2H); 1.9 #s, 6H).
1.3.5. Trimethyl-p-benzoquinone -6e). 1H NMR #250
MHz, CD3OD): d #ppm)6.5 #s, 1H); 1.9 #3£s, 9H);
GCMS: calcd m/z 150; found m/z 150.
1.1.1. Poly[styrene-co-4-iodo-N--40-vinyl-benzyl)-benz-
amide] -3a). Obtained 5.92 g, expected 5.90 g. Iodometric
analysis: calcd I 8.4; found I 8.9.
1.1.2.
Poly[styrene-co-2--40-iodo-phenyl)-N--400-vinyl-
benzyl)-acetamide] -3b). Obtained 6.11 g, expected
5.95 g. Iodometric analysis: calcd I 8.3; found I 8.8.
1
1.3.6. 2-Decanoylamino-p-benzoquinone -6f). H NMR
#500 MHz, CDCl3): d #ppm)8.02 #br, 1H, NH); 7.57 #d,
J2.4 Hz, 1H); 6.70±6.77 #m, 2H); 2.42 #t, J7.6 Hz, 2H);
1.64±1.70 #m, 2H); 1.24±1.34 #m, 12H); 0.85 #t, J7.0 Hz,
3H); 13C NMR #125.8 MHz, CDCl3): d #ppm)188.0;
182.8; 172.5; 138.2; 133.1; 114.7; 37.9; 31.8; 29.3; 29.2;
29.1; 25.0; 22.6; 14.1; MS #HR-EI, 808C) calcd m/z 277.2;
found m/z 277.2, mp 858C.
1.2. Synthesis of the aminomethylpolystyrene-supported
-diacetoxyiodo)benzenes 4a,b
Acetic anhydride and hydrogen peroxide solution #35%)
were mixed in a 4:1 ratio at 08C and stirred for 6 h. Thereby
the solution was slowly warmed up to room temperature.
This peracetic acid solution was added to the iodinated
polystyrene 3a or b #about 10 mL per gram resin) at exactly
408C and stirred at this temperature overnight. Thereafter,
the resin was ®ltered in a glass funnel and washed
1.4. General procedure for the oxidation of phenols
Phenols 7a±c #0.15 mmol) were dissolved in acetonitrile/