Hydrohalogenation reaction of 1,2-allenyl ketones revisited. Efficient and highly stereoselective synthesis of β,γ-unsaturated β-haloketones

Full text of DOI:10.1021/jo9903205

J . Org. Chem. 1999, 64, 5325-5328
5325
Sch em e 1
Sch em e 2
Hyd r oh a logen a tion Rea ction of 1,2-Allen yl
Keton es Revisited . Efficien t a n d High ly
Ster eoselective Syn th esis of
â,γ-Un sa tu r a ted â-Ha lok eton es
Shengming Ma,* Lintao Li, and Hexin Xie
Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, P. R. China
Received February 19, 1999
In tr od u ction
â,γ-Unsaturated enones, which can be prepared via
either a carbon-carbon or a carbon-oxygen double bond
formation reaction,1 are a class of compounds with high
synthetic significance. However, their syntheses are
compounded with difficulty due to the easy migration of
the carbon-carbon double bond from the â,γ-position to
the R,â-position.1,2 Thus, efficient and stereoselective new
synthetic routes to â,γ-unsaturated enones are of current
interest.
Allenes have been found to have high and unique
reactivities due to the existence of the two orthogonal
π-bonds.3,4 During the course of our study of allene
chemistry, we rationalized from the retrosynthetic analy-
sis that the hydrohalogenation reaction5 of 1,2-allenyl
ketones would be one of the most efficient methods for
the synthesis of â-halogen substituted â,γ-unsaturated
enones (Scheme 1).6 However, the hydrochlorination
reaction of 1,2-allenyl ketones by HCl was reported to
lead to polymerization, and hydrochlorination using N,N′-
dimethylhydrazine dihydrochloride or SnCl4 afforded a
mixture of â,γ-unsaturated and R,â-unsaturated â-chlo-
roenones, favoring the R,â-enones.2 Recently we disclosed
in a brief note7 that the hydrohalogenation reaction of
3,4-pentadien-2-one with metal halides in HOAc at room
temperature selectively afforded 4-halo-4-penten-2-ones
in high yields (eq 1). In this paper we wish to describe
some of our recent results in this area.
methods with modification (Scheme 2).8-10 3,4-Alkadien-
2-ones 1, 2, and 3 were synthesized via the elimination
of the corresponding 4-bromo-3-alken-2-ones.8,9 Allenes
4, 5, and 6 were prepared via the reaction of the
corresponding 1,2-allenyllithiums with CH3CONMe2.10
Hyd r oh a logen a tion Rea ction of 3,4-P en ta d ien -2-
on e w ith LiI or Na I. The results of the reaction of 3,4-
pentadien-2-one with LiI or NaI under different reaction
conditions are summarized in Table 1. When the hydro-
halogenation reaction with NaI was carried out in HOAc,
with prelonged reaction time the amount of the isomer-
ized R,â-unsaturated product 8 increased (compare en-
tries 2 and 3, Table 1). The reaction can also occur in a
1:1 mixture of HOAc and THF. The ratio of â,γ-unsatur-
ated enone 7 to R,â-unsaturated enone 8 is 87:13 (entry
4, Table 1), whereas in a 3 N solution of HOAc in THF
at a lower reaction temperature the selectivity of the
reaction is much higher (compare entries 5, 6, 9, and 10
with entries 1-4, 7, and 8, Table 1). The best results were
obtained using MI (M ) Na, Li) and HOAc (3 N) in THF
at 0 °C (entries 9 and 10, Table 1).
Resu lts a n d Discu ssion
Syn th esis of Sta r tin g Ma ter ia ls. 1,2-Allenyl ketones
were prepared according to the corresponding known
(1) Tidwell, T. T. Org. React. 1990, 39, 297 and references therein.
(2) Gras, J .-L.; Galledou, B. S. Bull. Soc. Chim. Fr. 1983, II-89.
(3) Schuster, H. F.; Coppola, G. M. Allenes in Organic Synthesis;
J ohn Wiley & Sons: New York, 1984.
(4) The Chemistry of Ketenes, Allenes, and Related Compounds, Part
1; Patai, S., Ed.; J ohn Wiley & Sons: New York, 1980.
(5) For hydrohalogenation reaction of electron-deficient alkynes,
see: Ma, S.; Lu, X. J . Chem. Soc., Chem. Commun. 1990, 1643. Ma,
S.; Lu, X. Tetrahedron Lett. 1990, 31, 7653. Ma, S.; Lu, X.; Li, Z. J .
