Catalytic hydromagnesiation of 2-alkylbutadienes

Article abstract of DOI:10.1023/A:1013906827883

The effect of alkyl substituents in 2-alkylbutadienes on their hydromagnesiation with alkylmagnesium halides was studied. 2001 MAIK "Nauka/Interperiodica".

Full text of DOI:10.1023/A:1013906827883

Russian Journal of General Chemistry, Vol. 71, No. 11, 2001, pp. 1773 1785. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 11, 2001,
pp. 1874 1886.
Original Russian Text Copyright
2001 by Viktorov, Zubritskii.
Catalytic Hydromagnesiation of 2-Alkylbutadienes
N. B. Viktorov and L. M. Zubritskii
St. Petersburg State Institute of Technology, St. Petersburg, Russia
Received August 28, 2000
Abstract The effect of alkyl substituents in 2-alkylbutadienes on their hydromagnesiation with alkyl-
magnesium halides was studied.
Our studies of the reaction of isoprene with alkyl-
magnesium halides in the presence of transition metal
complexes [1, 2] showed that the major reaction path-
way is hydromagnesiation of the diene with formation
of linear products containing both dimeric 3,7-dimeth-
yl-2,7-octadienylmagnesium halide and monomeric 2-
and 3-methyl-2-butenylmagnesium halides. At the
same time, telomeric products were also detected.
They formed in smaller amounts, and their relative
content largely depended on the reaction conditions
and nature of the alkylmagnesium halide and catalyst.
To obtain additional data on the reaction mechanism
and determine conditions for preparing hydromagnesi-
ation products of the required structure, we considered
in detail the influence of the reaction conditions on
the composition and structure of 2-alkylbutadiene
hydromagnesiation products.
Hydromagnesiation of isoprene (see scheme) can
yield two products of the type H(C5H8)1MgX (I, II)
and six products of the type H(C5H8)2MgX (III VIII).
By carboxylation of the reaction mixture, organomag-
nesium compounds I VIII are converted to carboxylic
acids IX XVI.
1070-3632/01/7111-1773$25.00 2001 MAIK Nauka/Interperiodica

1774
VIKTOROV, ZUBRITSKII
bond: CH=CH2 and C=CH2. These fragments give the
The simplest reaction pattern is observed with the
corresponding signals in the 1H NMR spectrum.
These results, in combination with analytical data,
suggest the presence in both acids of a cyclic frag-
ment. Further analysis of the structure of these two
cyclic acids by such NMR techniques as dept-135 and
C H and H H correlations allowed identification of
XV as 2-(2,5-dimethyl-2-vinylcyclopentyl)acetic acid
and of XVI as 2-(5-methyl-2-isopropenylcyclopentyl)-
acetic acid (Table 1).
system RMgBr ether Ni(PPh3)2Cl2. In the fraction of
carboxylic acids H(C5H8)2CO2H, the major compo-
nent (54%) is known 3,7-dimethyl-1,7-octadiene-3-
carboxylic acid XI. The structure of the second com-
ponent (27%) was determined as follows. The 13C
NMR spectrum of the mixture, after subtraction of
the signals of XI, contains five medium-intensity sig-
nals in the alkyl region (CH3, 2CH2, CH), two sig-
nals in the olefinic region (CH2, C), and a signal of
the carboxy group. Since this fraction, according to
elemental analysis, consists exclusively of the isomer-
ic acids H(C5H8)2CO2H, we thoroughly looked for the
In some cases, olefins can be separated by selective
addition of electrophilic agents, as different types of
C=C bonds react at different rates [3]. Our attempt to
selectively add HCl to the disubstituted double bond
in XVI failed: both acids XV and XVI remained un-
changed. At the same time, after prolonged shaking
of a mixture of XV and XVI with a concentrated HBr
solution we obtained a mixture consisting of un-
changed XV and the cyclization product of XVI,
(4a,5,7a)-1,1,5-trimethylperhydrocyclopenta[c]pyran-
3-one XVII [reaction (1)]. The mixture of XV and
XVII can be readily separated by selective uptake of
XV with aqueous alkali.
three lacking 13C signals. Remeasurement of partic-
ular regions of the 13C NMR spectrum showed that the
sought-for three signals overlap with the correspond-
ing signals of the major isomer, XI:
21.9 (CH3C7),
144.8 (C7), and 110.2 ppm (C8). AlonCg with the over-
estimated integral intensity of the CH2=C7 signal of
XI in the 13C NMR spectrum of the mixture, these
facts show that in the isomer under consideration the
isoprene unit remote from the carboxy group is identi-
cal to that in XI. The C H correlation NMR experi-
ment allowed reliable identification of the second
component as 2,7-dimethyl-1,7-octadiene-3-carboxylic
acid XII, whose precursor is 2,7-dimethyl-2,7-octadi-
enylmagnesium halide IV.
(1)
In the 13C NMR spectrum of the H(C5H8)2CO2H
acid fraction consisting mainly of acids XI and XII,
there are also weak signals from two more unsaturated
carboxylic acids ( 180.8 and 180.9 ppm). As fol-
lows from indirect Cevidences, these carboxylic acids
are formed from nonallylic organomagnesium com-
pounds; with i-PrMgCl used as the initial alkylmag-
nesium halide, their content is appreciably larger.
To isolate these two acids, we treated the reaction
mixture isoprene i-PrMgCl ether Ni(PPh3)2Cl2 with
trimethylchlorosilane to selectively scavenge allylic
Grignard reagents III and IV. Subsequent carboxy-
lation gave a mixture of two carboxylic acids XV
and XVI.
The NMR spectrum of XV showed that it is a mix-
ture of two stereoisomers in a 10 : 1 ratio. The minor
isomer gives weak signals of the vinyl group in the
13C NMR spectrum at
112.0 (CH2) and 144.4 ppm
C
(CH). The major isomer of XV readily undergoes io-
dolactonization (2), which proves the cis arrangement
of the reacting groups relative to the ring plane [4].
(2)
Elemental analysis of this mixture gave the empir-
ical formula C11H18O2, consistent with the composi-
tion H(C5H8)2CO2H. The 13C NMR spectrum showed
the absence of acids XI and XII and the presence of
two new acids giving the above-mentioned signals
at 180.8 and 180.9 ppm. The ratio of XV and XVI
depends on the nature of the initial alkylmagnesium
halide, which allowed us to distinguish, basing on the
ratio of the integral intensities, two sets of signals
corresponding to acids XV and XVI.
The cis arrangement of CH3C5 relative to the two
above-mentioned substituents follows from the C1H
proton chemical shift in XV, 1.61 ppm (Table 1).
If the two methyl groups, CH3C2 and CH3C5, were
located on the same side of the ring plane, the C1H
proton would give the signal at about 1.0 ppm [5, 6].
Hence, the major isomer of XV is [(1SR,2SR,5SR)-
2,5-dimethyl-2-vinylcyclopentyl]acetic acid.
