Notes
J . Org. Chem., Vol. 64, No. 18, 1999 6903
g, 83%) (ccsg, toluene/hexane ) 2:1) as a colorless oil that solidify
on standing: 1H NMR (CDCl3, 400 MHz) δ 6.67 (s, 1 H), 7.36 (t,
3 H, J ) 7.8 Hz), 7.68 (d, 2 H, J ) 8.4 Hz), 7.69 (2 H), 7.72 (2
H), 7.78 (d, 2 H, J ) 8.4 Hz),7.92 (t, 1 H, J ) 1.6 Hz); 13C NMR
(CDCl3, 100 MHz) δ 39.7, 122.6, 126.6, 128.4, 129.9, 130.2, 132.6,
135.5, 137.8, 138.8, 145.7, 193.6; MS m/z (%) 434 (M+) (2), 432
(M+) (2), 355 (56), 353 (100), 351 (58); HRMS calcd for C14H9O79
-
Br2 [(M - Br) +] 350.9020, found 350.9036.
4-(3-Br om oben zoyl)ben za ld eh yd e (5). To a solution of 4
(4.05 g, 9.36 mmol) in DMF (20 mL) was added sodium acetate
(3.84 g, 46.8 mmol), and the mixture was stirred at reflux for 8
h. The reaction mixture was evaporated to dryness in vacuo and
diluted with ethyl acetate. 5 (2.18 g, 81%) (ccsg, toluene/hexane
) 2:1): 1H NMR (CDCl3, 400 MHz) δ 7.38 (t, 1 H, J ) 8.0 Hz),
7.70 (d, 2 H, J ) 8.0 Hz), 7.74 (d, 2 H, J ) 8.0 Hz), 7.90 (d, 2 H,
J ) 8.4 Hz), 7.93 (t, 1 H, J ) 1.6 Hz), 8.00 (d, 2 H, J ) 8.4 Hz),
10.13 (s, 1 H); 13C NMR (CDCl3, 100 MHz) δ 122.7, 128.5, 129.5,
130.0, 130.2, 132.7, 135.8, 138.4, 138.6, 141.6, 191.6, 194.0; MS
m/z (%) 290 (M+) (73), 133 (100); HRMS calcd for C14H9O279Br
287.9786, found 287.9784.
4-(3-Br om oben zoyl)ben zon itr ile (6). To a mixture of 5
(2.53 g, 8.75 mmol) and sodium formate (915 mg, 13.5 mmol) in
formic acid (20 mL) was added hydroxylamine hydrochloride
(622 mg, 9.0 mmol), and the mixture was stirred at reflux for 3
h. 4 (2.12 g, 85%) (ccsg, hexane/ethyl acetate ) 8:1): 1H NMR
(CDCl3, 400 MHz) δ 7.38 (t, 1 H, J ) 8.0 Hz), 7.67 (m, 1 H), 7.75
(m, 1 H), 7.79 (d, 2 H, J ) 8.4 Hz), 7.85 (d, 2 H, J ) 8.4 Hz),
7.90 (t, 1 H, J ) 1.6 Hz); 13C NMR (CDCl3, 100 MHz) δ 116.0,
117.7, 122.8, 128.4, 130.0, 132.2, 132.6, 136. 0, 138.0, 140.3,
193.2; MS m/z (%) 287 (M+) (92), 285 (M+) (93), 130 (100); HRMS
calcd for C14H8ON79Br 284.9789, found 284.9781.
4-(3-Tr im eth ylsilyleth yn ylben zoyl)ben zon itr ile (7). To a
mixture of 6 (887 mg, 3.10 mmol), palladium(II) acetate (7.1 mg,
0.03 mmol), and triphenylphosphine (40.5 mg, 0.15 mmol) in
deaerated triethylamine (15 mL) was added ethynyltrimethyl-
silane (0.66 mL, 4.7 mmol), and the mixture was stirred at reflux
for 5 h under nitrogen. 7 (856 mg, 91%) (ccsg, hexane/ethyl
acetate ) 30:1): 1H NMR (CDCl3, 100 MHz) δ 0.23 (s, 9 H), 7.44
(t, 1 H, J ) 7.6), 7.70 (2 H), 7.85 (d, 2 H, J ) 8.4 Hz), 7.80 (s, 1
H), 7.90 (d, 2 H, J ) 8.4 Hz); 13C NMR (CDCl3, 100 MHz) δ 0.0,
96.2, 103.3, 115.8, 117.8, 123.8, 128.5, 129.5, 130.1, 132.1, 133.1,
136.2, 136.3, 140.6, 193.9; MS m/z (%) 303 (M+) (55), 288 (100);
HRMS calcd for C19H17ONSi 303.1080, found 303.1078.
F igu r e 2. CD spectra of dCNBPU-containing oligomer. CD
spectra of 12-mer duplex d(ACTGGTXACAGT)/d(ACTGTAAC-
CTCA) (150 µM base concentration for each strand) was
measured in 10 mM sodium cacodylate buffer (pH 7.0) and
100 mM NaCl: X ) CNBPU (solid line) and X ) T (dotted line).
served in the 290-330 nm range implies that the
benzophenone chromophore is in a chiral environment.
On the basis of these results, we concluded that the
CNBP chromophore in the duplex oligomer actually
located in the major groove of the B-form duplex without
perturbing the π-stack. Experiments on photoinduced
charge transport using dCNBPU-containing DNA oligomers
will be reported in due course.