Org. Chem. 1992, 57, 709. Lu, X.; Zhu, G.; Ma, S. Chin. J . Chem. 1993,
11, 267. Ma, S.; Lu, X. Org. Syn. 1995, 72, 112. For a review, see: Lu,
X.; Ma, S. Chin. J . Chem. 1998, 16, 388. For ZrCl4-catalyzed three-
component reaction of 1,2-allenyl ketones, aldehydes, and metallic
halides, see: Zhang, C.; Lu, X. Tetrahedron Lett. 1997, 38, 4831.
(6) For the synthesis of (Z)-2-iodo-2-alkenyl ketones from 1-alkynyl
ketones, see: Lou, F.-T.; Kumar, K. A.; Hsieh, L. C.; Mang, R. T.
Tetrahedron Lett. 1994, 35, 2553.
Hyd r oh a logen a tion of 3-Alk yl-1,2-a llen yl Keton es
w ith MX. Surprisingly, the hydroiodination and hydro-
bromination reactions of 3-alkyl-1,2-allenyl ketones with
MX in HOAc at 25 °C yielded the Z-isomer, i.e., Z-9, in
(7) Ma, S.; Shi, Z.; Li, L. J . Org. Chem. 1998, 63, 4522. For some
related studies of 2,3-allenyl carboxylic acid derivatives, see: Kurtz,
von P.; Gold, H.; Disselnkoetter, H. J ustus Liebigs Ann. 1959, 624, 1.
Rosenquist, N. R.; Chapman, O. L. J . Org. Chem. 1976, 41, 3326. Font,
J .; Gracia, A.; de March, P. Tetrahedron 1990, 46, 4407.
(8) Buono, G. Synthesis 1981, 872.
(9) Buono, G. Tetrahedron Lett. 1972, 32, 3257.
(10) Clinet, J . C.; Linstrumelle, G. Nouv. J . Chim. 1977, 1, 373.
10.1021/jo9903205 CCC: $18.00 © 1999 American Chemical Society
Published on Web 06/24/1999

5326 J . Org. Chem., Vol. 64, No. 14, 1999
Notes
Ta ble 1. Hyd r oiod in a tion Rea ction of
3,4-P en ta d ien -2-on e
Sch em e 4
NMR
yield (%)a
temp time
entry MX
solvent
(°C)
(h)
7
8
7/8
1
2
3
4
5
6
7
8
9
NaI HOAc-MeCN
NaI HOAc
NaI HOAc
NaI HOAc-THF(1:1)
NaI HOAc (1 N)-THF
LiI HOAc (1 N)-THF
NaI HOAc (3 N)-THF
LiI HOAc (3 N)-THF
LiI HOAc (3 N)-THF
NaI HOAc (3 N)-THF
25
25
25
25
0
3
3
5
5
5
5
5
5
5
25
44
74
58
56
63
64
59
76
79
3
89/11
94/6
91/9
3
7
9
87/13
0.9 98/2
2.2 97/3
7
7
1.7 98/2
1.9 98/2
0
25
25
0
90/10
89/11
10
0
10
a
Determined by 300 MHz 1H NMR spectra using CH2Br2 as
the internal standard.
Sch em e 5
Sch em e 3
Sch em e 6
high yield with fairly good stereoselectivity, although the
corresponding hydrochlorination reaction afforded the
products E-9 and Z-9 with lower stereoselectivity (Schemes
3 and 4). The formation of R,â-unsaturated â-haloenones
was not observed. The reaction of dodeca-3,4-dien-2-one
with MX afforded similar results (Scheme 4). The con-
figurations of the â,γ carbon-carbon double bonds were
determined by the 2D NOESY spectra of E-9c/Z-9c and
E-9d /Z-9d (Scheme 5). The reason for the different
stereoselectivity with LiCl monohydrate is not clear.
H yd r oh a logen a t ion R ea ct ion of 3,3-Dim et h yl-
Su bstitu ted 1,2-Allen yl Meth yl Keton e w ith MX.
Although 3,3-disubstituted 1,2-allenyl sulfones were
found to be much less reactive toward MX in HOAc than
1,2-propadienyl sulfones,11 the hydrohalogenation reac-
tion of 5-methyl-3,4-hexadien-2-one (4) with MX (X ) Cl,
Br, I) also went smoothly to afford 4-halo-5-methyl-4-
hexen-2-ones in high yields (Scheme 6). The â,γ carbon-
carbon double bonds of 10 are stabilized by the four
substituents;1 thus, the formation of R,â-unsaturated
enones was not observed.
Hyd r oh a logen a tion Rea ction of 1-Su bstitu ted 1,2-
Allen yl Keton es w ith MX. 1-Substituted 1,2-allenyl
ketones reacted with MI (M ) Na or Li) in HOAc afforded
a mixture of â,γ-unsaturated â-iodoenone 11a and R,â-
unsaturated â-iodoenone 12a with uninteresting ratio
(entries 1 and 2, Table 2). The corresponding reaction in
CF3COOH afforded 11a highly selectively, albeit in low
yield (entry 3, Table 2). Using a 3 N solution of CF3COOH
in THF as the solvent greatly improved the yields, but
the ratios of 11a /12a still need optimizing (entries 4 and
5, Table 2). Finally we found that the reaction could
afford the â,γ-unsaturated â-iodoenone 11a highly selec-
(11) For the results with 1,2-dienyl sulphones, see: Ma, S.; Wei, Q.
