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E. Perez-Sacau et al. / Tetrahedron 61 (2005) 437–445
443
H-140), 1.37 (18H, m, H-50CH-60CH-70CH-80CH-90C
H-100CH-110CH-120CH-130), 1.01 (s, 3H, H-20). 13C
NMR (C6D6) d: 196.9 (s, C-10), 171.5 (s, C-5), 164.3 (s, C-
10), 153.5 (s, C-15a), 150.2 (s, C-16b), 149.5 (s, C-11a),
148.9 (s, C-10a), 139.4 (s, C-16a), 133.8 (d, C-3), 132.6 (d,
C-2), 132.4 (s, C-4a), 131.2 (d, C-4), 128.5 (d, C-1), 84.8 (s,
C-7), 72.8 (d, C-8), 42.5 (t, C-40), 34.0 (t), 32.0!2 (t), 31.9
(t), 31.3 (t), 29.9 (t),029.7 (t), 29.6 (t), 29.5 (t), 29.3!2 (t),
24.9 (t), 23.8 (q, C-1 ), 22.5 (t), 22.2 (t), 18.6 (q, C-20), 14.1
(q, C-140). MS m/z (rel. int): 549 (MCC1, 41), 349 (MCC
1-OCO(CH2)10CH3, 23), 253 (349-CO(CH2)2C(Me)2, 7), 69
(100). HRMS: 549.3341 (calcd for C33H45N2O5 (MCC1)
549.3328).
JZ5.8 Hz, OH), 1.62 (3H, s, H-10), 1.51 (3H, s, H-20). 13C
NMR (CDCl3) d: 196.7 (s, C-10), 175.4 (s, C-5), 150.6 (s,
C-14a), 150.6 (s, C-4a), 144.7 (d, C-3), 140.9 (d, C-2), 134.6
(s, C-14b), 132.9!2 (d, C-12CC-13), 131.0 (d, C-11),
129.3 (s, C-10a), 129.1 (d, C-14), 86.6 (s, C-8), 74.1 (d,
C-7), 44.6 (t, C-6), 24.4 (q, C-10), 24.1 (q, C-20). Minor
1
conformer: H NMR (CDCl3) d: 8.77 (d, JZ2.3 Hz, 1H,
H-2), 8.51 (m, 1H, H-3), 8.03 (m, 1H, H-11), 7.67 (m, 1H,
H-14), 7.52 (m, 2H, H-12, 13), 4.50 (m, 1H, H-7), 4.04
(m, 1H, H-6a), 2.89 (dd, JZ12.9, 4.6 Hz, 1H, H-6b), 2.36
(bd, JZ4.1 Hz, 1H, OH), 1.70 (s, 3H, H-10), 1.16 (s, 3H,
H-20). MS m/z (rel. int): 312 (MC, 1), 297 (MCKMe, 2),
199 (MCKCOCH2CH(OH)C(CH3)2, 65), 183 (199-16,
100). HRMS: 312.1128 (calcd for C17H16N2O4 (MC)
312.1110).
3.3.7. 7-(1-Hydroxy-1-methylethyl)-6, 7-dihydro[2]
benzoxonino[6,7-b]pyrazine-5,9-dione (31). 37 mg
(0.13 mmol) of 20 in 10 mL of dry CH2Cl2 were ozonized
following the general procedure described above. The crude
was quenched with 20 mL of dry Me2S and chromato-
graphed by preparative-TLC using Hex/EtOAc (1:4) as
3.3.10. 5-(2, 3-Dihydroxy-3-methylbutyl)-5-hydroxy ben-
zo[ f]quinoxalin-6(5H)-one (36). 1H NMR (CDCl3) d: 8.57
(1H, d, JZ2.3 Hz, H-3), 8.52 (1H, d, JZ2.3 Hz, H-2), 8.46
(1H, d, JZ7.5 Hz, H-10), 8.00 (1H, m,0H-7), 7.60 (2H, m,
H-8CH-9), 4.44 (1H, d, JZ5.5 Hz, H-2 ), 3.35 (1H, dd, JZ
14.2, 5.5 Hz, H-1a0), 2.94 (1H, d, JZ14.2 Hz, H-1b0), 1.51
(6H, s, H-100CH-40). 13C NMR (CDCl3) d: 199.8 (s, C-6),
152.7 (s, C-10b), 151.0 (s, C-4a), 144.0 (d, C-3), 143.5 (d,
C-2), 132.1 (s, C-10a), 131.1 (d, C-8 or 9), 130.9 (d, C-8 or
9), 129.0 (s, C-6a), 127.5 (d, C-10), 125.6 (d, C-7), 84.0 (d,
C-20), 82.2 (s, C-5), 69.9 (s, C-30), 38.8 (t, C-10), 27.3 (q,
C-40), 22.7 (q, C-100). MS m/z (rel. int): 314 (MC, 15), 299
(MCKMe, 21), 221 (MCK93, 100). HRMS: 314.1285
(calcd for C17H18N2O4 (MC) 314.1267).
