Triethylaluminum- or triethylborane-induced free radical reaction of alkyl iodides and α,β-unsaturated compounds

Article abstract of DOI:10.1021/jo020681b

A series of α,β-unsaturated compounds, 1a-c, 9, 13, and 17, were used as reactants in free radical conjugate addition reactions with different radicals generated from alkyl iodides such as 3, 4, or 5 in the presence of triethylborane-oxygen in air or via the use of triethylaluminum-benzoyl peroxide as a free radical initiator. When the reactions were carried out using triethylborane-air, the products, in most cases, were clean and were easily purified. However, higher yields of the 1,4-adducts and less side reactions occurred when less reactive substrates were used as Michael acceptors in reactions with triethylaluminum-benzoyl peroxide and alkyl iodide under similar conditions. A mechanism for this is proposed in Scheme 1.

Full text of DOI:10.1021/jo020681b

Triethylaluminum- or Triethylborane-Induced Free Radical
Reaction of Alkyl Iodides and r,â-Unsaturated Compounds
†
†
†
‡
,†
Jing-Yuan Liu, Yoeng-Jiunn Jang, Wen-Wei Lin, Ju-Tsung Liu, and Ching-Fa Yao*
Department of Chemistry, National Taiwan Normal University, 88, Section 4, Tingchow Road,
Taipei, Taiwan 116, ROC, and Army Force of Military Police School, P.O. Box 90092,
Wugu, Taipei, Taiwan 248, ROC
cheyaocf@scc.ntnu.edu.tw
Received November 4, 2002
A series of R,â-unsaturated compounds, 1a-c, 9, 13, and 17, were used as reactants in free radical
conjugate addition reactions with different radicals generated from alkyl iodides such as 3, 4, or 5
in the presence of triethylborane-oxygen in air or via the use of triethylaluminum-benzoyl peroxide
as a free radical initiator. When the reactions were carried out using triethylborane-air, the
products, in most cases, were clean and were easily purified. However, higher yields of the 1,4-
adducts and less side reactions occurred when less reactive substrates were used as Michael
acceptors in reactions with triethylaluminum-benzoyl peroxide and alkyl iodide under similar
conditions. A mechanism for this is proposed in Scheme 1.
Introduction
Reactions of â-nitrostyrenes with organometallic re-
complexes has been shown to be an efficient method for
enantioselective carbon-carbon bond formation.
Utimoto and Oshima were the first to apply the
1
4
1a
1b,c
agents such as dialkylzinc or organozinc halides,
reaction of triethylborane with oxygen to initiate radical
2
3
t-BuHgX/KI, organomanganese, trialkylaluminum or
15
reactions. Over classical initiators, the system Et
3
B/O
2
4
5
dialkylaluminum chloride, trialkylgallium, and Grig-
nard reagents lead to the generation of alkenes and/or
offers the great advantage of being efficient even at low
temperature (-78 °C). Organoboranes exhibit a tendency
to undergo rapid conjugate addition to various types of
6
nitroalkanes or halooximes. A previous study found that
medium to high yields of alkenes can be generated when
(
E)-â-nitrostyrenes 1 are reacted with triethylborane in
(
8) (a) Posner, G. H. Org. React. (N. Y.) 1972, 19, 1. (b) Lipshutz, B.
a THF solution under reflux in the presence of a trace of
oxygen or by photolysis in the presence of tert-butyl
peroxide as a radical initiator. These results indicate
that â-nitrostyrenes are capable of reacting with different
organometallic reagents to generate nitroalkanes or
alkenes under different conditions and that the reaction
mechanism appears to be a free radical and/or an ionic
reaction. The 1,4-addition of hydrocarbon substituents
to R,â-unsaturated carbonyl compounds is usually achieved
using organocuprate reagents.
an organocopper reagent, an organozincate, an orga-
nomanaganese, an organotitanate, or a Grignard
reagent has been reported. In recent years, a catalytic
asymmetric Michael addition promoted by chiral metal
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7
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1-7
8,9a-j
Similarly, the use of
9k
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1
1
12
8,13
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†
National Taiwan Normal University.
‡
Army Force of Military Police School.
*
Corresponding author.
(
1) (a) Seebach, D.; Schafer, H.; Schmidt, B.; Schreiber, M. Angew.
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(
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(
3
(
(
(
10.1021/jo020681b CCC: $25.00 © 2003 American Chemical Society
4030
J. Org. Chem. 2003, 68, 4030-4038
Published on Web 04/19/2003

Free Radical Reaction of Alkyl Iodides
R,â-unsaturated ketones and aldehydes in the presence
trimethylaluminum with enones,25a,29 and of higher alkyl-
16
of a metal mediator. Without the assistance of a metal
aluminum compounds to R,â-unsaturated carboxylic acid
1
7
30
mediator, organoboranes also undergo conjugate addi-
derivatives. The Cu-catalyzed Michael-type reaction of
1
8a
18b
18c
31,32
tions to vinyl ketone, acrolein, R-methylacrolein,
trimethylaluminum and triethylaluminum with enones
1
8c
18d
R-bromoacrolein,
2-methylenecyclohexanone,
by a free radical mechanism,
and
and traces
and the Ni-catalyzed conjugate addition of trimethyl-
aluminum to sterically hindered enones have also been
reported.3
17a-c
19,20
quinines
1d,33,34
of oxygen in the reaction mixture are sufficient to initiate
these reactions. Various attempts to extend this reaction
to â-substituted R,â-unsaturated carbonyl compounds
1n 1973, Kabalka reported the first example of a free
radical chain reaction involving trialkylaluminum and
2
0,21
35
have been unsuccessful
unless a radical initiator is
cyclohexenone compounds. We also recently reported
2
1
22
used. For example, in the presence of oxygen or
that medium to high yields of alkenes and/or hydroximoyl
chloride can be generated when (E)-â-nitrostyrenes are
reacted with triethylaluminum or diethylaluminum chlo-
ride in diethyl ether solution under reflux in the presence
of a trace of oxygen in the nitrogen or by photolysis in
the presence of benzoyl peroxide as a radical initiator or
21
21
diacetyl peroxide or under photolysis, trialkylboranes
produce alkyl radicals which can be added to â-substi-
tuted R,â-unsaturated carbonyl compounds. Toru and co-
workers investigated the setereoselectivity of the conju-
gate addition of trialkylborane to 2-arylsulfinylcyclopen-
2
3
tenone. Interestingly, the use of Et
3
B along with an
2
in the presence of MgCl as the Lewis acid after workup
3
6
excess of secondary and tertiary alkyl iodides led to the
generation of secondary or tertiary radicals which could
then participate in free radical reactions.23
with ice-cold concentrated hydrochloric acid. In addi-
tion, triethylaluminum can also be used as a radical
initiator to generate different radicals that can further
37
Reactions of trialkylaluminum or triorganoaluminum-
ether complexes with R,â-unsaturated nitroalkenes giv-
ing high yields of 1,4-alkylated products have been
reported by Pecunioso and Menicagli.24 In 1974, Ashby
reported on the nickel- or copper-catalyzed 1,4-additions
to R,â-unsaturated ketones by trimethylaluminum or
react with â-nitrostyrenes to give substituted products.
