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A mixture of 4a (5.01
g, 7.21 mmol), dry CH2Cl2 (30 mL) and propyl
isocyanate (2.7 mL, 28.8 mmol) was agitated at 30 °C
for 24 h on an orbit shaker. The resin was filtered and washed with
DMF (4 × 40 mL), CHCl3 (4 × 40 mL),
MeOH (4 × 40 mL) and Et2O (1 × 40 mL)
to give 5a. A solution of DCC (8.91 g,
43.2 mmol) in dry THF (12 mL) was added dropwise to a stirred mixture
of 5a, malonic acid (2.25 g, 21.6 mmol)
and dry THF (36 mL) at 0 °C under Ar. When addition
was complete, the mixture was stirred for additional 3 h at r.t.
Then, the mixture was diluted with MeOH (100 mL) and heated at 60 °C
to dissolve by-products. The resin was collected by filtration and
washed with hot DMF (4 × 40 mL), CHCl3 (4 × 40
mL), MeOH (4 × 40 mL) and Et2O (1 × 40
mL) to give 1a (6.24 g, quant.).
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<A NAME="RU06303ST-8">8</A> The synthesis of 1a according
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Yogo M.
Hirota K.
Senda S.
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Garratt S.
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<A NAME="RU06303ST-12">12</A> Carbonate 9 was
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Spectra data of 7: 1H
NMR (300 MHz, CDCl3): δ = 5.70 (br s,
2 H), 4.57 (s, 2 H), 3.84 (t, 2 H, J = 7.7
Hz), 3.75 (s, 2 H), 1.63 (tq, 2 H, J = 7.7,
7.4 Hz), 0.94 (t, 3 H, J = 7.4
Hz). 13C NMR (75.4 MHz, CDCl3): δ = 168.2,
164.8, 164.5, 151.5, 43.7, 43.2, 39.4, 21.1, 11.0. IR(neat): νmax = 3348,
3199, 2966, 2935, 1659, 1410, 1362, 1289, 1204, 1177, 1140, 1086,
936, 758 cm-1. MS (EI): m/z (relative intensity) = 227 (5.6) [M]+ ,
210 (6.5), 184 (96), 169 (37), 143 (77), 98 (81), 56 (100). HRMS
(EI) calcd for C9H13N3O4 [M]+ 227.0906. Found:
227.0910. Spectra data of 8: 1H
NMR (300 MHz, CDCl3): δ = 7.27-7.23
(m, 8 H), 6.41 (d, 2 H, J = 15.7
Hz), 6.11 (dt, 2 H, J = 15.7,
7.7 Hz), 5.93-5.61 (m, 2 H), 4.55 (s, 2 H), 3.75 (t, 2
H, J = 7.7
Hz), 3.00-2.87 (m, 4 H), 1.41 (tq, 2 H, J = 7.7,
7.4 Hz), 0.73 (t, 3 H, J = 7.4
Hz). 13C NMR (75.4 MHz, CDCl3): δ = 171.0,
170.5, 168.3, 150.4, 135.1, 134.3, 133.5, 128.8, 127.7, 122.7, 57.2,
43.6, 43.4, 42.5, 21.1, 10.9. IR (neat): νmax = 3466,
3363, 2966, 2935, 1675, 1490, 1424, 1405, 1283, 1092, 971, 756 cm-1.
MS (EI): m/z (relative intensity) = 527
(32) [M]+, 510 (42), 385 (42),
376 (36), 359 (87), 331 (52), 287 (26), 246 (72), 240 (72), 223 (53),
151 (100), 116 (53), 115 (52). HRMS (EI) calcd for C27H27Cl2N3O4 [M]+ 527.1379.
Found: 527.1401.
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Högber T.
Rämsby S.
Ström P.
Acta
Chem. Scand.
1989,
43:
660