Examination of the olefinic region of the 13C NMR
spectrum shows that each acid contains one double
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
Table 1. 1H and 13C NMR spectra of XV and XVI
1775
13C NMR spectrum,
C, ppm
1H NMR spectrum,
13C NMR spectrum,
C, ppm
1H NMR spectrum,
, ppm (J, Hz)
, ppm (J, Hz)
53.6 (CH)
47.8 (C)
1.61 m
44.7 (CH)
48.4 (CH)
28.1 (CH2)
32.7 (CH2)
38.9 (CH)
21.8 (CH3)
35.2 (CH2)
180.8 (C)
2.09 m
2.65 m
1.59 m and 1.72 m
1.17 m and 1.97 m
1.84 m
1.02 d (5.8)
2.02 d.d (14.4; 5.3), 2.19 d.d (14.4; 4.1)
11.8 br.s
37.9 (CH2)
31.4 (CH2)
39.6 (CH)
19.8 (CH3)
34.9 (CH2)
180.9 (C)
1.53 m and 1.64 m
1.26 m and 1.90 m
1.70 m
1.00 d (6.5)
2.12 d.d (7.0; 15.6) 2.30 d.d (6.2; 15.6)
11.8 br.s
143.3 (CH)
112.2 (CH2)
24.9 (CH3)
5.80 d.d (11.1; 17.5)
4.95 d (17.5), 4.99 d (11.1)
1.11 s
145.6 (C)
111.5 (CH2)
23.0 (CH3)
4.67 s and 4.81 s
1.70 s
Table 2. Yields of products of isoprene hydromagnesiation with different alkylmagnesium halides RMgX (1 mol %
Ni(PPh3)2Cl2, isoprene : RMgX 1 : 1, 48 h, 18 20 C)
Content of indicated H(C5H8)2CO2H isomer, %b
IX + X
(IX/X)
RMgX
Acidsa
XI
XII
XIII
XIV
XV
XVI
In ether
MeMgBr
EtMgCl
EtMgBr
PrMgCl
PrMgBr
PrMgI
i-PrMgCl
i-PrMgBr
i-BuMgCl
s-BuMgCl
Traces
20
26
35
28
4
35
22
5
54
50
51
54
49
41
50
25
24
25
27
30
15
14
7
6
7
7
3
14
9
4
10
7
7
3
20
24
5
5 (3 : 1)
5 (2.5 : 1)
Traces
Traces
5
3
Traces
3 (1 : 1)
28
40
10
19
30
In THF
MeMgBr
EtMgCl
EtMgBr
PrMgCl
PrMgBr
i-PrMgCl
i-PrMgBr
i-Pr2Mg
s-BuMgCl
s-BuMgBr
4 (1.5 : 1)
6 (2 : 1)
5 (2 : 1)
4 (2 : 1)
9 (2.5 : 1)
Traces
26
22
33
28
41
37
26
11
57
44
56
55
40
42
46
29
15
24
22
23
17
15
12
20
22
19
8
10
18
14
16
14
Traces
5
Traces
Traces
3
7
7
14
20
17
3
3
Traces
Traces
4
4
5
5
8
5
Traces
2
a
b
Here and in Tables 3 and 4, H(C H ) CO H acids are meant. Here and in Tables 3 and 4, the quantitative composition of
5
8 2
2
1
the mixture of H(C H ) CO H acids was determined by integration of the H NMR spectra.
5
8 2
2
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

1776
VIKTOROV, ZUBRITSKII
Table 3. Yields of products of isoprene hydromagnesiation with different alkylmagnesium halides RMgX (1 mol %
NiPy4Cl2, isoprene : RMgX 1 : 1, 48 h, 18 20 C)
In ether
In THF
content of indicated H(C5H8)2CO2H isomer, %
RMgX
IX + X (IX/X)
Acids
IX + X
Acids
XI
XII
XIII
XIV
XV
XVI
MeMgBr
EtMgCl
EtMgBr
PrMgCl
PrMgBr
PrMgI
7 (3 : 1)
17 (1.5 : 1)
5 (2 : 1)
10 (2 : 1)
4 (2 : 1)
Traces
8 (2.5 : 1)
19 (2 : 1)
12 (2.5 : 1)
8 (4 : 1)
13
7
17
2
30
20
30
20
10
15
18
35
17
5
10
6
4
3
4
Traces
3
4
i-PrMgCl
i-PrMgBr
i-Pr2Mg
i-BuMgCl
s-BuMgCl
s-BuMgBr
5 (2 : 1)
11 (2 : 1)
Traces
17 (3 : 1)
12
10
5
40
5
Traces Traces
19 (1.5 : 1)
Traces
3 (2.5 : 1)
8 (1 : 1)
15 (4 : 1)
19 (4 : 1)
Similarly, facile formation of lactone XVII indi-
cates cis arrangement of the reacting groups in XVI
[scheme (1)] relative to the ring plane. The large C1H
ylmagnesium halide containing no -H atoms, no
diene conversion is observed. Acids IX and X are
formed only in minor amounts when the reaction is
performed in the presence of Ni(PPh3)2Cl2 catalyst
(in THF better than in ether), but their amount be-
comes noticeable in the presence of NiPy4Cl2; in
the latter case, acids IX and X are the only products
when the reaction is performed in ether. Replacement
of ether by THF in reactions performed in the pres-
ence of Ni(PPh3)2Cl2 results in regular decrease in
the yield of cyclic acids XV and XVI due to the lower
cyclization rate. With bromides RMgBr used instead
of chlorides RMgCl, the carboxylation products
H(C5H8)2CO2H are formed in lower yields or are not
formed at all (with R = s-Bu). Still lower yields
are obtained with RMgI. The influence of the alkyl
radical in RMgX on the yields of acids IX XVI is
complex. tert-Butylmagnesium chloride in reaction
with isoprene does not form hydromagnesiation prod-
ucts but forms 1,4- and 4,1-addition products [reac-
tion (5)] in low yield. Trace amounts of such products
are formed in the absence of the catalyst also.
1
proton chemical shift in the H NMR spectra of both
acid XVI (2.09 ppm) and lactone XVII (2.06 ppm)
suggests the absence of vicinal cis substituents.
Hence, the major isomer of XVI is [(1SR,2RS,5SR)-
5-methyl-2-isopropenylcyclopentyl]acetic acid.
The precursors of XV and XVI are cyclic organo-
magnesium compounds VII and VIII, which, in turn,
are formed by the magnesium ene reactions (3) and
(4) from open-chain Grignard reagents V and VI.
Such a cyclization, often going to completion in ether,
is suppressed in THF [4], and in this case after car-
boxylation we obtain acids XIII and XIV.
(3)
(4)
The ratio and yields of hydromagnesiation products
IX XVI strongly depend on the initial Grignard re-
agent, solvent, and catalyst (Tables 2, 3). With meth-
(5)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
1777
Table 4. Yields of products of isoprene hydromagnesiation in the presence of different catalysts (isoprene : i-PrMgCl/THF
1 : 1, 48 h, 18 20 C, 1 mol % catalyst)
Content of indicated H(C5H8)2CO2H isomer, %
Run
Catalyst
IX + X (IX/X)
Acids
no.
XI
XII
XIII
XIV
XV
XVI
1
2
3
4
5
6
7
8
9
Ni(PPh3)2Cl2
6 (2.5 : 1)
28 (2.5 : 1)
1 (1 : 1)
21 (3 : 1)
6 (2 : 1)
41
5
28
8
24
6
20
5
40
17
18
7
4
4
NiCl2
NiCl2 + 2PPh3
NiCl2 + 2AsPh3
NiCl2 + 2SbPh3
NiCl2 + 2BiPh3
Ni(PPh2Pr)2Cl2
Ni(PPhPr2)2Cl2
Ni(PBu3)2Br2
40
15
21
17
38
17
5
13
10
17
25
35
36
41
20
6
5
6
7
9
3
10
9
9
3
3
3
5
3
3
22 (3 : 1)
<4
40
5
10 Ni[(p-CH3 C6H4)3P]2Cl2
11 Ni(dppe)Cl2
12 Ni[P(OPh)3]4
13 Ni[P(OEt)3]4
14 Ni[P(OCH2Ph)3]2Br2
15 Ni(COD)2
16 NiCP2
17 NiPy4Cl2
18 Ni( -dipy)Cl2
19 Ni(acac)2
3 (1 : 1)
20 (2 : 1)
9
5
27
5
34
Traces
11 (2 : 1)
28 (3 : 1)
17 (3 : 1)
25 (3 : 1)
13 (3.5 : 1)
5
5
12
6
14
25
10
5
10
5
45
25
40
5
5
5
12
10
Traces
4
Traces
5
The influence of the nickel complex on the course
of isoprene hydromagnesiation is illustrated by
data in Table 4. It is seen that nickel phosphite com-
plexes (run nos. 12 14) do not catalyze the reaction.
