Reductive activation of arenes: XV. Anionic products of m-tolynitrile reduction with sodium in liquid ammonia, and their alkylation

Article abstract of DOI:10.1023/A:1020387003972

From results of oxidation, protonation, and alkylation of the products arising in one- or two-electron reduction of m-tolunitrile with sodium in liquid ammonia followed a conclusion that these products are respectively anion-radical of the compound and 3-methyl-1-cyano-2,5-cyclohexadienyl anion. The reaction of both reduction products with alkyl halides gives rise to compounds of ipso-alkylation with respect to cyano group: the corresponding alkyltoluenes and 1-alkyl-3-methyl-1-cyclohexadienes. The ratio of these products depends on the structure of alkyl halide. The possibility to prepare selectively m-alkyltoluenes by reaction of the product of two-electron reduction of m-tolunitrile with alkyl halides was demonstrated.

Full text of DOI:10.1023/A:1020387003972

Russian Journal of Organic Chemistry, Vol. 38, No. 6, 2002, pp. 823 829. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 6, 2002,
pp. 865 871.
Original Russian Text Copyright
,
2002 by Vaganova, Starokon , Shteingarts.
Reductive Activation of Arenes: XV.* Anionic Products
of m-Tolynitrile Reduction with Sodium in Liquid Ammonia,
and Their Alkylation**
T. A. Vaganova, E. V. Starokon,, and V. D. Shteingarts
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
Novosibirsk, 630090 Russia
Received November 21, 2001
Abstract From results of oxidation, protonation, and alkylation of the products arising in one- or two-
electron reduction of m-tolunitrile with sodium in liquid ammonia followed a conclusion that these products
are respectively anion-radical of the compound and 3-methyl-1-cyano-2,5-cyclohexadienyl anion. The
reaction of both reduction products with alkyl halides gives rise to compounds of ipso-alkylation with respect
to cyano group: the corresponding alkyltoluenes and 1-alkyl-3-methyl-1-cyclohexadienes. The ratio of these
products depends on the structure of alkyl halide. The possibility to prepare selectively m-alkyltoluenes by
reaction of the product of two-electron reduction of m-tolunitrile with alkyl halides was demonstrated.
Within the framework of systematic study on
reductive activation of functional arenes to reactions
with electrophilic agents we demonstrated formerly
that anionic products of one- and two-electron reduc-
tion of aromatic mononitriles produced by alkali
metal in the liquid ammonia react with primary alkyl
halides with replacement of the cyano group and/or
with ipso-addition disregarding the character of the
aromatic moiety (phenyl [2, 3], 1-naphthyl [3, 4],
9-anthracenyl [5, 6]). In the mechanistic study with
the use of model reagent of radical clock type we
established that all reduced forms of the above mono-
nitriles, anion-radicals, cyclodihydroaryl anions, and
in the latter case dianion, played in these processes
the role of nucleophiles. The introduction of an
additional electron-withdrawing substituent, the
second cyano group, into position 2 or 4 of benzo-
nitrile crucially changes the reaction mechanism and
related thereto alkylating orientation. In reactions of
anion-radicals formed from terephthalonitrile and
phthalonitrile with alkyl halides occurred electron
transfer followed by recombination of the anion-
radical with alkyl radical. As a result both cyano
group and hydrogen were substituted in 4: 1 ratio
[7, 8]. The reactivity of terephthalonitrile dianion is
of dual character and depends on the nature of the
alkyl halide [9].
The present study is an extension of this research
aimed to elucidation by an example of cyanoarenes
of the effect of structural factors on regioselectivity
and on alkylation mechanism of the anionic reduced
forms of functional arenes with electron-donor sub-
stituents. First of all we considered the methyl group.
As show published data [10, 11] the anion-radicals of
tolunitriles generated electrochemically in DMF in
millimolar concentration were quite stable and thus it
was possible to investigate their reaction with alkyl
halides. Taking into consideration the available data
on unsubstituted aromatic nitriles [1 6] it seems pre-
sumable to generate these anion-radicals in sufficient
concentrations for performing chemical experiments.
