7970 J . Org. Chem., Vol. 61, No. 22, 1996
Notes
Eth yl 2-(4-ch lor op h en yl)-1,3(2H,4H)-d ioxoisoqu in olin e-
4-ca r boxyla te (3c): mp 174-176 °C; yield 43%; H-NMR (60
MHz, DMSO-d6) δ 1.52 (t, J ) 7 Hz, 3H), 4.52 (q, J ) 7 Hz, 2H),
ethyl acetate/hexanes; yield 81%; 1H-NMR (300 MHz, DMSO-
d6) δ 1.25 (d, J ) 7.0 Hz, 6H), 2.35 (s, 3H), 3.15 (m, 1H), 5.30 (s,
1H), 6.90-7.22 (m, 3H), 7.35 (m, 4H), 7.41 (m, 4H), 7.75 (m, 1H),
8.12 (m, 1H), 10.7 (s, 1H); MS (EI) 412 au. Anal. Calcd for
1
7.0-8.6 (m, 8H); MS (EI) 342, 344 au. Anal. Calcd for C18H14
-
ClNO4: C, 62.89; H, 4.10; N, 4.07. Found: C, 63.25; H, 4.13; N,
4.10.
C
26H24N2O3: C, 75.71; H, 5.86 N, 6.79. Found: C, 75.53; H, 5.79;
N, 6.86.
N-P h en yl 2-(4-isop r op ylp h en yl)-1,3(2H ,4H )-d ioxoiso-
Eth yl 2-(3,5-d ich lor op h en yl)-1,3(2H,4H)-d ioxoisoqu in o-
lin e-4-ca r boxyla te (3d ): mp 191-193 °C; yield 47%; 1H-NMR
(300 MHz, DMSO-d6) δ 1.19 + 1.44 (2t, J ) 7.0 Hz, 3H), 4.23 +
4.53 (2q, J ) 7 Hz, 2H), 5.41 (s, ∼1H, C-4 methine), 7.37-7.85
(m, 5H), 8.17 (m, 1H), 8.52 (d, J ) 8.2 Hz, 1H); MS (EI) 377,
379 au. Anal. Calcd for C18H13Cl2NO4: C, 57.16; H, 3.46; N,
3.70. Found: C, 56.77; H, 3.39; N, 3.61.
qu in olin e-4-ca r boxa m id e (6i): mp 217-219 °C from acetone
or acetone/hexanes; yield 55%; 1H-NMR (300 MHz, DMSO-d6)
δ 1.30 (d, J ) 7.0 Hz, 6H), 3.00 (m, 1H), 5.35 (s, 1H), 7.15 (m,
3H), 7.42 (m, 3H), 7.63 (m, 5H), 7.75 (m, 1H), 8.10 (m, 1H), 11.0
(s, 1H); MS (EI) 398 au. Anal. Calcd for C25H22N2O3: C, 75.36;
H, 5.57; N, 7.03. Found: C, 75.46; H, 5.69; N, 7.09.
Eth yl 2-(3,5-d im eth oxyp h en yl)-1,3(2H,4H)-d ioxoisoqu in -
olin e-4-ca r boxyla te (3e): mp 161-163 °C; yield 52%; 1H-NMR
(300 MHz, DMSO-d6) δ 1.40 (t, J ) 7.0 Hz, 3H), 3.70 (s, 6H),
4.50 (q, J ) 7 Hz, 2H), 7.40-7.65 (m, 5H), 7.95 (m, 1H), 8.45 (d,
J ) 8.2 Hz, 1H); MS (EI) 369 au. Anal. Calcd for C20H19NO6:
C, 65.03; H, 5.18; N, 3.79. Found: C, 65.37; H, 5.09; N, 4.01.
