Biomedical Engineering Reference
In-Depth Information
R
2
[M]
[M]
R
1
n
n
R
2
R
2
R
1
M
Enyne
cross-
metathesis
Enyne
ring-closing
metathesis
M
M
M
n
R
2
n
R
2
R
1
M
n
M
SCHEME 5.2
Catalytic cycles for the enyne cross-metathesis and ring-closing metathesis.
[M]
R
R
n
R
n
R
R
M
M
Alkyne
ring-closing
metathesis
M
M
n
R
R
n
R
R
n
n
R
R
R
R
M
n
R
SCHEME 5.3
Catalytic cycle for the alkyne ring-closing metathesis.
R
2
R
[M]
R
R
1
R
1
R
1
R
R
R
1
Alkyne
cross-
metathesis
M
M
M
M
R
2
R
2
R
1
R
1
R
R
R
R
R
M
R
R
R
2
R
1
SCHEME 5.4
Catalytic cycle for the alkyne cross-metathesis.
5.2. RING-CLOSING OLEFIN METATHESIS
Cyclic framework is a prevalent structural motif found in a diverse array of natural and
designed bioactive compounds. As such, with the advent of the metathesis technology
in carbon-carbon bond constructions, this powerful synthetic transformation rapidly
elevated and cemented its position as an indispensable tool for the assembly of cyclic
motifs, namely, the venerable ring-closing metathesis reaction. Indeed, a cursory
literature survey immediately revealed ring-closing olefin metathesis as the most
widely used form of the metathesis reaction. The selected examples presented in this
section highlight the key concepts and recent advances in this vast and rapidly
expanding field of ring-closing olefin metathesis [10].
Inspired by the pentacyclic core structure of the potent antiangiogenic natural
product (
รพ
)-cortistatin A [11], Gung and Craft devised a strategy based on an
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