Heteroatom Chemistry
Volume 18, Number 4, 2007
N
ew Reaction of Pyridinium Ylide With
2
,4,6-Trinitrofluorobenzene Leading to Stable
Heptatrienide Moiety
Yuri G. Gololobov, Olesya A. Linchenko, Pavel V. Petrovskii,
Victor N. Khrustalev, and Irina A. Garbuzova
A.N. Nesmeyanov Institute of Organo-Element Compounds, Russian Academy of Science, 119991
M-334, Vavilov Str., 28, Moscow, Russia
Received 27 May 2006
It would be very interesting to expand the scope
ABSTRACT: A new reaction of pyridinium ylide
of the reaction to other types of zwitterions and other
(
4) with 2,4,6-trinitrofluorobenzene leading to sta-
electron-deficient fluoroarenes. In this work, we re-
port on a new reaction for other type of carbanions,
that is, pyridinium ylide derived from malonic ester
ble negatively charged heptatriene moiety (6) is de-
scribed. This reaction proceeds via a new route of
decomposition of intermediate σ-complex (5) oc-
curring with the formation of ethylfluoroformate.
ꢀ
C
4
4
with 2,4,6-trinitrofluorobenzene (TNFB) leading to
stable heptatrienide moiety 6.
2007 Wiley Periodicals, Inc. Heteroatom Chem 18:421–
24, 2007; Published online in Wiley InterScience
(
www.interscience.wiley.com). DOI 10.1002/hc.20315
RESULTS AND DISCUSSION
Nucleophilicity of pyridinium ylide 4 is just below
the nucleophilicity of zwitterion 2. This follows from
our observation that pyridinium ylide 4 reacts with
DNFB very slowly. We will discuss in details the
results of the latter reaction in the follow-up pub-
lication. Simultaneously, ylide 4 reacts with TNFB
INTRODUCTION
In a previous publication [1], we have described
an unusual aromatic nucleophilic substitution re-
action. Phosphorus-containing zwitterion 1 bearing
ethoxy and cyano groups at the carbanion center
forms, upon reaction with 2,4-dinitrofluorobenzene
in CDCl at room temperature very smoothly with
3
(DNFB), the first example of P-zwitterions 3 with a
the quantitative formation of an almost black pow-
der. The formation of ethylfluoroformate was estab-
negatively charged heptatriene moiety. This reaction
proceeds via a new route of decomposition of the
intermediate σ-complex 2 occurring with the forma-
tion of ethylfluoroformate (Scheme 1).
19
lished by the F NMR spectroscopy of the reaction
mixture. Most likely, similar to Scheme 1, at the first
stage of the reaction (Scheme 2), σ-complex 5 was
formed. At the second stage, the rupture of the weak
C C bond between the α-C atom and the C(O)OEt
moiety took place because the presence of second
C(O)OEt group and positively charged nitrogen
weakens the C C(O)OEt bond in the σ-complex 5.
The latter yielded ethylfluoroformate and a new type
of zwitterion (6).
Correspondence to: Yuri G. Gololobov; e-mail: Yugol
ineos.ac.ru.
@
Contract grant sponsor: Russian Foundation for Basic
Research.
Contract grant number: Project No. 04-03-32489.
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c 2007 Wiley Periodicals, Inc.
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