Electrochemical alkyl transfer reaction from trialkylboranes to polyhalo compounds

Article abstract of DOI:10.1016/j.jorganchem.2006.03.030

Reduction of decyl dichloro- and trichloroacetate, under mild electrolysis conditions by using the sacrificial anode process, affords α-chlorocarbanions which readily react with trialkylboranes to give alkylated products in a one step reaction.

Full text of DOI:10.1016/j.jorganchem.2006.03.030

Journal of Organometallic Chemistry 691 (2006) 3245–3250
www.elsevier.com/locate/jorganchem
Electrochemical alkyl transfer reaction from trialkylboranes
to polyhalo compounds
*
´ ´
Sylvie Condon , Chunhai Zou, Jean-Yves Nedelec
`
´
Laboratoire d’Electrochimie Catalyse et Synthese Organique, Universite Paris XII, CNRS, UMR 7582, 2 rue Henri Dunant 94320 Thiais, France
Received 16 January 2006; received in revised form 17 March 2006; accepted 17 March 2006
Available online 24 March 2006
Abstract
Reduction of decyl dichloro- and trichloroacetate, under mild electrolysis conditions by using the sacrificial anode process, affords a-
chlorocarbanions which readily react with trialkylboranes to give alkylated products in a one step reaction.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Electrochemistry; Alkylation; Trialkylborane; Polyhalo compound
1. Introduction
[4] in the mechanism has been suggested. Efficient reactions
of trialkylboranes with a,b-unsaturated esters to give 1,4-
addition products [5], as well as reactions with carbonyl
compounds [6] to give alcohols or ketones, have also been
described. Reduction of gem-dihalides under electrochemi-
cal conditions (Scheme 1, path B) is a straightforward alter-
native to obtain a-halocarbanions. We have reported that
reactions of polyhalo compounds with electrophiles can
be conducted in an undivided electrochemical cell by using
the sacrificial anode procedure [7]. Under these conditions,
selective reduction of easily electro-reducible compounds
(CCl4, PhCCl3, CCl3CO2Me, PhCHCl2, CH2Br2) affords
stable a-halogenated anions which then react with ketones
[7], aldehydes [8] and electron deficient olefins [9]. These
reactions usually take place at room temperature. The
use of the sacrificial anode process involves the release of
metallic cations in the reaction mixture and thus affords
formation of metalated species, which do not lead to car-
bene species. The reaction with trialkylboranes has not
been investigated thus far.
The ability of trialkylboranes to transfer alkyl groups is
a useful feature and has been advantageously applied to
CAC bond formation. The alkyl transfer from boron to
electrophilic carbon is usually promoted by an attack of
a nucleophile. If this reagent bears a leaving group, then
in the next step, an intramolecular substitution would
occur easily. Thus, the reaction is often conducted at low
temperature, under basic conditions for the preparation
and the stability of the a-halocarbanion. In the chemical
route reported by Brown et al., reaction of R3B with a-
haloesters, nitriles, ketones [1] and haloforms [2] is induced
by a sterically hindered strong base. The process involves
(i) formation of the carbanion by removal of an acidic
hydrogen (ii) formation of the organoborate (iii) 1,2-alkyl
transfer (Scheme 1, path A). Electroreduction chemistry
is also a convenient method to generate nucleophilic species
in non-basic conditions. Some reactions involving electro-
chemical alkyl transfer reaction of trialkylborane have
been reported in the literature. Suzuki et al. [3] reported
the electrochemical alkylation of compounds containing
acidic hydrogen by trialkyboranes. Involvement of radicals
Here, we report mainly our first results on the alkylation
of decyl dichloro- and trichloroacetate with triethylborane
(Scheme 2) under simple, mild electrolysis in N,N-dimethy-
lacetamide (DMAc). A widening of the method to sterically
different trialkylboranes and gem-polyhalo compounds is
also introduced at the end of this paper.
*
Corresponding author. Tel.: +33 1 4978126; fax: +33 1 49781148.