Besides in [11] was made a conclusion from the
electrochemical data, that anion-radicals of tolu-
nitriles even in reactions with primary alkyl halides
exhibit both nucleophilic and electron-donor reacti-
vity. In comparison with results we formerly had
obtained for anion-radical of benzonitrile [2] and
dinitriles [7, 8] the above facts showed that the intro-
duction of a methyl group into the anion-radical of
benzonitrile changed the pattern of its reactivity;
therewith in the case of para-isomer the change was
similar to that produced by electron-withdrawing
cyano group. However the approach used by Soren-
sen et al. [11] cannot reveal the orientation of anion-
radical alkylation inherent to each mechanism. Yet it
*
For communication XIV see [1].
The study was carried out under financial support of the
**
Russian Foundation for Basic Research (grant no. 99-03-
33111) and of Ministry of Education of the Russain Federa-
tion (grant no. 2000.5.90).
1070-4280/01/3806-823$27.00 2002 MAIK Nauka/Interperiodica

824
VAGANOVA et al.
is known that as a rule the change of reaction
mechanism is accompanied by the altered orientation
and therefore by another set of alkylation products
[7 9, 11 13]. Such data give the basis for conclusions
on the reaction mechanism on the structural level. In
the light of the above the goal of this study was
performing one- and two-electron reduction of
m-tolunitrile (I) with sodium in liquid ammonia,
chemical testing of the nature of arising anionic
reduction products, and establishing of the character
of alkylation products obtained therefrom.
It was established that oxidation with oxygen of the
product of the two-electron reduction of nitrile I did
not result in recovery of the initial compound. After
evaporation of ammonia, dilution of the reaction
mixture with water, and extraction we isolated only
1-% of m-toluamide. It is known [16] that at two-
electron reduction of benzonitrile with potassium in
the liquid ammonia arises a very basic dianion that is
protonated with ammonia to yield 1-cyano-2,5-cyclo-
hexadien-1-yl anion. Basing on these data it may be
expected that dianion of tolunitrile (I) also undergoes
protonation affording 3-methyl-1-cyano-2,5-cyclo-
hexadien-1-yl anion (III). Apparently the oxidation
of anion III gives rise to the corresponding methyl-
cyclohexadienone (see, e.g., [5]) that by reaction with
oxygen in an alkaline medium provides products of
deep oxidation, probably with cleavage of the benzene
skeleton and/or polymers that are not extracted from
the water solution. In contrast, the protonation of the
product of two-electron reduction of nitrile I with
water results in recovery of 70% of the initial
nitrile. Taking into account that in reactions with
unsubstituted 1-cyano-2,5-hexadien-1-yl anion an
electrophile adds to the ipso-position with respect to
cyano group [4] it is presumable that at treating with
water anion III forms 3-methyl-1-cyano-2,5-cyclo-
hexadiene that in the course of the workup transforms
into the initial nitrile I.
The reduced forms were generated along the
procedure that we had frequently used before in the
same purpose [1 9]: the reduction was carried out by
adding one or two equiv of metallic sodium to a
solution of nitrile I in the liquid ammonia at 33 C.
The study of reactivity of the anion-radical of m-tolu-
nitrile (II) might be hampered by its high basicity,
aptitude to disproportionation or dimerization. Since
the reduction potentials of benzonitrile [14] and nitrile
I [11] have close values, and the benzonitrile anion-
radical is stable in the liquid ammonia, it is presum-
able that the basicity of anion-radical II is also in-
sufficient to be protonated by ammonia. The differ-
ence between the first and the second reduction
potential for benzonitrile and tolunitriles is no less
than 0.5 V [11, 14], and this provides a possibility to
regard anion-radical II as not apt to disproportiona-
tion using the reasoning previously applied to the
anion-radical of terephthalonitrile [7]. To prevent the
two-electron reduction at generation of the anion-
radicals we used 10 15% excess of a substrate with
respect to the alkali metal. We checked the degree of
transformation of the initial compound under these
conditions by reaction with oxygen. The recovery of
the initial compound in such experiments indicates
that no deep transformations irreversibly changing its
structure have occurred (see, e.g., [4, 7, 15]). On the
other hand, it is an evidence of stability of the anion-
radical as a product of one-electron reduction. It was
established that at treating with oxygen the product
of one-electron reduction of nitrile I with sodium in
liquid ammonia preliminary kept for 30 min the
initial nitrile I is recovered to 75% from the amount
charged.*
Thus the reported data in combination with the
known facts on reduction of aromatic nitriles in the
liquid ammonia [2 9] and with results of electro-
chemical reduction of nitrile I [10, 11] permit the
assumption that its one- and two-electron reduction
in liquid ammonia performed in this study furnishes
respectively anion-radical II and anion III sufficiently
stable for investigation of their reactivity with respect
to alkyl halides.
