cmϪ1 3057, 1643, 1608, 1585, 1455, 1411, 1378, 1348, 1330,
1271, 1116 and 1106; δH (500 MHz; CDCl3) 12.45 (1 H, br s,
Ar-OH), 7.63 (1 H, br tapp, J ca. 8.0, H-7), 7.54 (2 H, dd, J 0.8
and 8.4, H-4Ј, H-5Ј), 7.47 (2 H, dd, J 7.5 and 8.4, H-3Ј, H-6Ј),
7.46 (1 H, dd, J 1.1 and 7.6, H-8), 7.11 (1 H, dd, J 1.1 and 8.5,
H-6), 6.98 (2 H, dd, J 0.8 and 7.5, H-2Ј, H-7Ј), 2.85 (2 H, t,
J 6.5, CH2-3), 2.50 (2 H, t, J 6.5, CH2-2); δC (125 MHz; CDCl3)
203.2 (C-4), 162.4 (C-5), 147.4 (C-1Ј, C-8Ј), 140.9 (C-8a), 137.2
(C-7), 134.2 (C-4aЈ), 127.5 (C-3Ј, C-6Ј), 120.9 (C-4Ј, C-5Ј),
119.6 (C-8), 116.7 (C-6), 115.4 (C-4a), 113.3 (C-8aЈ), 109.4
(C-2Ј, C-7Ј), 98.4 (C-1), 34.1 (C-3), 29.4 (C-2); m/z (CI) 319
(MHϩ, 100%) [HRMS (CI): calcd. for C20H15O4, 319.09703.
Found: MHϩ, 319.09723 (0.6 ppm error)].
(50 mg, 100%) as a white solid, mp >260 ЊC (decomp.); Rf 0.63
(DCM–EtOAc, 4:1); νmax (deposited)/cmϪ1 3573, 3444, 3057,
2956, 2937, 2839, 1607, 1594, 1411, 1380, 1328, 1272, 1061, 958,
820, 756 and 733; δH (500 MHz; CDCl3) 7.56 (1 H, br d, J 7.8,
H-8), 7.52 (2 H, dd, J 0.9 and 8.4, H-4Ј, H-5Ј), 7.46 (2 H, br tapp
,
J ca. 8.0, H-3Ј, H-6Ј), 7.44 (1 H, dd, J 7.8 and 8.2, H-7), 7.02
(1 H, br d, J 8.2, H-6), 6.98 (1 H, br d, J 7.4, H-2Ј or H-7Ј), 6.92
(1 H, br d, J 7.4, H-2Ј or H-7Ј), 5.20 (1 H, t, J 4.4, H-4), 3.96
(3 H, s, OMe), 3.10 (1 H, br s, OH), 2.36 (1 H, ddd, J 2.4, 11.3
and 13.9, H-2), 2.28–2.23 (1 H, m, H-2), 2.23–2.16 (1 H, m,
H-3), 2.08–2.04 (1 H, m, H-3); δC (125 MHz; CDCl3) 157.0
(C-5), 148.1 (C-1Ј or C-8Ј), 147.8 (C-1Ј or C-8Ј), 136.1 (C-8a),
134.1 (C-4aЈ), 129.3 (C-7), 127.8 (C-4a), 127.3 (C-3Ј or C-6Ј),
127.2 (C-3Ј or C-6Ј), 120.3 (C-4Ј or C-5Ј), 120.2 (C-4Ј or C-5Ј),
119.3 (C-8), 113.5 (C-8aЈ), 111.2 (C-6), 109.3 (C-2Ј or C-7Ј),
109.1 (C-2Ј or C-7Ј), 99.9 (C-1), 62.6 (C-4), 55.7 (OMe), 26.3
(C-3), 25.8 (C-2); m/z (EI) 334 (Mϩ, 20%), 316 (100) [HRMS
(EI): calcd. for C21H18O4, 334.12051. Found: Mϩ, 334.12030
(0.6 ppm error)].