Here we report that triethylaluminum can be used to
activate some Michael acceptors, and surprisingly, it is
superior to triethylborane in 1,4-addition reactions with
some R,â-unsaturated substrates in some cases.
2
5a
lithium tetramethylaluminate.
The 1,4-addition of
Results and Discussion
organoaluminum compounds25 has been reported for the
Alkenes with electronegative substituents are more
easily attacked by nucleophilic alkyl radicals. For ex-
ample, the use of 2,2-dicyanoalkene as the substrate in
transfer of the cyano group to R,â-unsaturated ketones
26
27
28
and esters, of alkynyl and alkenyl groups to enones,
of the methyl group in nickel-catalyzed reactions of
38
alkylation reactions with organotin, alkylmercury ha-
lides,39 organogallium, or organoindium reagents has
been reported. However, most of these reactions require
several hours to achieve medium to high yields of
40
40
(
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2
J. Org. Chem, Vol. 68, No. 10, 2003 4031

Liu et al.
TABLE 1. Reaction of 1-Aryl-2,2-dicyanoethenes (1 equiv) with RI (7.5-15 equiv) and Et3B (4-5 equiv) in THF Solution
in the Presence of Oxygen
RI
(equiv)
yielda
(%)
entry
1
product
1
2
3
4
5
6
7
8
9
1a
1b
1c
1a
1b
1c
1a
1b
1c
3 (15)
3 (15)
3 (15)
4 (15)
4 (15)
4 (15)
5 (7.5)
5 (7.5)
5 (7.5)
6a
6b
6c
7a
7b
7c
8a
8b
8c
99
99
100
95
95
100
92
99
100
a
For the NMR yields DMF was used as an internal standard.
products. Triethylborane not only can be used to generate
radical species, but also can be used as an effective
radical initiator for generating different radicals by the
reaction of triethylborane with an alkyl iodide under mild
ethenes 1a-c and an excess of the alkyl iodide such as
isopropyl iodide (3), cyclohexyl iodide (4), or tert-butyl io-
dide (5) (7.5-15 equiv) were added to the THF solution,
after which 2a (3 equiv) was slowly added at room temp-
erature under similar conditions (eq 1 and Table 1). The
products were easily purified by column chromatography,
and the spectral data of the known products are also
consistent with literature data.43 The use of an excess of
the alkyl iodide and the slow addition of triethylborane
are necessary to prevent the formation of ethyl addition
products.
4
1,42
conditions.
On the basis of these reports, we at-
tempted to utilize this methodology to react 1-aryl-2,2-
dicyanoethenes with radicals using triethylborane and
air as the free radical initiator to induce the generation
of different radicals from an alkyl iodide. As expected,
good to excellent yields (92-100%) of 6, 7, or 8 were
obtained within 10-30 min when 1-aryl-2,2-dicyano-
Our previous study reported that the substitution of
(
39) (a) Russell, G. A.; Shi, B. Z.; Jiang, W.; Hu, S.; Kim, B. H.; Bank,
â-nitrostyrenes can also be achieved using triethylalu-
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G. A.; Yao, C.-F.; Rajaratnam, R.; Kim, B. H. J. Am. Chem. Soc. 1991,
36a
minum and benzoyl peroxide as the initiator to induce
alkyl radicals from alkyl iodides.3 To compare differ-
ences in reactivity between triethylaluminum and tri-
ethylborane, we also examined the triethylaluminum-
benzoyl peroxide system.
6b
1
13, 373
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(
(
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ethenes 1a-c (1 mmol; a, Ar ) Ph; b, Ar ) 4-MeOC
6 4
H ;
c, Ar ) 4-ClC ), benzoyl peroxide (2 equiv), and excess
6
H
4
1
999, 64, 9189. (e) Miyabe, H.; Ushiro, C.; Ueda, M.; Yamakawa, K.;
alkyl iodide RI such as 3, 4, or 5 (10-15 equiv) in dry
diethyl ether at 0 °C for 30 min, after which the solution
was stirred at room temperature until all the starting
material had disappeared. After the solution was quenched
with ice-cold dilute hydrochloric acid solution and ex-
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2
6
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(e) Yamamoto, Y.; Nishii, S. J. Org. Chem. 1988, 56, 3597 and
references therein.
Liu, J.-T.; Jang, Y.-J.; Shih, Y.-K.; Hu, R.-S.; Chu, C.-M.; Yao, C.-F. J.
Org. Chem. 2001, 66, 6021 (d) Yorimitsu, H.; Nakamura, T.; Shinokubo,
Oshima, K. J. Org. Chem. 1998, 63, 8604. (e) Yorimitsu, H.; Shinokubo,
H.; Matsubara, S.; Oshima, K. J. Org. Chem. 2001, 66, 7776. (f) Fujita,
K.; Nakamura, T.; Yorimitsu, H.; Oshima, K. J. Am. Chem. Soc. 2001,
1
23, 3137.
4032 J. Org. Chem., Vol. 68, No. 10, 2003

Free Radical Reaction of Alkyl Iodides
TABLE 2. Reaction of 1-Aryl-2-2-dicyanoethenes (1 equiv) with RI (10-15 equiv), Et3Al (4-6 equiv), and Benzoyl
Peroxide (2 equiv) in Diethyl Ether at 0 °C for 30 min and Then at Room Temperature
RI
(equiv)
yielda
(%)
entry
1
product
1
2
3
4
5
6
7
8
9
1a
1b
1c
1a
1b
1c
1a
1b
1c
3 (10)
3 (10)
3 (10)
4 (10)
4 (10)
4 (10)
5 (10)
5 (10)
5 (10)
6a
6b
6c
7a
7b
7c
8a
8b
8c
85
100
100
76
96
95
100
100
100
a
For NMR yields DMF was used as an internal standard.
tracted with dichloromethane, product yields were mea-
sured by H NMR, and medium to high (76-100%) yields
of the product 6, 7, or 8 were observed. These compounds
were also easily purified by flash column chromatography
as described above (eq 2 and Table 2).
gents,44c triorganogallium,40 or triorganoindium40 with
alkylidenemalonates also lead to the formation of 1,4-ad-
ducts. The first asymmetric conjugate addition of dialkyl-
zinc and triethylaluminum reagents to aryl- and alkyl-
idenemalonates using a catalytic copper/homochiral phos-
1
On the basis of the above results, either triethylborane
in the presence of air or triethylaluminum in the presence
of benzoyl peroxide reacts rapidly and completely with
an alkyl iodide under mild conditions. Using a variety of
alkyl iodides, such products can be prepared under one-
pot conditions. Better and clean results were obtained
by the reaction of triethylborane with three different
types of 1-aryl-2,2-dicyanoethenes. Ethyl addition prod-
ucts are always generated when the triethylborane
solution is added to the alkyl iodide solution too rapidly,
thus complicating the purification procedure. When ben-
zylidenemalononitrile was used, the yield of 6a or 7a was
lower, when the triethylaluminum-benzoyl peroxide
system was used (Table 2, entries 1 and 4). Although the
yield of the expected product was slightly lower and the
reaction rate was also slower compared to those of the
triethylaluminum-benzoyl peroxide with triethylborane-
air system, the formation of the ethyl addition product
was easily avoided provided the triethylaluminum was
added slowly to the RI solution.
