J. N. Moorthy, W. M. Nau et al.
7.21–7.32 (m, 15H), 7.45 ppm (d, J=7.5 Hz, 2H); 13C NMR (CDCl3,
125 MHz): d=55.3, 82.6, 114.1, 116.7, 121.0, 122.6, 122.8, 123.0, 124.6,
124.8, 127.6, 127.7, 127.9, 129.2, 133.3, 133.8, 138.6, 147.0, 147.6, 151.7,
158.7 ppm; IR (neat): n˜ =3034, 2929, 1591, 1486 cmÀ1; HRMS (ESI-MS+):
m/z: calcd for C52H40N2O2 [M++H]: 725.3168, found: 725.3162.
contributes mesomerically to the development of charge on
the quinonoid oxygen and any substituent on the C6-/C7-
aryl ring that exerts ÀI effect appear to expedite thermal
decay. Thus, the results with diverse chromenes suggest that
the kinetic behaviour of colored intermediates can be modu-
lated in a wide window by a judicious choice of substituents
of varying electronic nature, that is, NPh2 and CN, in the
C2- and C6-/C7-aryl rings, particularly when dealing with
polymeric matrices, where the decays are relatively longer.
6-(4-Bromophenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene
(6-
BN): Colorless solid; yield 44%; m.p. 114–1168C; 1H NMR (CDCl3,
500 MHz): d=6.17 (d, J=9.8 Hz, 1H), 6.62 (d, J=9.8 Hz, 1H), 6.96 (d,
J=8.6 Hz, 1H), 6.99–7.02 (m, 8H), 7.08 (d, J=7.8 Hz, 8H), 7.19–7.29 (m,
13H), 7.32 (dd, J1 =8.3 Hz, J2 =2.3 Hz, 1H), 7.38 (d, J=8.6 Hz, 2H),
7.51 ppm (d, J=8.6 Hz, 2H); 13C NMR (CDCl3, 125 MHz): d=82.8,
116.8, 120.8, 121.2, 122.51, 122.56, 123.0, 124.6, 125.0, 127.8, 127.9, 128.2,
129.2, 129.5, 131.7, 132.8, 138.4, 139.6, 147.1, 147.5, 152.5 ppm; IR (neat):
n˜ =3034, 2923, 1590, 1491, 1276 cmÀ1; HRMS (ESI-MS+): m/z: calcd for
C51H37BrN2O [M++H]: 773.2167, found: 773.2163.
Experimental Section
6-(4-Cyanophenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene
(6-
CN): Colorless solid; yield 25%; m.p. 185–1888C; 1H NMR (CDCl3,
500 MHz): d=6.20 (d, J=9.8 Hz, 1H), 6.63 (d, J=9.8 Hz, 1H), 6.99–7.03
(m, 9H), 7.08 (d, J=7.8 Hz, 8H), 7.22–7.28 (m, 13H), 7.37 (dd, J1 =
8.3 Hz, J2 =2.3 Hz, 1H), 7.61 (d, J=8.6 Hz, 2H), 7.68 ppm (d, J=8.6 Hz,
2H); 13C NMR (CDCl3, 125 MHz): d=83.0, 110.1, 117.1, 119.1, 121.4,
122.3, 122.4, 123.1, 124.7, 125.3, 127.0, 127.8, 128.2, 129.2, 129.8, 131.9,
132.5, 138.1, 145.1, 147.2, 147.5, 153.4 ppm; IR (neat): n˜ =3034, 2923,
2852, 2226, 1591, 1486, 1276 cmÀ1; HRMS (ESI-MS+): m/z: calcd for
C52H37N3O [M++H]: 720.3014, found: 720.3012.
Synthesis of chromenes: All the chromenes with the exception of 2,2-
bis(4-diphenylaminophenyl)-2H-chromenes were synthesized by follow-
ing procedure “A”.[14a] The 2,2-bis(4-diphenylamino-phenyl)-2H-chro-
menes were prepared by following procedure “B”.[14b]
Procedure A: To a mixture of 3-/4-arylphenol (0.6 mmol), 1,1-diarylprop-
2-yn-1-ol (1.8 mmol) and catalytic amount of PPTS (5 mol%) was added
dry 1,2-dichloroethane (10 mL). The contents were heated at reflux for
18–20 h under nitrogen gas atmosphere. After this period, the contents
were cooled, washed with saturated Na2CO3 solution, and the organic
contents were extracted with chloroform. The combined extract was
dried over anhydrous Na2SO4, filtered and evaporated to give the crude
compound. Further purification by silica-gel column chromatography af-
forded the chromene in 62–73% yields.
