A. López, R. Pleixats / Tetrahedron: Asymmetry 9 (1998) 1967–1977
1971
3282, 1700, 1614; 1H NMR (CDCl3): 0.94 (s, 3H), 1.06 (s, 3H), 1.18–1.36 (m, 2H), 1.66–1.85 (m, 3H),
1.99 (apparent t, J=2.5 Hz, 1H), 2.06–2.10 (m, 2H), 2.76 (ddd, J=16.1 Hz, 5.8 Hz, 2.9 Hz, 1H), 2.89
(ddd, J=16.1 Hz, 5.8 Hz, 2.2 Hz, 1H), 3.32 (d, J=13.2 Hz, 1H), 3.41 (d, J=13.2 Hz, 1H), 3.92 (dd, J=7.2
Hz, 5.4 Hz, 1H), 4.89 (t, J=5.8 Hz, 1H), 7.12–7.72 (m, 10H); 13C NMR (CDCl3): 19.8, 20.5, 25.1, 26.4,
32.6, 38.1, 44.4, 47.7, 48.4, 52.9, 63.7, 65.1, 71.0, 79.7, 127.8, 127.9, 128.4, 128.7, 129.0, 130.3, 135.6,
139.3, 170.7, 171.6; MS (m/z, %): 474 (M+, 2), 473 (M−1, 6), 232 (100), 220 (12), 192 (27), 165 (19),
128 (13). Anal. calcd for C28H30N2SO3: C, 70.86; H, 6.38; N, 5.91; S, 6.74. Found: C, 70.72; H, 6.87;
N, 5.50; S, 6.34.
3.2. (2R)-N-[(2S)-2-((Diphenylmethylidene)amino)-4-bromo-4-penten-1-oyl]bornane-10,2-sultam 2b
Prepared as for 2a. The crude solid residue was purified by digestion in diethyl ether to afford 2b in
80% yield; m.p. 193°C; [α]D20=−91.8 (c=1.5, CHCl3); IR (KBr, cm−1): 1708, 1630; 1H NMR (CDCl3):
0.93 (s, 3H), 1.11 (s, 3H), 1.25–1.46 (m, 2H), 1.78–2.13 (m, 5H), 2.86 (dd, J=13.9 Hz, 7.3 Hz, 1H), 3.29
(dd, J=13.9 Hz, 6.6 Hz, 1H), 3.34 (d, J=13.8 Hz, 1H), 3.41 (d, J=13.8 Hz, 1H), 3.93 (dd, J=7.3 Hz, 5.1
Hz, 1H), 5.11 (apparent t, J=6.9 Hz, 1H), 5.43 (d, J=1.5 Hz, 1H), 5.69 (broad s, 1H), 7.17–7.72 (m, 10H);
13C NMR (CDCl3): 19.8, 20.7, 26.4, 32.7, 38.3, 44.5, 46.3, 47.8, 48.5, 53.0, 63.7, 65.3, 120.3, 127.9,
128.2, 128.4, 128.6, 128.7, 130.0, 130.3, 135.7, 139.5, 171.3, 171.7. Anal. calcd for C28H31N2SO3Br: C,
60.64; H, 5.64; N; 5.05; S, 5.77; Br, 14.20. Found: C, 60.42; H, 5.61; N, 5.00; S, 5.62; Br, 14.35.
3.3. (2R)-N-[(2S)-2-((Diphenylmethylidene)amino)-4-ethoxycarbonyl-4-penten-1-oyl]bornane-10,2-
sultam 2c
Prepared as for 2a, but the reaction was performed at room temperature for 6 h. The crude solid
residue was recrystallized from diethyl ether to give 2c in 83% yield; m.p. 150°C; [α]D20=−96.0 (c=1.5,
CHCl3); IR (KBr, cm−1): 1715, 1694, 1623; 1H NMR (CDCl3): 0.91 (s, 3H), 1.06 (s, 3H), 1.10 (t, J=6.9
Hz, 3H), 1.25–1.45 (m, 2H), 1.77–1.95 (m, 3H), 1.95–2.11 (m, 2H), 2.78 (dd, J=13.2 Hz, 7.3 Hz, 1H),
3.08 (dd, J=13.2 Hz, 6.6 Hz, 1H), 3.31 (d, J=13.5 Hz, 1H), 3.38 (d, J=13.5 Hz, 1H), 3.93 (t, J=5.1 Hz,
1H), 3.975 (m, 2H), 5.03 (apparent t, J=6.9 Hz, 1H), 5.58 (s, 1H), 6.19 (d, J=1.5 Hz, 1H), 7.15–7.68
(m, 10H); 13C NMR (CDCl3): 14.5, 20.4, 21.2, 26.9, 33.4, 37.7, 38.8, 45.1, 48.2, 48.9, 53.7, 61.2, 64.8,
65.9, 128.4, 128.7, 128.8, 129.0, 129.3, 130.7, 136.4, 136.8, 140.2, 166.8, 171.2, 172.3. Anal. calcd for
C31H36N2O5S: C, 67.85; H, 6.62; N, 5.11; S, 5.83. Found: C, 67.68; H, 6.67; N, 5.06; S, 5.76.
3.4. (2R)-N-[(2S)-2-Amino-4-pentin-1-oyl]bornane-10,2-sultam 3a
A vigorously magnetically stirred mixture of 2a (1.10 g, 2.32 mmol) in diethyl ether (30 ml) and
1 M hydrochloric acid (30 ml, 28.3 mmol) was left at room temperature for 10 h (TLC monitoring).
The two phases were separated, the aqueous layer was washed with diethyl ether (3×25 ml) to separate
benzophenone, then it was basified with potassium carbonate and extracted with ethyl acetate (3×30
ml). The combined ethyl acetate extracts were dried with anhydrous sodium sulfate and the solvent was
evaporated to give a solid residue which was recrystallized from diethyl ether, yielding 3a (0.60 g, 84%);
m.p. 153–154°C; [α]D20=−95.7 (c=1.5, CHCl3); IR (KBr, cm−1): 3393, 3286, 1701; 1H NMR (CDCl3):
0.95 (s, 3H), 1.14 (s, 3H), 1.25–1.48 (m, 2H), 1.72 (broad s, 2H), 1.81–1.97 (m, 3H), 2.00 (t, J=2.8 Hz,
1H), 2.02–2.08 (m, 2H), 2.62 (ddd, J=16.8 Hz, 5.8 Hz, 2.8 Hz, 1H), 2.71 (ddd, J=16.8 Hz, 5.8 Hz, 2.8
Hz, 1H), 3.41 (d, J=13.9 Hz, 1H), 3.49 (d, J=13.9 Hz, 1H), 3.89 (t, J=6.2 Hz, 1H), 4.16 (t, J=5.8 Hz,
1H); 13C NMR (CDCl3): 19.9, 20.6, 25.6, 26.5, 32.7, 38.1, 44.6, 47.8, 48.8, 53.0, 53.4, 65.1, 71.5, 79.0,