45
phorus ligand system was also reported by Alexakis.
On the basis of the above reports, dimethyl benzyliden-
emalonate (9) was chosen as an alternate Michael ac-
ceptor to examine the efficiency of the triethylborane and
triethylaluminum systems. As shown in Table 3, the
reactions of alkyl halides with this substrate afford only
low to medium (25-80%) yields of 1,4-adduct 10, 11, or
1
2 (eq 3 and Table 3, entries 1-3). Dimethyl benzyliden-
emalonate is not always entirely consumed, even when
the amount of triethylborane is increased and the reac-
tion time is extended. In addition, dialkylated products
are produced, along with the monoalkylated products,
when triethylborane and air as the radical initiator is
used. For example, the dialkylated product PhCH(i-Pr)-
2 2
C(i-Pr)(CO Me) (10a) could be isolated when isopropyl
iodide was used (Table 3, entry 1).
Although low yields of 1,4-adducts were obtained when
9 was reacted with alkyl halide in the presence of
triethylborane-air, the system using triethylaluminum
and benzoyl peroxide resulted in high yields (91-95%).
Fortunately, no dialkylated products were observed, and
only high yields of the 1,4-adducts were generated (eq 4
and Table 4). These different results possibly can be
explained by the different coordination abilities of tri-
ethylborane vis- a` -vis triethylaluminum for the same
substrate. It is possible that the size of the aluminum
atom permits it to coordinate to the oxygen of the
substrate more tightly so that the substrates can be
The regioselective 1,4-addition of alkylidenemalonates
can be achieved via the use of several types of organo-
metallic reagents. The reactions of Grignard reagents
with R,â-unsaturated carbonyl compounds usually afford
1
,2-addition products. However, regioselective 1,4-addi-
tion was also reported for reactions of Grignard reagent
with alkylidenemalonates and alkylidenecyanoacetates.
43
44a
Similarly, reactions of tetraorganogallate complexes,
dialkylaluminum chlorides,44b organomanganese rea-
(
44) (a) Han, Y.; Huang, Y.-Z.; Fang, L.; Tao, W.-T. Synth. Commun.
1
1
999, 29, 867. (b) Maas, S.; Stamm, A.; Kunz, H. Synthesis 1999, 10,
(45) Alexakis, A.; Benhaim, C. Tetrahedron: Asymmetry 2001, 12,
1151.
792. (c) Cahiez, G.; Alami, M. Tetrahedron 1989, 45, 4163.
J. Org. Chem, Vol. 68, No. 10, 2003 4033

Liu et al.
TABLE 3. Reaction of Dimethyl Benzylidenemalonate (1 equiv) with RI (7.5-15 equiv) and Et3B (4-6 equiv) in THF
Solution in the Presence of Oxygen at Room Temperature
RI
(equiv)
yielda
(%)
entry
product
b
1
2
3
3 (15)
4 (15)
5 (7.5)
10
11
12
80
55
25
a
For NMR yields DMF was used as an internal standard. b The crude mixture contains 24% dialkylated product 10a.
TABLE 4. Reaction of Dimethyl Benzylidenemalonate (1 equiv) with RI (6-10 equiv), Et3Al (About 6 equiv), and
Benzoyl Peroxide (2 equiv) in Diethyl Ether at 0 °C for 30 min and Then at Room Temperature for 1.5-2 h
RI
(equiv)
yielda
(%)
entry
product
1
2
3
3 (10)
4 (10)
5 (6)
10
11
12
95
93
91
a
For NMR yields DMF was used as an internal standard.
TABLE 5. Reaction of Benzylideneacetylacetone (1 equiv) with RI (7.5-15 equiv), Et3Al (8-10 equiv), and Benzoyl
Peroxide (2 equiv) in Diethyl Ether at Room Temperature for 4-5 h
RI
(equiv)
yielda
(%)
entry
product
1
2
3
3 (15)
4 (15)
5 (7.5)
14
15
16
50
81
30
a
For NMR yields dibromomethane was used as an internal standard.
activated more efficiently and be easily attacked by the
nucleophilic alkyl radical.
It has been reported that medium to high yields of
conjugate allylation to acceptor 13 can be achieved using
triallylgallium or triallylindium.40 In the case of substrate
gate addition to this substrate. However, 1,4-addition can
be achieved when the triethylaluminum-benzoyl perox-
ide system (30-81%) is used, but the yields of 1,4-adduct
were significantly decreased when the reaction was
carried out at 0 °C because of the low activity of substrate
13 (eq 5 and Table 5). However, the yield can be improved
13, the triethylborane system failed to undergo a conju-
4034 J. Org. Chem., Vol. 68, No. 10, 2003

Free Radical Reaction of Alkyl Iodides
TABLE 6. Reaction of 2-Cyclohexen-1-one (1 equiv) with RI (7.5-15 equiv) and Et3B (8-10 equiv) in THF Solution in
the Presence of Oxygen
a
entry
RI (equiv)
solvent
product
yield (%)
1
2
3
4
5
6
3 (10)
3 (15)
4 (15)
4 (15)
5 (7.5)
5 (7.5)
THF
18
18
19
19
20
20
91
88
THF/H2O
THF
b
64
c
THF/H2O
THF
THF/H2O
67
52
d
64
a
For NMR yields dibromomethane was used as an internal standard. b The yield was calculated by H NMR after removing the cyclohexyl
1
iodide and other compounds by flash column chromatography, and a 33% yield of the THF radical addition products 21a and 21b was
observed. c A 32% yield of THF adducts was observed. Traces of THF adducts were observed.
d
TABLE 7. Reaction of 2-Cyclohexen-1-one (1 equiv) with RI (7.5-15 equiv), Et3Al (6-10 equiv), and Benzoyl Peroxide (2
equiv) in Diethyl Ether at 0 °C for 30 min and Then at Room Temperature for 0.5-1 h
a
entry
RI (equiv)
product
yield (%)
1
2
3
3 (10)
4 (10)
5 (10)
18
19
20
77
99
100
a
For NMR yields dibromomethane was used as an internal standard. b 17 was entirely consumed.
by carrying out the reaction at room temperature for
several hours and using larger amounts of triethylalu-
minum.
extended to several hours (eq 6 and Table 6, entry 5).