The alkylation of the reduced forms of nitrile I was
carried out by adding alkyl halides to their solutions
in liquid ammonia at 33 C. The analyses of com-
1
pounds mixtures formed was performed by H NMR
spectroscopy, GLC, and GC-MS. The reagents ratio
and products composition are given in a table, the
spectral characteristics are listed in EXPERI-
MENTAL.
To ensure the completeness of the two-electron
reduction in this case was used 2.2 equiv of sodium.
It was established that the products of one-electron
and two-electron reduction of nitrile I with sodium
reacted with butyl bromide to afford mainly 3-butyl-
toluene (IV) (table, runs nos. 1, 2). This compound
and the other alkyltoluenes (see below) are described
in the literature (see, e.g., [17]) but spectral data
sufficient for identification are lacking. Therefore we
*
In experiments carried out in liquid ammonia with solutions
of concentration 0.01 M and with amount of reagents 0.5 g
the relatively volatile organic compounds usually are not
quantitatively recovered for the compounds are carried away
with evaporated ammonia.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 6 2002

REDUCTIVE ACTIVATION OF ARENES: XV.
825
Reaction between products of nitrile
I
reduction with sodium in liquid ammonia and alkyl halides
Quantity of reagents, mmol
Composition of reaction products, mmol (GLC data)`
Run
no.
nitrile I
sodium
AlkHlg
nitrile I
alkyltoluene
cyanodialkylcyclohexadiene
1
2
3
4
5
6
7b
3.5
3.0
3.0
3.0
3.0
3.0
3.0
3.0
6.5
6.5
6.5
6.5
6.5
6.5
BuBr 1.6
BuBr 6.5
BuI 6.5
BuCl 6.5
i-BuBr 6.5
s-BuI 6.5
c-HexBr 6.5
0.81
0.05
0.02
1.49
0.01
0.01
0.70
(IV) 1.39
(IV) 2.16
(IV) 2.48
(IV) 0.75
(VII) 1.90
(VIII) 1.92
(IX) 0.40
(V) 0.07
(V) 0.08
(V) 0.02
(V) 0.02
(X) 0.30
(XI) 0.52
(XII) 0.99
`
b
Data averaged for 2 3 runs. The mixture of reaction products contained 0.9 mmol of cyclohexene.
isolated the compounds synthesized from the mixtures
obtained by chromatography, and their structure was
confirmed by spectral method. The H NMR spec-
region of olefin protons three groups of signals are
observed: The most upfield multiplet ( 5.35 ppm)
having no splitting with JH,H 10 Hz that is character-
istic of a vicinal coupling through a double bond
belongs to a proton at C2 adjacent to a methyl group.
The protons attached to C5 and C6 in analogous struc-
tures appear as doublets of triplets in the region
5.60 6.00 ppm (JH,H 10 and 3 Hz). However in the
spectrum of compound V the signal of H6 proton has
a more complicated pattern presumably because of
specific stereochemistry of the compound (cf. [3, 6]).
The structure assumed for nitrile V is also confirmed
by the data of high-resolution mass spectrometry.