E-mail address: Sylvie.condon@glvt-cnrs.fr (S. Condon).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.03.030

3246
S. Condon et al. / Journal of Organometallic Chemistry 691 (2006) 3245–3250
H
Cl
2e-
Et3B
2 B
R
-CCl2-CO2C10H21
R1
R1
1a
Et3B C CO2C10H21
R1
R2
BR3
BH
Cl
6
BR2
R2
Cl (A)
Cl
Cl
Et
7
SNi
R3B
R1
R2
R1
2 e-
H+/H2O
Cl
Et
OC10H21
OBEt2
2a
R2 -(B)
-Cl
Cl
R
Et2B C CO2C10H21
9
Cl
8
Cl
Scheme 1.
Scheme 3.
the main product along with, depending on the conditions,
decyl 2-ethylbutanoate 3, decyl 2,2-dichloroacetate 1b, dec-
anol 4 and succinate 5. Formation of 2a can be explained
(Scheme 3) by bi-electronic reduction of 1a to give carban-
ionic dihalide 6 which then reacts with Et3B to form orga-
noborate 7. Then 1,2-migration occurs and the resulting
a-chloroborylester 8 tautomerizes to alkenyloxyborane 9.
Under the above described electrochemical conditions,
only a small excess of R3B (1.14 equiv.) is required. Only
one out of the three alkyl groups of the trialkylborane is
transferred to the organic halide. Chemical yields are
higher with zinc and magnesium (Table 1, entries 1 and
4) as the anode than with iron and aluminum. Also, taking
into account that 1 h is required for full consumption of the
starting halo compound, some chemical reduction should
occur at the polarized zinc or magnesium anode accounting
for the shorter reaction times. Reduction products are also
formed in yields depending on the anode. Product 1b is
formed by simple protonation of 6 and this importantly
occurs with iron and aluminum (Table 1, entries 2 and
3). The reduction of the ester group leading to 4 has
already been observed with magnesium [10] as the anode.
By holding the electrosynthesis for 2 extra hours, decyl but-
anoate 2b, which is not observed otherwise, is obtained as
the main product (isolated yield 59%). Two pathways
(Scheme 4) can be proposed to account for the formation
of 2b. In the first pathway, reduction of a-chloroborylester
8 occurs and decyl propanoate 2b is obtained after proton-
ation. The second pathway is based on the in situ forma-
tion of 2a by protonation of alkenyloxyborane 9 because
of the presence of residual water in the solvent, followed
by bi-electronic reduction to 12.
1. Et3B / 2e-
2. H+/ H2O
Et
CH
2
R1CCl2CO2R2
R1
CO2R
1a R1: Cl
2a R1: Cl
2b R1: H
R2: C10H21
1b R1: H
Scheme 2.
2. Results and discussion
Reactions are carried out in an undivided cell, equipped
with a stainless steel grid (area 30 cm2) as the cathode and a
metal rod (see below) as the anode. Trialkylborane
(4 mmol; 1 N in THF) is added at room temperature in
one portion to a stirred solution of the organic halide
(3.5 mmol) and NBu4Br as supporting electrolyte in DMAc
(20 mL). Electrolysis is run at constant current density
(0.66 A dmÀ2). The temperature is allowed to rise gradually
to ca. 40 ꢁC. The cathode potential throughout the electrol-
ysis is at À1.2 V vs. SCE. The current is turned off after
consumption of the polyhalo compound, as monitored by
GC analysis. Then the reaction is stirred for 20 min and
quenched by HCl. After the work up, the products are
purified by column chromatography.