4-(3-Eth yn ylben zoyl)ben zon itr ile (12). To a solution of 7
(730 mg, 2.40 mmol) in THF (10 mL) were added acetic acid
(0.2 mL, 3.5 mmol) and tetrabutylammonium fluoride (3.60 mL
of a 1.0 M solution in THF, 3.6 mmol), and the mixture was
stirred at ambient temperature for 2 h. 6 (513 mg, 92%) (ccsg,
hexane/ethyl acetate ) 15:1): 1H NMR (CDCl3, 400 MHz) δ 3.13
(s, 1 H), 7.47 (t, 1 H, J ) 7.8), 7.74 (2 H), 7.79 (d, 2 H, J ) 8.2
Hz), 7.85 (s, 1 H), 7.85 (d, 2 H, J ) 8.2 Hz); 13C NMR (CDCl3,
100 MHz) δ 78.8, 82.2, 115.9, 117.8, 122.8, 128.7, 129.9, 130.0,
132.1, 133.3, 136.3, 136.4, 140.5, 193.8; MS m/z (%) 231 (M+)
(100), 129 (77), 101 (20); HRMS calcd for C16H9ON (M+)
231.0685, found 231.0692.
5-{3-(4-Cya n oben zoyl)p h en yleth yn yl}-2′-d eoxy-5′-O-(4,4′-
d im eth oxytr ityl) Ur id in e (1). To a solution of 12 (275 mg,
1.19 mmol), 2′-deoxy-5′-O-(4,4′-dimethoxytrityl)-5-iodouridine
(13) (651 mg, 0.99 mmol), and triethylamine (0.28 mL, 2.0 mmol)
in 10 mL of deaerated DMF were added tetrakis(triphenylphos-
phine)palladium(0) (121 mg, 0.11 mmol) and copper(I) iodide
(189 mg, 1.0 mmol) under nitrogen. The mixture was stirred at
ambient temperature for 5 h. 1 (720 mg, 93%) (ccsg, chloroform/
methanol ) 100:1) as pale yellow foamy solids: 1H NMR (CDCl3,
400 MHz) δ 2.33 (m, 1 H), 2.53 (m, 1 H), 3.31 (m, 1 H), 3.42 (m,
1 H), 3.66 (s, 3 H), 3.67 (s, 3 H), 4.09 (m, 1 H), 4.57 (m, 1 H),
6.34 (m, 1 H), 6.72-6.76 (4 H), 7.07-7.42 (12 H), 7.65-7.77 (5
H), 8.26 (s, 1 H); 13C NMR (CDCl3, 100 MHz) δ 40.4, 54.9, 63.4,
70.4, 79.1, 83.1, 85.2, 85.9, 86.1, 90.7, 98.0, 113.1, 113.2, 114.7,
118.0, 122.6, 126.6, 127.5, 127.8, 129.1, 129.3, 129.4, 129.5, 129.7,
129.9, 131.7, 135.2, 135.5, 136.3, 140.4, 143.1, 144.5, 149.2, 158.0,
158.0, 161.3, 194.0; FABMS m/z 760 [(M + H)+]; HRMS calcd
for C46H38O8N3 [(M + H)+] 760.2660, found 760.2660.
Exp er im en ta l Section
Gen er a l P r oced u r e for Wor k u p a n d P u r ifica tion . The
reaction mixture was diluted with water and extracted with
ethyl acetate or chloroform. The extracts were washed with
saturated NaHCO3 and brine, dried over anhydrous MgSO4,
filtered, and concentrated in vacuo. The crude products were
purified by column chromatography on silica gel (ccsg) with the
indicated elution solvent.
3′-Br om o-4-m eth ylben zop h en on e (3). A mixture of 3-bro-
mobenzoic acid (2) (5.16 g, 25.7 mmol) and thionyl chloride (30
mL) was refluxed for 1 h. Excess reagent was removed in vacuo,
and the residue was dissolved in toluene (40 mL). To the solution
was added anhydrous aluminum trichloride (7.28 g, 54.6 mmol)
in several portions, and the mixture was stirred for 3 h at
ambient temperature. The reaction mixture was poured onto
crushed ice (45 g) and concentrated hydrochloric acid (10 mL).
The produced suspension was stirred for 30 min and extracted
with ethyl acetate. The crude product was recrystalized from
hexane and ethyl acetate to give 3 (5.75 g, 81%): 1H NMR
(CDCl3, 400 MHz) δ 2.43 (s, 3 H), 7.28 (d, 2 H, J ) 8.4 Hz), 7.33
(t, 1 H, J ) 8.0 Hz), 7.66-7.69 (2 H), 7.68 (d, 2 H, J ) 8.4 Hz),
7.89 (t, 1 H, J ) 1.4 Hz); 13C NMR (CDCl3, 100 MHz) δ 21.8,
122.4, 128.2, 129.0, 129.7, 130.1, 132.5, 134.6, 134.9, 139.7, 143.6,
194.5; MS m/z (%) 276 (M+) (48), 274 (M+) (48), 119 (100); HRMS
calcd for C14H11O79Br 273.9993, found 273.9989.
3′-Br om o-4-(d ibr om om eth yl)ben zop h en on e (4). To a so-
lution of 3 (1.03 g, 3.75 mmol) in acetonitrile (20 mL) was added
N-bromosuccinimide (1.65 g, 9.29 mmol) and 2,2′-azobisisobu-
tyronitrile (63.7 mg, 0.39 mmol), and the mixture was stirred
at reflux for 5 h. The reaction mixture was concentrated in vacuo,
and the residue was dissolved in ethyl acetate and filtered. The
crude product was obtained by concentrating the filtrate. 2 (1.35
5-{3-(4-Cya n oben zoyl)p h en yleth yn yl}-2′-d eoxy-5′-O-(4,4′-
d im eth oxytr ityl) Ur id in e 3′-O-(2-Cya n oeth yl N,N-d iiso-
p r op ylp h osp h or a m id ite) (14). To a solution of 1 (241 mg, 0.34