DNA Wire with High Hole Transport Ability
A R T I C L E S
123.7, 121.4, 121.0, 108.9, 88.8, 85.7, 74.0, 63.8, 41.2, 39.9, 35.2, 31.4.
MS (FAB, NBA/CH2Cl2): m/z (%) 356 [(M + H)+]. HRMS (FAB)
calcd for C18H22N5O3 [(M + H)+] 356.1723, found 356.1722.
bionanomaterial that will be widely applicable to electronic
devices and biosensors.
Experimental Section
4-(N,N′-Dimethylaminomethylidene)amino-9-(2′-deoxy-5′-O-
dimethoxytrityl-â-D-erythro-pentofuranosyl)-9H-pyrimido[4,5-b]-
indole (4). A solution of 3 (60 mg, 0.18 mmol) and 4,4′-dimethoxytrityl
chloride (8.0 mg, 0.24 mmol) was stirred in anhydrous pyridine (10
mL) for 2 h at ambient temperature. The reaction mixture was
concentrated to a brown oil and purified by column chromatography
on silica gel, eluting with a mixed solution of 50:50:5 (v/v/v) hexane,
ethyl acetate, and triethylamine to give compound 4 (80 mg, 72%). 1H
NMR (CDCl3): δ 8.91 (s, 1H), 8.53 (s, 1H), 8.39 (d, 1H, J ) 7.7 Hz),
7.70 (d, 1H, J ) 8.3 Hz), 7.43 (dd, 2H, J ) 8.6, 1.5 Hz), 7.31 (dd, 4H,
J ) 9.0, 1.5 Hz), 7.27-7.13 (5H), 6.94 (t, 1H, J ) 7.3 Hz), 6.75 (dt,
4H, J ) 9.9, 3.1 Hz), 4.85 (dt, 1H, J ) 7.7, 4.4 Hz), 4.04 (q, 1H, J )
4.6 Hz), 3.747 (s, 3H), 3.745 (s, 3H), 3.48 (d, 1H, J ) 4.6 Hz), 3.30
(s, 3H), 3.21 (s, 3H), 3.25-3.19 (m, 1H), 2.29 (ddd, 1H, J ) 13.7,
7.0, 3.8 Hz). 13C NMR (CDCl3): δ 161.3, 158.4, 156.52, 156.47, 154.0,
144.7, 136.8, 135.8, 130.14, 130.11, 128.2, 127.8, 126.8, 125.6, 123.5,
121.8, 121.4, 113.1, 111.7, 105.6, 86.5, 84.5, 82.7, 72.6, 63.6, 60.4,
55.2, 45.6, 41.0, 37.7, 35.1, 21.1, 14.2. MS (FAB, NBA/CH2Cl2): m/z
(%) 658 [(M + H)+]. HRMS (FAB) calcd for C39H40N5O5 [(M + H)+]
658.2951, found 658.3038.
General. 1H NMR spectra were measured with Varian Mercury 400
(400 MHz) spectrometer. 13C NMR spectra were measured with JEOL
JNM a-500 (500 MHz) spectrometer. Coupling constants (J value) are
reported in hertz. The chemical shifts are expressed in ppm downfield
from tetramethylsilane, using residual chloroform (δ ) 7.24 in 1H NMR,
δ ) 77.0 in 13C NMR) and dimethyl sulfoxide (δ ) 2.48 in 1H NMR,
δ ) 39.5 in 13C NMR) as an internal standard. FAB mass spectra were
recorded on a JEOL JMS DX-300 spectrometer or JEOL JMS SX-
102A spectrometer. HPLC was performed on a Cosmosil 5C-18AR or
CHEMCOBOND 5-ODS-H column (4.6 × 150 mm) with a Gilson
chromatography model 305 using a UV detector model 118 at 254 nm.
4-Chloro-7-(2-deoxy-3,5-di-O-p-toluoyl-â-D-erythro-pentofurano-
syl)-7H-pyrimido[4,5-b]indole (1). 4-Chloro-1H-pyrimido[4,5-b]indole
(360 mg, 1.77 mmol) was suspended in dry acetonitrile (250 mL) at
ambient temperature. To this suspension was added sodium hydride
(60% in oil; 142 mg, 3.54 mmol), and the mixture was stirred at reflux
for 10 min. The ribose 6 (687 mg, 1.77 mmol) was added, and the
mixture was stirred for 1 h at ambient temperature. The reaction mixture
was concentrated and purified by column chromatography on silica
gel, eluting with 20% ethyl acetate in hexane to give compound 1 (890
4-(N,N′-Dimethylaminomethylidene)amino-9-(2′-deoxy-5′-O-
dimethoxytrityl-â-D-erythro-pentofuranosyl-3′-O-cyanoethyl-N,N′-
diisopropylphosphoramidite)-9H-pyrimido[4,5-b]indole (5). A so-
lution of 4 (10 mg, 15.2 µmol), 2-cyanoethyl tetraisopropylphosphorodi-
amidite (5.3 µL, 16.7 mmol), and tetrazole (1.2 mg, 16.7 mmol) in
acetonitrile (400 µL) was stirred at ambient temperature for 2 h. The
mixture was filtered off and used without further purification.