We first examined reaction of decyl trichloroacetate 1a
with triethylborane. The obtained results are summarized
in Table 1 for each anode routinely used in electrosynthe-
sis. With every tested anode, reduction of decyl trichloroac-
etate occurs and decyl 2-chlorobutanoate 2a is formed as
Table 1
Attempts to trap intermediates 10 and 12, under elec-
trolysis conditions, have been conducted after full con-
sumption of starting material 1a by adding methyl vinyl
ketone (MVK) as the electrophile. The expected coupling
Anode effect in the reaction of decyl trichloroacetate 1a with triethylbo-
rane
1. Et3B, 2e-
2. H+/H2O
Et-CHCl-CO R
Et-CH-CO2R
+
+
1a
2
2a
Et
3
+
Cl2CH-CO2R
C10H21OH
(CH2-CO2R)2
+
R: C10H21
1b
4
5
Et
2e-
H
C
Entrya Anode Reaction time Yield (%)b 2a Other products (%)c
H2O
Et2B C CO2R
Et2B
C
CO2R
Et2B
CO2R
1
2
3
4
Zn
Fe
Al
30 min
1 h 15 min
1 h
59
31
36
45
3: 8
1b: 20; 5: 20
1b: 35
Cl
8
10
11
Et
Et
in or ex situ
Et
2e-
H
Cl
Et
H2O
OR
H
C
CO2R
C
CO2R
Mg
30 min
1b: 13; 4: 6
in situ
OBEt2
9
Cl
2a
Et
a
Decyl trichloroacetate 3.5 mmol; Et3B 4 mmol (1 N in THF); solvent:
12
H2O
DMAc 20 mL; supporting electrolyte NBu4Br; temperature: 20 ꢁC;
stainless steel cathode; I = 0.2 A; anticipated reaction time 1 h.
Et-CH2-CO2R
11
12
and/or
R: C10H21
2b
b
Isolated yield.
Determinated by GC.
c
Scheme 4.

S. Condon et al. / Journal of Organometallic Chemistry 691 (2006) 3245–3250
3247
product did not occur and only 2b was obtained. The sac-
rificial anode process associated with transition metal as
the catalyst is also an efficient method to allow activation
of organic halides, in mild reaction conditions, and further
reaction with electrophile. We thus decided to perform a
tion of 1b occurs, 2b is obtained but more decanol (Table 2,
entry 5) is observed. An explanation to account for the
uncontrolled formation of decanol, would be the chemical
reduction of the ester group at the surface of the anode and
this occurs more importantly when a magnesium rod is
used. Formation of desired compound 2b and side product
2a is depicted in Scheme 6.
Reduction of decyl dichloroacetate 1b affords formation
of the carbanionic species 15 (A) which either reacts with
triethylborane (C) to give expected compound 2b or reacts
(B) with its precursor 1b to give carbanionic species 6. This
latter also undergoes reaction (D) with triethylborane to
give compound 2a. Compound 2a coming from 8 and 9
can be transformed into 2b by maintaining electron supply
(Scheme 4) for 15 min (Table 2, entry 3). Then we have
examined whether the reaction can be extended to other
organoboranes and gem-dihalo compounds from commer-
cial sources. Particularly the length and the steric hindrance
of the transferable groups as well as steric and electronic
effects on the electrophilic carbon of the organic halide
have been considered.
coupling reaction of a-chloroborylester
8
and/or
alkenyloxyborane 9 and methyl vinyl ketone under the con-
ditions described for the conjugate addition reaction [11] of
organic halides with activated olefins mediated by nickel
catalysis. NiBr2 Æ 3H2O as the catalyst precursor, pyridine
as the cosolvent and MVK (2.5 equiv.) were successively
added after full consumption of 1a (Scheme 3). The zinc
anode was replaced by iron which is the most appropriate
for the conjugate addition reaction [11] and electrolysis was
run at 70 ꢁC. A mixture of 1,2- and 1,4-adducts (13 and 14)
in a 34/66 ratio in GC was obtained and these were isolated
in 13% and 34% yield, respectively (Scheme 5).
We also investigated the behaviour of decyl dichloroac-
etate 1b with triethylborane in these reaction conditions.