1
trum of compound IV by the position and pattern of
the signals resembles that of its structural analog,
3-ethyltoluene [18]: m-Dialkylbenzenes have a char-
acteristic multiplet in the region 6.5 7.0 ppm, and
although the individual signals of the four aromatic
protons cannot be singled out, the pattern cannot be
mistaken for the corresponding spectra of the ortho-
or para-isomers. Alongside arene IV and initial
nitrile I in the products mixture is present in a small
quantity (2 3%) a previously unknown 1-butyl-3-
methyl-1-cyano-2,5-cyclohexadiene (V). The assign-
Thus in both cases form the same products with
the only difference, that the yield of alkylation pro-
ducts with anion radical II according to GLC data
attains 48% with respect to sodium used; in keeping
with the typical stereochemistry in reaction of anion-
radical with electrophile it corresponds to the reaction
completion to 95%. At the same time the two-elec-
tron reduction product is virtually completely
consumed, and butyltoluene IV forms consequently
in 70% yield.
1
ment of the signals in its H NMR spectrum was done
basing on the spectrum of 1-butyl-1-cyano-2,5-cyclo-
hexadiene [3]. The singlet of methyl group at the
double bond appears at 1.77 ppm; the signals of the
butyl moiety attached to C1 and geminal with respect
to cyano group are shifted upfield as compared to the
signals of this substituent in an aromatic ring; the
protons of the methylene C4H2 group give rise to a
typical multiplet at 2.57 ppm. In the resonance
Alk = Bu (IV, V), i-Bu (VII, X), s-Bu (VIII, XI), c-Hex (IX, XII).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 6 2002

826
VAGANOVA et al.
1-cyclohexyl-3-methyl-2,5-cyclohexadiene
Basing on the structure of the alkylation products
(XII).
IV and V obtained, and taking into account the data
on orientation of protonation and alkylation of the
reduced forms of benzonitrile [2, 3] the reaction of
butyl bromide with the products of one- and two-
electron reduction of nitrile I may be described by the
following scheme:
Alkyltoluenes VII IX have been described in the
literature (see, e.g., [17]), and cyclohexadienes X
XII were synthesized for the first time. Compounds
VII XII were isolated from the mixtures by
chromatography, their structure was established from
spectral data analogous to the corresponding spectra
of compounds IV, V. Alongside the mentioned com-
pounds in the reaction mixtures were present
unidentified compounds in overall amounts not
exceeding 5% (GLC data), and in reaction with
cyclohexyl bromide alongside with 20% of the
recovered initial nitrile some cyclohexene was
detected. The reaction of the product of two-electron
reduction of nitrile I with tert-butyl bromide did not
result in alkylation, and 85% of the initial nitrile I
was recovered.
Anion-radical II, the product of one-electron
reduction of nitrile I, is alkylated into the ipso-posi-
tion with respect to cyano group affording 1-alkyl-
cyano-3-methylcyclohexadien-4-yl anion VI that
either suffers decyanation to give arene IV or takes
up a proton providing cyanodialkylcyclohexadiene V.
At the lack of an efficient proton source the second
reaction route occurs to a small degree. Dianion
generated by two-electron reduction of nitrile I is
protonated by ammonia giving anion III (cf. [3, 18]
that on alkylation furnishes cyanodialkylcyclohexa-
diene V. However in this case in the mixture arises
an equivalent amount of amide ion that effects
dehydrocyanation of nitrile V with formation of
dialkylarene IV.
The results of runs nos 2, 5 7 presented in the
table show that irrespective of the structure of the
alkyl moiety the alkylation occurs at the ipso-position
with respect to cyano group (see the scheme).
Similarly to the data obtained previously both for
anion-radicals of aromatic nitriles [2, 4 6] and cyano-
dihydroaryl anions [3, 6] the above mentioned results
testify to the occurrence of SN reaction mechanism.