J . Org. Chem. 1999, 64, 1026.

Notes
J . Org. Chem., Vol. 64, No. 14, 1999 5327
Ta ble 2. Hyd r oh a logen a tion Rea ction of
3-Meth yl-3,4-p en ta d ien -2-on e
Sch em e 8
NMR
yield (%)
temp time
entry MX
solvent
(°C) (h) 11a 12a 11a /12a
1
2
3
4
5
6
7
NaI HOAc
NaI HOAc
NaI CF3CO2H
50
25
25
25
25
22
24
24
24
24
24
24
25 55
43 41
31/69
51/49
96/4
80/20
76/24
96/4
25
1.1
NaI CF3CO2H (3 N)-THF
78 19
74 23
LiI CF3CO2H (3 N)-THF
NaI HOAc-CF3CO2H (1:1) 25
82
70
3
2
LiI HOAc-CF3CO2H (1:1) 25
97/3
Sch em e 7
1
commercially available and used without purification. H NMR
spectra were measured using CDCl3 as the solvent and the
internal standard. The NMR yields were measured using CH2-
Br2 as the internal standard.
Syn th esis of 1,2-Allen yl Keton es. 3,4-Pentadien-2-one (1),8
3-methyl-3,4-pentadien-2-one (2),8,9 3-butyl-3,4-pentadien-2-one
(3),8,9 5-methyl-3,4-hexadien-2-one (4),10 3,4-nonadien-2-one (5),10,12
and 3,4-dodecadien-2-one (6)10 were prepared according to the
published procedures with modification.
3-Bu tyl-3,4-p en ta d ien -2-on e (3). Triethylamine (1.01 g, 10
mmol) was added to a stirred solution of 4-bromo-3-butyl-4-
penten-2-one8,13 (2.19 g, 10 mmol) in anhydrous CH3CN (10 mL)
at room temperature. Then, the mixture was refluxed for 20 h,
diluted with ether, washed with 5% hydrochloric acid and cold
water, and dried with magnesium sulfate. The solvent was
evaporated and the residue was purified by chromatography on
silica gel (eluent, pentane-ether ) 200:1) to afford 0.745 g (54%)
of 3: liquid; 1H NMR δ 0.87 (t, J ) 6.97 Hz, 3 H), 1.20-1.42 (m,
4 H), 2.08-2.18 (m, 2 H), 2.27 (s, 3 H), 5.16 (t, J ) 2.91 Hz, 2
tively when the reaction was carried out in a 1:1 mixture
of CF3COOH and HOAc (entries 6 and 7, Table 2).
Under these conditions, 3-methyl-3,4-pentadien-2-one
also reacted smoothly with LiBr or LiCl and afforded the
corresponding 4-halo-3-methyl-4-penten-2-ones 11 in high
yields with high selectivity over the R,â-unsaturated
enones 12 (Scheme 7).
H); MS (m/e) 138 (M+, 3.02), 43 (100); IR (neat) 1927, 1676 cm-1
;
HRMS calcd for C9H14O 138.1045, found 138.1042.
3,4-Non a d ien -2-on e (5). 1,2-Heptadiene (1.92 g, 20 mmol)
was treated with n-BuLi (20 mmol) in THF (20 mL) at -50 °C
for 2 h, followed by the dropwise addition of N,N-dimethylac-
etamide (2.61 g, 30 mmol) at -78 °C, and reacted at this
temperature for 2 h. The resulting solution was slowly trans-
ferred into an ice-cold aqueous HCl solution (0.1 N, 400 mL)
and extracted with ether. Drying over MgSO4, rotary evapora-
tion, and chromatography on silica gel (eluent, pentane-ether
) 40:1) afforded 1.46 g (53%) of the title compound:12 liquid; 1H
NMR δ 0.90 (t, J ) 6.87 Hz, 3 H), 1.33-1.48 (m, 4 H), 2.12-
2.25 (m, 2 H), 2.21 (s, 3 H), 5.63 (q, J ) 6.68 Hz, 1 H), 5,68-
5.71 (m, 1 H); MS (m/e) 138 (M+, 14.91), 43 (100); IR (neat) 1940,
The corresponding results of 3-butyl-3,4-pentadien-2-
one were listed in Scheme 8.