When the reaction was carried out in THF/H O solution,
2
the yield of adduct was increased from 52% to 64% (Table
1
The conjugate addition of an enone can be achieved
by many types of organometallic reagents. In recent
years, the catalytic asymmetric conjugate addition of
organometallic reagents to enones has also been re-
6, entry 6). Because the H NMR spectrum of the
cyclohexyl iodide was seriously overlapped with the
1
addition product, the H NMR yield of adduct was
calculated by isolation after removal of the cyclohexyl
iodide and other impurities (Table 6, entry 3). The case
where cyclohexyl iodide is used as the radical source is
1
4
ported. Here, we chose 2-cyclohexen-1-one (17) as a
representative enone to study the difference between the
triethylborane and triethylaluminum systems.
1
also of interest. From the H NMR spectrum, although
Only medium to high yields of product were obtained
all the starting material was consumed, only a medium
yield of the cyclohexyl addition product was obtained
because of the competition of the THF radical addition
reaction. An approximate yield of 33% of THF adducts
21a and 21b was observed in the cyclohexyl iodide case
and only traces of THF adducts were observed in the tert-
butyl iodide case in the presence or absence of water in
the THF solution. This indicates that the tert-butyl
radical is more reactive than the cyclohexyl radical, and
as a result, the yield of the THF adducts 21a and 21b
was decreased under similar conditions.
using the triethylborane system in THF or in THF/H
2
O
solution (9/1 volume ratio of THF/H O) when the sub-
2
strate was 17. In the case of isopropyl iodide, the product
yield was acceptable (eq 6 and Table 6, entry 1). However,
when tert-butyl iodide was used as the alkyl halide and
5
equiv of triethylborane was used, the adduct was
obtained in only 42% yield, after the mixture was stirred
for 30 min in THF solution, and only 52% of the same
adduct was obtained when the amount of triethylborane
was increased to 10 equiv and the reaction time was
J. Org. Chem, Vol. 68, No. 10, 2003 4035

Liu et al.
SCHEME 1
On the basis of the above observation, the rates of the
conjugate addition of the triethylaluminum system to
Materials. Triethylborane (2a), triethylaluminum (2b),
-iodopropane (3), cyclohexyl iodide (4), 2-iodo-2-methylpro-
2
pane (5), and 2-cyclohexen-1-one (17) were obtained com-
2
-cyclohexen-1-one were faster and the yields of the
mercially, and other commercially available reagents were
product were also better than those of the triethylborane
system (77-100%). The different coordination ability
between aluminum and borane atoms may account for
this behavior as describe above (eq 7, Table 7).
used without further purification. The starting materials
46
1
-aryl-2,2-dicyanoethenes 1a-c, dimethyl benzylidenema-
47
48
lonate (9), and benzylideneacetylacetone (13) were prepared
according to literature procedures.
In conclusion, we describe an easy method for the syn-
thesis of different products by reactions of R,â-unsatur-
ated compounds with different radicals, prepared from
alkyl iodides and triethylborane in the presence of oxygen
at room temperature or alkyl iodides and triethylalumi-
num in the presence of benzoyl peroxide. The use of tri-
ethylborane and air to initiate the radical conjugate ad-
dition is a good choice, because the reactions are clean
and products easily purified. However, when less reactive
substrates are used and lower yields of the 1,4-adducts
are obtained, triethylborane can be replaced with tri-
ethylaluminum to generate the same products. The high-
er yields of the 1,4-adducts in the triethylaluminum sys-
tem can be explained by the better coordination ability
of the aluminum atom to the less reactive substrate. A
mechanism for the above reactions is proposed in Scheme
1-Phenyl-2,2-dicyanoethene (1a). This compound was
4
6 1
prepared according to literature procedures: H NMR (400
MHz, CDCl
3
) δ 7.92-7.90 (m, 2H), 7.78 (s, 1H), 766-7.50 (m,
H); C NMR (100 MHz, CDCl ) δ 159.87, 134.58, 130.93,
30.69, 129.60, 113.65, 112.50, 82.92.
-(4-Methoxyphenyl)-2,2-dicyanoethene (1b). This com-
1
3
3
1
3
1
4
6 1
pound was prepared according to literature procedures:
H
NMR (400 MHz, CDCl3) δ 7.91 (d, J ) 8.8 Hz, 2H), 7.65 (s,
13
1
H), 7.02 (d, J ) 8.8 Hz, 2H), 3.92 (s, 3H); C NMR (100 MHz,
3
CDCl ) δ 164.81, 158.80, 133.41, 124.02, 115.12, 114.38, 113.30,
78.61, 55.77.
1-(4-Chlorophenyl)-2,2-dicyanoethene (1c). This com-
4
6 1
pound was prepared according to literature procedures:
H
NMR (200 MHz, CDCl
3
) δ 7.87 (d, J ) 9.0 Hz, 2H), 7.75 (s,
1
3
1
1
3
H), 7.53 (d, J ) 9.0 Hz, 2H); C NMR (100 MHz, CDCl ) δ
58.23, 141.11, 131.80, 130.04, 129.26, 113.40, 112.30, 83.36.
Dimethyl Benzylidenemalonate (9). This compound was
4
7 1
prepared according to literature procedures: H NMR (200
1
.
MHz, CDCl
3
) δ 7.73 (s, 1H), 7.40-7.38 (m, 5H), 3.840 (s, 3H),
The application of these two methods could broaden
13
3
1
3
.837 (s, 3H); C NMR (50 MHz, CDCl ) δ 167.07, 164.47,
the scope of the utility of organoborane and organoalu-
minum reagents in organic synthesis.
42.86, 132.76, 130.63, 129.33, 128.83, 125.52, 52.48.
Benzylideneacetylacetone (13). This compound was
4
8 1
prepared according to literature procedures: H NMR (200
3
MHz, CDCl ) δ 7.50 (s, 1H), 7.40 (s, 5H), 2.43 (s, 3H), 2.29 (s,
Experimental Section
General Procedures. All reactions were performed in
flame- or oven-dried glassware under a positive pressure of
air or nitrogen. Analytical thin-layer chromatography was
performed with silica gel 60F glass plates and flash chroma-
tography by use of silica gel 60 (230-400 mesh).
(
46) Oh, H. K.; Yang, J. H.; Lee, H. W.; Lee, I. J. Org. Chem. 2000,
6
5, 2188.
