LETTER
Synthesis of Cryptopleurine and Boehmeriasin A
2253
R1
R1
R1
MeO
MeO
MeO
MeO
H
N
O
H
N
H
N
1. Pd/C, H2
KOH, EtOH
O
Cbz
2. DMAP, CH2Cl2,
11a for 7a or
11b for 7b
O
O
7a: R1= OMe, 93:7 er
7b: R1 = H, 95:5 er
MeO
R2
2a: R1 = OMe, R2 = H
53% yield for 3 steps, 95:5 er
2b: R1 = H, R2 = OMe
R2
3a: R1 = OMe, R2 = H
3b: R1 = H, R2 = OMe
53% yield for 3 steps, 92:8 er
R1
R1
MeO
MeO
Cl
H
N
H
N
Red-Al, dioxane
VOF3, TFAA
O
MeO
CH2Cl2, EtOAc
11a
MeO
Cl
MeO
R2
(R)-cryptopleurine (1a):
1 = OMe, R2 = H (80%)
(R)-boehmeriasin A (1b):
1 = H, R2 = OMe (92%)
R2
O
10a: R1 = OMe, R2 = H (95%)
10b: R1 = H, R2 = OMe (73%)
MeO
R
OMe
11b
R
Scheme 3 Synthesis of (R)-cryptopleurine and (R)-boehmeriasin A
Supporting Information for this article is available online at
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m
iotSrat
ungIifoop
r
t
References and Notes
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© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 2251–2254