Regular increase in the donor power of the phosphine
ligand on replacing aryl groups by alkyl groups (run
nos. 1, 7 9) seem to result in a regular decrease in
the yield of the reaction products. However, with
Ni[(p-CH3C6H4)3P]2Cl2 (run no. 10), in which the li-
gand basicity is intermediate between those of PPh2Pr
and PPhPr2 [7], the yields of the hydromagnesia-
tion products are similar to those obtained with
Ni(PPh3)2Cl2. Thus,the catalyst activity increases with
increasing number of aryl substituents in the ligand.
Presumably, the course of the catalytic process is in-
fluenced by the configuration of the nickel complex:
With decreasing number of aryl substituents in the
phosphine the structure of the complex changes from
tetrahedral (with PAr3) to planar (with PAlk3) [7].
Variation of the central atom in ligands EPh3
(run nos. 3 6) shows that with weakly coordinating
AsPh3 and BiPh3 the yield of H(diene)1CO2H acids
is higher than with PPh3 and SbPh3. A similar pattern
was observed in hydromagnesiation of piperylene [6].
We also tested as isoprene hydromagnesiation cata-
lysts some other transition metal complexes. With
Fe(acac)2, Fe(acac)3, Co(PPh3O)2Cl2, Cu( -dipy)2Cl2,
and Pt(PPh3)2Cl2 no diene conversion was observed,
and with Cr(acac)3, Pd(PPh3)2Cl2, (PhCN)2PdCl2, and
Rh(PPh3)3Cl the conversion was insignificant.
The influence of the chain length in the primary
substituent in 2-substituted butadiene was examined
with myrcene XXIII as example. 7-Methyl-3-methyl-
ene-1,6-octadiene XXIII proved to be considerably
less active in hydrmagnesiation (6) with i-PrMgCl
THF Ni(PPh3)2Cl2, giving after carboxylation only
a
2 : 1 mixture of acids XXVII and XXVIII in
a 5% yield and traces of telomeric acid XXIX:
(6)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

1778
VIKTOROV, ZUBRITSKII
[scheme (7)] by branching in the -position of the
With NiPy4Cl2 as catalyst, the yield of acids
alkyl substituent in 2-alkyl-substituted butadienes.
(XXVII/XXVIII, 70 : 30) increases to 16%, and telo-
dimerization products XXIX ( 12%) are formed as a
nondistillable (at 1 mm Hg) residue. Owing to the
large difference between the content of acids XXVII
Reaction (7) is considerably slower than hydromag-
nesiation of isoprene. For example, from the reaction
performed for 24 h in the presence of NiPy4Cl2, we
isolated only acids XXXV and XXXVI ( 1.5 : 1 ratio)
in a low (3%) yield. The prolonged (100 h) reaction
gave a higher (17%) yield of XXXV and XXXVI
( 1 : 1 ratio), and additionally a mixture of telodi-
mers H[(XXX)2]CO2H was obtained in 15% yield,
with 3,7-diisopropyl-1,7-octadiene-3-carboxylic acid
XXXVII prevailing. When reaction (7) was performed
with Ni(PPh3)2Cl2 as catalyst, in 24 h we obtained
only traces of unsaturated acids, and in 100 h we iso-
lated, along with a mixture of XXXV and XXXVI
( 1.5 : 1 ratio, yield 2%), also telodimer XXXVII
(yield 19%) containing a 20% impurity of other telo-
dimers XXXVIII.
1
and XXVIII, the 13C and H NMR signals could be
assigned to particular isomers. For accurate assign-
ment, we used data of [8 10].
Thus, as the length of the primary substituent in
2-substituted butadiene is increased, the number of
hydromagnesiation products formed in the presence of
Ni(PPh3)2Cl2 decreases; in the presence of NiPy4Cl2,
the compounds H(diene)1MgX and H(diene)2MgX are
formed.
With 2-isopropylbutadiene XXX as example, we
studied the effect exerted on hydromagnesiation
(7)
With 2-tert-butylbutadiene XXXIX, in which the
steric hindrance is still stronger, we obtained no
noticeable amounts of hydromagnesiation products
[reaction (8)] in the presence of Ni(PPh3)2Cl2, and in
the presence of NiPy4Cl2 allylic organomagnesium
compounds XL and XLI were obtained.
(8)
As the volume of the alkyl substituent increased in
going from isoprene to myrcene, 2-isopropylbutadi-
ene, and 2-tert-butylbutadiene, the ratio of the 4,1-
However, in the NMR spectra of the fraction of
H[(XXXIX)1]CO2H acids we observed, along with
1
signals of XLII, also the second sets of H and 13C
and 1,4-hydromagnesiation products decreased, and signals, inconsistent with the structure of 2-methyl-
from XXXIX we obtained isomer XL only. 3-tert-butyl-3-butenoic acid. We suggested that the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
1779
steric hindrance in 3,4,4-trimethyl-2-pentenylmagne-
sium chloride XL prevents complete rearrangement
in the reaction with CO2, so that the -product, 4,5,5-
trimethyl-3-hexenoic acid XLIII, is partially formed.
dimethyl-2-pentenylmagnesium halide reacts with ke-
tones to give a significant amount of the crotyl com-
pound in a mixture with the usual -product [12].
By independent synthesis (9), we prepared 3,4,4-
trimethyl-2-pentenylmagnesium chloride XL, which
after carboxylation gave, indeed, the -product XLIII
along with the -product XLII.
It is known that allylmagnesium halides react with
sterically hindered di-tert-butyl ketone without rear-
rangement [11]. Furthermore, structurally related 4,4-
(9)
The fraction of H[(XXXIX)2]CO2H acids contains,
along with major isomer XLIV, also an impurity acid
Grignard reagents were prepared under argon. Their
solutions were filtered through glass wool and stored
in Schlenk vessels. The Grignard reagents were used
as 2.0 2.5 N solutions; the solutions of RMgBr in
THF had a lower concentration, 0.9 1.0 N, because of
the limited solubility. The solution concentration was
determined by back-titration with alkali.
1
identified by H and 13C NMR spectroscopy as 3,8-di-
tert-butyl-3,8-nonadienoic acid XLV. Here, also, the
steric hindrance produced by the tert-butyl substituent
in XLI prevents complete allyl rearrangement in the
carboxylation stage. 2,7-Di-tert-butyl-1,7-octadiene-
3-carboxylic acid XLIV can be readily separated from
the impurity of XLV by recrystallization from aque-
ous methanol.
The nickel complexes were obtained by published
procedures. Isoprene was dried over CaH2 and dis-
tilled under argon; technical-grade myrcene was used.
Thus, as the size of the alkyl substituent in 2-alkyl-
butadienes is increased, their hydromagnesiation in-
volving both studied catalysts, Ni(PPh3)2Cl2 and
NiPy4Cl2, becomes more difficult, but the reaction
selectivity increases. The reaction yields allylic organ-
omagnesium compounds of the types H(diene)1MgX
and H(diene)2MgX. The monomeric species are
formed by 1,4- and 4,1-addition of [HMgX] to the
diene molecule, with the ratio of the 4,1- and 1,4-ad-
dition products decreasing as the size of the alkyl sub-
stituent is increased. In the structure of the telodimers,
one diene unit forms a bond from the inside to the
outside via one of the double bonds, and the other
diene unit is subject to conjugated addition, mostly
by the 1,4 scheme. Only in the presence of the bulky
tert-butyl group the addition to the second unit fol-
lows exclusively the 4,1 scheme.
