10.1021/acs.joc.9b01083.s001
Jonas
J. Koenig
Jonas
J.
Koenig
Thiemo Arndt
Thiemo
Arndt
Nora Gildemeister
Nora
Gildemeister
Jörg-M. Neudörfl
Jörg-M.
Neudörfl
Martin Breugst
Martin
Breugst
Iodine-Catalyzed Nazarov
Cyclizations
American Chemical Society
2019
metal-free reaction conditions
apolar solvents
halogen bond
iodine-catalyzed reaction
side reaction
iodonium ion catalysis
pericyclic reaction
divinyl ketones
Iodine-Catalyzed Nazarov Cyclizations
Br ønsted acid
carbonyl group
Nazarov cyclization
catalyst
Nazarov system
2019-06-06 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Iodine-Catalyzed_Nazarov_Cyclizations/8264174
The Nazarov cyclization is an important
pericyclic reaction that
allows the synthesis of substituted cyclopentenones. We now demonstrate
that this reaction can be performed under very mild, metal-free reaction
conditions using molecular iodine as the catalyst. A variety of different
divinyl ketones including aromatic systems undergo the iodine-catalyzed
reaction with moderate to very good yields in both polar and apolar
solvents. Our mechanistic studies indicate that the Nazarov system
is activated through a halogen bond between the carbonyl group and
the catalyst, and other modes of action like Brønsted acid or
iodonium ion catalysis are unlikely. Furthermore, addition of iodine
to the double bond or a putative iodine-catalyzed <i>cis</i>–<i>trans</i> isomerization of the employed olefins
seem not to be an important side reaction here.