Results are reported in Table 2. Decyl butanoate 2b is
obtained as the main product along with decyl 2-chlorobut-
anoate 2a, decyl chloroacetate 16, decyl acetate 17 and dec-
anol. Comparison of zinc and magnesium has been
achieved. Full consumption of the starting material 1b is
reached after 1 h which means that no chemical reduction
occurs at the surface of the anode (Table 2, entries 2 and
5). The best result is again obtained with zinc as the con-
sumable anode. In the presence of a magnesium rod, reduc-
In Table 3 are reported the results we have obtained
until now. A noticeable disparity in chemical yields was
found between sterically different trialkylboranes (entries
4, 5 vs. 1) as well as sterically hindered gem-polyhalide
derivatives (entries 6–8 vs. 1). Also, yields decrease with
2e-
Cl-CH-CO2R
(A)
Cl2CH-CO2R
+
1b
15
(B)
Et
Cl-CH -CO R
16
Cl2C-CO2R +
2
2
Cl-CH-CO R Cl2CH-CO2R
+
2 15
Et3B
Cl
Et
OC10H21
OBEt2
2e- / Fe, 70˚C
2e-/Zn
6
1a
Et2B C CO2C10H21
1b
Et3B
Et
(C)
Et2B
9
(D)
Et2B
Cl 8
H
C
CO2R
C
CO2R
9
NiBr2.3H2O 5%
2.4 eq MVK
Et
Cl
11
8
H+/H2O
Et
H+/H2O
Et-CH2-CO2R
O
Et
+
CO2C10H21
CO2C10H21
H
C
CO2R
2a
2b
H3C OH
13
14
Et
Cl
Scheme 5.
Scheme 6.
Table 2
Reaction of decyl dichloroacetate with triethylborane
1. Et3B, 2e-
2. H+/H2O
Cl2CH-CO2R
1b
R: C10H21
Et-CH -CO R Et-CHCl-CO2R+ ClCH -CO R
CH -CO R C10H21OH
+
+
+
2
2
2
2
3
2
2b
2a
16
17
4
Entrya
Anode
Time
% GC
Isolated yield%
2b
2a
16
17
4
1b
2b
1
2
3
4
5
a
Zn
Zn
Zn
Mg
Mg
30 min
1 h
1 h 30 min
30 min
1 h
55.5
76.5
86.5
31
7
7
0
4.5
1
14
14
0
18
10
1.5
1.5
13.5
5
0
0
0
15
32
23
1
0
20
2
71
23
44
9
Decyl dichloroacetate 3.5 mmol (0.14 N); Et3B 4 mmol (1 N in THF); solvent: DMAc; supporting electrolyte: NBu4Br; 20 ꢁC; stainless steel cathode;
I = 0.2 A; anticipated reaction time: 1 h.

3248
S. Condon et al. / Journal of Organometallic Chemistry 691 (2006) 3245–3250
Table 3
4. Experimental
Reaction with various trialkylboranes
-
,
H
1. 2e , DMAc
2. H+/H2O
All solvents and reagents were purchased from commer-
cial sources and used as received unless indicated. N,N-
dimethylacetamide (DMAc) is of spectrophotometric grade
99+%- water content 0.05% and is stored under an argon
atmosphere. Triethylborane (1 M in THF) tri-nbutylbo-
rane (1 M in diethyl ether) and sec-butylborane (1 M in
Et2O) are the commercial products. Tricyclohexylborane
and trioctylborane have been prepared by hydroboration
[12] from the corresponding alkene and standardized by
oxidation with alkaline-hydrogen peroxide. Decyl dichlo-
roacetate and decyl trichloroacetate were prepared by
esterification from dichloro- and trichloroacethyl chloride.
GC analysis was carried out using a 25 m DB-1 capillary
+
R1 C CO2R2
R
R1CCl2CO2R2
R3B
Entry Chlorinated compoundsa R3B
No. Isolated yield (%)
1
2
3b
4b
5
Cl2CH–CO2C10H21
Cl2CH–CO2C10H21
Cl2CH–CO2C10H21
Cl2CH–CO2C10H21
Cl2CH–CO2C10H21
Cl3C–CO2C10H21
Et3B
nBu3B
nOct3B
(C6H11)3B 20
secBu3B
Et3B
2b
18
19
71
62
47
30
32
59
47
40c
21
2a
22
23
6
7
8
Cl2(CH3)C–CO2C10H21
Cl2(OCH3)C–CO2CH3
Et3B
nBu3B
a
Chlorinated compound 3.5 mmol; R3B 4 mmol (1 N in THF or Et2O);
solvent DMAc; supporting electrolyte NBu4Br; zinc anode; temperature
20 ꢁC; Intensity 0.1–0.2 A.
