Short-LiVed 1,5-Biradicals from Anthraquinones
J. Am. Chem. Soc., Vol. 119, No. 3, 1997 465
(m, 9H). 13C NMR (250 MHz, acetone-d
): δ 199.5, 169.8, 149.9,
1
a rotary evaporator and the residue (∼60% 5 by H NMR integration)
6
was separated using preparative HPLC. The major product was further
139.9, 139.4, 135.4, 132.4, 131.4, 130.8, 130.5, 130.3, 129.3, 128.0,
purified by recrystallization in methanol (53 mg, 22.5%). [1R-(1R,4â,-
125.6, 36.6, and 32.1. IR (KBr): 3300-2500, 1698, 1673, 1296, 1255,
-
1
13aâ)]-1,2,3,4-Tetrahydro-1-phenyl-6-(phenylmethyl)-9H-4,13b-epoxy-
930, 765, and 638 cm
-(1,1-Dimethylethyl)-9,10-anthracenedione (12). A solution of
-carboxy-2′-(1,1-dimethylethyl)benzophenone (500 mg, 1.89 mmol)
in 5.0 mL of concentrated H SO was heated at 70-75 °C for 1.5 h,
cooled, and poured over approximately 50 g of ice water. The mixture
was extracted with CH Cl
(3 × 20 mL) and the extracts were combined
and dried over CaCl After the solvent was removed in a rotary
evaporator under reduced pressure, the yellow residue was chromato-
graphed on silica gel. Elution with hexane-CH Cl (5:3) gave a single
.
1
anthra[1, 9-bc]oxocin-9-one (5). H NMR (500 MHz, CDCl
3
): δ 1.85
1
(
1
br dq, J ) 17.5 and 3.5 Hz, 1H), 2.08 (ddd, J ) 17.5, 13 and 5.5 Hz,
2
H), 2.24 (m, 2H), 3.25 (dd, J ) 13, and 3.5 Hz, 1H), 4.08 (s, 2H), 6.0
2
4
(
2
(
br d, J ) 7.0 Hz, 2H), 6.10 (t, 1H), 6.86 (dd, J ) 7.2 and 7.5 Hz,
H), 7.06 (dt, J ) 1.0 and 7.5 Hz, 1H), 7.19 (d, J ) 7.5 Hz, 1H), 7.21
m, 1H), 7.25 (m, 4H), 7.36 (dd, J ) 7.5 and 1.0 Hz, 1H), 7.41 (d, J
2
2
2
.
)
)
7.5 Hz, 1H), 7.66 (ddd, J ) 7.5, 7.0, and 1.0 Hz, 1H), 7.70 (dd, J
13
7.5 Hz and 1.0 Hz, 1H), and 7.94 (d, J ) 7.5 Hz, 1H). C NMR
): δ 181.77, 149.97, 143.12, 139.97, 137.64, 132.57,
2
2
(250 MHz, CDCl
3
yellow band which contained 368 mg (80%) of 12. An analytically
1
1
3
1
4
32.40, 131.52, 130.92, 130.01, 129.22, 128.90, 128.44, 127.97, 127.52,
27.43, 126.17, 125.73, 123.72, 121.79, 117.34, 96.18, 74.09, 56.97,
5.93, 32.87, and 22.20. IR (neat): 2922, 1672, 1588, 1441, 1302,
pure sample was obtained by recrystallization from heptane which gave
1
the desired AQ as yellow needles: mp 103-104 °C. H NMR (250
13
MHz, CDCl
MHz, CDCl
3
): δ 1.54 (s, 9H) and 7.59-8.26 (m, 7H). C NMR (250
): δ 188.3, 183.6, 153.6, 136.7, 136.0, 135.4, 134.1, 133.7,
-
1
283, 1246, 1125, and 1032 cm . HRMS (EI) calcd for C31
44.1725, found 444.1744.
24 3
H O
3
1
1
33.0, 132.5, 132.2, 126.9, 126.2, 126.0, 37.1, and 31.5. IR (KBr):
678, 1580, 1304, 1262, 964, 852, 808, and 710 cm . MS, m/e (rel
Crystal Structure of 5. X-ray crystallography was performed on
-
1
a 0.17 × 0.25 × 0.45 mm crystal with Mo KR radiation (λ ) 0.71073
Å) on a Rigaku MSC-AFC6S. Unit cell dimensions (triclinic, space
group P - 1h ,No. 2) are as follows: a ) 8.888(4) Å, b ) 18.204(5) Å,
c ) 7.888(4) Å, R ) 95.78(3)°, â ) 114.53(4)°, γ ) 96.39(3)°, V )
intensity) 264 (59), 247 (100), 231 (41), 222 (65), 202 (19), 165 (22),
52 (16), and 117 (14). Anal. Calcd for C18 : C, 81.79; H, 6.10.
Found: C, 82.08; H, 6.06.
1
16 2
H O
3
3
Irradiation of 12. A solution of 1-(1,1-dimethylethyl)-9,10-
anthracenedione (56 mg, 0.014 M) in methanol (15 mL) was deoxy-
genated with argon and irradiated for 3 h in a Rayonet (350 nm). HPLC
analysis of the reaction mixture indicated almost 60% conversion of
12. Three products were observed by HPLC, with one comprising the
major amount (∼85%). The solvent was removed under reduced
pressure to give a yellow oil, which was separated by preparative HPLC
1
138.5(8) Å , Z ) 2, D ) 1.297 g/cm . Data were collected at 293 K
using the θ-2θ scan technique. A total of 4299 reflections were
collected, of which 4017 were unique. The structure was solved by
the direct methods program SHELXS-86 with full-matrix least-squares
refinement on F (R ) 0.0478 and R ) 0.0962).