In both cases this orientation corresponds to the
position with maximum localization of the negative
charge [6, 7, 17]. In contrast, on introducing the
second cyano group into the anion-radical of benzo-
nitrile resulting in the change of its reactivity from
nucleophilic to electron-donating one [7, 8] the alkyl-
ation occurs both in the ipso and unsubstituted posi-
tion of the ring. Additional proof that in reaction with
alkyl halides anion III plays the role of nucleophile
is the lack of reaction with tert-butyl bromide which
provides alkylation products by ET mechanism [8, 9,
19]. To a certain extent the tert-butyl bromide may be
regarded as a test reagent for primary evaluation of
the reactivity of an anionic species that may react
both by SN and ET mechanisms. Nonetheless the
above reasoning provides only indirect evidence for
the occurrence of the SN mechanism in reactions of
anion-radical II and anion III with alkyl halides. To
obtain direct proofs the reactions should be performed
with model reagents that would fix various structural
fragments in the reaction products depending on the
reaction mechanism. This study is planned for the
future.
In order to elucidate the effect of halogen nature
and alkyl structure on the alkylation process of the
reduced forms under investigation we carried out
reaction of the product of two-electron reduction of
nitrile I with a series of alkyl halides. We established
that a dialkylarene IV was the main product of anion
III alkylation disregarding the halogen nature (Hlg =
Cl, Br, I) in butyl halide (see table, runs nos. 2 4).
However in reaction with butyl chloride a consider-
able amount of initial nitrile I is recovered. Taking
into account a similar result obtained at protonation of
the product of two-electron reduction of nitrile I (see
above) it is presumable that butyl chloride shows not
only electrophilic but also CH-acidic properties. A
similar change in reaction direction was previously
observed in reaction of two-electron reduction pro-
ducts obtained from benzonitrile and 1-naphthonitrile
in going from butyl iodide and butyl bromide to butyl
chloride [3].
Variation of alkyl moiety was performed in the
following series: BuBr, i-BuBr, s-BuBr, c-HexBr,
t-BuBr (see table, runs nos.2, 5 7). It was established
that in reactions of the above alkyl halides with the
product of two-electron reduction of nitrile I were
obtained the corresponding alkyltoluenes: 3-iso-butyl-
toluene (VII), 3-sec-butyltoluene (VIII), 3-cyclo-
hexyltoluene (IX), and the corresponding 1-alkyl-1-
cyano-3-methyl-2,5-cyclohexadienes: 1-iso-butyl-1-
cyano-3-methyl-2,5-cyclohexadiene (X), 1-sec-butyl-
1-cyano-3-methyl-2,5-cyclohexadiene (XI), 1-cyano-
It is obvious that the ratio of alkylarene to cyclo-
hexadiene in the reactions with branched alkyl halides
is quite different from that observed at the use ot
primary alkyl halides. Within the framework of the
above scheme the growth of diene X XII content in
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 6 2002

REDUCTIVE ACTIVATION OF ARENES: XV.
827
the reaction products should be apparently ascribed to
the increasing aptitude of alkyl halide with branched
alkyl to operate as CH-acid with hydrogen halide
elimination; this assumption is supported by the
detection of cyclohexene among the products obtained
in run no.7 (see table). This process ensures more
effective neutralization of sodium amide and thus
decreases the dehydrocyanation of the primary reac-
tion product. The recovery of the initial nitrile in
reaction with cyclohexyl bromide, same as in reac-
tion with butyl chloride, is probably due to basic
properties of anion III that compete with its nucleo-
philicity.
energy 70 eV, column HP5 (5% of diphenylsiloxane,
95% dimethylsioxane), 30 0.25 0.25 m, carrier gas
helium, heating mode: 2 min at 50 C, then 10 /min,
5 min at 200 C, evaporator temperature 280 C, ion
source temperature 173 C. The data sampling rate
1.2 scan/sec in the mass region 30 650 a.u.
The following compounds and solvents were used
in the study: Liquid ammonia was purified by dis-
solving sodium metal with subsequent evaporation
into a reactor cooled to 70 C. The oxides from the
surface of sodium metal of pure grade were
removed under a layer of dry hexane. m-Tolunitrile
was obtained by procedure from [22] from m-toluic
acid, bp 57 58 C (3mm Hg), publ. 84 C (10mm Hg)
[23]. Alkyl halides were purified by passing through
alumina followed by distillation; boiling points were
consistent with published data [23].