1
column. H and 13C spectra were recorded on a Bruker
b
Trialkylboranes prepared by hydroboration reaction from corre-
Avance 300 spectrometer unless indicated. Mass spectra
were obtained on a GCQ Thermoquest spectrometer cou-
pled to a chromatograph fitted with a 25 m CPSIL5 CB
capillary column. The electrochemical cell has been previ-
ously described [7].
sponding alkenes.
c
Determinated by standard internal GC.
the lengthening of the transferable alkyl group (entries 1–3).
However, the successful alkylation of decyl 2,2- dichloro-
propanoate (entry 7) and methyl dichloromethoxy-acetate
(entry 8) indicates that the reaction is not confined to the
alkylation of decyl trichloroacetate and dichloroacetate
and allows envisaging further extension to various poly-
halo compounds.
4.1. Electrochemical procedure for the preparation of decyl
butanoate (2b)
The reaction was conducted in an undivided cell
equipped with stainless steel grid (area 30 cm2) as the cath-
ode and zinc rod as the anode. Triethylborane (4 mL,
4 mmol) was added at 20 ꢁC in one portion to a stirred
solution of decyl dichloroacetate 1b (0.94 g; 3.5 mmol)
and tetrabutylammonium bromide (0.20 g; 0.62 mmol) as
supporting electrolyte in DMAc (20 mL). Electrolysis was
run at constant current density (0.66 A dmÀ2). Tempera-
ture was allowed to rise gradually to 40 ꢁC. The current
was turned off after consumption of 1b and after the reduc-
tion of side product, decyl 2-chlorobutanoate 2a, con-
trolled by GC monitoring. Then reaction was stirred for
15 min and quenched by HCl 1 N. The mixture was then
extracted twice with diethylether (2 · 40 mL), dried over
MgSO4, evaporated to dryness. Purification by column
chromatography over silica gel (eluting with 9.5:0.5 pen-
tane/ethyl ether) gave 2b (0.57 g; 71%) as a liquid.
3. Conclusions
We have described, in this paper, the reaction of poly-
halogenated derivatives with trialkylboranes to afford a-
alkylated esters with moderate to good yields. The reac-
tions are conducted in an undivided cell fitted with a con-
sumable zinc rod under mild electrochemical conditions.
Products of the reaction of decyl dichloroacetate and tri-
chloroacetate with alkylboranes are indeed accessible
under Brown reaction conditions from chloroacetates and
dichloroacetates. However, under electrolysis, carbanions
are smoothly obtained and the use of strong base is dis-
carded. Alkylation of polyhalo compounds such as decyl
2,2-dichloropropanoate and methyl dichloromethoxyace-
tate illustrates the potential of this new method. Recently,
we have found that the method can also be applied to the
alkylation of benzal halides.
4.1.1. Decyl butanoate (2b)
1
Colourless oil; H NMR (300 MHz, CDCl3) d 4.01 (t,
2H, J = 6.72 Hz), 2.23 (t, 2H, J = 7.40 Hz), 1.60 (m, 4H),
1.36–1.12 (m, 14H), 0.90 (t, 3H, J = 7.40 Hz), 0.83 (t, 3H,
3
1. e-
J = 6.63 Hz). C NMR (75.46 MHz, CDCl3) d 173.8, 64.4,
OH
CH
2. H2O2, OH-
36.3, 31.9, 29.5 (2C), 29.3, 29.2, 28.7, 25.9, 22.7, 28.5,
14.1, 13.7. EIMS (m/z), 229, 213, 185, 157, 140, 126, 111,
97, 89, 83, 69, 55 (100%). IR (NaCl) m 2958, 2922, 2856,
1740, 1466, 1254, 1181, 723 cmÀ1. Anal. Calc. for
C14H28O2: C, 73.63; H, 12.36. Found: C, 73.58; H, 12.32%.