2-Isopropyl-1,3-butadiene XXX. The precursor,
3,4-dimethyl-1-pentyn-3-ol, was prepared by the Fa-
vorskii reaction. A 2-l vessel equipped with a high-
power Hershberg stirrer, a reflux condenser, a drop-
ping funnel, and a gas-feeding tube was charged with
350 g of granulated KOH and 300 ml of absolute
ether. The vessel was cooled with a water ice mix-
ture, and a stream of purified acetylene was passed
to saturation. Then, a solution of 134 g of methyl iso-
propyl ketone (prepared from tert-amyl alcohol [13])
in 600 ml of absolute ether was added dropwise over
a period of 4 h, with acetylene bubbling ( 5 bubbles
per second) and cooling being continued, after which
the mixture was stirred for an additional 1 h in an
acetylene stream and left overnight. After that, the
reaction mixture was decomposed with ice at cooling,
the organic layer was separated, and the aqueous layer
was extracted with ether (2 100 ml). The combined
organic phases were dried over K2CO3, the solvent
was evaporated, and the residue was distilled. The fol-
lowing fractions were obtained: the first fraction,
5.0 g, bp 30 60 C (70 mm Hg), a mixture of un-
changed methyl isopropyl ketone and 3,4-dimethyl-1-
pentyn-3-ol, 1 : 1; the second fraction, 75.8 g, bp
60 100 C (70 mm Hg), mainly 3,4-dimethyl-1-pen-
EXPERIMENTAL
The IR spectra were recorded on an IKS-29 spec-
trophotometer from 5% solutions in CCl4 (layer thick-
ness 250 m). The NMR spectra were taken with a
Bruker AC-500 spectrometer (500 MHz, 20 30 vol %
solutions in CDCl3, internal reference HMDS).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

1780
VIKTOROV, ZUBRITSKII
tyn-3-ol; and the residue, 48.0 g, crystallizing on
cooling. Recrystallization of the residue from hexane
gave 22.0 g of pure 2,7-dimethyl-4-octyne-3,6-diol,
(500 MHz), , ppm: 1.08 d (6H, 2CH3, J 6.6 Hz),
2.59 septet (1H, CHC2, J 6.6 Hz), 4.96 s and 4.98 s
(1H and 1H, C1HH), 5.03 d (1H, C4HH, J4, 3 10.9 Hz),
5.26 d (1H, C4HH, J4, 3 17.5 Hz), 6.32 d.d (1H,
C3H, J3,4 10.9, 17.5 Hz). 13C NMR spectrum
(125 MHz), C, ppm: 22.1 (2CH3), 28.6 (CHC2),
112.2 (C1), 112.6 (C4), 138.7 (C3), 152.9 (C2).
1H NMR spectrum of 2,3-dimethyl-1,3-pentadiene
(500 MHz), , ppm: 1.72 d (3H, C5H3, J5, 4 7.0 Hz),
1.74 1.89 (2CH3), 4.84 s and 4.95 s (C1HH), 5.68 q
1
bp 74 75 C. H NMR spectrum (500 MHz), , ppm:
0.98 d and 1.02 d (12H, 4CH3, J 6.8 Hz), 1.43 s (6H,
CH3C3 and CH3C6), 1.79 septet (2H, C2H and C7H,
J 6.8 Hz), 2.43 br.s and 2.46 br.s (2H, 2OH). 13C
NMR spectrum (125 MHz), C, ppm: 17.5 and 17.8
(4CH3), 27.3 (CH3C3 and CH3C6), 38.8 (C2 and C7),
71.5 (C3 and C6), 86.7 (C4 and C5).
1
(1H, C4H, J4, 5 6.8 Hz). H NMR spectrum of 3,4-di-
Repeated fractionation of the combined first and
second fractions gave 69.0 g of 3,4-dimethyl-1-pen-
tyn-3-ol (yield 40%), bp 132 137 C. Published data:
methyl-1,3-pentadiene (500 MHz), , ppm: 1.74 1.89
(3CH3), 4.95 d (C1HH), 5.07 d (C1HH, J1, 2 17.3 Hz),
6.83 d.d (C2H, J2, 1 10.9, 17.3 Hz).
1
bp 134 134.5 C [14]. H NMR spectrum (500 MHz),
, ppm: 0.99 d (3H, C5H3, J5, 4 6.3 Hz), 1.03 d (3H,
CH3C4, J 7.3 Hz), 1.44 s (3H, CH3C3), 1.80 septet
(1H, C4H, J 6.8 Hz), 2.40 br.s (1H, OH), 2.42 s (1H,
C1H). 13C NMR spectrum (125 MHz), C, ppm:
17.2 and 17.6 (2CH3), 27.0 (CH3C3), 38.6 (C4),
71.4 (C3), 71.8 (C1), 86.8 (C2).
2-tert-Butyl-1,3-butadiene was prepared according
to [16]; its constants agreed with published data.
Hydromagnesiation of 2-alkylbutadienes (general
procedure). A one-necked flask purged with argon
(the presence of air, however, does not decrease the
yield) was charged with 0.01 equiv of a catalyst and
1.0 equiv of a diene. The mixture was cooled with ice,
and 1.1 equiv of a solution of alkylmagnesium halide
was added, after which the mixture was allowed to
warm up to room temperature. Then the flask was
equipped with a hydroseal filled with silicone oil.
The mixture was kept for 40 48 h at 20 C with inter-
mittent shaking. Then the mixture was poured onto
excess of crushed dry ice with stirring. After the mix-
ture became liquid, ice and a saturated aqueous solu-
tion of oxalic acid were added to acidic reaction,
avoiding self-heating (acidification with dilute HCl
results in partial isomerization of the methylene dou-
ble bond into an internal double bond). The mixture
was extracted with two portions of ether. The com-
bined extract was shaken with an excess of 10%
NaOH. The alkaline aqueous layer was separated and
washed with ether. Then the alkaline aqueous solution
was cooled with ice and acidified with a saturated
oxalic acid solution; the released carboxylic acids
were extracted with ether. The combined ether extracts
were dried over MgSO4, the solvent was evaporated,
and the residue was vacuum-distilled.
The resulting acetylenic alcohol (69.0 g) was hy-
drogenated at atmospheric pressure in 100 ml of
cyclohexane in the presence of 10.4 g of Lindlar cata-
lyst without adding quinoline for 24 h. After uptake
of the calculated amount of hydrogen ( 15 l), the
filtered solution was distilled with a dephlegmator; the
fraction boiling at 130 135 C (3,4-dimethyl-1-pen-
ten-3-ol) was collected. Yield 65.0 g (93%). Published
1
data: bp 131 C [14]. H NMR spectrum (500 MHz),
, ppm: 0.89 two d (6H, 2CH3, J 6.8 Hz), 1.21 s (3H,
CH3C3), 1.68 septet (1H, C4H, J 6.8 Hz), 2.08 br.s
(1H, OH), 5.03 d (1H, C1HH, J1, 2 10.6 Hz), 5.20 d
(1H, C1HH, J 17.3 Hz), 5.89 d.d (1H, C2H, J2, 1 10.6,
17.3 Hz).
The resulting 3,4-dimethyl-1-penten-3-ol (65 g)
was dehydrated by dropping onto KHSO4 at 200 C,
with simultaneous distillation of the products. The
alcohol dropping rate was adjusted so as to keep the
vapor temperature within 100 C [15]. The distillate
was washed with water (2 50 ml) and dried over
CaCl2. The resulting product (51.0 g) was distilled;
the fraction boiling below 120 C (28.8 g) was col-
lected. After additional drying over CaCl2, this prod-
uct was fractionated. The following fractions were
obtained: the first fraction, 13.1 g, bp 85 87 C, 2-iso-
propylbutadiene, purity 90% (yield 22%, bp 86
87 C [14]); the second fraction, 11.8 g (16%), bp 90
110 C, a mixture of 2,3-dimethyl-1,3-pentadiene and
3,4-dimethyl-1,3-pentadiene, 1 : 1, purity 75%; and
the residue, 2.5 g, mainly unchanged unsaturated
Below we give an example of fractionating the
mixture of carboxylic acids obtained from carboxyla-
tion of the system isoprene (3.4 g) i-PrMgCl THF
Ni(PPh3)2Cl2: the first fraction, 1.7 g, bp 70 85 C
(20 mm Hg), isobutyric acid, traces of butyric acid,
7% impurity of acids IX and X; the second fraction,
0.4 g, bp 100 105 C (20 mm Hg), mixture of acids
IX and X, 2.5 : 1; the third fraction, 1.9 g, bp 145
155 C (20 mm Hg), mixture of acids XI (40%), XII
1
alcohol. H NMR spectrum of 2-isopropylbutadiene
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
1781
(17%), XIII (18%), XIV (7%), XV (4%), and XVI
(C3H, J 7.6 Hz), 4.9 s (C1H2), 4.9 5.0 m (C8H2),
5.65 m (C7H), 12 br.s (CO2H). 13C NMR spectrum
(125 MHz), C, ppm: 19.8 (CH3C6), 19.9 (CH3C2),
27.5 (C5), 34.1 (C4), 37.7 (C6), 53.0 (C3), 113.0
(C8), 144.4 (C1), 141.8 (C2), 143.9 (C7), 180.3
(CO2H).