In conclusion let us consider the synthetic
opportunities of the results obtained. The most
general alkylation method for aromatic ring is tradi-
tionally Friedel Krafts reaction that within over a
century of its investigation has undergone numerous
modifications resulting in creation of new catalysts
and reagents [20]. However the opportunity to pre-
pare individual dialkylbenzenes by this reaction
remains very limited. Therefore the alternative
methods of aromatic ring alkylation are also under
lively development; they are mostly concerned with
the use of organometallic reagents [21]. The alkyla-
tion of reduced forms of easily available tolunitriles
performed in this study by an example of nitrile I
may be regarded as such alternative approach to
aromatic ring alkylation. The compounds correspond-
ing to ipso-alkylation of anion-radical II and cyano-
methylcyclohexadienyl anion III, m-alkyltoluenes
IV, VII IX, in both cases form as the main product.
Taking into account the high degree of nitrile I
conversion the reaction between the product of its
two-electron reduction and alkyl halides may be used
for preparation of individual m-alkyltoluenes.
Reduction of m-tolunitrile (I) with sodium in the
liquid ammonia. To a solution of nitrile I in liquid
ammonia (of concn. 0.05 M) at 33 C was added
while stirring a required amount of sodium metal,
and then the reaction mixture was maintained at the
same conditions for 10 30 min.
REACTIONS OF REDUCTION PRODUCTS
OF m-TOLUNITRILE (I) WITH ELECTROPHILIC
REAGENTS
Oxidation of reduction products of m-tolunitrile
(I). Through the solutions of reduction products
obtained from nitrile I by the action of 3.0 mmol of
sodium (0.069 g) on 3.3 mmol of nitrile I (0.386 g)
or of 6.5 mmol of sodium (0.149 g) on 3.0 mmol of
nitrile I (0.351 g) was passed for 15 20 min a flow
of oxygen dried by passing through a layer of calcium
chloride. The reaction mixture was stirred for 20 min,
and then was added 5 ml of methanol and 50 ml of
ethyl ether. The reaction mixture was stirred to
complete evaporation of liquid ammonia, and to the
residue 50 ml of water was added. The ether layer
was separated, the water layer was extracted with
ether (2 50 ml), the combined ether solutions were
washed with water and dried on MgSO4. After
distilling off the solvent the residue was analyzed by
1H NMR and GLC. On oxidation of the product of
one-electron reduction 0.3 g of compound was
obtained containing 96% of initial nitrile I (yield
75%). On oxidation of the product of two-electron
reduction m-toluamide was isolated (0.042 g, 10%).
EXPERIMENTAL
1H NMR spectra were registered on spectrometer
Bruker WP-200SY from solutions in CDCl3. The
precise values of molecular ions mass were measured
by high-resolution mass spectrometry on Finnigan
MAT-8200 instrument. Reaction mixtures were
analyzed by GLC on chromatograph LKhM-7A under
the following conditions: stationary phase 15%
SKTFV-83 on Chromosorb W, oven temperature
programmed from 100 to 300 C at a rate 10 C/min,
1
carrier gas helium, flow rate 0.6 l h , column
2500 2 mm. The GC-MS measurements were carried
out on a Hewlett-Packard system G1081A composed
of a gas chromatograph HP 5890 of series II and
mass-selective detector HP 5971, ionizing electrons
Protonation of the product of two-electron
reduction of m-tolunitrile (I). To a solution of a
product of two-electron reduction of nitrile I obtained
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 6 2002

828
VAGANOVA et al.
by treating with 6.5 mmol of sodium (0.149 g)
3.0 mmol of nitrile I (0.351 g) was added dropwise
while stirring 0.01 mol of water (0.18 ml). The reac-
tion mixture was kept for 29 min, and then 50 ml of
ethyl ether was added. Further workup was carried
out as above. On removing the solvent 0.25 g ( 70%)
of initial nitrile I was obtained.
1.59 m (2H, CH2), 2.34 s (3H, CH3), 2.56 m (1H,
CH), 6.95 7.25m (4H, H2,4,5,6). Found: M 148.1246.
C11H16. Calculated: M 148.1251.
