6
H.ꢀR. YAꢁꢂ ꢃT AL.
1
3
H), 7.92 (d, J = 8.0, 1 H), 7.74–7.66 (m, 2 H), 4.16 (d, J = 4.0, 1 H), 4.11 (d, J = 4.0, 1 H); C
NMR (100 MHz, CDCl ): δ 193.4 (C), 191.9 (C), 136.6 (C), 135.1 (CH), 131.6 (C), 129.6 (C),
3
1
29.5 (C), 129.1 (CH), 128.8 (CH), 128.6 (CH), 127.1 (CH), 122.0 (CH), 54.7 (CH), 54.7
(
CH); Under similar reaction condition, 8-methylphenanthrene-1,4-dione was converted
1
to 16a in 85% yield, mp 174–175 °C, H NMR (400 MHz, CDCl ): δ 8.71 (d, J = 8.6, 1 H),
3
8
.33 (d, J = 8.8, 1 H), 7.97 (d, J = 8.8, 1 H), 7.59–7.55 (m, 1 H), 7.48 (d, J = 8.8, 1 H), 4.14 (d,
1
3
J = 4.1, 1 H), 4.08 (d, J = 4.1, 1 H), 2.71 (s, 3H); C NMR (100 MHz, CDCl ): δ 193.6 (C),
3
1
1
92.0 (C), 135.9 (C), 134.9 (C), 131.1 (C), 131.0(CH), 129.9 (C), 129.8 (CH), 129.3 (CH),
29.2 (C), 125.3 (CH), 121.8 (CH), 54.8 (CH), 54.7 (CH), 19.7 (CH3).
3
.4. 1-Methylphenanthro[1,2-b]furan-10,11-dione (2) and tanshinone 1 (1)
To 4-methyl-7a,8a-dihydrophenanthro[2,3-b]oxirene-7,9-dione (0.0240 g, 0.1 mmol) in a
sealed tube, was added bromo-2-propanone (40 μl, 65 mg, 0.47 mmol), NH OAc (0.0121 g,
4
0
.15 mmol), and anhydrous toluene (5 ml). e mixture was heated to 120 °C for 10 h in
the dark. Af er cooling to rt, the reaction mixture was acidified with 1 N HCl (3 ml) and
extracted with CH Cl (3×20 ml). e combined organic solution was washed with brine,
2
2
dried over anhydrous Na SO , filtered and evaporated to give a solid residue. e residue
was further purified using chromatography developed by petroleum ether: CH Cl to afford
2
4
2
2
1
1
0 mg product (1) as orange powder (36% yield), mp 230–232 °C, H NMR (400 MHz,
CDCl ): δ 9.23 (d, J = 8.8 Hz, 1H), 8.27 (d, J = 8.6 Hz, 1H), 7.78 (d, J = 8.7 Hz, 1H), 7.55–7.51
3
13
(
m, 1H), 7.33 (d, J = 6.9 Hz, 1H), 7.29 (s, 1H), 2.67 (s, 3H), 2.28 (s, 3H); C NMR (100 MHz,
CDCl ): δ 183.5 (C), 175.6 (C), 161.2 (C), 142.0 (CH), 135.2 (C), 133.6 (C), 132.9 (C), 132.7
3
(
CH), 130.6 (CH), 129.6 (C), 128.3 (CH), 124.8 (CH), 123.1 (C), 121.8 (C), 120.5 (C), 118.7
+
(CH), 19.8 (CH ), 8.8 (CH ). ESI-MS: m/z 276.8 [M+H ].
3
3
rough the similar procedure, 8-demethyl tanshinone I (2) was prepared from phe-
nanthro[2,3-b]oxirene-7,9(7aH,8aH)-dione (0.0224 g, 0.1 mmol) in 34% yield. Orange
1
color solid, mp 227–229 °C, H NMR (400 MHz, CDCl ): δ 9.41 (d, J = 8.0, 1 H), 8.12 (d,
3
1
2
1
2
1
J = 12.0, 1 H), 7.82 (t, J = 8.0, J = 4.0, 2 H), 7.70 (t, J = 8.0, J = 8.0, 1 H), 7.53 (t, J = 8.0,
2
13
J = 4.0, 1 H), 7.32 (s, 1 H), 2.31 (s, 3 H); C NMR (100 MHz, CDCl ): δ 183.4 (C), 175.6
3
(
(
C), 161.2 (C), 142.1 (CH), 137.1 (CH), 134.4 (C), 132.4 (CH), 131.0 (C), 130.3 (C), 129.1
CH), 127.5 (CH), 126.6 (CH), 122.9 (C), 121.9 (C), 120.6 (C), 119.0 (CH), 8.8 (CH ).
3
+
ESI-MS: m/z 262.8 [M+H ].
Acknowledgments
We thank University of Science & Technology Beijing for financial support of this work.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
is research was financially supported by Beijing Science Nova Program [grant number 2008B20];
Fundamental Research Funds for the Central Universities [grant number FRF-BR-14-002A].