Eth yl 2-(4-m eth ylp h en yl)-1,3(2H,4H)-d ioxoisoqu in olin e-
4-ca r boxyla te (3f): mp 164-166 °C; yield 56%; 1H-NMR (300
MHz, CDCl3) δ 1.25 + 1.55 (2t, J ) 7.0 Hz, 3H), 2.40 + 2.50 (2s,
3H), 4.25 + 4.55 (2q, J ) 7.0 Hz, 2H), 7.12-7.84 (m, 6H), 7.95
(m, 1H), 8.40 (dd, J ) 8.2, 2.1 Hz, 1H), 8.55 (dd, J ) 8.2, 2.1 Hz,
1H); MS (EI) 323 au. Anal. Calcd for C19H17NO4: C, 70.58; H,
5.30; N, 4.33. Found: C, 70.67; H, 5.65; N, 4.29.
Eth yl 2-(3-m eth ylp h en yl)-1,3(2H,4H)-d ioxoisoqu in olin e-
4-ca r boxyla te (3g): mp 130-132 °C; yield 26%; 1H-NMR (300
MHz, CDCl3) δ 1.30 + 1.55 (2t, J ) 7.0 Hz, 3H), 2.40 (s, 3H),
4.24 + 4.54 (2 q, J ) 7.0 Hz, 2H), 7.00-7.82 (m, 6H), 7.95 (m,
1H), 8.42 (dd, J ) 7.4, 2.0 Hz, 1H), 8.58 (dd, J ) 7.4, 2.0 Hz,
1H); MS (EI) 323 au. Anal. Calcd for C19H17NO4: C, 70.58; H,
5.30; N, 4.33. Found: C, 70.46; H, 5.46; N, 4.51.
N-P h en yl 2-[3,5-bis(tr iflu or om eth yl)p h en yl]-1,3(2H,4H)-
d ioxoisoqu in olin e-4-ca r boxa m id e (6j): mp 188-190 °C (dec)
from acetone or acetone/hexanes; yield 95%; 1H-NMR (300 MHz,
DMSO-d6) δ 5.40 (s, 1H), 7.15 (t, J ) 7.0 Hz, 1H), 7.40 (t, J )
7.0 Hz, 2H), 7.65 (m, 4H), 7.70 (t, J ) 7.0 Hz, 1H), 8.10 (br s,
2H), 8.22 (d, J ) 7.0 Hz, 1H), 8.3 (br s, 1H), 11.0 (s, 1H); MS
(EI) 492 au. Anal. Calcd for C24H14F6N2O3: C, 58.55; H, 2.87;
N, 5.69. Found: C, 58.47; H, 2.63; N, 5.47.
Meth od B-2. Gen er a l P r oced u r e for th e Alcoh olysis of
th e C-4 N-P h en ylca r boxa m id e Der iva tives 6b,d ,e,h -j To
Affor d Eth yl 2-Ar yl-1,3(2H,4H)-d ioxoisoqu in olin e-4-ca r -
boxyla tes 3b,d ,e,h -j. A suspension of 6b,d ,e,h -j (0.020 mol)
in 300-400 mL of ethanol was stirred and heated at reflux for
12-36 h, reaction progress being monitored by TLC (EtOAc/
hexane mixtures) as well as by complete dissolution of the
starting material. The solution was cooled to ambient temper-
ature and then refrigerated overnight at 0-4 °C. The resultant
products were collected by suction filtration and dried to afford
nearly colorless crystalline products 3b,d ,e,h -j which were
usually obtained in analytically pure form. Where appropriate,
recrystallization from ethanol afforded 3b,d ,e,h -j as colorless
solids.
Eth yl 2-[4-(eth oxyca r bon yl)p h en yl]-1,3(2H,4H)-dioxoiso-
qu in olin e-4-ca r boxyla te (3b): mp 176-177 °C; yield 87%;
same physical properties and spectra as material prepared above
via the ethyl chloroformate protocol.
Eth yl 2-(3,5-Dich lor op h en yl)-1,3(2H,4H)-d ioxoisoqu in o-
lin e-4-ca r boxyla te (3d ): mp 192-194 °C; yield 87%; same
physical properties and spectra as material prepared above via
the ethyl chloroformate protocol.