7-(4-Diphenylaminophenyl)-2,2-bis-(4-methoxyphenyl)-2H-chromene (7-
NM): Colorless solid; m.p. 142–1448C; 1H NMR (CDCl3, 500 MHz): d=
3.77 (s, 6H), 6.10 (d, J=9.8 Hz, 1H), 6.60 (d, J=9.8 Hz, 1H), 6.84 (d, J=
9.0 Hz, 4H), 7.02–7.04 (m, 3H), 7.08–7.12 (m, 7H), 7.24–7.27 (m, 5H),
7.35 (d, J=9.5 Hz, 4H), 7.43 ppm (d, J=8.5 Hz, 2H); 13C NMR (CDCl3,
125 MHz): d=55.2, 82.4, 113.4, 114.4, 119.3, 119.8, 122.7, 122.9, 123.7,
124.4, 126.8, 127.5, 128.3, 128.9, 129.2, 134.4, 137.3, 141.8, 147.3, 147.6,
Procedure B: To a stirred solution of 3-/4-arylphenol (1.0 mmol) and 1,1-
diarylprop-2-yn-1-ol (1.5 mmol) in toluene (10 mL) under nitrogen gas
atmosphere was added acidic Al2O3. The resulting heterogeneous reac-
tion mixture was heated at reflux for 3–4 h. The reaction mixture was di-
luted with chloroform and filtered. The solvent was removed in vacuo
and the residue obtained was chromatographed on silica gel to yield aryl-
chromenes in ca. 25–60% yields.
152.8, 158.8 ppm; IR (neat): n˜ =3035, 2927, 1591, 1509, 1489 cmÀ1
;
HRMS (ESI-MS+): m/z: calcd for C41H33NO3 [M++H]: 588.2538, found:
588.2538.
7-(4-Diphenylaminophenyl)-2,2-bis-(4-bromophenyl)-2H-chromene
(7-
In both procedures “A” and “B”, the 4-arylphenols led exclusively to 6-
aryl chromenes, while 3-arylphenols led to a mixture of regioisomeric 5-
and 7-arylchromenes in ca. 1:1.5 ratios, respectively. The regioisomeric
chromenes were separated either by a careful silica gel column chroma-
tography or by radial chromatography technique using chromatotron,
and the pure regioisomers thus isolated were thoroughly characterized by
1H, 13C NMR, IR and mass spectral analyses. The characterization data
are provided below for 6- and 7-arylchromenes.
NB): Colorless solid; yield 53%; m.p. 127–1308C; 1H NMR (CDCl3,
400 MHz): d=6.04 (d, J=9.8 Hz, 1H), 6.67 (d, J=9.8 Hz, 1H), 7.01–7.12
(m, 12H), 7.24–7.31 (m, 7H), 7.42–7.46 ppm (m, 6H); 13C NMR (CDCl3,
100 MHz): d=82.0, 114.5, 119.5, 119.8, 121.9, 123.1, 123.6, 124.0, 124.5,
127.0, 127.3, 127.5, 128.8, 129.3, 131.4, 134.1, 142.4, 143.5, 147.5, 147.6,
152.4 ppm; IR (neat): n˜ =3035, 2925, 2853, 1591, 1488, 1281 cmÀ1; HRMS
(ESI-MS+): m/z: calcd for C39H27Br2NO [M++H]: 684.0537, found:
684.0537.
6-(4-Diphenylaminophenyl)-2,2-bis-(4-methoxyphenyl)-2H-chromene (6-
NM): Colorless solid; yield 73%; m.p. 75–778C; 1H NMR (CDCl3,
400 MHz): d=3.79 (s, 6H), 6.15 (d, J=9.8 Hz, 1H), 6.63 (d, J=9.8 Hz,
1H), 6.86 (d, J=9.0 Hz, 4H), 6.94 (d, J=8.6 Hz, 1H), 7.02 (t, J=7.3 Hz,
2H), 7.09–7.13 (m, 5H), 7.20 (d, J=2.2 Hz, 1H), 7.24–7.29 (m, 4H),
7.30–7.39 ppm (m, 8H); 13C NMR (CDCl3, 100 MHz): d=55.2, 76.7, 82.4,
113.4, 116.7, 121.2, 122.7, 123.0, 124.1, 124.2, 124.7, 127.3, 127.7, 128.3,
129.2, 129.5, 133.7, 134.9, 137.3, 146.6, 147.7, 151.9, 158.9 ppm; IR (neat):
7-(4-Methoxyphenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene (7-
MN): Colorless solid; m.p. 132–1358C; 1H NMR (CDCl3, 500 MHz): d=
3.83 (s, 6H), 6.11 (d, J=9.8 Hz, 1H), 6.60 (d, J=9.8 Hz, 1H), 6.94 (d, J=
8.3 Hz, 2H), 6.96–7.01 (m, 8H), 7.03–7.13 (m, 8H), 7.20–7.25 (m, 8H),
7.29 (d, J=8.6 Hz, 4H), 7.51 ppm (d, J=8.3 Hz, 2H); 13C NMR (CDCl3,
125 MHz): d=55.3, 82.6, 114.1, 114.4, 119.3, 119.5, 122.5, 122.6, 122.9,
124.6, 126.8, 127.8, 127.9, 128.5, 129.2, 133.1, 138.7, 142.0, 147.0, 147.6,
152.9, 159.2 ppm; IR (neat): n˜ =3035, 2925, 1591, 1491, 1277 cmÀ1
;
n˜ =3034, 2930, 2835, 1484 cmÀ1
;
HRMS (ESI-MS+): m/z: calcd for
HRMS (ESI-MS+): m/z: calcd for C52H40N2O2 [M++H]: 725.3168, found:
C41H33NO3 [M++H]: 588.2538, found: 588.2538.