(
(
47) Liao, Y.; Huang, Y.-Z. Tetrahedron Lett. 1990, 31, 5897.
48) Attanasi, O.; Fillippone, P.; Mei, A. Synth. Commun. 1983, 13,
1203.
4036 J. Org. Chem., Vol. 68, No. 10, 2003

Free Radical Reaction of Alkyl Iodides
3
1
H); 13C NMR (100 MHz, CDCl
3
) δ 205.46, 196.41, 142.81,
data:39b 1H NMR (200 MHz, CDCl
5.6 Hz, 1H), 3.01 (d, J ) 5.6 Hz, 1H), 1.10 (s, 9H); C NMR
3
) δ 7.39 (s, 5H), 4.23 (d, J )
13
39.76, 132.89, 130.59, 129.64, 128.98, 31.57, 26.45.
Typical Procedures for the Synthesis of 6, 7, or 8 from
3
(50 MHz, CDCl ) δ136.29, 129.28, 128.65, 128.53, 113.26,
the Reaction of 1-Aryl-2,2-dicyanoethenes 1a-c (a, Ar
)
3
113.17, 56.53, 34.76, 28.27, 24.88; MS m/z (relative intensity)
+
Ph; b, Ar ) 4-MeOC
6
H
4
; c, Ar ) 4-ClC
6
H
4
) Alkyl Iodide
212 (M , 35), 197 (19), 156 (8), 147 (57), 132 (31), 105 (34), 91
+
, 4, or 5, and 2a in THF Solution in the Presence of the
(51), 77 (11), 57 (100); HRMS m/z calcd for C14
H
15
N
2
Cl (M )
Oxygen in the Air (Eq 1 and Table 1). In a Pyrex test tube
with a magnetic stirrer were placed 1 mmol of 1-aryl-2,2-
dicyanoethene 1a, 1b, or 1c, 4 mmol of 2a (1.0 M in hexane
solution), and 7.5-15 mmol of alkyl iodide 3, 4, or 5 in 8 mL
of THF, and the solution was bubbled with air from a balloon.
After 10-30 min, the solvent was evaporated and the oily
residue was purified by flash column chromatography to give
a 92-100% yield of 6a-c, 7a-c, or 8a-c. In the case of known
compounds, all spectral data are consistent with literature
212.1313, found 212.1311.
1,1-Dicyano-3,3-dimethyl-2-(4-methoxyphenyl)bu-
tane (8b). The spectra data for this compound are consistent
5
0 1
3
with the literature data: H NMR (200 MHz, CDCl ) δ 7.32
(d, J ) 8.8 Hz, 2H), 6.92 (d, J ) 8.8 Hz, 2H), 4.2 (d, J ) 5.6
Hz, 1H), 3.82 (s, 3H), 2.97 (d, J ) 5.6 Hz, 1H), 1.09 (s, 9H);
1
3
C NMR (50 MHz, CDCl
113.31, 113.25, 55.99, 55.12, 34.90, 28.28, 25.10.
,1-Dicyano-3,3-dimethyl-2-(4-chlorophenyl)butane (8c).
3
) δ 159.61, 130.42, 128.24, 113.99,
1
3
9b,49,50
reports.
,1-Dicyano-3-methyl-2-phenylbutane (6a). The spectral
data for this compound are consistent with the literature data:
All experimental results are shown in Table 1.
The spectra data for this compound are consistent with the
5
0 1
1
literature data: H NMR (200 MHz, CDCl ) δ 7.37-7.36 (m,
3
4H), 4.22 (d, J ) 5.4 Hz, 1H), 2.99 (d, J ) 5.4 Hz, 1H), 1.07 (s,
49 1
13
H NMR (400 MHz, CDCl
3
) δ 7.40-7.30 (m, 5H), 4.16 (d, J
9H); C NMR (50 MHz, CDCl ) δ 134.81, 134.67, 130.68,
3
)
5.7 Hz, 1H), 2.83 (dd, J ) 9.7, 5.7 Hz, 1H), 2.40-2.34 (m,
129.04, 112.97, 112.85, 56.15, 34.87, 28.30, 24.82; MS m/z
H), 1.12 (d, J ) 6.6 Hz, 3H), 0.82 (d, J ) 6.6 Hz, 3H); 13
C
+
+
1
(relative intensity) 248 ((M + 2) , 5) 246 (M , 14), 181 (76),
NMR (100 MHz, CDCl
3
) δ 136.59, 129.01, 128.68, 128.21,
166 (31), 139 (24), 125 (37), 115 (24), 107 (11), 57 (100); HRMS
37
+
1
12.14, 111.86, 53.29, 30.18, 27.69, 20.80, 20.21; MS m/z
m/z calcd for C H N Cl (M + 2) 248.0894, found 248.0892,
1
4
15
2
+
35
+
(
relative intensity) 198 (M , 25), 180 (81), 169 (100), 162 (31);
HRMS m/z calcd for C14 O 198.1157, found 198.1154.
,1-Dicyano-3-methyl-2-(4-methoxyphenyl)butane (6b).
H NMR (200 MHz, CDCl ) δ 7.24 (d, J ) 8.4 Hz, 2H), 6.93 (d,
J ) 8.4 Hz, 2H), 4.14 (d, J ) 5.5 Hz, 1H), 3.82 (s, 3H), 2.80
dd, J ) 9.7, 5.5 Hz, 1H), 2.43-2.25 (m, 1H), 1.12 (d, J ) 6.6
calcd for C H N Cl (M ) 246.0924, found 246.0919.
1
4
15
2
16 2
H N
Typical Procedures for the Synthesis of 6, 7, or 8 from
the Reaction of 1-Aryl-2,2-dicyanoethenes 1a-c, Alkyl
Iodide 3, 4, or 5, and 2b in Dry Ether Solution in the
Presence of the Benzoyl Peroxide (Eq 2 and Table 2).
About 6 mL of 15% triethylaluminum in hexane (5.4 equiv)
was slowly added by a syringe three times (2 mL × 3) to a
stirred solution which contained 1 mmol of 1-aryl-2,2-dicya-
noethene 1a, 1b, or 1c, 2 mmol of benzoyl peroxide, and 10-
15 mmol of an alkyl iodide RI such as 3, 4, or 5 in dry diethyl
ether (10 mL) at 0 °C over a period of 30 min. The stirred
solution was then stirred at room temperature for a further
0.5-1 h, and the reaction was checked by TLC continuously
until all the starting material disappeared. After the reaction
was quenched by slowly pouring the solution into an ice-cold
diluted hydrochloric acid aqueous solution, the product was
extracted with dichloromethane. The yield was measured by
1
1
3
(
1
3
3
Hz, 3H), 0.83 (d, J ) 6.6 Hz, 3H); C NMR (50 MHz, CDCl )
δ 159.78, 129.37, 128.51, 114.38, 112.34, 111.94, 55.15, 52.59,
+
3
0.12, 27.87, 20.74, 20.15; MS m/z (relative intensity) 228 (M ,
8
), 185 (8), 164 (10), 163 (100), 135(9), 121 (92), 91 (15), 77
(
16 2
17), 55 (20); HRMS m/z calcd for C14H N O 228.1262, found
2
28.1260.