Eth yl 2-(3,5-d im eth oxyp h en yl)-1,3(2H,4H)-d ioxoisoqu in -
olin e-4-ca r boxyla te (3e): mp 176-177 °C; yield 88%; same
physical properties and spectra as material prepared above via
the ethyl chloroformate protocol.
Eth yl 2-(3-m eth yl-4-isop r op ylp h en yl)-1,3(2H,4H)-d iox-
oisoqu in olin e-4-ca r boxyla te (3h ): mp 135-137 °C; yield 79%;
1H-NMR (300 MHz, CDCl3) δ 1.30 (d, J ) 7.0 Hz, 6H), 1.55 (t,
J ) 7.0 Hz, 3H), 2.40 (s, 3H), 3.21 (m, 1H), 4.25 + 4.55 (2 q, J
) 7.0 Hz, 2H), 7.00-7.73 (m, 5H), 8.41 (dd, J ) 7.2, 2.1 Hz, 1H),
Syn th esis of Eth yl 2-Ar yl-1,3(2H,4H)-d ioxoisoqu in olin e-
4-ca r boxyla tes 3b,d ,e,h -j via Alcoh olysis of th e C-4 N-
P h en ylca r boxa m id e Der iva tives 6b,d ,e,h -j. Meth od B-1.
Gen er a l P r oced u r e for th e Syn th esis of th e N-P h en ylca r -
boxa m id e Der iva tives 6b,d ,e,h -j. To a suspension of sodium
hydride (0.26 g, 0.011 mol, from 0.44 g of 60% dispersion in oil,
washed three times with dry hexane) in 50 mL of anhydrous
THF at 0 °C was added with good stirring a solution of
2b,d ,e,h -j (0.010 mol) in 50 mL of dry THF over about 30 min.
After 15 min, the solution was briefly warmed to ambient
temperature and recooled to 0 °C, and then phenyl isocyanate
(1.31 g, 0.0110 mol, 1.20 mL) was added rapidly dropwise over
1 min. After 30 min at 0 °C, the mixture was stirred at ambient
temperature for 2-12 h (TLC monitoring; THF/H2O/EtOAc, 10/
1/39 or EtOAc/hexane mixtures). The solution was poured into
500-600 mL of ice/water and acidified to pH ∼1-2 with 12 N
HCl. After stirring at 0 °C for 30 min, the resultant solid was
collected by suction filtration, washed with several portions of
ice/water, dried, and recrystallized from the appropriate solvents
indicated below to afford 6b,d ,e,h -j as nearly colorless, volu-
minous solids. Principal IR bands (KBr): 3275, 1715-1720,
8.55 (d, J ) 7.2 Hz, 1H); MS (EI) 365 au. Anal. Calcd for C22H23
-
NO4: C, 72.31; H, 6.34; N, 3.83. Found: C, 72.65; H, 6.63; N,
3.76.
1670, 1645, 1590, 1250 cm-1
.
N-P h en yl 2-[4-(eth oxyca r bon yl)p h en yl]-1,3(2H,4H)-d i-
oxoisoqu in olin e-4-ca r boxa m id e (6b): mp 220.5-222.5 °C
Eth yl 2-(4-isop r op ylp h en yl)-1,3(2H,4H)-d ioxoisoqu in o-
lin e-4-ca r boxyla te (3i): mp 160-161.5 °C; yield 81%; 1H-NMR
(300 MHz, CDCl3) δ 1.30 (d, J ) 8.0 Hz, 6H), 1.55 (t, J ) 7.4
Hz, 3H), 3.00 (m, 1H), 4.60 (q, J ) 7.4 Hz, 2H), 7.12-7.62 (m,
5H), 7.70 (m, 1H), 8.40 (dd, J ) 7.2, 2.1 Hz, 1H), 8.55 (dd, J )
7.2, 2.1 Hz, 1H); MS (EI) 351 au. Anal. Calcd for C21H21NO4:
C, 71.78; H, 6.02; N, 3.99. Found: C, 71.59; H, 5.83; N, 3.94.
