Biomedical Engineering Reference
In-Depth Information
N
2
Rh
2
(Oct)
4
(0.5 mol%)
Hexane, 4 Å MS
O
O
O
O
+
O
TBDPSO
TBDPSO
O
60%
H
H
OTBDPS
366
367
368
steps
O
+
O
O
O
O
O
OTBDPS
OTBDPS
Indicol
371
369
370
SCHEME 9.64
Chiu and Lam's synthesis of (
)-indicol (
371
).
OPMP
OTBDMS
Rh
2
(OAc)
4
(5 mol%)
PhCF
3
, 100°C, 5 mi
n
73%
O
N
2
4
8
O
4
8
OTBDMS
OPMP
H
O
O
O
O
H
372
373
O
OPMP
MeO
H
4
H
8
steps
O
H
O
HO
O
O
R
O
OTBDMS
O
H
O
374
Polygalolide A (R = H,
375
)
Polygalolide B (R = OMe,
376
)
SCHEME 9.65
Synthesis of polygalolides A
375
and B
376
by Hashimoto and coworkers.
then underwent an intramolecular 1,3-dipolar cycloaddition to form the desired furan
374
as a single isomer in 73% yield. Compound
374
was then carried through to
polygalolides A (
375
) and B (
376
) in 25 steps and 3.8% and 3.2% overall yields,
respectively.
9.7.3. Ruthenium-Catalyzed Domino Reactions
Applying Metatheses
The natural product (
) belongs to a class of diterpenoids
possessing a 7/6/5-ring system, also labeled as a reduced cyclohepta[
e
]indene.
This family of compounds possesses a broad range of biological activities from
inhibition of tuberculosis bacterium (
M. tuberculosis
, MTB) to nerve growth factor
stimulation. Although they have been isolated from fungal and marine sources,
þ
)-cyanthiwigin U (
383
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