1
mg, 91%). H NMR (CDCl3): δ 8.71 (s, 1H), 8.36 (d, 1H, J ) 7.9
Hz), 7.99 (d, 2H, J ) 8.2 Hz), 7.95 (d, 2H, J ) 6.6 Hz), 7.79 (d, 1H,
J ) 8.4 Hz), 7.37 (dt, 1H, J ) 8.1, 0.7 Hz), 7.28 (d, 2H, J ) 8.1 Hz),
7.27 (dt, 1H, J ) 8.2, 1.1 Hz), 7.23 (d, 2H, J ) 8.4 Hz), 7.03 (dd, 1H,
J ) 8.8, 6.2 Hz), 5.93 (dt, 1H, J ) 6.2, 2.7 Hz), 4.86 (dd, 2H, J )
11.1, 3.5 Hz), 4.59 (dd, 1H, J ) 7.2, 3.9 Hz), 3.56 (ddd, 1H, J ) 16.1,
7.5, 7.2 Hz), 2.59 (ddd, 1H, J ) 14.4, 6.2, 2.4 Hz), 2.43 (s, 3H), 2.41
(s, 3H). 13C NMR (CDCl3): δ 166.2, 166.1, 155.6, 153.5, 152.7, 144.4,
144.0, 137.8, 129.8, 129.7, 129.3, 129.2, 128.3, 126.9, 126.5, 123.4,
122.6, 119.1, 112.8, 112.1, 83.6, 81.8, 74.4, 63.8, 35.3, 21.73, 21.70.
MS (FAB, NBA/CH2Cl2): m/z (%) 556 [(M + H)+]. HRMS (FAB)
calcd for C31H27ClN3O7 [(M + H)+] 556.1639, found 556.1638.
4-Amino-9-(2′-deoxy-â-D-erythro-pentofuranosyl)-7H-pyrimido-
[4,5-b]indole (2, BDA). A suspension of 1 (300 mg, 0.54 mmol) in 20
mL of methanolic ammonia (saturated at -76 °C) was stirred at
150 °C in a sealed bottle for 10 h. The turbid solution was concentrated
and purified by column chromatography on silica gel, eluting with 10%
methanol in chloroform to give compound 2 (117 mg, 72%). 1H NMR
(DMSO-d6): δ 8.31 (d, 1H, J ) 7.7 Hz), 8.27 (s, 1H), 7.84 (d, 1H, J
) 8.2 Hz), 7.37 (dt, 1H, J ) 8.2, 1.1 Hz), 7.32-7.25 (3H), 6.82 (dd,
1H, J ) 8.8, 6.0 Hz), 5.32 (d, 1H, J ) 4.4 Hz), 5.28 (t, 1H, J ) 4.9
Hz), 4.46 (m, 1H), 3.86 (dd, 1H, J ) 7.3, 3.8 Hz), 3.66 (m, 2H), 2.88
(ddd, 1H, J ) 15.6, 8.8, 6.6 Hz), 2.05 (ddd, 1H, J ) 15.4, 6.0, 2.2
Hz). 13C NMR (DMSO-d6): δ 157.7, 154.7, 154.4, 135.5, 124.7, 121.3,
121.0, 120.2, 111.8, 87.1, 82.8, 70.9, 61.9, 37.5, 31.5. MS (FAB, NBA/
DMSO): m/z (%) 301 [(M + H)+]. HRMS (FAB) calcd for C15H17N4O3
[(M + H)+] 301.1301, found 301.1297.
4-Chloro-6-methoxy-7-(2-deoxy-3,5-di-O-p-toluoyl-â-D-erythro-
pentofuranosyl)-7H-pyrimido[4,5-b]indole (7). 4-Chloro-6-methoxy-
1H-pyrimido[4,5-b]indole (100 mg, 0.43 mmol) was suspended in dry
acetonitrile (10 mL) at ambient temperature. To this suspension was
added sodium hydride (60% in oil; 19 mg, 0.47 mmol), and the mixture
was stirred at reflux for 10 min. The ribose 6 (184 mg, 0.47 mmol)
was added, and the mixture was stirred for 1 h at ambient temperature.