PhCHCl2
Et3B
Ph
Et
+
Study of the reaction conditions (temperature, solvent,
concentration of starting material) and extension to other
pohyhalide derivatives (haloform, PhCHCl2, RRCCl2) to
define the scope and limitation of the method are
underway.
4.1.2. Decyl 2-chlorobutanoate (2a)
Prepared according to the procedure described above.
1
Colourless oil; H NMR (200 MHz, CDCl3) d 4.15 (dd,

S. Condon et al. / Journal of Organometallic Chemistry 691 (2006) 3245–3250
3249
1H, J = 7.41 and 6.34 Hz), 4.10 (t, 2H, J = 6.65 Hz), 1.93
(m, 2H), 1.59 (m, 2H), 1.36–1.13 (m, 14H), 0.96 (t, 3H,
J = 7.32 Hz), 0.81 (t, 3H, J = 6.73 Hz). 13C NMR
(50.32 MHz, CDCl3) d 169.4, 65.7, 58.7, 31.6, 29.2 (2C),
29.0, 28.9, 28.2, 28.1, 25.5, 22.4, 13.8, 10.2. EIMS (m/z),
265, 263, 228, 199, 185, 163, 141, 123, 97, 83, 69, 55
(100%). IR (NaCl) m 2958, 2927, 2855, 1742, 1461, 1175,
735 cmÀ1. 1H and 13C spectra are consistent with authentic
sample prepared from decyl dichloroacetate and triethylbo-
rane following procedure reported in literature [12].
ture was allowed to rise gradually to 40 ꢁC. The current
was turned off after consumption of 1a. Zinc rod was then
replaced by iron rod. Pyridine (2.50 mL) as co-solvent was
added in the cell followed by introduction of NiBr2 Æ 3H2O
(0.33 mmol; 72 mg) and methyl vinyl ketone (0.58 g;
8.27 mmol). The mixture was heated at 70 ꢁC and electro-
synthesis was run at constant current intensity
(0.66 A dmÀ2). The reaction was monitored by GC and
current was turned off after consumption of decyl 2-chloro-
butanoate which is the protonated form of a-chlorobory-
lester 8 and alkenyloxyborane 9. Then the reaction
mixture was quenched by HCl 1 N, extracted twice with
diethylether (2 · 40 mL), dried over MgSO4 and evapo-
rated to dryness. After purification by column chromatog-
raphy on silica gel (230–400 Mesh, eluent: pentane/diethyl
ether 9.5:0.5), 0.13 g (13%) of 13 and 0.34 g (34%) of 14
were obtained.
4.1.3. Decyl 3-methylpentanoate (21)
Prepared according to the procedure described above.
Colourless oil; 1H NMR (300 MHz, CDCl3) d 4.09 (t,
2H, J = 6.70 Hz), 2.33 (dd, 1H, J = 14.55 and 6.15 Hz),
2.13 (dd, 1H, J = 14.55 and 8.10 Hz), 1.92 (m, 1H), 1.65
(m, 2H), 1.39–1.28 (m, 16H), 0.95 (t, 3H, J = 7.20 Hz),
0.90 (m, 6H). 13C NMR (75.46 MHz, CDCl3) d 173.5,
64.3, 41.6, 32.0, 31.9, 29.5 (2C), 29.3 (2C), 29.2, 28.7,
26.0, 22.7, 19.3, 14.1, 11.3. EIMS (m/z), 257, 227, 185,
157, 141, 117 (100%), 97, 83, 69, 55; IR (NaCl) m 2958,
4.2.1. Decyl 2-ethyl-3-hydroxy-3-methylpent-4-enoate (13)
Compound 13 is a mixture of two diastereoisomers in
1/1 ratio:
2927, 2855, 1737, 1464, 1181, 722 cmÀ1
.
