D. Brugier et al. / Tetrahedron 56 (2000) 2985±2993
2991
(d, 1H, CHvCH, J15.6 Hz), 7.38 (bs, 1H, H5), 7.22 (bs,
NH), 6.70 (bs, NH), 6.14 (d, 1H, CHvCH, J15.6 Hz),
4.20 (q, 2H, CH2, J7.1 Hz), 1.48, 1.47 (2s, 18H,
CH3),1.28 (t, 3H, CH3, J7.1 Hz). 13C NMR, d: 166.7
(CO), 153.9, 152.9 (CO), 133.8 (CHvCH), 132.6 (C3),
128.7 (C4), 116.3 (CHvCH), 81.8, 80.6 (C), 60.4 (CH2),
28.1, 27.9 (CH3), 14.1 (CH3). Anal. Calcd for C19H28N2O6S:
C, 55.32; H, 6.84; N, 6.79; S, 7.77; found: C, 55.41; H, 6.86;
N, 6.81; S, 7.33.
Ethyl (2-trimethylsilylethynylthien-3-yl)carbamate 23.
Yield: 70%. H NMR, d: 7.58 (bs, 1H, H5), 7.12 (d, 1H,
1
H4, J5.5 Hz), 6.99 (bs, NH), 4.22 (q, 2H, CH2, J7.1 Hz),
1.31 (t, 3H, CH3, J7.1 Hz), 0.24 (s, 9H, SiCH3). 13C NMR,
d: 152.7 (CO), 141.2 (C3), 126.3 (C5), 120.3 (C4), 104.4 (C),
94.8 (C), 61.5 (CH2), 14.4 (CH3), 0.1 (SiCH3). Anal. Calcd
for C12H17NO2SSi: C, 53.89; H, 6.41; N, 5.24; S, 11.99;
found: C, 53.06; H, 6.21; N, 5.82; S, 11.72.
t-Butyl (2-phenylethynylthien-3-yl)carbamate 22b. Mp
838C, Yield: 83%. 1H NMR, d: 7.65 (bs, 1H, H5), 7.53±7.47
(m, 2H, Ph), 7.35±7.33 (m, 3H, Ph), 7.17 (d, 1H, H4,
J5.5 Hz), 6.96 (bs, NH), 1.53 (s, 9H, CH3). 13C NMR, d:
151.5 (CO), 140.5 (C3), 131.0, 128.1, 128.0, 122.3 (Ph)
125.9 (C5), 120.5 (C4), 103.0 (C2), 97.8 (C), 80.6 (C), 79.5
(C), 27.9 (CH3). Anal. Calcd for C17H17NO2S: C, 68.20; H,
5.72; N, 4.68; found: C, 68.49; H, 5.91; N, 4.64.
4-[3,4-Bis(t-butoxycarbonylamino)thien-2-yl]butenone
20b. Yield: 30%. 1H NMR, d: 7.55 (d, 1H, CHvCH,
J15.7 Hz), 7.41 (bs, 1H, H5), 7.20 (bs, NH), 6.75 (bs,
NH), 6.45 (d, 1H, CHvCH, J15.7 Hz), 2.28 (s, 3H,
CH3), 1.49, 1.47 (2s, 18H, CH3). 13C NMR, d: 154.6,
153.1 (CO), 132.6 (CHvCH), 134.1 (C3), 124.6 (CHvCH),
107.2 (C2), 81.6, 80.7 (C), 29.7 (CH3), 28.0, 27.9 (CH3).
Anal. Calcd for C18H26N2O5S: C, 56.53; H, 6.85; N, 7.32;
S, 8.38; found: C, 56.68; H, 7.14; N, 7.42; S, 7.55.
Ethyl 5-(3-t-butoxycarbonylaminothien-2-yl)pent-4-ynoate
22c. Yield: 53%. 1H NMR, d: 7.55 (bs, 1H, H5), 7.01 (d, 1H,
H4, J5.5 Hz), 6.91 (bs, NH), 4.13 (q, 2H, CH2, J7.1 Hz),
2.74 (t, 2H, CH2, J7.2 Hz), 2.56 (t, 2H, CH2, J7.2 Hz),
1.46 (s, 9H, CH3), 1.21 (t, 3H, CH3, J7.1 Hz). 13C NMR,
d: 171.3 (C10), 150.6 (CO), 140.4 (C3), 124.5 (C5), 119.9
(C4), 102.9 (C2), 96.8 (C6), 80.3 (C), 71.4 (C7.), 60.2 (CH2),
33.0 (C9), 27.7 (CH3), 15.5 (C8), 13.7 (CH3). Anal. Calcd for
C16H21NO4S: C, 58.23; H, 6.19; N, 4.53; S, 10.36; found: C,
58.30; H, 6.58; N, 4.08; S, 9.99.
Ethyl 3-(3,4-diaminothien-2-yl)propenoate 21. Dicarba-
mate 20a (0.412 g, 1 mmol) in a 20% solution of hydro-
bromic acid in acetic acid (0.450 g, 1 mmol) was stirred
for 20 min at room temperature and anhydrous ether
(20 ml) was added. The reaction was stirred for another
15 min. The ®ltered salt was washed with ether and
dissolved in water (20 ml). After neutralization with diluted
NaOH aq. solution, the diamine 21 was extracted with ether
(3£10 ml) and obtained in a pure form after concentration.