725.3162.
6-(4-Diphenylaminophenyl)-2,2-bis-(4-bromophenyl)-2H-chromene
(6-
7-(4-Bromophenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene
(7-
NB): Colorless solid; yield 62%; m.p. 112–1168C; 1H NMR (CDCl3,
400 MHz): d=6.08 (d, J=9.8 Hz, 1H), 6.69 (d, J=9.8 Hz, 1H), 6.93 (d,
J=8.3 Hz, 1H), 7.02 (t, J=7.3 Hz, 2H), 7.08–7.12 (m, 6H), 7.21–7.38 (m,
12H), 7.46 ppm (d, J=8.6 Hz, 4H); 13C NMR (CDCl3, 100 MHz): d=
82.0, 116.8, 121.0, 122.0, 122.8, 124.0, 124.3, 124.9, 127.3, 128.0, 128.1,
128.7, 129.2, 129.7, 131.4, 131.6, 134.4, 134.6, 143.4, 146.8, 147.7,
151.2 ppm; IR (neat): n˜ =3339, 3033, 2926, 2854, 1590, 1483 cmÀ1; HRMS
(ESI-MS+): m/z: calcd for C39H27Br2NO [M++H]: 684.0537, found:
684.0535.
BN): Colorless solid; m.p. 172–1748C; 1H NMR (CDCl3, 500 MHz): d=
6.14 (d, J=9.8 Hz, 1H), 6.60 (d, J=9.8 Hz, 1H), 6.98–7.01 (m, 8H), 7.04–
7.10 (m, 10H), 7.20–7.29 (m, 13H), 7.42 (d, J=8.6 Hz, 2H), 7.51 ppm (d,
J=8.6 Hz, 2H); 13C NMR (CDCl3, 125 MHz): d=82.7, 114.7, 119.5,
120.3, 121.6, 122.3, 122.5, 123.0, 124.6, 127.0, 127.9, 128.4, 129.1, 129.2,
131.8, 138.4, 139.4, 141.1, 147.1, 147.5, 153.0 ppm; IR (neat): n˜ =3034,
2923, 2852, 1591, 1491, 1276 cmÀ1; HRMS (ESI-MS+): m/z: calcd for
C51H37BrN2O [M++H]: 773.2167, found: 773.2166.
7-(4-Cyanophenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene
(7-
6-(4-Methoxyphenyl)-2,2-bis-(4-diphenylaminophenyl)-2H-chromene (6-
MN): Colorless solid; yield 60%; m.p. 112–1148C; 1H NMR (CDCl3,
500 MHz): d=3.83 (s, 3H), 6.15 (d, J=9.8 Hz, 1H), 6.62 (d, J=9.8 Hz,
1H), 6.93–6.95 (m, 2H), 6.99–7.02 (m, 8H), 7.08 (d, J=8.3 Hz, 8H),
CN): Colorless solid; m.p. 204–2068C; 1H NMR (CDCl3, 500 MHz): d=
6.18 (d, J=9.8 Hz, 1H), 6.61 (d, J=9.8 Hz, 1H), 6.99–7.02 (m, 8H), 7.07–
7.12 (m, 9H), 7.21–7.28 (m, 14H), 7.65 (d, J=8.3 Hz, 2H), 7.68 ppm (d,
J=8.3 Hz, 2H); 13C NMR (CDCl3, 125 MHz): d=82.9, 110.8, 115.0,
4298
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Chem. Eur. J. 2009, 15, 4289 – 4300