1H NMR (300 MHz, CDCl3) d 5.93 (dd, 1H, J trans:
17.2 Hz, J cis: 10.65), 5.77 (dd, 1H, J trans: 17.2 Hz, J
cis: 10.73), 5.32 (dd, 1H, J trans: 17.2 Hz, J gem: 1.55),
5.27 (dd, 1H, J trans: 17.2 Hz, J cis: 1.27 Hz), 5.12 (dd,
1H, J trans: 10.73 Hz, J gem: 1.55 Hz), 5.04 (dd, 1H, J
trans: 10.65 Hz, J gem: 1.27 Hz), 4.08 (t, 2H, OCH2, J:
6.66 Hz), 4.15 (t, 2H, OCH2, J: 6.66 Hz), 3.20 (s,
2 · OH), 2.39 (dd, 1H, J: 10.58 Hz, J: 4.76 Hz), 2.34 (dd
1H, J: 10.72 Hz, J: 4.31 Hz), 1.8–1.6 (m, 2 · 4H), 1.29–
1.26 (m, 2 · 17H), 0.90 (m, 2 · 6H). EIMS (m/z), 299
(M+1), 281 (MÀ18), 271, 251, 229, 185, 143, 131, 125,
111, 97, 89, 73 (100%), 55.
4.1.4. Decyl 2-methylbutanoate (22)
Prepared according to the procedure described above.
Colourless oil; 1H NMR (300 MHz, CDCl3) d 4.09 (t,
2H, J = 6.59 Hz), 2.40 (sextuplet, 1H, J = 6.98 Hz), 1.78–
1.60 (m, 3H), 1.50 (m, 1H), 1.40–1.25 (m, 14H), 1.17 (d,
3H, J = 6.98 Hz), 0.92 (m, 6H). 13C NMR (75.46 MHz,
CDCl3) d 176.8, 64.3, 41.2, 31.9, 29.5 (2), 29.3, 29.2, 28.7,
26.8, 25.9, 22.7, 16.7, 14.1, 11.6. EIMS (m/z), 243, 185,
158, 140, 111, 103 (100%), 97, 83, 75, 69, 57. IR (NaCl) m
2958, 2926, 2856, 1736, 1463, 1381, 1184, 1153, 734 cmÀ1
.
Anal. Calc. for C15H30O2: C, 74.32; H, 12.47. Found: C,
74.40; H, 12.50%.
4.2.2. Decyl 2-ethyl-5-oxohexanoate (14)
1H NMR (300 MHz, CDCl3) d 3.99 (2H, t, J: 6.67 Hz),
2.36 (2H, t, J: 6.63 Hz), 2.19 (1H, m), 2.04 (3H, s), 1.72
(2H, q, J: 7.34 Hz), 1.54 (2H, m), 1.45 (2H, m), 1.28–1.10
(14H, m), 0.80 (6H, m). 13C NMR (75.46 MHz, CDCl3) d
175.6, 64.2, 46.3, 41.0, 31.8, 29.8, 29.4 (3C), 29.2, 29.1,
28.6, 25.9, 25.5, 25.4, 22.6, 14.0, 11.6. EIMS (m/z), 298,
241, 185, 159, 141, 112 (100%), 97, 81, 55. IR (NaCl)
1720 cmÀ1. Anal. Calc. for C18H34O3: C, 72.44; H, 11.48.
Found: C, 72.41; H, 11.46%.
4.1.5. Methyl 2-methoxyhexanoate (23)
Prepared according to the procedure described above.
Colourless oil; 1H NMR (300 MHz, CDCl3) d 3.76 (m,
4H), 3.38 (s, 3H), 1.73–1.69 (m, 2H), 1.43–1.22 (m, 4H),
0.90 (m, 3H); 13C NMR (75.46 MHz, CDCl3) d 173.4,
80.6, 58.1, 51.8, 32.5, 27.2, 22.4, 13.9. EIMS (m/z), 159,
131, 115, 101, 87 (100%), 72. IR (NaCl) m 2957, 2874,
1752, 1459, 1437, 1200, 1167, 735 cmÀ1. 1H and 13C spectra
are consistent with literature data [13].
References
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2018.