The reaction mixture was concentrated and purified by column
chromatography on silica gel, eluting with 20% ethyl acetate in hexane
1
to give compound 7 (210 mg, 82%). H NMR (CDCl3): δ 8.69 (s,
1H), 7.97 (d, 2H, J ) 14.8 Hz), 7.96 (d, 2H, J ) 14.8 Hz), 7.82 (d,
1H, J ) 2.6 Hz), 7.68 (d, 1H, J ) 4.0 Hz), 7.27 (d, 2H, J ) 16.8 Hz),
7.24 (d, 2H, J ) 15.7 Hz), 7.00 (dd, 1H, J ) 8.8, 6.1 Hz), 6.82 (dd,
1H, J ) 9.0, 2.6 Hz), 5.90 (dt, 1H, J ) 7.0, 3.3 Hz), 4.85 (dd, 1H, J
) 12.1, 3.3 Hz), 4.70 (dd, 1H, J ) 12.1, 4.0 Hz), 4.57 (dt, 1H, J )
7.1, 3.6 Hz), 3.87 (s, 3H), 3.48 (ddd, 1H, J ) 16.3, 8.8, 5.7 Hz), 2.57
(ddd, 1H, J ) 14.3, 6.0, 2.9 Hz), 2.43 (s, 3H), 2.41 (s, 3H). 13C NMR
(CDCl3): δ 166.2, 166.1, 155.8, 155.7, 153.4, 152.7, 144.4, 144.0,
132.2, 129.8, 129.7, 129.3, 129.2, 126.9, 126.5, 119.9, 117.1, 113.0,
112.7, 106.1, 83.6, 81.7, 74.4, 63.8, 55.9, 35.4, 21.74, 21.71. MS (FAB,
NBA/CH2Cl2): m/z (%) 634 [(M + H)+]. HRMS (FAB) calcd for
C32H29ClN3O8 [(M + H)+] 634.2552, found 634.2553.
4-(N,N′-Dimethylaminomethylidene)amino-9-(2′-deoxy-â-D-erythro-
pentofuranosyl)-9H-pyrimido[4,5-b]indole (3). A solution of 2 (130
mg, 0.43 mmol) and N,N-dimethylformamide dimethylacetal (5 mL,
28.3 mmol) in N,N-dimethylformamide (5 mL) was stirred for 18 h at
55 °C. The reaction mixture was concentrated to a brown oil and
purified by column chromatography on silica gel, eluting with 10%
methanol in chloroform to give compound 3 (134 mg, 87%). 1H NMR
(CDCl3): δ 8.94 (s, 1H), 8.53 (s, 1H), 8.41 (d, 1H, J ) 7.1 Hz), 7.49
(d, 1H, J ) 8.1 Hz), 7.44 (dt, 1H, J ) 7.1, 1.1 Hz), 7.30 (dt, 1H, J )
7.8, 0.9 Hz), 6.73 (dd, 1H, J ) 8.9, 5.5 Hz), 4.83 (d, 1H, J ) 5.1 Hz),
4.23 (s, 1H), 4.01 (dd, 1H, J ) 2.9, 1.4 Hz), 3.82 (m, 1H), 3.31 (s,
3H), 3.29-3.22 (m, 2H), 3.21 (s, 3H), 2.23 (dd, 2H, J ) 15.4, 5.7
Hz). 13C NMR (CDCl3): δ 161.9, 156.8, 155.2, 153.1, 137.9, 125.9,
4-Amino-6-methoxy-9-(2′-deoxy-â-D-erythro-pentofuranosyl)-7H-
pyrimido[4,5-b]indole (8, MDA). A suspension of 7 (500 mg, 0.85
mmol) in 20 mL of methanolic ammonia (saturated at -76 °C) was
stirred at 150 °C in a sealed bottle for 10 h. The turbid solution was
concentrated and purified by column chromatography on silica gel,
eluting with 10% methanol in chloroform to give compound 8 (420
mg, 75%). 1H NMR (DMSO-d6): δ 8.23 (s, 1H), 7.86 (d, 1H, J ) 2.4
Hz), 7.73 (d, 1H, J ) 8.8 Hz), 7.29 (br, 2H), 6.97 (dd, 1H, J ) 9.0,
2.6 Hz), 6.78 (dd, 1H, J ) 9.0, 6.2 Hz), 5.26 (d, 1H, J ) 4.4 Hz), 5.20
(t, 1H, J ) 5.8 Hz), 4.43 (m, 1H), 3.85 (s, 3H), 3.65 (m, 2H), 3.27 (s,
3H), 2.82 (ddd, 1H, J ) 13.0, 6.8, 2.8 Hz), 2.01 (ddd, 1H, J ) 13.1,
6.2, 2.3 Hz). 13C NMR (DMSO-d6): δ 157.6, 154.8, 154.7, 154.3, 129.9,
120.8, 113.0, 112.4, 104.9, 95.6, 86.9, 82.7, 70.8, 61.8, 55.9, 37.4. MS
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J. AM. CHEM. SOC. VOL. 125, NO. 17, 2003 5069