Eth yl 2-[3,5-bis(tr iflu or om eth yl)p h en yl]-1,3(2H,4H)-d i-
oxoisoqu in olin e-4-ca r boxyla te (3j): mp 161-163 °C; yield
1
from THF or acetone; yield 66%; H-NMR (60 MHz, DMSO-d6)
δ 1.35 (t, J ) 7 Hz, 3H), 4.37 (q, J ) 7 Hz, 2H), 5.43 (s, 1H),
6.95-8.15 (m, 13H), 10.8 (br s, 1H); MS (EI) 428 au. Anal.
Calcd for C25H20N2O5: C, 70.09; H, 4.71; N, 6.54. Found: C,
70.42; H, 4.80; N, 6.64.
N-P h en yl 2-(3,5-d ich lor op h en yl)-1,3(2H ,4H )-d ioxoiso-
qu in olin e-4-ca r boxa m id e (6d ): mp 252-254 °C from acetone;
yield 69%; 1H-NMR (300 MHz, DMSO-d6) δ 5.37 (s, 1H), 7.14 (t,
J ) 8.0 Hz, 1H), 7.38 (m, 4H), 7.62 (m, 4H), 7.80 (m, 2H), 8.16
(d, J ) 8.0 Hz, 1H), 10.8 (br s, 1H); MS (EI) 424, 426 au. Anal.
Calcd for C22H14Cl2N2O3: C, 62.14; H, 3.32; N, 6.59. Found: C,
62.48; H, 3.28; N, 6.55.
1
62%; H-NMR (300 MHz, CDCl3) δ 1.30 + 1.60 (2t, J ) 7.2 Hz,
3H), 4.32 + 4.60 (2q, J ) 7.2 Hz, 2H), 7.31-8.10 (m, 5H), 8.40
(m, 1H), 8.55 (d, J ) 7.2 Hz, 1H); MS (EI) 445 au. Anal. Calcd
for C20H13F6NO4: C, 53.94; H, 2.94; N, 3.15. Found: C, 54.17;
H, 3.08; N, 3.37.
N-P h en yl 2-(3,5-d im eth oxyp h en yl)-1,3(2H,4H)-d ioxoiso-
qu in olin e-4-ca r boxa m id e (6e): mp 211-213 °C from acetone;
yield 86%; 1H-NMR (300 MHz, DMSO-d6) δ 3.75 (s, 6H), 5.35
(s, 1H), 6.43 (br, 2H), 6.63 (m, 1H), 7.15 (m, 1H), 7.35 (m, 2H),
7.61 (m, 4H), 7.75 (m, 1H), 8.15 (m, 1H), 10.9 (s, 1H); MS (EI)
416 au. Anal. Calcd for C24H20N2O5: C, 69.22; H, 4.84; N, 6.73.
Found: C, 69.51; H, 5.02; N, 6.65.
Gen er a l P r oced u r e for th e Ben zoyloxya tion of 3a -j.
Syn th esis of Eth yl 2-Ar yl-4-(ben zoyloxy)-1,3(2H,4H)-d iox-
oisoqu in olin e-4-ca r boxyla tes 4a -j. To a magnetically stirred
suspension of sodium hydride (0.26 g, 0.011 mol, from 0.43 g of
60% oil dispersion, washed three times with dry hexane) in 50
mL of anhydrous THF at 0 °C was added intermediate 3a-j
(0.010 mol) portionwise over 10-15 min. After stirring at 0 °C
for 1 h, a solution of benzoyl peroxide (2.67 g, 0.011 mol) in 25
mL of anhydrous THF was added dropwise over 15 min. The
N-P h en yl 2-(3-m eth yl-4-isop r op ylp h en yl)-1,3(2H,4H)-d i-
oxoisoqu in olin e-4-ca r boxa m id e (6h ): mp 200-202 °C from