,1-Dicyano-3-methyl-2-(4-chlorophenyl)butane (6c).
H NMR (400 MHz, CDCl ) δ 7.40 (d, J ) 8.6 Hz, 2H), 7.28 (d,
1
1
3
J ) 8.6 Hz, 2H), 4.16 (d, J ) 5.6 Hz, 1H), 2.82 (dd, J ) 9.8,
5
(
.6 Hz, 1H), 2.40-2.29 (m, 1H), 1.13 (d, J ) 6.6 Hz, 3H), 0.82
d, J ) 6.6 Hz, 3H); 13C NMR (100 MHz, CDCl
) δ 135.02,
3
1
1
2
34.79, 129.60, 129.35, 111.91, 111.52, 52.81, 30.16, 27.64,
H NMR, and medium to high (77-100%) yields of the product
+
0.76, 20.31; MS m/z (relative intensity) 234 ((M + 2) , 5) 232
6, 7, or 8 were observed, which also could be easily purified
by flash column chromatography. All spectral data of the final
products are consistent with those shown in Table 1.
Typical Procedures for the Synthesis of 10, 11, or 12
from the Reaction of 9, Alkyl Iodide 3, 4, or 5, and 2a in
THF Solution in the Presence of the Oxygen in the Air
(Eq 3 and Table 3). These procedures are similar to the
synthesis of 6, 7, and 8 except the amount of triethylborane
was increased to 8-10 equiv and the reaction time was
increased to 4-5 h.
+
(
M , 23), 189 (5), 169 (39), 167 (96), 163(68), 153 (23), 139 (15),
1
25 (100), 115 (25), 103 (7), 89 (13), 73 (9), 55(16); HRMS m/z
3
7
+
found for C13
13 2 13
H N Cl (M + 2) 234.0733, calcd for C13H -
3
5
+
N
2
Cl (M ) 232.0767, found 232.0754.
1
1
,1-Dicyano-2-cyclohexyl-2-phenylethane (7a). H NMR
200 MHz, CDCl ) δ 7.44-7.29 (m, 5H), 4.18 (d, J ) 5.5 Hz,
H), 2.88 (dd, J ) 9.8, 5.5 Hz, 1H), 2.05-0.78 (m, 11H);
NMR (50 MHz, CDCl ) δ 136.76, 129.15, 128.75, 128.33,
12.22, 111.96, 52.30, 39.18, 31.12, 30.48, 27.02, 25.75, 25.63.
,1-Dicyano-2-cyclohexyl-2-(4-methoxyphenyl)-
(
1
3
1
3
C
3
1
1
Typical Procedures for the Synthesis of 10, 11, or 12
from the Reaction of 9, Alkyl Iodide 3, 4, or 5, and 2b in
Dry Ether Solution in the Presence of Benzoyl Peroxide
(Eq 4 and Table 4). These procedures are similar to those
used for the preparation of alkanes 6, 7, and 8 as described
above.
1
ethane (7b). H NMR (200 MHz, CDCl
3
) δ 7.24 (d, J ) 8.8
Hz, 2H), 6.92 (d, J ) 8.8 Hz, 2H), 4.17 (d, J ) 5.4 Hz, 1H),
3
.81 (s, 3H), 2.84 (dd, J ) 9.7, 5.4 Hz, 1H), 2.04-0.75 (m, 11H);
1
3
3
C NMR (50 MHz, CDCl ) δ 159.76, 129.40, 128.57, 114.40,
1
2
1
12.40, 112.00, 55.15, 51.51, 39.15, 31.06, 30.42, 27.21, 25.72,
+
5.67, 25.60; MS m/z (relative intensity) 268 (M , 34), 203 (94),
2
-(2-Methyl-1-phenyl)propylmalonic Acid Dimethyl
85 (13), 159 (27), 122(24), 121 (100), 122 (24), 115 (12), 91
1
Ester (10). H NMR (200 MHz, CDCl
.99 (d, J ) 11.2 Hz, 1H), 3.77 (s, 3H), 3.40 (s, 3H), 3.38 (dd,
J ) 11.2, 5.0 Hz, 1H), 2.04-1.92 (m, 1H), 0.84 (d, J ) 6.8 Hz,
3
) δ 7.27-7.12 (m, 5H),
(
20 2
11), 55 (17); HRMS m/z calcd for C17H N O 268.1576, found
3
2
68.1571.
,1-Dicyano-2-cyclohexyl-2-(4-chlorophenyl)ethane (7c).
H NMR (400 MHz, CDCl ) δ 7.39 (d, J ) 8.4 Hz, 2H), 7.27 (d,
1
13
3
1
5
2
3
H), 0.79 (d, J ) 6.8 Hz, 3H); C NMR (50 MHz, CDCl ) δ
1
3
69.23, 168.46, 138.25, 129.41, 127.78, 116.80, 55.56, 52.53,
J ) 8.4 Hz, 2H), 4.19 (d, J ) 5.4 Hz, 1H), 2.86 (dd, J ) 9.8,
.4 Hz, 1H), 2.20-0.75 (m, 11H); 13C NMR (100 MHz, CDCl
δ 135.06, 134.65, 129.63, 129.30, 112.03, 111.62, 51.61, 39.07,
0.98, 30.51, 26.92, 25.69, 25.66, 25.58.
,1-Dicyano-3,3-dimethyl-2-phenylbutane (8a). The spec-
tral data for this compound are consistent with the literature
2.10, 51.15, 30.27, 21.39, 17.65; MS m/z (relative intensity)
5
3
)
+
64 (M , 2), 222 (6), 201 (14), 189 (9), 163 (14), 162 (61), 132
(
100), 121 (50), 103 (13), 91 (18), 77 (8), 59 (3); HRMS m/z calcd
3
for C15
20 4
H O 264.13616, found 264.13605.
1
2
-(2-Methyl-1-phenyl)propyl-2-isopropylmalonic Acid
1
Dimethyl Ester (10a). H NMR (200 MHz, CDCl
3
) δ 7.26-
.17 (m, 5H), 3.82 (s, 3H), 3.78 (s, 3H), 3.47 (d, J ) 5.4 Hz,
H), 2.16-2.04 (m, 1H), 2.04-1.92 (m, 1H), 0.99 (d, J ) 6.8
7
1
(
49) Campaigne, E.; Roelofse, W. L. J. Org. Chem. 1965, 30, 396.