Palmarumycin CP1 (5-hydroxyspiro[naphthalene-1(4H),2Ј-
naphtho[1,8-de][1,3]dioxin]-4-one) (5) and 3-bromo-5-hydroxy-
spiro[naphthalene-1(4H),2Ј-naphtho[1,8-de][1,3]dioxin]-4-one
(36)
This reaction was carried out as described for the preparation
of compound 6. Starting with 35 (40 mg, 0.12 mmol) the reac-
tion gave a mixture of two products which were separated by
preparative TLC (DCM). The more polar fraction afforded
palmarumycin CP1 (5) (22 mg, 58%) as a yellow solid, mp
170 ЊC (decomp.) [lit.,3a mp 170 ЊC (decomp.)]; Rf 0.63 (EtOAc–
PE, 4:6), 0.60 (DCM); λmax(DCM)/nm 288 (ε/dm3 molϪ1 cmϪ1
8452), 296 (8770), 312 (5902), 330 (5781) and 362 (4742); νmax
(deposited)/cmϪ1 3059, 1662, 1608, 1456, 1412, 1378, 1346,
1268, 1239, 1114, 1075 and 944; δH (500 MHz; CDCl3) 12.17
(1 H, br s, Ar-OH), 7.67 (1 H, br tapp, J ca. 8.0, H-7), 7.59 (2 H,
dd, J 0.5 and 8.4, H-4Ј, H-5Ј), 7.48 (2 H, br tapp, J ca. 8.0, H-3Ј,
H-6Ј), 7.47 (1 H, br d, J 7.5, H-8), 7.15 (1 H, dd, J 0.9 and 8.4,
H-6), 7.03 (1 H, d, J 10.5, H-2), 6.99 (2 H, dd, J 0.5 and 7.6,
H-2Ј, H-7Ј), 6.37 (1 H, d, J 10.5, H-3); δC (125 MHz; CDCl3)
188.7 (C-4), 161.8 (C-5), 147.2 (C-1Ј, C-8Ј), 139.7 (C-2), 138.8
(C-8a), 136.6 (C-7), 134.1 (C-4aЈ), 129.7 (C-3), 127.6 (C-3Ј,
C-6Ј), 121.3 (C-4Ј, C-5Ј), 119.7 (C-8), 119.3 (C-6), 113.8 (C-4a),
113.0 (C-8aЈ), 109.9 (C-2Ј, C-7Ј), 92.8 (C-1); m/z (EI) 316 (Mϩ,
100%), 288 (Mϩ Ϫ CO, 20) and 287 (Mϩ Ϫ CHO, 25) [HRMS
(EI): calcd. for C20H12O4, 316.07356. Found: Mϩ, 316.07390
(1.1 ppm error)].
The less polar fraction afforded the bromide 36 (4 mg, 8%) as
a yellow powder, mp 179–180 ЊC (decomp.); Rf 0.80 (DCM);
λmax(DCM)/nm 258 (ε/dm3 molϪ1 cmϪ1 4498), 286 sh (5730), 299
(6194), 314 (4416), 328 (3459) and 370 (3184); νmax (deposited)/
cmϪ1 3059, 2924, 2850, 1651, 1609, 1584, 1455, 1411, 1379,
1347, 1271, 1228, 1169, 1068, 941 and 898; δH (500 MHz;
CDCl3) 11.90 (1 H, br s, Ar-OH), 7.70 (1 H, br tapp, J ca. 8.0, H-
7), 7.62 (2 H, dd, J 1.0 and 8.4, H-4Ј, H-5Ј), 7.51 (2 H, dd, J 7.6
and 8.4, H-3Ј, H-6Ј), 7.47 (1 H, dd, J 1.0 and 7.6, H-8), 7.44
(1 H, s, H-2), 7.19 (1 H, dd, J 1.0 and 8.4, H-6), 7.01 (2 H, br d,
J 7.6, H-2Ј, H-7Ј); δC (125 MHz; CDCl3) 181.9 (C-4), 162.1
(C-5), 146.7 (C-1Ј, C-8Ј), 140.0 (C-2), 138.5 (C-8a), 137.2 (C-7),
134.2 (C-4aЈ), 127.7 (C-3Ј, C-6Ј), 127.1 (C-3), 121.7 (C-4Ј,
C-5Ј), 120.0 (C-8), 119.7 (C-6), 112.8 (C-4a), 112.7 (C-8aЈ),
110.1 (C-2Ј, C-7Ј), 93.8 (C-1); m/z (CI) 397, 395 (MHϩ, 100%)
[HRMS (CI): calcd. for C20H13O479Br 394.99189. Found: MHϩ,
394.99277 (2.2 ppm error)].
CJ-12,371 (4,5-dihydroxy-1,2,3,4-tetrahydrospiro[naphthalene-
1(4H),2Ј-naphtho[1,8-de][1,3]dioxine]) (11)
Palmarumycin CP2 (6) (9 mg, 0.03 mmol) was dissolved in
methanol (2 mL) by gently warming the solution with an air
gun. Sodium borohydride (1 mg, 0.026 mmol) was added and
after 10 min TLC showed a clean and complete conversion.