3-Cyclohexyltoluene (IX). 1H NMR spectrum
(CDCl3), , ppm: 1.38 m (4H, 2CH2), 1.78 m (4H,
2CH2), 2.02 m (2H, CH2), 2.27 s (3H, CH3), 4.27 m
(1H, CH), 6.91 7.19 m (4H, H2,4,5,6). Found: M
174.1411. C13H18. Calculated: M 174.1408.
Reaction of reduction products of m-tolunitrile
(I) with alkyl halides. To a solution of reduction
products prepared by the above described procedure
was added alkyl halide in amount and at reagents ratio
indicated in the table. The reaction mixture was
stirred till evaporation of the half of liquid ammonia
( 0.5 h), and then 50 ml of ethyl ether was added.
Further workup was carried out as above. The com-
position of reaction products mixtures was determin-
1-Butyl-1-cyano-3-methyl-2,5-cyclohexadiene
1
(V). H NMR spectrum (CDCl3), , ppm, 2 stereoiso-
mers: 0.84 m (3H, CH3), 1.10 1.70 (6H, [CH2)3],
1.77 s (3H, CH3), 2.57 m (2H, H4) 5.35 m (1H, H2),
5,6
5.60 d.t, 5.61 d.t (1H, H6), 6.03 d.t (1H, H5). J
H,H
5,4
6,4
10 Hz, J 3.5 Hz, J 2 Hz. Found: M 175.1359.
H,H
H,H
C12H17N. Calculated: M 175.1360.
1
ed from H NMR spectra, GLC and GC-MS analyses
1-iso-Butyl-1-cyano-3-methyl-2,5-cyclohexa-2,5-
(see table). Individual compounds were isolated by
column chromatography on silica gel 40/8- , eluent
hexane ethyl ether, 95:5 by volume, or by TLC on
plates with a fixed layer of sorbent (silica gel LSL254
6/40 with addition of 13 wt% of gypsum), eluent
hexane ethyl ether, 9: 1 by volume. The visualization
of spots was under UV irradiation of the dried plate.
The structure of compounds was derived from
1H NMR and high resolution mass spectra.
1
diene (X). H NMR spectrum (CDCl3), , ppm, 2
stereoisomers: 0.91 d (6H, 2CH3), 1.62 d (2H, CH2),
1.72 s (3H, CH3), 1.74 m (1H, CH), 2.55 m (2H,
H4), 5.34 m (1H, H2), 5.62 d.t, 5.63 d.t (1H, H6),
5,6
5,4
6,4
5.88 d.t (1H, H5). J 10 Hz, J 3.5 Hz, J 2 Hz.
H,H
H,H
H,H
Found:
M 175.1362. C12H17N. Calculated: M
175.1360.
1-Cyano-1-cyclohexyl-3-methyl-2,5-cyclohexa-di-
ene (XII). 1H NMR spectrum (CDCl3), , ppm,
2 stereoisomers: 1.12 m (4H, 2CH2), 1.73 s (3H,
CH3), 1.78m (7H, 3CH2, CH), 2.53(2H, H4), 5.28m
(1H, H2), 5.55 d.t, 5.56 d.t (1H, H6), 5.93 d.t (1H,
By separation of compounds mixture obtained in
reaction of two-electron reduction product of nitrile I
and sec-butyl bromide (table, run no.6) we isolated
a fraction containing according to 1H NMR and
GC-MS data nitrile I and 1-sec-butyl-1-cyano-3-
methyl-2,5-cyclohexadiene (XI) (M 175). In the
1H NMR spectrum of the mixture to compound XI
[CDCl3, , ppm] correspond the signals: 0.80
1.70m (9H, C4H9), 1.77s (3H, CH3), 2.57m (2H,
H4), 5.35 m (1H, H2), 5.61 m (1H, H6), 6.03 m (1H,
H5).
5,6
5,4
6,4
H5), J 10 Hz, J 3.5 Hz, J 2 Hz. Found: M
H,H
H,H
H,H
201.1514. C14H19N. Calculated: M 201.1517.
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1
toluene (IV). H NMR spectrum (CDCl3), , ppm:
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