3214
R. Suleiman, B. El Ali / Tetrahedron Letters 51 (2010) 3211–3215
(s, 2Hb, @CH2), 7.40 (s, 4H arom.); 13C NMR (125 MHz, CDCl3): d
O
24.8, 25.4, 32.9, 48.5, 121.1, 128.1, 137.0, 144.7, 166.5; EI-MS m/z
380 (M+). Anal. Calcd for C24H32N2O2 (380.64): C, 75.73; H, 8.47;
N, 7.39. Found: C, 75.66; H, 8.43; N, 7.33.
N
3. General procedure for the alkoxycarbonylation of mono and
bis-acrylate amides
O
Figure 1. Structure of cyclic product 5da.
A mixture of Pd(PPh3)2Cl2 (0.04 mmol), a,b-unsaturated amide
(0.5 mmol for mono amide, and 0.25 mmol for bis amide), and
H2O (8.0 mmol) in methanol (8 ml) was placed in a glass liner,
equipped with a stirring bar, and placed in a 45 ml Parr autoclave.
The autoclave was vented three times with CO and then pressured
at room temperature with CO (100 psi). The mixture was stirred
and heated at 110 °C for 6 h. After cooling, the pressure was re-
leased, and the reaction mixture was filtered after adding anhy-
drous Na2SO4. A sample of the filtrate was analyzed by GC and
GC–MS. The solvent was removed and the products were separated
by preparative TLC (30% EtOAc/petroleum ether 40–70 °C). The
products were identified by 1H and 13C NMR, FT-IR, and GC–MS
2. General procedure for the synthesis of unsaturated amides
and diacrylate amides
a
,b-Unsaturated amides 1a–c,e11 and 1d12 were synthesized
according to literature procedures. ,b-Unsaturated amides 1c
a
and 1e are novel while a,b-unsaturated amides 1a,b,d are known.
The literature method11 was adopted for the synthesis of bis-
acrylate amido esters 6a,b, but with a slight modification:
A
mixture of Pd(OAc)2 (0.02 mmol), 1,4-bis(diphenylphos-
phino)butane (dppb) (0.08 mmol), p-TsOH (0.3 mmol), dialkyne
(1.0 mmol), and cyclohexylamine (2.0 mmol) in MeCN (10 ml)
was placed in a glass liner, equipped with a stirrer bar, and then
placed in a 45 ml Parr autoclave. The autoclave was vented three
times with CO and then pressured at room temperature with CO
(100 psi). The mixture was stirred and heated at 110 °C for 20 h.
After cooling, the pressure was released, and the products were
collected on a filter paper, washed with MeOH, and dried under
vacuum. The products were identified by 1H and 13C NMR, FT-IR,
and EI-MS analyses.
analyses. All the
x-amido esters obtained in this study are new
compounds. The hydrogenation by-product 3aa is known.13
3.1. Dimethyl 3,30-(1,4-phenylene)bis[4-(cyclohexylamino)-4-
oxobutanoate] (8aa)
White solid, mp 175–176 °C, IR (KBr)
1738 (CO ester), 3324 (NH); 1H NMR (500 MHz, CDCl3): d 0.95–
v
(cmꢀ1) 1639 (CO amide),
1.89 (m, 20H, –(CH2)5–), 2.61 (m, 2H , CH2COOMe), 3.22 (m, 2Hb,
a
CH2COOMe), 3.63 (s, 6H, OCH3), 3.69 (m, 2H, PhCH), 3.89 (m, 2H,
NCH), 5.80 (br s, 2H, NH), 7.37 (s, 4H arom.); 13C NMR (125 MHz,
CDCl3): d 24.5, 25.2, 32.5, 37.5, 48.0, 48.2, 51.5, 128.0, 138.2,
170.9, 172.3; EI-MS m/z 500 (M+). Anal. Calcd for C28H40N2O6
(500.62): C, 67.18; H, 8.05; N, 5.59. Found: C, 67.24; H, 7.89; N,
5.64.
2.1. 2,20-(1,4-Phenylene)bis(N-cyclohexylacrylamide) (7aa)
White solid, mp 215–216 °C; IR (KBr)
v
(cmꢀ1) 1636 (CO), 3263
(NH); 1H NMR (500 MHz, CDCl3): d 1.10–1.97 (m, 20H, –(CH2)5–),
3.91 (m, 2H, NCH), 5.63 (br s, 2H, NH), 5.65 (s, 2H , @CH2), 6.02
a
NH2
Pd(OAc)2, dppb, p-TsOH
H
N
H
N
X
+
+
CO
X
°
CH3CN, 110 C, 20 h
100 psi
O
O
6a,b
7aa 95%
a: X =
b
7ba
: X = -(CH2)4-
82%
Pd(PPh3)2Cl2 (0.04 mmol)
CH3OH (8ml), H2O (8 mmol)
CO (100 psi)
O
O
O
O
O
OCH3
H3CO
N
N
H
H
N
°
CaH, DMF, 50 C, 12 h
N
X
X
- CH3OH
O
O
O
8aa (quantitative)
9aa 84%
9ba 67%
8ba
(quantitative)
Scheme 1. The synthesis of N-substituted bis-cyclic succinimides 9 starting from diacetylenes 6 and cyclohexylamine.