50) Mitchell, T. N. J. Organomet. Chem. 1974, 71, 27.
(
Hz, 3H), 0.88 (d, J ) 6.8 Hz, 3H), 0.76 (d, J ) 6.8 Hz, 3H),
J. Org. Chem, Vol. 68, No. 10, 2003 4037

Liu et al.
0
1
5
.49 (d, J ) 6.8 Hz, 3H); 13C NMR (50 MHz, CDCl
3
) δ 171.81,
171 (6), 147 (100), 129 (63), 128 (20), 103 (34), 91 (22), 57 (66);
71.16, 138.49, 130.80, 127.55, 126.57, 64.91, 54.88, 51.66,
24 2
HRMS m/z calcd for C18H O 246.1619, found 246.1632.
1.57, 31.73, 31.07, 23.35, 20.82, 19.76, 17.39; MS m/z (relative
2
,4-DNP Derivative of 3-(2,2-Dimethyl-1-phenylpro-
+
intensity) 306 (M , 1), 243 (3), 231 (13), 221 (34), 189 (100),
pyl)pentane-2,4-dione (16a). The color of this derivative is
1
74 (60), 159 (47), 121 (59), 91 (36), 59 (6); HRMS m/z calcd
for C18 306.18311, found 306.18288.
-(Cyclohexylphenyl)methylmalonic Acid Dimethyl
1
orange-yellow, and it decomposes at 151-154 °C: H NMR
26 4
H O
(
3
400 MHz, CDCl ) δ 11.15 (s, 1H), 10.70 (s, 1H), 9.14 (d, J )
2
2
1
7
.5 Hz, 1H), 9.06 (d, J ) 2.5 Hz, 1H), 8.43 (dd, J ) 9.5, 2.5 Hz,
1
Ester (11). H NMR (200 MHz, CDCl
3
) δ 7.27-7.11 (m, 5H),
H), 8.36 (dd, J ) 9.5, 2.4 Hz, 1H), 807 (d, J ) 9.5 Hz, 1H),
.96 (d, J ) 9.5 Hz, 1H), 7.40-7.20 (m, 5H), 4.21 (d, J ) 11.0
4
.01 (d, J ) 11.0 Hz, 1H), 3.77 (s, 3H), 3.39 (s, 3H), 3.36 (dd,
1
3
J ) 14.0, 5.0 Hz, 1H), 1.74-0.68 (m, 11H); C NMR (50 MHz,
CDCl ) δ 169.23, 168.49, 138.95, 129.25, 127.72, 126.69, 54.99,
2.47, 52.03, 51.00, 40.74, 31.80, 28.34, 26.45, 26.28, 26.02;
Hz, 1H), 3.68 (d, J ) 11.0 Hz, 1H), 2.25 (s, 3H), 1.57 (s, 3H),
.96 (s, 9H); C NMR (100 MHz, CDCl ) δ 155.81, 155.26,
3
44.94, 144.75, 140.74, 138.26, 138.02, 130.35, 130.01, 129.59,
29.30, 127.57, 126.60, 123.47, 123.37, 116.20, 116.04, 58.81,
4.98, 34.92, 29.04, 16.21, 14.69.
3
0
1
1
5
13
5
+
MS m/z (relative intensity) 304 (M , 11), 271 (11), 254 (22),
44 (16), 222 (30), 200 (10), 172 (100), 162 (62), 148 (6), 105
8); HRMS m/z calcd for C18 304.16746, found 304.16741.
-(2,2-Dimethyl-1-phenyl)propylmalonic Acid Dime-
2
(
26 4
H O
Typical Procedures for the Synthesis of 18, 19, or 20
2
from the Reaction of 2-Cyclohexen-1-one (17), Alkyl
Iodide 3, 4, or 5, and 2a in THF Solution in the Presence
of the Oxygen in the Air (Eq 6 and Table 6). These
procedures are similar to those used for the synthesis of
alkenes 6, 7, and 8, except the amount of triethylborane was
increased to 8-10 equiv and the reaction time was increased
to 4-5 h.
1
thyl Ester (12). H NMR (200 MHz, CDCl
3
) δ 7.24-7.12 (m,
5
H), 4.03 (d, J ) 11.0 Hz, 1H), 3.76 (s, 3H), 3.47 (d, J ) 11.0
1
3
3
Hz, 1H), 3.24 (s, 3H), 0.89 (s, 9H); C NMR (50 MHz, CDCl )
δ 169.98, 168.63, 140.01, 129.91 (br), 127.43, 126.57, 55.23,
5
2
4.64, 52.68, 52.00, 34.26, 28.07; MS m/z (relative intensity)
+
78 (M , 2), 263 (4), 245 (2), 222 (100), 215 (7), 190 (11), 172
(
6), 163 (24), 162 (92), 131 (7), 121 (3), 57 (1); HRMS m/z calcd
Typical Procedures for the Synthesis of 18, 19, or 20
from the Reaction of 17, Alkyl Iodide 3, 4, or 5, and 2b
in Dry Ether Solution in the Presence of Benzoyl
Peroxide (Eq 7 and Table 7). These procedures are similar
to those used for the synthesis of 6, 7, and 8.
for C16
22 4
H O 278.15181, found 278.15227.
Typical Procedures for the Synthesis of 14, 15, or 16
from the Reaction of 13, Alkyl Iodide 3, 4, or 5, and 2b
in Dry Ether Solution in the Presence of Benzoyl
Peroxide (Eq 5 and Table 5). These procedures are similar
to those used for the synthesis of 6, 7, and 8 which is shown
in eq 2 and Table 2, except the reactions were carried out at
room temperature for 4-5 h and a larger amount of triethyl-
3-Isopropylcyclohexanone (18). The spectral data for this
4
1d 1
compound are consistent with the literature data:
H NMR
3
(400 MHz, CDCl ) δ 2.50-1.20 (m, 10H), 0.91 (d, J ) 6.4 Hz,
1
3
aluminum (about 8-10 equiv) was added to the solution.
3
3H), 0.90 (d, J ) 6.4 Hz, 3H); C NMR (100 MHz, CDCl ) δ
1
3
-(1-Phenyl-2-methylpropyl)pentane-2,4-dione (14). H
212.57, 45.42, 45.33, 41.49, 32.49, 28.34, 25.52, 19.54, 19.31.
