2388
M. C. Davis
dissolved in the solvent, and then the oil bath was removed. After 10 min, a
yellow crystalline solid precipitated, and stirring stopped. Another 40 mL of
the solvent mixture was added, and the solid was broken up. The product
was collected on a coarse-porosity glass frit. It was not possible to rinse the
solid thoroughly on the frit, so the crude was recrystallized from a mixture
of 60 mL of H2O and 40 mL of EtOH. After filtering on a coarse-porosity
glass frit, the small, bright yellow flakes were dried overnight (10 Torr,
608C) to remove residual H2O. The mass of product was 26.3 g, representing
a 65% yield (calculated on anhydrous product). Mp 121–1238C (lit.[1] 126–
127 C). dH (CDCl3): 9.14 (t, J ¼ 6 Hz, 1H), 8.68 (s, 1H), 7.42 (d, J ¼ 9.4 Hz,
1H), 6.65 (dd, J ¼ 9.0 and 2.5 Hz, 1H), 6.49 (d, J ¼ 2.4 Hz, 1H), 3.83
(t, J ¼ 5.1 Hz, 2H), 3.62 (q, J ¼ 4.9 Hz, 2H), 3.46 (q, J ¼ 7.1 Hz, 4H), 2.03
(bs, 1H), 1.25 (t, J ¼ 7.1 Hz, 6H); dC (CDCl3): 165.07, 162.94, 157.95,
152.96, 148.53, 131.48, 110.29, 109.96, 108.58, 96.80, 63.15, 45.33, 43.29,
.
12.65. Elemental analysis calculated for C16H20N2O4 1/2 H2O: C, 61.34; H,
6.71; N, 8.94. Found: C, 61.64; H, 6.70; N, 8.94.
3-N-(2-Methacryloxyethyl)carboxamido-7-(diethylamino)coumarin (4)
The product is light sensitive; all operations were performed under cloth or
foil covers to avoid exposure to light as far as possible.
A two-necked, 500-mL, round-bottomed flask equipped with magnetic
stirbar was charged with 26.3 g of compound 3 (0.084 mol), 21.47 g of
DMAP (0.176 mol, 2 equiv), 20 mg of 4-methoxyphenol, and 250 mL of
THF (anhydrous, inhibitor free). An N2 bubbler was equipped to one neck,
and a 10-mL pressure-equalizing addition funnel was equipped to the
second neck. The mixture was stirred in a warm H2O bath until complete
dissolution. The mixture was cooled in an ice bath, and the addition funnel
was charged with 19.55 mL of methacrylic anhydride (20.33 g, 0.132 mol,
1.5 equiv). The addition was made dropwise over 5 min. After 30 min, TLC
showed complete consumption of 3. The reaction mixture was poured into
750 mL of vigorously stirred, cold H2O. A pale yellow solid precipitated,
and after 20 min, the solid was collected on a coarse-porosity glass frit. The
solid was broken up and rinsed on the frit twice with 150-mL portions of
cold H2O. The solid was air dried under vacuum on the frit for 2 h to obtain
40.5 g of crude product. The crude contained some H2O but was otherwise
more than 95% by 1H NMR. The yellow solid was recrystallized from
400 mL of EtOH to give 19.9 g of the title compound 4 as a pale yellow
powder (62%). Mp 138–1408C (lit.[1] 143–1448C). dH (CDCl3): 9.08
(t, J ¼ 4.9 Hz, 1H), 8.71 (s, 1H), 7.45 (d, J ¼ 9.2 Hz, 1H), 6.65 (dd, J ¼ 8.9
and 2.6 Hz, 1H), 6.49 (d, J ¼ 2.4 Hz, 1H), 6.19 (pent, J ¼ 1.2 Hz, 1H), 5.59
(pent, J ¼ 1.6 Hz, 1H), 4.32 (t, J ¼ 5.6 Hz, 2H), 3.77 (q, J ¼ 5.8 Hz, 2H),
3.46 (q, J ¼ 7.2 Hz, 4H), 1.98 (m, J ꢀ 1.2 Hz, 3H), 1.24 (t, J ¼ 7.2 Hz,
6H); dC (CDCl3): 167.49, 163.62, 162.98, 157.92, 152.86, 148.44, 136.27,