(4%). The yields of the compounds from the reactions
1
with isoprene are listed in Tables 2 4. H NMR spec-
trum of 2,3-dimethyl-3-butenoic acid IX (without its
isolation; 80 MHz), , ppm: 1.30 d (3H, CH3C2,
J 7.0 Hz), 1.82 s (3H, CH3C3), 3.10 q (1H, C2H,
J 7.0 Hz), 4.87 s (2H, C4H2), 12.5 br.s (1H, CO2H).
13C NMR spectrum (50 MHz), C, ppm: 15.3
(CH3C2), 20.1 (CH3C3), 46.5 (C2), 112.9 (C4), 143.1
(C3), 181.0 (C1).
1H NMR spectrum of 2,2-dimethyl-3-butenoic
acid X (without its isolation; 80 MHz), , ppm: 1.32 s
(6H, 2CH3), 5.04 d.d (1H, C4HH, J 10.5, 1 Hz),
5.09 d.d (1H, C4HH, J 17.5, 1 Hz), 6.03 d.d (1H,
C3H, J 10.5, 17.5 Hz), 12.5 br.s (CO2H). 13C NMR
spectrum (50 MHz), C, ppm: 24.3 (2CH3), 44.6 (C2),
113.2 (C4), 141.9 (C3), 183.2 (C1).
2-(2,5-Dimethyl-2-vinylcyclopentyl)acetic acid
XV and 2-(5-methyl-2-isopropenylcyclopentyl)acetic
acid XVI. A mixture of 27.2 g of isoprene, 250 mmol
of i-PrMgCl in ether, and 1.3 g of Ni(PPh3)2Cl2 was
allowed to stand at room temperature for 24 h. Then
35 ml of Me3SiCl was added with cooling, and the
mixture was allowed to stand for an additional 24 h.
The resulting mixture was poured onto an excess of
crushed dry ice and worked up as described above
(with oxalic acid). After distilling off isobutyric acid
[bp 93 C (80 mm Hg)], 3 ml of water was added to
the residue, and the remaining traces of butyric acids
were steam-distilled. The residue was fractionated; the
fraction with bp 132 134 C (4 mm Hg) was collected
(2.8 g, mixture of acids XV and XVI, 1 : 1, yield
8%). Found, %: C 72.31; H 10.20. C11H18O2. Cal-
culated, %: C 72.49; H 9.95. The NMR spectra
are given in Table 1. The major ( 90%) isomers
in the products are [(1SR,2SR,5SR)-2,5-dimethyl-2-
vinylcyclopentyl]acetic acid and 2-[(1SR,2RS,5SR)-
5-methyl-2-isopropenylcyclopentyl]acetic acid, re-
spectively.
1H NMR spectrum of 3,7-dimethyl-1,7-octadiene-
3-carboxylic acid XI (500 MHz), , ppm: 1.27 s
(CH3C3), 1.41 m (C5H2), 1.56 m and 1.70 m (C4H2),
1.66 s (CH3C7), 1.98 t (C6H2, J 7.2 Hz), 4.64 s and
4.68 s (C8H2), 5.10 d (C1HH, J 11.0 Hz), 5.11 d
(C1HH, J 17.7 Hz), 6.01 d.d (C2H, J 17.7, 11.0 Hz),
11.9 br.s (CO2H). 13C NMR spectrum (125 MHz),
,
C
ppm: 20.1 (CH3C3), 21.9 (CH3C7), 22.1 (C5), 37.8
(C6), 38.3 (C4), 48.2 (C3), 110.2 (C8), 113.8 (C1),
140.9 (C2), 144.8 (C7), 182.6 (CO2H).
1H NMR spectrum of 2,7-dimethyl-1,7-octadiene-
3-carboxylic acid XII (500 MHz), , ppm: 1.41 m
(C5H2), 1.57 m and 1.76 m (C4H2), 1.67 s (CH3C7),
1.75 s (CH3C2), 2.00 m (C6H2), 3.03 t (C3H, J
7.5 Hz), 4.90 s (C1H2), 4.64 s and 4.68 s (C8H2),
2-(2,5-Dimethyl-2-vinylcyclopentyl)acetic acid
XV and (4aSR,5SR,7aRS)-1,1,5-trimethylperhydro-
cyclopenta[c]pyran-3-one XVII. A 40% aqueous so-
lution of HBr (7 ml) was added to 1.7 g of the ob-
tained mixture of acids XV and XVI. The mixture
was shaken on a rocker at room temperature for 10 h,
after which it was extracted with pentane (2 10 ml).
The extract was washed with 10 ml of water and
dried over MgSO4; the solvent was evaporated. The
residue was a 1 : 1 mixture of XV and XVII. This
residue was dissolved in 10 ml of 5 M NaOH; the
solution was extracted with pentane (2 10 ml). The
extract was dried over MgSO4, evaporated, and dis-
tilled [bp 91 92 C (1 2 mm Hg)] to give 0.7 g (82%)
of lactone XVII. The alkaline solution was acidified
with 10% HCl and extracted with pentane (2 10 ml).
The extract was dried over MgSO4, evaporated, and
distilled to give 0.7 g (82%) of pure acid XV, bp 97
98 C (1 mm Hg). Compound XVII. IR spectrum, ,
11.9 br.s (CO2H). 13C NMR spectrum (125 MHz),
,
C
ppm: 19.8 (CH3C2), 21.9 (CH3C7), 25.1 (C5), 29.3
(C4), 37.3 (C6), 52.8 (C3), 110.2 (C8), 114.3 (C1),
141.7 (C2), 144.8 (C7), 180.2 (CO2H).
1H NMR spectrum of 3,6-dimethyl-1,7-octadi-
ene-3-carboxylic acid XIII (without its isolation;
500 MHz), , ppm: 0.98 d (CH3C6, J 7 Hz), 1.26 s
(CH3C3), 1.4 2.2 m (C4H2 + C5H2 + C6H2), 4.9
5.0 m (C8H2), 5.10 d.d (C1H2), 5.65 m (C7H),
6.00 d.d (C2H, J 18 and 11 Hz), 12 br.s (CO2H). 13C
NMR spectrum (125 MHz), C, ppm: 20.0 (CH3C6),
20.1 (CH3C3), 31.0 (C5), 36.5 (C4), 38.0 (C6),
48.2 (C3), 112.9 (C8), 113.9 (C1), 140.9 (C2), 144.0
(C7), 182.5 (CO2H).
1H NMR spectrum of 2,6-dimethyl-1,7-octadi-
ene-3-carboxylic acid XIV (without its isolation;
500 MHz), , ppm: 0.98 d (CH3C6), 1.4 2.2 m
(C4H2 + C5H2 + C6H2), 1.75 s (CH3C2), 3.00 t
1
cm : 2940, 2865, 1750, 1440, 1405, 1370, 1290,
1255, 1223, 1184, 1155, 1130, 970, 950, 930, 908.
1H NMR spectrum (500 MHz), , ppm: 0.96 s (3H,
CH3C9-exo), 0.96 d (3H, CH3C9-endo, J 13.4 Hz),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

1782
VIKTOROV, ZUBRITSKII
1
1.01 d (3H, CH3C5, J6, 5 5.9 Hz), 1.24 m and 1.85 m
(C4H2), 1.79 m (C5H), 1.83 m (C2H), 1.86 m and
2.01 m (C3H2), 2.06 m (C1H), 2.30 d (1H, CHHCO2,
J 18.5 Hz), 2.75 d.d (1H, CHHCO2, J 9.6, 18.5 Hz).