NMR (400 MHz, CDCl
Hz, 1H), 3.53 (dd, J ) 12.0, 4.0 Hz, 1H), 2.29 (s, 3H), 1.82 (s,
H), 081 (d, J ) 6.8 Hz, 3H), 0.76 (d, J ) 6.8 Hz, 3H); 13
NMR (100 MHz, CDCl ) δ 203.62, 203.32, 137.79, 129.54,
28.02, 126.86, 73.69, 50.75, 30.61, 30.05, 28.33, 21.77, 17.21;
3
) δ 7.29-7.05 (m, 5H), 4.43 (d, J ) 12.0
3-Cyclohexylcyclohexanone (19). The spectral data for
5
1 1
this compound are consistent with the literature data:
H
3
C
NMR (400 MHz, CDCl ) δ 2.50-0.82 (m, 20H); C NMR (100
MHz, CDCl ) δ 212.57, 45.46, 44.56, 42.57, 41.49, 29.86, 29.76,
13
3
3
3
1
28.33, 26.49, 26.47, 26.43, 25.52.
+
MS m/z (relative intensity) 232 (M , 2), 231 (10), 229 (43), 227,
16), 201 (13), 189 (50), 175 (12), 173 (15), 171 (20), 159 (15),
57 (10), 148 (13), 147 (100), 145 (16), 143(18), 132 (27), 131
3
-tert-Butylcyclohexanone (20). The spectral data for this
(
41d 1
compound are consistent with the literature data:
H NMR
1
13
(
200 MHz, CDCl
3
) δ 2.50-1.20 (m, 9H), 0.90 (s, 9H); C NMR
3
) δ 212.77, 49.24, 43.51, 41.19, 32.58, 27.04,
(
34), 129 (32), 128 (18), 117 (21), 115 (13), 105 (23), 103 (13),
(
2
100 MHz, CDCl
20 2
91 (35), 77 (11); HRMS m/z calcd for C15H O 232.1536, found
6.02, 25.54.
2
32.1456.
1
21a. H NMR (400 MHz, CDCl
3
) δ 3.87-3.79 (m, 1H), 3.79-
2
,4-DNP Derivative of 3-(1-Phenyl-2-methylpropyl)-
13
3
.68 (m, 1H), 3.66-3.60 (m, 1H), 2.50-1.40 (m, 13H); C NMR
) δ 211.22, 82.35, 67.90, 44.67, 44.11, 41.43,
pentane-2,4-dione (14a). The color of this derivative is
1
(100 MHz, CDCl
3
orange-yellow, and the mp is 228-232 °C: H NMR (400 MHz,
+
2
9.12, 27.65, 25.77, 24.94; MS m/z (relative intensity) 168 (M ,
), 122 (1), 111 (1), 110 (9), 105 (1), 98 (4), 97 (7), 96 (3), 85
3
CDCl ) δ 11.20 (s, 1H), 10.81 (s, 1H), 9.16 (d, J ) 2.8 Hz, 1H),
2
9
.06 (d, J ) 2.8 Hz, 1H), 8.42 (dd, J ) 9.5, 2.4 Hz, 1H), 8.33
dd, J ) 9.5, 2.4 Hz, 1H), 8.07 (d, J ) 9.5 Hz, 1H), 7.79 (d, J
9.5 Hz, 1H), 7.30-7.16 (m, 5H), 4.23 (d, J ) 12.1 Hz, 1H),
.59 (dd, J ) 12.1, 3.4 Hz, 1H), 2.20 (s, 3H), 1.86 (s, 3H), 0.87
(
7), 83 (2), 81 (2), 79(2), 77 (2), 72 (4), 70 (100), 69 (4); HRMS
m/z calcd for C10
(
H
16
O
2
168.1150, found 168.1170.
) δ 3.85-3.60 (m, 3H), 2.60-
) δ 211.67, 82.36,
)
1
3
21b. H NMR (400 MHz, CDCl
1.42 (m, 13H); C NMR (100 MHz, CDCl
3
1
3
13
(
d, J ) 6.8 Hz, 6H); C NMR (100 MHz, CDCl
3
) δ 154.70,
3
1
1
5
44.99, 144.85, 138.22, 138.08, 137.98, 130.24, 129.94, 129.78,
29.54, 129.25, 128.45, 127.81, 126.69, 123.38, 123.28, 116.31,
9.29, 50.07, 31.42, 29.63, 22.05, 16.30, 15.09, 14.10.
68.07, 43.73, 43.64, 41.39, 29.06, 28.25, 25.85, 25.15; MS m/z
+
(relative intensity) 168 (M , 2), 149 (7), 141 (12), 129 (5), 110
(11), 97 (26), 85 (17), 83 (12), 81 (8), 77 (18), 70 (100), 69 (15);
1
10 16 2
HRMS m/z calcd for C H O 168.1150, found 168.1173.
3
-(Phenylcyclohexylmethyl)pentane-2,4-dione (15). H
NMR (200 MHz, CDCl ) δ 7.31-7.06 (m, 5H), 4.46 (d, J ) 12.0
Hz, 1H), 3.51 (dd, J ) 12.0, 4.5 Hz, 1H), 2.29 (s, 3H), 1.81 (s,
3
Acknowledgment. Financial support of this work
by the National Science Council of the Republic of China
is gratefully acknowledged.
3
2
3
H), 1.78-0.63 (m, 11H); 13C NMR (50 MHz, CDCl
3
) δ 203.85,
03.66, 138.72, 129.47, 128.09, 126.86, 73.21, 50.77, 41.27,
2.32, 30.16, 28.22, 28.10, 26.48, 26.30, 26.00; MS m/z (relative
intensity) 273 ((M + 1) , 3), 254 (4), 229 (74), 211 (26), 189
+
Supporting Information Available: 1H and 13C spectra
of compounds 1a-c, 6a-c, 7a-c, 8a-c, 9, 10, 10a, 11-14,
14a, 15, 16, 16a, 18-20, and 21a,b. This material is available
free of charge via the Internet at http://pubs.acs.org.
(
(
4), 174 (8), 172 (81), 147 (100), 129 (51), 103 (17), 91 (38), 77
13), 67 (4), 55 (27); HRMS m/z calcd for C18 272.1802,
24 2
H O
found 278.1767.
-(2,2-Dimethyl-1-phenylpropyl)pentane-2,4-dione (16).
H NMR (400 MHz, CDCl ) δ 7.27-7.18 (m, 5H), 4.44 (d, J )
1.0 Hz, 1H), 3.62 (d, J ) 11.0 Hz, 1H), 2.33 (s, 3H), 1.55 (s,
3
1
3
JO020681B
1
3
1
H), 0.82 (s, 9H); 1 C NMR (125 MHz, CDCl
3
3
) δ 204.07, 203.88,
39.84, 127.81, 126.72, 73.94, 54.19, 34.74, 30.49, 28.42, 26.73;
(51) Rieke, R. D.; Klein, W. R.; Wu, T.-C. J. Org. Chem. 1993, 58,
2492.
+
MS m/z (relative intensity) 247 ((M + 1) , 3), 203 (8), 190 (56),
4038 J. Org. Chem., Vol. 68, No. 10, 2003