STEREOCONTROLLED FUNCTIONALIZATION OF CYCLOHEXENE USING ORGANOMOLYBDENUM CHEMISTRY

Article abstract of DOI:10.1016/S0040-4039(01)91061-5

Cyclohexadiene-Mo(CO)2Cp cations react stereospecifically with stabilised enolate nucleophiles to give ?-allyl complexes wich are converted to substituted allylic iodides on treatment with iodine.

Full text of DOI:10.1016/S0040-4039(01)91061-5

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STEREOCONTROLLED FUNCTIONALIZATION OF CYCLOHEXENE
USING ORGANOMOLYBDENUM CHEMISTRY
Anthony
Pearson* and Md. Nazrul I. Khan
Department of Chemistry, Case Western Reserve University
Cleveland, OH 44106, U.S.A.
cations react stereospecifically with stabilised enolate
complexes which are converted to substituted allylic
iodides on treatment with iodine.
Abstract.
nucleophiles to give
Attachment of a transition metal moiety to an olefinic ligand results in activation of
the olefin toward nucleophilic attack, thereby providing methods for carbon-carbon bond for-
1
mation which complement those already available to the synthetic organic chemist.
In cases
where the metal remains attached to the ligand after bond formation (i.e., non-catalytic
reactions) it is possible to utilize the metal moiety to effect further transformations,
whose regio- and stereochemical outcome is controlled. In this respect, we have already
described efficient vicinal stereocontrol using cyclohexadienyliron cations‘ and
3
Faller's group have
and Sweigart has
control
demonstrated 1,3-stereocontrol using
reported on arenemanganese and derived complexes.
seven-membered ring using cycloheptadienyliron complexes.
5
For organic synthesis purposes the cylohexadiene-molybdenum complexes, readily prepared
from cyclohexene as outlined in Scheme 1, have considerable potential, offering
zation modes complementary to e.g., dienyliron complexes. The major problem is the manipula-
tion of
complexes, such as
The
resulting from nucleophile addition.
replacement of CO by NO+ previously described
not useful when sensitive functional groups are present,
tionalization in the ring.
provides one answer to this problem, but is
nor does it allow controlled
We recently described6 an iodolactonisation procedure, allowing
conversion of
investigated the reaction of these types of complex with iodine,
allylic iodies,
complexes 3 directly to
4. We have further
resulting in conversion to
and these results are reported in the present communication.
Complexes 5(a)-5(d) and
with enolate nucleophiles (e.g.,
were prepared by the reaction of the known4
diene complexes
and
to give
and complex
All of these reactions
was prepared by reaction of
proceed in high yield
with p-methoxyphenylmagnesium bromide.
and the reactions with methyl-substituted complex
were
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