Irradiation of 1cp. A solution of 1-(cyclopropylmethoxy)-2-
methyl-9,10-anthraquinone (102 mg) in approximately 75 mL of HPLC
grade methanol and under argon was irradiated for 2 h in a Rayonet
24
2
w
9
(
eluent, methanol): 12 (21 mg) and 13 (25 mg, 77%) as a pale yellow
1
oil. H NMR (250 MHz, CDCl ): δ 1.6 (s, 6H), 7.15 (s, 1H), 7.5 (dd,
3
(350 nm). Workup provided 1-hydroxy-2-methyl-9,10-anthraquinone
(
68.5 mg, 82.4%) and cyclopropanecarboxaldehyde (16.2 mg, 68%):
J ) 7.6 and 7.4 Hz, 1H), 7.55 (dt, J ) 1.4 and 7.3 Hz, 1H), 7.6 (dtd,
J ) 8, 7.3, and 1.4 Hz, 1H), 7.7 (dt, J ) 1.46 and 7.65 Hz, 1H), 8.0
(dd, J ) 7.64 and 1.5 Hz, 1H), 8.1 (dd, J ) 7.66 and 0.6 Hz, 1H), and
1
H NMR (250 MHz, CDCl
3
) δ 0.9-1.0 (d, 4H), 1.9 (m, 1H), and 8.9
d, 1H). C NMR (250 MHz, CDCl ): δ 201.6, 22.6, and 7.3.
-Carboxy-2′-(1,1-dimethylethyl)benzophenone. To a mixture of
1
3
(
3
13
2
8.5 (dd, J ) 7.9 and 1.5 Hz, 1H). C NMR (250 MHz, CDCl ): δ
3
Mg (0.341 g, 14.0 mmol) and 10 mL of anhydrous ether under argon
179.77, 151.52, 144.25, 143.94, 132.49, 132.34, 131.30, 128.77, 128.42,
127.11, 126.82, 125.31, 124.78, 124.73, 123.65, 51.83, and 24.24. IR:
3059, 2963, 2926, 2861, 1652, 1599, 1581, 1462, 1300, 1262, 1159,
was added approximately one-third of a solution of 85% o-bromo-tert-
25
butylbenzene (1.99 g, 7.94 mmol) in 10 mL of anhydrous ether. Once
the reaction was initiated, the remaining bromide was added slowly to
maintain a steady reflux (20 min). After the addition, the reaction
mixture was heated at reflux for 30 min, cooled in an ice bath, and
added to a solution of freshly sublimed phthalic anhydride (1.40 g,
-
1
777, 748, and 702 cm . MS, m/e (rel intensity) 246 (75), 231 (100),
202 (55), and 101 (22). HRMS (EI) calcd for C18H14O 246.1045, found
246.1042.
9
.46 mmol) in 50 mL of anhydrous ether. A solid separated
Acknowledgment. We gratefully acknowledge the donors
of the Petroleum Research Fund, administered by the American
Chemical Society, for partial support of this research. R.P.S.
thanks the Camille and Henry Dreyfus Foundation for financial
support. R.L.B. thanks Calvin College for a Calvin Research
Fellowship. T.J.P. thanks HHMI for a Summer Research
Fellowship. Mass spectral data were obtained at the Michigan
State University Mass Spectrometry Facility which is supported,
in part, by a grant (DRR-00480) from the Biotechnology
Research Technology Program, National Center for Research
Resources, National Institutes of Health.
immediately and the reaction mixture was heated to reflux for 1.25 h.
Aqueous HCl (6.0 M, 25 mL), previously cooled in an ice bath, was
slowly added to the reaction mixture and the ether layer was separated.
The aqueous layer was extracted with 25 mL of ether. The ether
extracts were combined and washed with 90 mL of saturated aqueous
NaHCO
carded. The aqueous NaHCO
concentrated HCl resulting in the separation of the above acid as a
viscous liquid. The acid was extracted into CH Cl
(3 × 25 mL) and
isolated from the solution after drying (CaCl ) and removal of solvent
3
.
The ether layer containing isopropenylbenzene was dis-
3
extract was acidified with 25 mL of
2
2
2
under reduced pressure in a rotary evaporator. The residue (1.24 g)
solidified upon standing and was recrystallized from aqueous ethanol
giving 765 mg (34%) of the desired acid as colorless plates: mp 171-2
1
Supporting Information Available: Crystallographic sum-
mary for 5 including tables of crystal data and structure
refinement, bond lengths and angles, least-squares planes, atomic
coordinates, and stereoviews for 5 (12 pages). See any current
masthead for ordering and Internet access instructions.
°
C; H NMR (250 MHz, acetone-d
6
): δ 1.41 (s, 9H) and 7.24-7.77
(
24) Sheldrick, G. M. In Crystallographic Computing 3; Sheldrick, G.
M., Kruger, C., Goddard, R., Eds.; Oxford University Press: Cary, NC,
985; pp 175-189.
25) Approximately 15% isopropylbenzene is present using the method
of Olah et al. (Olah, G. A.; Lapierre, J. C.; Schreier, U. H. J. Org. Chem.
966, 31, 1268).
1
(
1
JA962633C