183.3 (C1O2H). To compound XXII in the H NMR
spectrum of the mixture correspond the signals at
4.85 and 4.93 ppm, s (C4H2), and in the 13C NMR
spectrum, the signals at
and 180.8 ppm (C1).
113.3 (C4), 143.7 (C3),
C
13C NMR spectrum (125 MHz),
,
ppm:
16.8 (CH3C9-exo), 17.2 (CH3C9-endo), 18.8C(CH3C5),
32.3 (C4), 34.3 (C3), 35.75 (C2), 35.78 (C7), 42.1
(C5), 48.1 (C1), 100.7 (C9), 176.9 (CO2). Found, %:
C 72.15; H 10.18. C11H18O2. Calculated, %: C 72.49;
Hydromagnesiation of myrcene XXIII. From
8.5 g of myrcene (75% content), 55 mmol of i-PrMgCl
in THF, and 0.327 g of Ni(PPh3)2Cl2, the following
fractions were obtained after distillation: the first frac-
tion, 2.5 g, bp 100 102 C (160 mm Hg), a mixture
of 91% of isobutyric acid (traces of PrCO2H) and 9%
of 2,7-dimethyl-3-methylene-6-octenoic acid XXVII +
3,7-dimethyl-1,6-octadiene-3-carboxylic acid XXVIII,
2 : 1; residue, 0.2 g. Yield of XXVII + XXVIII 5%.
1
H 9.95. Compound XV. IR spectrum, , cm : 3400
2400 br, 1755, 1685, 1620, 1440, 1395, 1370, 1290,
1228, 1180, 910. Acid XVI does not react with con-
centrated HCl solutions at room temperature.
(4aSR,5SR,7aRS)-1-Iodomethyl-5,7a-dimethyl-
perhydrocyclopenta[c]pyran-3-one XVIII. A solu-
tion of 0.4 g of XV in 10 ml of 5% NaHCO3 was
added dropwise with stirring at 20 C to a solution of
0.65 g of KI and 1.0 g of I2 in 5 ml of H2O. The mix-
ture was stirred for 15 min and extracted with ether
(2 15 ml); the extract was washed with a dilute
Na2SO3 solution and dried over MgSO4. The solvent
was vacuum-evaporated. The residue crystallized
From 8.5 g of myrcene (75% content), 55 mmol of
i-PrMgCl in THF, and 0.242 g of NiPy4Cl2, the fol-
lowing fractions were obtained after distillation: the
first fraction, 1.3 g, bp 100 105 C (110 mm Hg),
a mixture of isobutyric (80%) and butyric (20%) acids;
the second fraction, 1.5 g, bp 103 107 C (2 mm Hg),
acids XXVII and XXVIII in a 70 : 30 ratio, yield
16%; the residue, a dark viscous tar, nondistillable at
2 mm Hg (dec.), presumably H(myrcene)2CO2H.
1H NMR spectrum of XXVII (500 MHz), , ppm:
1.28 d (CH3C2, J 7.0 Hz), 1.59 s (CH3C7), 1.66 s
(C8H3), 2.0 2.15 m (C4H2 + C5H2), 3.14 q (C2H,
J 7.0 Hz), 4.92 s and 4.98 s (CH2=C3), 5.10 m
(C6H), 11.9 br.s (C1O2H). 13C NMR spectrum
(125 MHz), C, ppm: 15.9 (CH3C2), 17.5 (CH3C7),
25.5 (C8), 26.3 (C5), 34.6 (C4), 45.5 (C2), 111.3
1
(0.55 g, mainly XVIII, yield 81%). H NMR spec-
trum of the major isomer, XVIII (500 MHz), , ppm:
0.97 s (3H, CH3C7a), 1.05 d (3H, CH3C5, J 6.4 Hz),
1.31 1.43 m (2H), 1.51 m (1H), 1.55 1.68 m (2H),
1.82 m (1H), 2.21 d.d (1H, C4HH, J4, 4 14.6, J4, 4a
11.1 Hz), 2.70 d.d (1H, C4HH, J4, 4 14.6, J4, 4a
6.2 Hz), 3.21 3.32 m (2H, CH2I), 4.21 m (1H, C1H).
13C NMR spectrum of the major isomer, XVIII
(125 MHz), C, ppm: 1.4 (CH2I), 18.1 (CH3), 21.3
(CH3), 33.7 (CH2), 34.3 (CH2), 36.9 (CH2), 44.4
(CH), 46.5 (C7a), 52.0 (CH), 85.6 (C1H), 172.2
(C3).
(CH2=C3), 123.7 (C6), 131.6 (C7), 147.4 (C3), 181.0
1
(CO2H). H NMR spectrum of XXVIII (500 MHz),
, ppm: 1.28 s (CH3C3), 1.56 s (CH3C7), 1.64 s
(C8), 1.5 2.0 m (C4H2 + C5H2), 5.05 5.15 m (C1H2),
5.10 m (C6H), 6.03 d.d (C2H, J1, 2 10.6, 17.6 Hz),
Reaction of isoprene with tert-butylmagnesium
chloride. From 50 mmol of isoprene, 55 mmol of
t-BuMgCl in THF, and 0.5 mmol of Ni(PPh3)2Cl2,
the following fractions were obtained after distillation:
the first fraction, 1.8 g, bp 88 C (40 mm Hg), 2,2-di-
methylpropanoic acid; the residue, 0.3 g of a liquid,
a mixture of 50% of 2,2-dimethylpropanoic acid and
50% of 2-methyl-2-neopentyl-3-butenoic acid XXI
and 3-methyl-2-neopentyl-3-butenoic acid XXII ( 5:1,
11.9 br.s (CO2H). 13C NMR spectrum (125 MHz),
,
C
ppm: 17.4 (CH3C7), 20.0 (CH3C3), 23.2 (C5), 25.4
(C8), 38.9 (C4), 48.3 (C3), 113.8 (C1), 123.6 (C6),
131.8 (C7), 141.0 (C2), 182.5 (CO2H).
Hydromagnesiation of 2-isopropylbutadiene
XXX. A mixture of 6.7 g of 2-isopropylbutadiene,
75 mmol of i-PrMgCl in THF, and 0.458 g of
Ni(PPh3)2Cl2 was allowed to stand for 24 h and
worked up by a common procedure. The residue
(0.2 g) after distilling off 2.9 g of isobutyric acid was
a mixture of unsaturated acids.
1
yield 2%). H NMR spectrum of XXI (500 MHz),
, ppm: 0.95 s [9H, (CH3)3C], 1.37 s (3H, CH3C2),
1.66 d and 1.85 d (1H and 1H, CH2C2, Jgem 14.3 Hz),
5.06 d (1H, C4HH, J4, 3 10.8 Hz), 5.10 d (1H, C4HH,
J4, 3 17.5 Hz), 6.10 d.d (1H, C3H, J3, 4 10.8, 17.5 Hz),
A mixture of 7.2 g of 2-isopropylbutadiene,
100 mmol of i-PrMgCl in THF, and 0.621 g of
Ni(PPh3)2Cl2 was allowed to stand for 100 h and
carboxylated as described above. The following frac-
11.5 br.s (CO2H). 13C NMR spectrum (125 MHz),
,
C
ppm: 22.2 (CH3C2), 31.0 [(CH3)3C], 31.8 [(CH3)3C],
48.2 (CH2C2), 52.6 (C2), 112.8 (C4), 142.8 (C3),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
1783
tions were obtained after distillation: the first fraction,
0.8 g, bp 100 C (100 mm Hg), pure isobutyric acid;
the second fraction, 0.3 g, bp 45 55 C (1 2 mm Hg),
consisting to 80% of a mixture of 2-methyl-3-iso-
propyl-3-butenoic acid XXXV and 2-methyl-2-iso-
propyl-3-butenoic acid XXXVI, 1.5 : 1 (yield 2%);
and the third fraction, 2.2 g, bp 136 142 C (3 mm
Hg), 3,7-diisopropyl-1,7-octadiene-3-carboxylic acid
The following fraction were obtained: the first fraction,
2.1 g, bp 69 74 C (18 mm Hg), isobutyric acid + 6%
PrCO2H; the second fraction, 2.3 g, bp 122 124 C
(18 mm Hg), a mixture of acids XXXV and XXXVI,
1 : 1 (yield 17%); the third fraction, 1.7 g, bp 133 -
136 C (3 mm Hg), a mixture of telodimers consisting
to more than 50% of acid XXXVII (total yield 15%);
and the residue, 1.5 g of a dark tar.