EtOAc and water were added, the two layers were separated
and the organic phase washed with water and brine, and
dried (MgSO4). Evaporation of the solvent in vacuo yielded a
colourless oil. Purification though a microcolumn (EtOAc)
afforded the title compound (11) (9 mg, 100%) as a white solid,
mp >260 ЊC (decomp.) [lit.,4 mp >260 ЊC (decomp.)]; Rf 0.31
(PE–EtOAc, 6:4); νmax (deposited)/cmϪ1 3299, 3059, 3017,
2927, 2855, 1633, 1607, 1463, 1411, 1380, 1326, 1272, 1216,
1112, 1067, 1051, 1023, 957, 821, 794 and 756; δH (500 MHz;
DMSO-d6) 9.67 (1 H, br s, Ar-OH), 7.57 (1 H, br d, J 8.4, H-4Ј),
7.57 (1 H, br d, J 8.4, H-5Ј), 7.49 (1 H, br tapp, J ca. 8.0, H-3Ј),
7.47 (1 H, br tapp, J ca. 8.0, H-6Ј), 7.24 (1 H, dt, J 0.7 and 7.9, H-
7), 7.16 (1 H, br d, J 7.9, H-8), 6.99 (1 H, br d, J 7.4, H-2Ј), 6.93
(1 H, br d, J 7.9, H-6), 6.92 (1 H, br d, J 7.4, H-7Ј), 5.12 (1 H, br
d, J 4.5, 4-OH), 4.98 (1 H, br q, J 4.0, H-4), 2.26–2.21 (1 H, m,
H-2), 2.01–1.95 (2 H, m, H-2, H-3), 1.84–1.79 (1 H, m, H-3);
δC (125 MHz; DMSO-d6) 155.4 (C-5), 147.8 (C-8Ј), 147.5
(C-1Ј), 135.5 (C-8a), 133.7 (C-4aЈ), 128.5 (C-7), 127.7 (C-3Ј,
C-6Ј), 126.4 (C-4a), 120.2 (C-4Ј, C-5Ј), 117.4 (C-8), 116.1 (C-6),
113.0 (C-8aЈ), 109.14 (C-2Ј), 109.12 (C-7Ј), 100.0 (C-1), 60.9
(C-4), 27.7 (C-3), 25.3 (C-2); m/z (EI) 320 (Mϩ, 5%), 302 (100)
[HRMS (EI): calcd. for C20H16O4, 320.10486. Found: Mϩ,
320.10509 (0.7 ppm error)].
Palmarumycin C2 (2,3-epoxy-2,3-dihydro-5-hydroxyspiro-
[naphthalene-1(4H),2Ј-naphtho[1,8-de][1,3]dioxin]-4-one)
(deoxypreussomerin A, 3)
A solution of enone 5 (90 mg, 0.28 mmol) and 1,5,7-triaza-
bicyclo[4.4.0]dec-5-ene (21 mg, 0.15 mmol) in toluene (2 mL)
under nitrogen was cooled to 0 ЊC. tBHP in toluene (2.65 M,
0.53 mL, 1.4 mmol) was slowly added over 5 min and the mix-
ture was left under stirring for 2 h at RT. The reaction was
quenched by addition of a saturated solution of Na2SO3
(1 mL), and then EtOAc (15 mL) and brine (5 mL) were added,
and the two layers were separated. The aqueous phase was
extracted twice with EtOAc, and the organic layers were com-
bined and dried (MgSO4). Evaporation of the solvents followed
by column chromatography (DCM) and then preparative TLC
(DCM) gave palmarumycin C2 (3) (50 mg, 53%) as a pale yellow
solid, mp 225–228 ЊC (decomp.) [lit.,3b mp 228 ЊC (decomp.)]; Rf
0.60 (DCM); λmax (CHCl3)/nm 283 (ε/dm3 molϪ1 cmϪ1 14265),
300 (13529), 314 (12206) and 329 (12647); νmax (deposited)/cmϪ1
1654, 1608, 1456, 1412, 1379, 1268, 1239, 1180, 1113, 1065,
5-Methoxy-1,2,3,4-tetrahydrospiro[naphthalene-1,2Ј-naphtho-
[1,8-de][1,3]dioxin]-4-ol (37)
Ketone 34 (50 mg, 0.15 mmol) was dissolved in methanol (2
mL) by gently warming the solution with an air gun. Sodium
borohydride (3 mg, 0.08 mmol) was added to the gold yellow
solution which turned pale yellow after 10 min. TLC showed a
clean and complete conversion. EtOAc and water were added,
the two layers were separated and the organic phase washed
with water and brine, and dried (MgSO4). Evaporation of the
solvent in vacuo yielded a colourless oil. Column chromato-
graphy (DCM–EtOAc, 8:2) afforded the title compound 37
J. Chem. Soc., Perkin Trans. 1, 1999, 1073–1082
1079