1
eluent, to obtain 28 mg (70%) of 31. H NMR (CDCl3) d:
8.74 (1H, d, JZ2.4 Hz, H-2), 8.50 (1H, d, JZ2.4 Hz, H-3),
8.19 (1H, bs, H-13), 7.92 (1H, d, JZ7.8 Hz, H-10), 7.72
(1H, m, H-12), 7.56 (1H, m, H-11), 5.53 (1H, bs, H-7), 2.86
(1H, bs, H-6a), 1.87 (1H, bs, H-6b), 1.15 (3H, s, H-10), 1.13
(3H, s, H-20). MS m/z (rel. int): 312 (MC, 1), 297 (MCK
Me, 5), 254 (MCKMe–CO2, 54), 183 (254-
CHCOH(CH3)2, 100). HRMS: 297.0863 (calcd for C16H13
N2O4 (MCKMe) 297.0875).
3.3.8. 8,8-Dimethyl-7,8-dihydro-6H-[2]benzoxecino [7,8-
b]pyrazine-5,10-dione (32). 58 mg (0.21 mmol) of 21 in
10 mL of dry CH2Cl2 were ozonized following the general
procedure described above. The crude was quenched with
27 mL of dry Me2S and chromatographed by preparative-
TLC using Hex/EtOAc (3:2) as eluent, to obtain 38 mg
3.3.11. 7-Bromo-8,8-dimethyl-7,8-dihydro-6H-[2] benz-
oxecino[7,8-b]pyrazine-5,10-dione
(34).
57 mg
(0.17 mmol) of 23 in 10 mL of dry CH2Cl2 were ozonized
following the general procedure described above. The crude
was quenched with 20 mL of dry Me2S and chromato-
graphed by preparative-TLC using Hex/EtOAc (7:3) as
1
(61%) of 32. H NMR (CDCl3) d: 8.70 (1H, m, H-2), 8.49
(1H, m, H-3), 8.04 (1H, m, H-11), 7.65 (1H, m, H-14), 7.51
(2H, m, H-12CH-13), 3.65 (1H, ddd, JZ14.5, 5.8, 4.1 Hz,
H-6a), 2.67 (1H, ddd, JZ16.5, 14.5, 3.9 Hz, H-6b), 2.18
(1H, ddd, JZ18.7, 4.1, 3.9 Hz, H-7b), 1.990 (1H, ddd, JZ
18.7, 16.5, 5.8 Hz, H-7a), 1.63 (3H, s, H-1 ), 1.39 (3H, s,
H-20). 13C NMR (CDCl3) d: 201.9 (s, C-5), 164.9 (s, C-10),
153.4 (s, C-14b), 151.6 (s, C-4a), 144.4 (d, C-2), 140.5 (d,
C-3), 137.9 (s, C-14a), 132.7!2 (d, C-12, 13), 130.8 (d,
C-11), 129.0 (d, C-14), 128.2 (s, C-10a), 84.4 (s, 0C-8), 38.3
(t, C-7), 36.3 (t, C-6), 26.9 (q, C-10), 23.7 (q, C-2 ). MS m/z
(rel. int): 296 (MC, 17), 268 (MCKCO, 9), 199 (MCK
CO–Me–NCH]CHN, 100). HRMS: 296.1164 (calcd for
C17H16N2O3 (MC) 296.1161).