Yield63%. 1H NMR, d: 7.70 (d, 1H, CHvCH, J
15.3 Hz), 6.25 (s, 1H, H5), 5.91 (d, 1H, CHvCH,
J15.3 Hz), 4.19 (q, 2H, CH2, J7.1 Hz), 4.00 (bs, 4H,
NH2), 1.28 (t, 3H, CH3, J7.1 Hz). 13C NMR, d: 166.2
(CO), 140.6 (C4), 136.0 (C3), 134.6 (CHvCH), 111.2
(CHvCH), 105.5 (C5), 60.1 (CH2), 14.2 (CH3). Anal.
Calcd for C9H12N2O2S: C, 50.93; H, 5.70; N, 13.20; S,
15.10; found: C, 51.45; H, 6.02; N, 12.98; S, 14.98.
Di-t-butyl (2-trimethylsilylethynylthiophen-3,4-diyl)di-
1
carbamate 24a. Mp1358C, Yield: 66%. H NMR, d:
8.50 (bs, NH), 7.35 (s, 1H, H5), 6.47 (bs, NH), 1.48 (s,
18H, CH3), 0.23 (s, 9H, SiCH3). 13C NMR, d: 153.7,
152.8 (CO), 131.8, 130.3 (C3, C4), 110.2 (C5), 104.1 (C),
95.0 (C), 81.6, 80.1 (C), 28.1, 27.9 (CH3), 20.3 (SiCH3).
Anal. Calcd for C19H30N2O4SSi: C, 55.58; H, 7.36; N, 6.82;
S, 7.81; found: C, 55.44; H, 7.25; N, 6.92; S, 7.37.
Sonogashira type coupling reaction. To a degased solu-
tion of bromocarbamate 17b (0.695 g, 2.5 mmol) in tri-
ethylamine (5 ml) was added, successively, the acetylenic
reagent (3.75 mmol), PdCl2 (0.022 g, 0.125 mmol), PPh3
(0.066 g, 0.25 mmol.), and CuI (0.024 g, 0.125 mmol).
The mixture was stirred on heating for 4 h under argon
and then diluted with ether (50 ml) and water (10 ml).
After ®ltration, the organic layer was dried and evaporated.
The product was puri®ed by silica gel chromatography
(eluent CH2Cl2/light petroleum: 1/1). Using the same
experimental procedure, iodocarbamates 17a and 17c have
led at room temperature to the carbamates 22 and 23,
respectively. Dicarbamates 24 were obtained by the same
way from 10b. Dicarbamates 25 were prepared using double
amounts of the acetylenic reagent, PdCl2, PPh3 and CuI.
Compounds 24 and 25 were puri®ed by silica gel chromato-
graphy (eluent: CH2Cl2).
Di-t-butyl (2-phenylethynylthiophen-3,4-diyl)dicarbamate
1
24b. Mp1788C, Yield: 70%. H NMR, d: 8.71 (bs, NH),
7.51±7.32 (m, 6H, Ph, H5), 6.58 (bs, NH), 1.50 (s, 18H,
CH3). 13C NMR, d: 153.9, 153.0 (CO), 130.7 (C3, C4),
131.2, 128.6, 128.3, 122.3 (Ph), 110.6 (C5), 97.8 (C.),
81.9, 80.3 (C), 80.0 (C), 28.1, 28.0 (CH3). Anal. Calcd for
C22H26N2O4S: C, 63.75; H, 6.32; N, 6.76; S, 7.73; found: C,
63.62; H, 5.98; N, 6.92; S, 7.64.
Ethyl 5-[3,4-bis(t-butoxycarbonylamino)thien-2-yl]pent-
4-ynoate 24c. Yield: 46%. 1H NMR, d: 8.00 (bs, NH), 7.08
(s, 1H, H5), 6.48 (bs, NH), 4.11 (q, 2H, CH2, J7.2 Hz),
2.72 (t, 2H, CH2, J7.1 Hz), 2.54 (t, 2H, CH2, J7.1 Hz),
1.46,1.42 (s, 18H, CH3), 1.18 (t, 3H, CH3, J7.2 Hz). 13C
NMR, d: 171.5 (C10), 153.9, 153.0 (CO), 130.8, 129.3 (C3,
C4), 109.5 (C5), 97.2 (C6), 81.7 (C7), 80.7, 80.1 (C), 60.6
(CH2), 33.2 (C9), 28.1, 28.0 (CH3), 15.7 (C8), 14.0 (CH3).
Anal. Calcd for C21H30N2O6S: C, 56.59; H, 6.65; N, 6.60; S,
7.55; found: C, 56.68; H, 7.14; N, 6.42; S, 7.92.
t-Butyl (2-trimethylsilylethynylthien-3-yl)carbamate 22a.
Yield: 70%. 1H NMR, d: 7.57 (bs, 1H, H5), 7.10 (d, 1H, H4,
J5.4 Hz), 6.87 (bs, NH), 1.50 (s, 9H, CH3), 0.24 (s, 9H,
SiCH3). 13C NMR, d: 151.4 (CO), 141.6 (C3), 125.9 (C5),
120.0 (C4), 104.0 (C), 102.8 (C2), 94.9 (C), 80.6 (C), 27.9
(CH3), 20.3 (SiCH3). Anal. Calcd for C14H21NO2SSi: C,
56.91; H, 7.16; N, 4.74; found: C, 56.95; H, 6.84; N, 5.27.
Di-t-butyl [2,5-bis(trimethylsilylethynyl)thiophen-3,4-diyl]-
1
dicarbamate 25a Mp1458C, Yield: 83%. H NMR, d:
6.75 (bs, 2H, NH), 1.46 (s, 18H, CH3), 0.20 (s, 18H,
SiCH3). 13C NMR, d: 152.6 (CO), 133.9 (C3, C4), 104.2
(C), 94.9 (C), 80.6 (C), 27.8 (CH3), 20.5 (SiCH3). Anal.