222
N. N. Win and H. Morita
O
O
19 kbar
CH 2 Cl 2
RT, 3 d
93%
O
O
O
O
methyl cinnamate
172 (panduratin H)
173 (panduratin I)
1:2.9
+
LiAlH 4 , THF
RT, 2 h
79%
OH
HO
+
DMP, CH 2 Cl 2
RT, 1 h
78%
O
i) nBuLi, MOM-bromobenzenes
THF, -78 °C;
ii) DMP, CH 2 Cl 2
RT, 2 h
O
MOMO
MOMO
R
HCl, MeOH
50°C, 2 h
O
OH
OH
R
179 (panduratin A) R = OMe
181 (4-hydroxypanduratin A) R = OH
179: 70%
181: 71%
R = OMe or OMOM
MOM:methoxymethyl ether
R
Br
MOMO
MOMO
Scheme 2 Synthesis of panduratins H (172), I (173), A (179), and 4-hydroxypanduratin A (181)
material (Scheme 5) [242]. Compound 222 was semi-synthesized from 6-butyryl5,7-dihydroxy-4-propylcoumarin (Scheme 6) [244], and further converted to 225
(Scheme 6) [244]. Compounds 223 and 224 were generated from 6-butyryl5,7-dihydroxy-4-phenylcoumarin (Scheme 7) [245]. The synthesis of additional
bioactive compounds from Myanmar medicinal plants is expected in the future.