1
eluent, to obtain 23 mg (37%) of 34. Major conformer: H
NMR (CDCl3) d: 8.74 (1H, m, H-2), 8.55 (1H, m, H-3), 8.10
(1H, d, JZ7.9 Hz, H-11), 7.73 (1H, m, H-14), 7.51 (2H, m,
H-12CH-13), 4.30 (1H, dd, JZ12.5, 4.0 Hz, H-7), 4.08
(1H, dd, JZ14.3, 4.0 Hz, H-6b), 3.13 (1H, dd, JZ14.3,
12.5 Hz, H-6b), 1.76 (3H, s, H-10), 1.66 (3H, s, H-20). 13C
NMR (CDCl3) d: 196.8 (s, C-5), 163.9 (s, C-10), 153.5 (s,
C-14b), 151.1 (s, C-4a), 144.8 (d, C-2), 141.0 (d, C-3), 137.7
(s, C-14a), 133.1 (d, C-12), 132.9 (d, C-13), 131.4 (d, C-11),
129.1 (d, C-14), 127.6 (s, C-10a), 87.3 (d, C-8), 52.3 (d,
C-7), 47.1 (t, C-6), 25.3 (q, C-10), 18.3 (q, C-20). Minor
conformer: 1H NMR (CDCl3) d: 8.79 (m, 1H, H-2), 8.56 (m,
1H, H-3), 7.97 (d, JZ7.8 Hz, 1H, H-11), 7.73 (m, 1H,
H-14), 7.51 (m, 2H, H-12CH-13), 5.25 (dd, JZ12.6,
4.6 Hz, 1H, H-7), 4.47 (dd, JZ12.6, 12.1 Hz, 1H, H-6a),
3.06 (dd, JZ12.1, 4.6 Hz, 1H, H-6b), 1.87 (s, 3H, H-10),
1.13 (s, 3H, H-10). 13C NMR (CDCl3) d: 197.7 (s, C-5),
163.8 (s, C-10), 153.5 (s, C-14b), 151.1 (s, C-4a), 145.5 (d,
C-2), 140.7 (d, C-3), 137.7 (s, C-14a), 133.0 (d, C-12), 132.9
(d, C-13), 131.1 (d, C-11), 129.5 (d, C-14), 119.9 (s, C-10a),
86.4 (d, C-8), 51.4 (d, C-7), 44.5 (t, C-6), 26.8 (q, C-10), 21.6
(q, C-20). MS m/z (rel. int): 376 (MCC2, 0.4), 374 (MC,
0.4), 295 (MCKBr, 7), 199 (MCKCO(CH2)-
CH(Br)C(Me)2, 100). HRMS: 374.0350 (calcd for
C17H15N2O3Br79 (MC) 374.0266).
3.3.9. 7-Hydroxy-8,8-dimethyl-7,8-dihydro-6H-[2] benz-
oxecino[7,8-b]pyrazine-5, 10-dione (33). 21 mg
(0.08 mmol) of 22 in 10 mL of dry CH2Cl2 were ozonized
following the general procedure described above. The crude
was quenched with 10 mL of dry Me2S and chromato-
graphed by preparative-TLC using Hex/EtOAc (7:3) as
eluent, to obtain 16 mg (68%) of 33 and 5 mg (21%) of 36.
1
Major conformer: H NMR (CDCl3) d: 8.77 (1H, d, JZ
2.3 Hz, H-2), 8.51 (1H, d, JZ2.3 Hz, H-3), 8.05 (1H, d, JZ
7.8 Hz, H-11), 7.67 (1H, m, H-14), 7.52 (2H, m, H-12C
H-13), 4.12 (1H, m, H-7), 3.90 (1H, dd, JZ13.9, 4.4 Hz,
H-6a), 2.79 (1H, dd, JZ13.9, 10.3 Hz, H-6b), 2.26 (1H, bd,