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J. A. Valderrama et al.
LETTER
Torres, S.; Miret, J.; Ferreira, M. E. Tetrahedron 2001, 57,
8653.
(9) Ruiz, V. M.; Tapia, R.; Valderrama, J. A.; Vega, J. C. J.
Heterocycl. Chem. 1981, 18, 1161.
(13) The LUMO eigenvector coefficients were determined using
the semiempirical PM3 method implemented in the Spartan
package: Spartan version 5.1.3; Wavefunction Inc.: Irvine
CA, 1999.
(10) Cassis, R.; Valderrama, J. A. Synth. Commun. 1983, 13, 347.
(11) Synthesis of 3,3,6-Trimethyl-2H-3,4-dihydrophen-
anthridine-1,7,10-trione (5d); Typical Procedure. A
suspension of 2,5-dihydroxyacetophenone (1b; 152 mg, 1.0
mmol), 3-amino-5,5-dimethyl-2-cyclohexen-1-one (2b; 139
mg, 1.0 mmol), silver(I) oxide (464 mg, 2.0 mmol), MgSO4
(420 mg) and CH2Cl2 (20 mL) was vigorously stirred for 2 h
at r.t. The mixture was filtered and the filtrate was
(14) Valderrama, J. A.; Araya-Maturana, R.; González, F.; Tapia,
R.; Fariña, F.; Paredes, M. C. J. Chem. Soc., Perkin Trans. 1
1991, 555.
(15) Krohn, K. Tetrahedron Lett. 1980, 21, 3557.
(16) Synthesis of Benzo[j]phenanthridine-1,7,12-trione 7h;
Typical Procedure for Method B: A solution of 6d (105
mg, 0.25 mmol), HCl acid (3 drops, 5%) in aq THF (6 mL,
90%) was left at r.t. for 1 h. The mixture was diluted with
H2O (10 mL) and then extracted with CHCl3 (2 × 15 mL).
The organic layer was washed with H2O (2 × 10 mL), dried
over MgSO4, and evaporated under vacuum. The residue
was dissolved in CH2Cl2 (10 mL) and the solution was added
to a stirred solution of pyridinium chlorochromate (412 mg,
1.91 mmol), NaOAc (95 mg, 1.16 mmol) in CH2Cl2 (10 mL),
and the mixture was stirred for 1.5 h at r.t. The resulting
mixture was chromatographed (silica; CH2Cl2–EtOAc, 9:1)
to give pure 7h (65.4 mg, 0.195 mmol, 78%) as an orange
solid; mp 166–167 °C (dec.); Rf 0.14 (silica; CH2Cl2–EtOAc,
9:1). IR (KBr): 3449 (w), 1708 (s), 1678 (s), 1636 (vs), 1571
(s), 1447 (s), 1367 (m), 1333 (s), 1283 (s), 1270 (s), 1243 (m)
cm–1. 1H NMR (400 MHz, CDCl3): d = 1.15 (s, 6 H), 2.77 (s,
2 H), 3.07 (s, 5 H), 7.28 (m, 1 H), 7.60 (m, 2 H), 12.30 (s, 1
H). 13C NMR (100 MHz, CDCl3): d = 27.33 (CH3), 28.80 (2
× CH3), 47.5 (CH2), 53.3 (CH2), 116.1 (C), 119.0 (CH),
124.5 (CH), 125.0 (C), 127.0 (C), 134.3 (C), 136.8 (CH),
144.4 (C), 162.0 (C), 164.5 (C), 166.0 (C), 183.6 (C), 189.0
(C), 197.0 (C). Anal. Calcd for C20H17NO4: C, 71.63; H,
5.11; N, 4.18. Found: C, 71.45; H, 4.94; N, 4.21.
evaporated under vacuum to give crude quinone 5d (214 mg,
0.8 mmol, 80%). Further column chromatography of the
crude product (silica; CH2Cl2–EtOAc, 9:1) yielded pure 5d
(175 mg, 0.65 mmol, 65%) as a yellow solid; mp 131–132
°C; Rf 0.49 (silica; CH2Cl2–EtOAc, 9:1). IR (KBr): 2969
(w), 1694 (s), 1668 (vs), 1610 (w), 1556 (s), 1469 (w), 1437
(w), 1391 (m), 1373 (m), 1359 (w), 1338 (s), 1311 (m), 1258
(s), 1225 (s), 1182 (w), 1155 (w), 1110 (m), 1052 (m) cm–1.
1H NMR (400 MHz, CDCl3): d = 1.15 (s, 6 H), 2.75 (s, 2 H),
2.97 (s, 3 H), 3.06 (s, 2 H), 6.86 (d, J = 10.3 Hz, 1 H), 7.05
(d, J = 10.3 Hz, 1 H). 13C NMR (100 MHz, CDCl3): d =
26.22 (CH3), 28.73 (2 × CH3), 33.51 (C), 47.47 (CH2), 53.28
(CH2), 123.57 (C), 126.08 (C), 138.09 (CH), 138.48 (CH),
141.57 (C), 163.53 (C), 165.66 (C), 184.78 (C), 184.91 (C),
196.96 (C). Anal. Calcd for C16H15NO3: C, 71.36; H, 5.61;
N, 5.20. Found: C, 71.22; H, 5.50; N, 5.19.
(12) (a) Flemming, I. Frontier Orbitals and Organic Chemical
Reactions; Wiley: New York, 1976. (b) Rozeboom, M. D.;
Tegmo-Larsson, I.-M.; Houk, K. N. J. Org. Chem. 1981, 46,
2338.
Synlett 2006, No. 17, 2777–2780 © Thieme Stuttgart · New York