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Hz, H-30), 4.26 (1H, dd, J=2.4, 5.4 Hz, H-20), 5.95 (1H, dd, J=2.4, 8.7 Hz, H-10), 6.38 (1H, d, J=6.5 Hz,
CH(OEt)2), 8.18 (1H, s, H-3), 9.30 (1H, d, J=6.4 Hz, NHCH(OEt)2), 9.73 (1H, d, J=8.7 Hz, NH); δC
(125 MHz, CDCl3) 14.95 (2×q, CH(OCH2CH3)2), 18.44 (q, C-60), 26.40, 28.16 (2×q, C(CH3)2), 61.14,
61.25 (2×t, CH(OCH2CH3)2), 66.38, 71.44, 73.59, 76.31, 78.16 (5×d, C-10, C-20, C-30, C-40, C-50),
99.51 (d, CH(OEt)2), 111.09 (s, C(CH3)2), 113.26 (s, C-6), 156.17, 156.72 (2×s, C-1, C-5), 159.51 (d,
C-3); m/z (APCI+) 469 (MH+, 33%), 423 (M+−OEt, 65%), 103 (100%); HRMS m/z found: 469.215200
(MH+); C18H29N8O7 requires: 469.215921.
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Further elution afforded the compound 13a (47.5 mg, 35%) as a colourless oil; [α]D −34.4 (c 0.59,
CHCl3); νmax (film) 3361 (NH), 2111 (N3), 1585 (NO2) cm−1; δH (500 MHz, CDCl3) 1.27 (6H, t, J=7.1
Hz, 2×CH(OCH2CH3)), 1.35 (6H, d, J=6.1 Hz, H3-60), 1.42, 1.64 (2×6H, 2×s, 2×C(CH3)2), 3.26 (2H,
dd, J=7.6, 9.9 Hz, H-40), 3.39 (2H, ddd, J=6.0, 6.1, 9.9 Hz, H-50), 3.41, 3.42 (2×3H, 2×s, 2×OMe),
3.66–3.74 (4H, m, 2×CH(OCH2CH3)), 4.22 (2H, dd, J=5.3, 7.5 Hz, H-30), 4.27 (1H, dd, J=2.4, 5.4
Hz, H-20), 5.97 (2H, dd, J=2.4, 8.1 Hz, H-10), 6.32 (1H, d, J=6.3 Hz, CH(OEt)(OMe)), 6.33 (1H, d,
J=6.4 Hz, CH(OEt)(OMe)), 8.19 (2H, s, H-3), 9.28 (2H, d, J=6.3 Hz, 2×NHCH(OEt)(OMe)), 9.73
(2H, d, J=8.6 Hz, NH); δC (125 MHz, CDCl3) 14.91 (2×q, CH(OCH2CH3)), 18.42 (2×q, C-60), 26.39,
28.15 (4×q, 2×C(CH3)2), 52.00, 52.07 (2×q, 2×CH(OMe)), 61.51, 61.56 (2×t, CH(OCH2CH3)), 66.36,
71.43, 73.56, 76.30, 78.14 (10×d, C-10, C-20, C-30, C-40, C-50), 100.20 (2×d, CH(OEt)(OMe)), 111.08
(2×s, C(CH3)2), 113.30 (2×s, C-6), 156.17, 156.69 (4×s, C-1, C-5), 159.53 (2×d, C-3); m/z (APCI+)
455 (MH+, 5%), 423 (M+−OMe, 100%); HRMS m/z found: 455.200981 (MH+); C17H27N8O7 requires:
455.200271.
5.7.2. Method 2
A solution of the amine 11a (189 mg, 0.516 mmol) in triethylorthoformate (9.2 ml) was heated to
140°C. TLC (ethyl acetate:hexane, 7:3) after 19 h showed traces of starting material (Rf 0.35) and one
main product (Rf 0.65). The mixture was cooled and concentrated in high vacuo. The residue was pre-
adsorbed on silica gel with ethanol and purified by flash column chromatography (hexane:ethyl acetate,
85:15) to give the compound 12a (80 mg, 33%; 82% over recovered starting material) as a colourless
oil, identical to the material above. Further elution (hexane:ethyl acetate, 4:6) gave recovered starting
material 11a (116 mg, 61%).
Following the above procedure described in method 1, the amine 11b (190 mg, 0.519 mmol) gave
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the enantiomeric pyrimidine 12b (50 mg, 20%) as a colourless oil; [α]D +24.4 (c 0.98, CHCl3);
νmax (film) 3362 (NH), 2111 (N3), 1586 (NO2) cm−1; δH (500 MHz, CDCl3) 1.26 (6H, t, J=7.1 Hz,
CH(OCH2CH3)2), 1.35 (3H, d, J=6.1 Hz, H3-60), 1.42, 1.64 (2×3H, 2×s, C(CH3)2), 3.27 (1H, dd, J=7.6,
9.9 Hz, H-40), 3.40 (1H, ddd, J=6.1, 6.1, 9.9 Hz, H-50), 3.66–3.74 (4H, m, CH(OCH2CH3)2), 4.23 (1H,
dd, J=5.3, 7.5 Hz, H-30), 4.27 (1H, dd, J=3.4, 5.3 Hz, H-20), 5.98 (1H, dd, J=2.4, 8.7 Hz, H-10), 6.39
(1H, d, J=6.5 Hz, CH(OEt)2), 8.19 (1H, s, H-3), 9.31 (1H, d, J=6.4 Hz, NHCH(OEt)2), 9.74 (1H, d,
J=8.6 Hz, NH); δC (125 MHz, CDCl3) 14.94 (2×q, CH(OCH2CH3)2), 18.41 (q, C-60), 26.39, 28.15
(2×q, C(CH3)2), 61.10, 61.21 (2×t, CH(OCH2CH3)2), 66.35, 71.39, 73.54, 76.24, 78.13 (5×d, C-10,
C-20, C-30, C-40, C-50), 99.45 (d, CH(OEt)2), 111.07 (s, C(CH3)2), 113.21 (s, C-6), 156.13, 156.68 (2×s,
C-1, C-5), 159.49 (d, C-3); m/z (APCI−) 467 (M−H−, 15%), 421 (M+−EtOH, 100%); HRMS m/z found:
469.215328 (MH+); C18H29N8O7 requires: 469.215921. Further elution afforded the compound 13b (92
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mg, 39%) as a colourless oil; [α]D +27.1 (c 0.93, CHCl3); νmax (film) 3362 (NH), 2111 (N3), 1587
(NO2) cm−1; δH (500 MHz, CDCl3) 1.26 (6H, t, J=7.1 Hz, 2×CH(OCH2CH3)), 1.35 (6H, d, J=6.1 Hz,
H3-60), 1.41, 1.63 (2×6H, 2×s, 2×C(CH3)2), 3.25 (2H, dd, J=7.6, 9.8 Hz, H-40), 3.38 (2H, ddd, J=6.1,
6.2, 9.8 Hz, H-50), 3.40, 3.41 (2×3H, 2×s, 2×OMe), 3.65–3.73 (4H, m, 2×CH(OCH2CH3)), 4.21 (2H,
dd, J=5.4, 7.2 Hz, H-30), 4.26 (1H, dd, J=2.2, 5.2 Hz, H-20), 5.96 (2H, dd, J=2.3, 8.7 Hz, H-10), 6.31