1
XXXVII ( 80% in the mixture). H NMR spectrum
Hydromagnesiation of 2-tert-butylbutadiene
XXXIX. A mixture of 5.5 g of 2-tert-butylbutadiene,
55 mmol of i-PrMgCl in THF, and 0.327 g of
Ni(PPh3)2Cl2 was allowed to stand for 50 h, carboxy-
lated, and distilled. The following fractions were ob-
tained: the first fraction, 2.3 g, bp 100 C (100 mm Hg),
isobutyric acid; the second fraction, 0.2 g (the 1H NMR
spectrum contains noticeable signals of vinyl protons).
of acid XXXV (without its isolation; 500 MHz), ,
ppm: 1.05 d and 1.07 d [(CH3)2CH, J 6.8 Hz], 1.29 d
(CH3C2, J 7.1 Hz), 2.34 septet [(CH3)2CH, J 6.8 Hz],
3.14 q (C2H, J 7.1 Hz), 4.96 s and 4.98 s (C4H2),
12.0 br.s (C1O2H). 13C NMR spectrum (125 MHz),
C, ppm: 17.3 (CH3C2), 21.8 and 22.0 [(CH3)2CH],
33.9 [(CH3)2CH], 43.7 (C2), 109.0 (C4), 154.5 (C3),
181.6 (C1O2H).
A mixture of 5.3 g of 2-tert-butylbutadiene,
55 mmol of i-PrMgCl in THF, and 0.242 g of
NiPy4Cl2 was allowed to stand for 50 h, carboxylated,
and distilled. The following fractions were obtained:
the first fraction, 1.8 g, bp 74 75 C (30 mm Hg), iso-
butyric acid containing 2% PrCO2H; the second frac-
tion, 0.1 g, bp 100 130 C (3 mm Hg), a mixture of
acids XLII and XLIII; the third fraction, 1.0 g, bp
130 150 C (3 mm Hg), a mixture of acids XLII,
XLIII, and XLIV + XLV in the 20 : 20 : 60 ratio;
the fourth fraction, 0.3 g, bp 150 C (3 mm Hg), a mix-
ture of acids XLIV and XLV, 5 : 1; and the residue,
0.8 g, a viscous tar. Total yield of acids XLII and
XLIII ( 1 : 1) 7%; total yield of acids XLIV and
XLV ( 5 : 1) 14%.
1H NMR spectrum of XXXVI (without its isola-
tion; 500 MHz), , ppm: 0.84 d and 0.88 d [(CH3)2CH,
J 6.8 Hz], 1.17 s (CH3C2), 2.15 septet [(CH3)2CH,
J 6.8 Hz], 5.11 d (C4HH, J 17.4 Hz), 5.17 d
(C4HH, J 11.6 Hz), 6.0 d.d (C3H, J3, 4 11.6, 17.4 Hz),
12.0 br.s (C1O2H). 13C NMR spectrum (125 MHz),
C, ppm: 13.9 (CH3C2), 17.1 and 17.6 [(CH3)2CH],
34.5 [(CH3)2CH], 52.4 (C2), 114.9 (C4), 140.3 (C3),
182.9 (C1O2H).
1H NMR spectrum of acid XXXVII (500 MHz), ,
ppm: 0.83
d
and 0.88 d [6H, (CH3)2CHC3,
J 7.0 Hz], 1.00 d [6H, (CH3)2CHC7, J 6.8 Hz],
1.31 m and 1.48 m (C5H2), 1.71 m (C4H2), 2.02 m
(C6H2), 2.08 septet [1H, (CH3)2CHC3, J 7.0 Hz],
2.18 septet [1H, (CH3)2CHC7, J 6.8 Hz], 4.64 s and
4.72 s (2H, C8H2), 5.04 d (1H, C1HH, J 18.0 Hz),
5.28 d (1H, C1HH, J 11.3 Hz), 6.01 d.d (1H,
C2H, J 11.3, 18.0 Hz), 11.5 br.s (CO2H). 13C NMR
spectrum (125 MHz), C, ppm: 16.8 and 18.6
[(CH3)2CHC3], 21.8 [(CH3)2CHC7], 23.2 (C5), 33.4
(C4), 33.5 [(CH3)2CHC7], 34.8 (C6), 35.4 (C9),
56.2 (C3), 106.6 (C8), 115.8 (C1), 135.2 (C2),
155.2 (C7), 182.5 (CO2H).
A 0.1-g portion of the viscous liquid from the
fourth fraction was heated with 1 ml of water to
80 C, and methanol was added dropwise until the
mixture became homogeneous. The solution was left
overnight in a refrigerator ( 8 C), and the colorless
crystals that formed were filtered off and dried in a
desiccator. Pure 2,7-di-tert-butyl-1,7-octadiene-3-car-
boxylic acid XLIV was obtained; mp 73 74 C. IR
1
spectrum, , cm : 3400 2400 br, 1695, 1620, 1470,
1450, 1400, 1360, 1280, 1230, 1200, 1158, 908, 890,
715. Found, %: C 76.32; H 11.41. C17H30O2. Calcu-
lated, %: C 76.64; H 11.35.
A mixture of 5.1 g of 2-isopropylbutadiene, 60 mmol
of i-PrMgCl in THF, and 0.257 g of NiPy4Cl2 was
allowed to stand for 24 h, carboxylated, and distilled.
The following fractions were obtained: the first frac-
tion, 1.7 g, bp 75 90 C (40 35 mm Hg), isobutyric
acid + 6% PrCO2H; and the second fraction, 0.4 g, bp
74 80 C (3 mm Hg), consisting to 75% of a mix-
ture of acids XXXV and XXXVI, 1.5 : 1 (yield 3%).
A mixture of 9.1 g of 2-isopropylbutadiene, 100 mmol
of i-PrMgCl in THF, and 0.46 g of NiPy4Cl2 was al-
lowed to stand for 100 h, carboxylated, and distilled.
1H NMR spectrum of 2-methyl-2-tert-butyl-3-
butenoic acid XLII (500 MHz), , ppm: 0.98 s
[(CH3)3CC2], 1.26 s (CH3C2), 5.07 d (C4HH, J4, 3
17.5 Hz), 5.16 d (C4HH, J4, 3 11.2 Hz), 6.31 d.d (C3H,
J3, 4 11.2, 17.5 Hz), 10.5 br.s (C1O2H). 13C NMR
spectrum (125 MHz), C, ppm: 15.7 (CH3C2), 26.3
[(CH3)3C], 36.1 [(CH3)3C], 54.1 (C2), 114.4 (C4),
139.2 (C3), 181.9 (C1).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

1784
VIKTOROV, ZUBRITSKII
The solvent was evaporated, and the residue was dis-
1H NMR spectrum of 4,5,5-trimethyl-3-hexenoic
acid XLIII (500 MHz), , ppm: 1.04 s [(CH3)3CC4],
1.63 s (CH3C4), 3.08 d (C2H2, J2, 3 6.6 Hz), 5.39 t
tilled; the fraction boiling at 69 70 C (30 mm Hg)
was collected. 3,4,4-Trimethyl-1-chloro-2-pentene,
1
(C3H, J3, 2 6.6 Hz), 10.5 br.s (C1O2H). 13C NMR
spectrum (125 MHz), C, ppm: 13.1 (CH3C4), 28.8
[(CH3)3C], 33.7 (C2), 36.3 [(CH3)3C], 112.0 (C3),
147.3 (C4), 179.2 (C1).
