J.H. Yang et al. / Chinese Chemical Letters 23 (2012) 1375–1377
1377
relatively high yield (10.4%) by treatment of 4-hydroxybenzaldehyde 5 with isoprenyl bromide (4 equiv.) and
potassium hydroxide (4 equiv.) in water. It is worthy to note that 4-hydroxy-3,5-di-(3-methylbut-2-enyl)-
benzaldehyde 6 could not be separated from the mixture by direct silica gel column chromatography because of
having the same polarity with an another product. It was get by a two-step sequence: (1) the mixture was separated
from the reaction residue by Si gel column chromatography eluting with petroleum ether-EtOAc (10:1); (2) pure
product 6 was obtained by crystallizing with petroleum ether at 0 8C for 24 h in 10.4% yield based on unrecovered
starting material as a white solid.
In summary, we have synthesized (ꢀ)-abyssinone-VI-4-O-methyl ether 1, (ꢀ)-abyssinone-IV-40-O-methyl ether 2,
(ꢀ)-abyssinone-V-40-O-methyl ether 3 and (ꢀ)-sigmoidin E 4 for the first time [15]. 4-Hydroxy-3,5-di-(3-methylbut-
2-enyl)benzaldehyde was also synthesized for the first time, which would be a useful intermediate for synthesis of
diprenylated flavonoids.
Acknowledgments
This work was financially supported by the National Natural Science Foundation (Nos. 21162021, 20962016),
Ningxia Natural Science Foundation (No. NZ1006), Program for New Century Excellent Talents in University (No.
NCET-09-0860) and the National Basic Research Program 973 of China (No. 2010CB534916).
References
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[15] Spectral data of (ꢀ)-abyssinone-VI-4-O-methyl ether: yellow powder, mp 90–93 8C; IR (KBr): 3300, 2968, 2920, 1633, 1570, 1365, 1265,
1130 cmꢁ1 1H NMR (CDCl3, 400 MHz): (13.47 (s, 1H, OH), 7.84 (d, 1H, J = 8.8 Hz, H-60), 7.82 (d, 1H, J = 16 Hz, H-b), 7.43 (d, 1H,
;
J = 15.6 Hz, H-a), 7.32 (s, 2H, H-2 and 6), 6.45 (dd, 1H, J = 2.4, 8.8 Hz, H-50), 6.43 (d, 1H, J = 2.4 Hz, H-30), 5.30 (m, 2H, H-200 and 2000), 3.77
(s, 3H, OCH3), 3.39 (d, 4H, J = 7.2 Hz, H-100 and 1000), 1.77 (12H, s, H-400, 4000, 500 and 5000); EIMS m/z [M+] 406 (31.73), 391 (3.93), 375 (7.47),
43 (100.00). HREIMS m/z [M+] 406.2136 (calcd. for C26H30O4 406.2144). Spectral data of (ꢀ)-abyssinone-IV-40-O-methyl ether: white
+
powder, mp 72ꢁ73 8C; IR (KBr): 3200 (br, OH), 2970, 2920, 1650, 1600, 1460, 1370, 1270, 1125 cmꢁ1; 1H NMR (CDCl3, 400 MHz): (7.85 (d,
1H, J = 8.4 Hz, H-5), 7.11 (s, 2H, H-20 and 60), 6.53 (dd, 1H, J = 2.4, 8.4 Hz, H-6), 6.45 (d, 1H, J = 2.4 Hz, H-8), 5.37 (dd, 1H, J = 2.8, 13.6 Hz,
H-2), 5.29 (m, 2H, H-200 and 2000), 5.20 (s, 1H, OH), 3.75 (s, 3H, OCH3), 3.39 (d, 4H, J = 6.8 Hz, H-100 and 1000), 3.04 (dd, 1H, J = 13.2, 16.8 Hz,
H-3ax), 2.79 (dd, 1H, J = 2.8, 16.8 Hz, H-3eq), 1.75 (s, 6H, H-400 and 4000), 1.73 (s, 6H, H-500 and 5000); EIMS m/z [M]+ 406 (59.42), 243 (55.74),
201 (40.55), 171 (52.00), 163 (38.85), 137 (100.00), 69 (93.14), 43 (50.26). HREIMS m/z [M+] 406.2140 (calcd. for C26H30O4+ 406.2144).
Spectral data of (ꢀ)-abyssinone-V-40-O-methyl ether: white solid, mp 146–147 8C; IR (KBr): 3360, 2970, 2920, 1680, 1605, 1580, 1435, 1370,
1260, 1210, 1145, 1065 cmꢁ1; 1H NMR (CDCl3, 400 MHz): (12.06 (s, 1H, OH), 7.09 (s, 2H, H-20 and 60), 5.99 (d, 1H, J = 2.0 Hz, ArH), 5.98
(d, 1H, J = 2.0 Hz, ArH), 5.33 (dd, 1H, J = 2.8, 13.2 Hz, H-2), 5.28 (m, 2H, H-200 and 2000), 3.75 (s, 3H, OCH3), 3.39 (d, 4H, J = 7.2 Hz, H-100
and 1000), 3.10 (dd, 1H, J = 13.2, 17.2 Hz, H-3ax), 2.78 (dd, 1H, J = 2.8, 17.2 Hz, H-3eq), 1.75 (s, 6H, H-400 and 4000), 1.73 (s, 6H, H-500 and 5000);
EIMS m/z [M]+ 422 (62.65), 391 (86.38), 243 (59.08), 179 (47.40), 153 (100.00). HREIMS m/z [M+] 422.2095 (calcd. for C26H30O5
+
422.2093). Spectral data of (ꢀ)-sigmoidin E: white solid, IR (KBr): 3200 (br, OH), 2970, 2920, 1635, 1594, 1500, 1460, 1340, 1265, 1150,
1080 cmꢁ1 1H NMR (CDCl3, 400 MHz): (12.07 (s, 1H, OH), 7.02 (d, 1H, J = 2.4 Hz, H-60), 6.92 (d, 1H, J = 2.0 Hz, H-20), 6.31 (d, 1H,
;
J = 9.6 Hz, H-400), 5.99 (d, 1H, J = 2.0 Hz, ArH), 5.98 (d, 1H, J = 2.0 Hz, ArH), 5.64 (d, 1H, J = 9.6 Hz, H-300), 5.29 (dd, 1H, J = 2.8, 13.2 Hz,
H-2), 5.26 (m, 1H, H-2000), 3.28 (d, 2H, J = 7.6 Hz, H-1000), 3.11 (dd, 1H, J = 13.2, 17.2 Hz, H-3ax), 2.76 (dd, 1H, J = 2.8, 17.2 Hz, H-3eq), 1.73
(s, 6H, H-400 and 500), 1.43 (s, 6H, H-500 and 600); EIMS m/z [M]+ 406 (18.26), 391 (100.00), 239 (17.60); HREIMS m/z [M+] 406.1781 (calcd. for
+
25H26O5 406.1780).
C