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10
General Procedure
A
mixture of the starting 2H-pyran-2-one 1 (1 mmol), ethyl vinyl ether (2, 721.1 mg, 10 mmol), and DABCO (11.2
mg, 0.1 mol) in MeCN (2 mL) was irradiated in the focused microwave
equipment (CEM Discover) for the time specified (Table
[¹]
). The final temperature
was set to 120 ˚C, the power to 120 W, and the
ramp time to 5 min. Thereafter, the reaction mixture was cooled,
the volatile components were removed in vacuo, the remaining solid
was treated with mixture of EtOH and H2O (10:1), and
cooled. The precipitated product 5 was
filtered off and washed with EtOH-H2O (10:1).
Selected Data of the ProductsMethyl
5-(Benzoylamino)-2-[(methoxycarbonyl)-methyl]benzoate
(5a)
Mp 169-171 ˚C (MeOH). IR (KBr):
3339, 1737, 1720, 1653, 1590, 1526, 1435, 1419 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 3.71
(s, 3 H, Me), 3.83 (s, 3 H, Me), 3.98 (s, 2 H, CH2),
7.21 (d, 1 H, J = 8.4
Hz, 3-H), 7.52 (m, 3 H, Ph), 7.86 (m, 3 H, Ph, 4-H), 8.10 (br s,
1 H, NH), 8.18 (d, 1 H, J = 2.1
Hz, 6-H). ¹³C NMR (75.5 MHz, DMSO-d
6): δ = 39.1,
51.4, 51.9, 122.0, 123.8, 127.6, 128.4, 129.4, 130.9, 131.7, 132.8,
134.5, 138.3, 165.6, 166.7, 171.5. MS (EI): m/z (%) = 327
(5) [M+], 105 (100). Anal.
Calcd for C18H17NO5: C, 66.05;
H, 5.23; N, 4.28. Found: C, 66.32; H, 5.17; N, 4.26.
Ethyl 5-(Benzoylamino)-2-[(ethoxycarbonyl)-methyl]benzoate
(5b)
Mp 170.5-171.5 ˚C
(MeOH). IR (KBr): 3298, 1736, 1714, 1651, 1588, 1523, 1420 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 1.25
(t, 3 H, J = 7.1
Hz, CH2CH
3), 1.37
(t, 3 H, J = 7.1 Hz,
CH2CH
3), 3.99 (s,
2 H, CH2), 4.15 (q, 2 H, J = 7.1
Hz, CH
2CH3), 4.32
(q, 2 H, J = 7.1
Hz, CH
2
CH3),
7.24 (d, 1 H, J = 8.9
Hz, 3-H), 7.53 (m, 3 H, Ph), 7.88 (m, 2 H, Ph), 7.95 (dd, 1 H, J
1 = 8.9
Hz, J
2 = 2.4
Hz, 4-H), 7.98 (br s, 1 H, NH), 8.10 (d, 1 H, J = 2.4
Hz, 6-H).
Methyl 5-(Benzoylamino)-2-methylbenzoate
(5c)
Mp 126-127 ˚C (EtOH-H2O).
IR (KBr): 3270, 1732, 1720, 1649, 1582, 1528, 1498, 1428 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 2.57
(s, 3 H, Me), 3.86 (s, 3 H, Me), 7.22 (d,
1 H, J = 8.3 Hz,
3-H), 7.50 (m, 3 H, Ph), 7.81 (dd, 1 H, J
1 = 2.2
Hz, J
2 = 8.3
Hz, 4-H), 7.86 (m, 2 H, Ph), 8.02 (br s, 1 H, NH), 8.08 (d, 1 H, J = 2.2 Hz,
6-H). ¹³C NMR (75.5 MHz, CDCl3): δ = 21.1,
51.9, 122.3, 124.0, 127.0, 128.7, 129.8, 131.9, 132.3, 134.6, 135.7,
136.3, 165.8, 167.5. MS (EI): m/z (%) = 269
(30) [M+], 105 (100). Anal.
Calcd for C16H15NO3: C, 71.36;
H, 5.61; N, 5.20. Found: C, 71.30; H, 5.68; N, 5.22.
Ethyl 5-(Benzoylamino)-2-methylbenzoate (5d)
Mp
119-120.5 ˚C (EtOH-H2O).
IR (KBr): 3296, 1726, 1648, 1583, 1530, 1448, 1404 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 1.38
(t, 3 H, J = 7.1
Hz, CH2CH
3), 2.57
(s, 3 H, Me), 4.35 (q, 2 H, J = 7.1
Hz, CH
2CH3), 7.23
(d, 1 H, J =
8.1
Hz, 3-H), 7.50 (m, 3 H, Ph), 7.87 (m, 3 H, Ph, 4-H), 7.96 (br s,
1 H, NH), 8.02 (d, 1 H, J = 2.4
Hz, 6-H).
N
-(3-Acetyl-4-methylphenyl)benzamide
(5e)
¹¹
Mp 131-132 ˚C
(EtOH-H2O); lit.¹¹ mp
137-138 ˚C (EtOH). IR (KBr): 3410, 1861,
1788, 1699, 1653, 1533, 1492 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 2.49
(s, 3 H, Me), 2.57 (s, 3 H, Me), 7.21 (d, 1 H, J = 8.4
Hz, 5-H), 7.53 (m, 4 H, Ph,
6-H), 7.87 (m, 2 H, Ph), 8.05
(br s, 1 H, NH), 8.13 (d, 1 H, J = 2.4
Hz, 2-H).
N
-(3-Benzoyl-4-methylphenyl)benzamide
(5f)
Mp <35 ˚C (EtOH-H2O).
IR (neat): 1671, 1597, 1522, 1501 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 2.28
(s, 3 H, Me), 7.28 (d, 1 H, J = 8.4
Hz, 5-H), 7.52 (m, 7 H, 2 × Ph, 2-H), 7.77
(dd, 1 H, J
1 = 2.4
Hz, J
2 = 8.4
Hz, 6-H), 7.83 (m, 4 H, Ph), 7.94 (br s, 1 H, NH).
N
-(3-Acetyl-4-methylphenyl)acetamide
(5g)
¹¹,¹²
Mp 86-88 ˚C
(EtOH-H2O); lit.¹¹ mp
94-95 ˚C (EtOH); lit.¹² mp
124 ˚C (EtOH). IR (KBr): 3331, 1686, 1668, 1585,
1536, 1497, 1453 cm-¹. ¹H
NMR (300 MHz, CDCl3): δ = 2.19
(s, 3 H, Me), 2.47 (s, 3 H, Me), 2.57 (s, 3 H, Me), 7.16 (br s,
1
H, NH), 7.18 (d, 1 H, J = 8.2
Hz, 5-H), 7.40 (dd, 1 H, J
1 = 2.0
Hz, J
2 = 8.2
Hz, 6-H), 7.97 (d, 1 H, J = 2.0
Hz, 2-H).