yield 13.4 g (59%). H NMR spectrum (500 MHz),
, ppm: 1.04 s [9H, (CH3)3C], 1.71 s (3H, CH3C3),
4.10 d (2H, C1H2, J1, 2 8.3 Hz), 5.50 t (1H, C2H, J2, 1
8.3 Hz). 13C NMR spectrum (125 MHz), C, ppm:
12.6 (CH3C3), 28.7 [(CH3)3C], 36.4 (C4), 41.6 (C1),
1H NMR spectrum of XLIV (500 MHz), , ppm:
1.03 s and 1.09 s [9H and 9H, 2(CH3)3C], 1.41
1.59 m (C5H2 and C4HH), 1.91 m (1H, C4HH),
2.03 m (2H, C6H2), 3.12 d.d (1H, C3H, J3, 4 9.8,
3.8 Hz), 4.66 s and 4.84 s (2H, C8H2), 5.06 s and
5.07 s (2H, C1H2), 11.7 br.s (CO2H). 13C NMR spec-
trum (125 MHz), C, ppm: 27.7 (C5), 28.7 and 29.3
[2(CH3)3C], 31.0 (C4), 35.0 (C6), 36.0 and 36.9
[2(CH3)3C], 46.3 (C3), 105.8 (C8), 109.3 (C1), 155.6
(C2), 157.5 (C7), 180.8 (CO2H).
1H NMR spectrum of 3,8-di-tert-butyl-3,8-nona-
dienoic acid XLV (without its isolation; 500 MHz), ,
ppm: 1.03 s and 1.06 s [2(CH3)3C], 1.50 1.59 m
(C6H2), 2.0 2.1 m (C5H2 + C7H2), 3.05 3.12 m
(C2H2), 4.69 s and 4.87 s (C9H2), 5.45 m (C4H),
11.7 br.s (C1O2H). 13C NMR spectrum (125 MHz),
C, ppm: 28.5 (C6), 28.7 and 29.3 [2(CH3)3C], 30.2
(C5), 32.0 (C7), 33.8 (C2), 36.1 and 36.7 [2(CH3)3C],
106.3 (C9), 113.3 (C4), 151.2 (C3), 157.2 (C8), 179.1
(C1O2H).
117.3 (C2), 150.5 (C3).
A solution of 6.5 g of 3,4,4-trimethyl-1-chloro-2-
pentene in 20 ml of absolute THF was added drop-
wise with stirring and cooling with water to 2.4 g of
Mg in 100 ml of absolute THF at a rate at which the
mixture did not boil. The ready solution of Grignard
reagent XL was decanted from excess magnesium and
its salts and poured onto an excess of crushed dry ice.
The mixture was acidified with an HCl solution and
extracted with pentane (2 40 ml). The acids were
transferred into an alkaline aqueous solution, which
was then acidified and extracted with pentane (2
30 ml). The extract was evaporated, and the residue
was distilled; bp 90 95 C (2 mm Hg), 1.0 g (14%),
liquid solidifying in a refrigerator to give white crys-
tals of a mixture of 3,4,4-trimethyl-1-pentene-3-car-
boxylic acid XLII and 4,5,5-trimethyl-3-hexenoic
acid XLIII in a 68 : 32 ratio.
Carboxylation of a 1 : 2 mixture of organomagne-
sium compound XL and i-PrMgCl in THF yielded
carboxylic acids XLII and XLIII, 57 : 43. Carboxyla-
tion of Grignard reagent XL prepared in ether yielded
a mixture of acids XLII and XLIII in a 91 : 9 ratio.
Independent synthesis of 3,4,4-trimethyl-2-pen-
tenylmagnesium chloride XL. A solution of 25.2 g of
3,4,4-trimethyl-1-pentyn-3-ol in 70 ml of cyclohexane
was hydrogenated in the presence of 5 g of Lindlar
catalyst and 1 g of quinoline until 4.8 l of hydrogen
was taken up. The solution was filtered, and the sol-
vent was distilled off at temperatures of up to 90 C.
The residue was distilled, and the fraction boiling
at 56 C (35 mm Hg) was collected. 3,4,4-Trimeth-
ACKNOWLEDGMENTS
The study was financially supported by the Russian
Foundation for Basic Research (project no. 97-03-
33056a).
1
REFERENCES
yl-1-penten-3-ol, yield 20.2 g (79%). H NMR spec-
trum (500 MHz), , ppm: 0.93 s [9H, (CH3)3C],
1.23 s (3H, CH3C3), 5.08 d (1H, C1HH, J1, 2 11.1 Hz),
5.21 d (1H, C1HH, J1, 2 17.0 Hz), 6.07 d.d (1H, C2H,
J2, 1 11.2, 17.0 Hz).
1. Viktorov, N.B., Zubritskii, L.M., and Petrov, A.A.,
Zh. Obshch. Khim., 1993, vol. 63, no. 7,
pp. 1601 1606.
2. Viktorov, N.B. and Zubritskii, L.M., Zh. Obshch.
Khim., 1995, vol. 65, no. 2, pp. 311 314.
Thionyl chloride (19.3 g) was added dropwise with
stirring and cooling with ice to a mixture of 20.0 g of
3,4,4-trimethyl-1-penten-3-ol and 12.6 g of pyridine
in 70 ml of absolute ether. The resulting white sus-
pension was allowed to stand for 2 h at 15 20 C and
then decomposed by adding water until the precipitate
completely dissolved. The ether layer was separated,
washed with water (2 50 ml), and dried over CaCl2.
3. Neilan, J.P., Laine, R.M., Cortese, N., and Heck, R.F.,
J. Org. Chem., 1976, vol. 41, no. 21, pp. 3455 3460.
4. Oppolzer, W., Angew. Chem., Int. Ed., 1989, vol. 28,
no. 1, pp. 38 52.
5. Negishi, E., Jesen, M.D., Kondakov, D.Y., and
Wang, S., J. Am. Chem. Soc., 1994, vol. 116, no. 18,
pp. 8404 8405.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001

CATALYTIC HYDROMAGNESIATION OF 2-ALKYLBUTADIENES
1785
6. Viktorov, N.B. and Zubritskii, L.M., Zh. Org. Khim.,
Jones, D.A., J. Am. Chem. Soc., 1969, vol. 91, no. 1,
1997, vol. 33, no. 3, pp. 351 362.
pp. 132 137.
7. Comprehensive Coordination Chemistry, Wilkin-
son, G., Ed., Oxford: Pergamon, 1987, vol. 2,
pp. 1016 1031.
8. Couperus, P.A., Clague, A.D.H., and Don-
gen, J.P.C.M. van, Org. Magn. Reson., 1976, vol. 8,
pp. 426 431.
9. Bible, R.H., Jr., Interpretation of NMR Spectra.
An Empirical Approach, New York: Plenum, 1965.
Translated under the title Interpretatsiya spektrov
yadernogo magnitnogo rezonansa, Moscow: Atom-
izdat, 1969.
12. Cherest, M., Felkin, H., and Frajerman, C., Tetra-
hedron Lett., 1971, no. 5, pp. 379 382.
13. Organic Syntheses, Blatt, A.H., Ed., New York:
Wiley, 1944. Translated under the title Sintezy orga-
nicheskikh preparatov, Moscow: Inostrannaya Lite-
ratura, 1949, coll. 2, pp. 323 325.
14. Nazarov, I.N. and Mavrov, M.V., Zh. Obshch. Khim.,
1959, vol. 29, no. 4, pp. 1158 1168.
15. Arai, A. and Ichikizaki, I., Bull. Chem. Soc. Jpn.,
1962, vol. 35, no. 1, pp. 45 51.
10. Bohlmann, F., Zeisberg, R., and Klein, E., Org. Magn.
Reson., 1975, vol. 7, pp. 426 432.
11. Benkeser, R.A., Young, W.G., Braxterman, W.E., and
16. Huyser, E.S., Siegert, F.W., Sinnige, H.J.W., and
Wynberg, H., J. Org. Chem., 1966, vol. 31,
pp. 2437 2441.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001