the antiperiplanar position, essentially as in the concerted
E2 elimination. Thus, the difference between E2 and
El in basic solvents may only be a matter of degree
of polarization of the bond between the leaving group
and the a-carbon.
A41though it is not possible completely to rule out
gegcnion free carbonium ions in each of the solvents,
it is clear that they do not play a major role in these
solvolytic eliminations. Streitwieser and Walsh' have
demonstrated that the solvolytic
tosylate by acetate group in the 2-octyl system occurs
with 100% inversion in glacial acetic acid.
resiilts are best accommodated
the idea that
these soholytic processes the fate of the carbonium
work was supported by the
U. S. Xrmy Research Office (Durham).
. and T 11. Walih,
The Cyclononatetraenyl Anion
The cyclononatetraenyl anion I should have a closed
shell configuration of 10
electrons and should be highly
That it should be aromatic is,
however, questionable for two reasons: (1) The energy
required to distort the angles of its bonds might be
excessively large? and (2) the nine-membered ring might
valence tautomerize3 spontaneously to form a single
bond at the expense of a double
cyclononatetraenyl anion does appear to be aromatic.
Its synthesis is the subject of this report.
Cold chloroform reacts with
in tetrahydrofuran (THF) to yield, after
(0.2 mm.), in
218 mp (log
Calcd. for CsH9C1: C.
H. j.94; C1,
Found: C, il.06; H,
Similarly, dichloromethyl methyl
ether reacts to yield 9-methoxybicyclo [6.1
(IIb) in 267'
yield; b.p. 54-56
Calcd. for CIoH110:
C,Sl.O9; H,S.11. Found: C,80.80; H,8.18. SIeth-
ylene chloride yields bicyclo [6.1
IIa was identified by its ultraviolet spectrum and by
its n.in.r. spectrum. The latter exhibited a multiplet
It- Huckel mulecular orbital delocalization energy is
(21 'The ccimpressiona! harrier i
huwever, overcome by its next lower
homolog. Lhr cyclr,,xtatetraenyI d nion IT. J Katz, W H Reinmuth, and
J. Am ('hem
and references therein]
J Am (hem.
(IOiil), and private c<,mmunicatim
at 4.1 (rel. int.
and a coupled
(rel. int. 1) and doublet a't 8.14
(rel. int. 2).
IIb exhibited a similar n.m.r. spectrum: a multiplet
at 4.2 (rel. int. Ci), a singlet at 6.70 (rel. int.
c.P.s.) triplet at
(rel. int. 1) and
doublet at 8.40
Only the anti isomers
appear to be found, in striking contrast to the forma-
tion of mixtures of comparable amounts of