The mechanism for the current regio- and/or stereo-
selective hydrohalogenation is a nucleophilic conjugate
addition reaction of X- with 1,2-allenyl ketones at the
â-position to afford the expected â,γ-unsaturated â-ha-
loketone product. As a result of the relatively mild acidic
reaction conditions, the isomerization of the â,γ-unsatur-
ated ketone to the R,â-unsaturated ketone is suppressed.
In conclusion, the methodology discussed in this paper
provides an efficient general high-yielding route to â,γ-
unsaturated â-haloketones with different substitution
patterns. Because of the ease of converting the carbon-
halogen bond, the carbonyl group, and the carbon-carbon
double bond to other functional groups, this methodology
will show its utility in the organic syntheses of com-
pounds such as substituted â,γ-unsaturated enones,
homoallylic alcohols, etc.
1682 cm-1
.
3,4-Dod eca d ien -2-on e (6). Liquid; 1H NMR δ 0.87 (t, J )
6.57 Hz, 3 H), 1.26-1.49 (m, 10 H), 2.11-2.26 (m, 2 H), 2.21 (s,
3 H), 5.62 (q, J ) 6.58 Hz, 1 H), 5.69-5.73 (m, 1 H), MS (m/e)
180 (M+, 0.38); IR (neat) 1940, 1678 cm-1. HRMS calcd for
C12H20O 180.1515, found 180.1514.
Hyd r oiod in a tion Rea ction of 3,4-P en ta d ien -2-on e. NaI
or LiI (2.2 mmol) was added to the solution of 3,4-pentadien-2-
one (2.0 mmol) in the specified solvent (see Table 1), and the
mixture was stirred for the time listed in Table 1. Then the
mixture was diluted with ether and neutralized with aqueous
K2CO3 at 0 °C. The ether layer was separated, the aqueous layer
was extracted with ether, and the combined ether layers were
dried over MgSO4. Evaporation of the solvent afforded the crude
Exp er im en ta l Section
(12) Ma, D.; Yu, Y.; Lu, X. J . Org. Chem. 1989, 54, 1105.
(13) Ono, N.; Yoshimura, T.; Saito, T.; Tamura, R.; Tanikaga, R.;
Kaji, A. Bull. Chem. Soc. J pn. 1979, 52, 1716.
Gen er a l. Lithium iodide, lithium bromide monohydrate,
lithium chloride monohydrate, NaI, THF, and CF3COOH were

5328 J . Org. Chem., Vol. 64, No. 14, 1999
Notes
product, which was analyzed by 300 MHz 1H NMR spectroscopy
using CH2Br2 as the internal standard. The spectral data of
4-iodo-4-penten-2-one are the same as reported in ref 7.
4-Iod o-5-m eth yl-4-h exen -2-on e (10a ). Liquid; 1H NMR δ
1.82 (s, 3 H), 2.00 (s, 3 H), 2.17 (s, 3 H), 3.80 (s, 2 H); MS (m/e)
238 (M+, 24.12), 43 (100); IR (neat) 1716, 1632 cm-1; HRMS calcd
for C7H11IO 237.9855, found 237.9865.
Syn th esis of 4-Iod o-4-n on en -2-on e (9a ). Typical procedure.
A solution of 3,4-nonadien-2-one (138 mg, 1.0 mmol) and NaI
(180 mg, 1.2 mmol) in HOAc (1 mL) was stirred at 25 °C for 24
h. After complete conversion of the starting material as moni-
tored by TLC, the mixture was diluted with ether and neutral-
ized with aqueous K2CO3 at 0 °C. The ether layer was separated,
the aqueous layer was extracted with ether, and the combined
ether layers were dried over MgSO4. Evaporation of the solvent
and chromatography on silica gel (petroleum ether-ether ) 100:
1
4-Br om o-5-m eth yl-4-h exen -2-on e (10b). Liquid; H NMR
δ 1.77 (s, 3 H), 1.93 (s, 3H), 2.19 (s, 3 H), 3.63 (s, 2 H); MS (m/e)
192 (M+(81Br), 4.09), 190 (M+(79Br), 3.71), 43(100); IR (neat) 1710,
1650 cm-1; HRMS calcd for C7H11BrO 189.9992, found 189.9968.
4-Ch lor o-5-m eth yl-4-h exen -2-on e (10c).15,16 Liquid; 1H NMR
δ 1.75 (s, 3 H), 1.88 (s, 3 H), 2.18 (s, 3 H), 3.45 (s, 2 H); MS (m/e)
148 (M+(37Cl), 3.02), 146 (M+(35Cl), 5.71), 43 (100); IR (neat) 1715,
1655 cm-1
.
1
1) afforded Z-9a in 76% yield (202 mg): liquid; H NMR δ 0.91
Syn th esis of 4-Iod o-3-bu tyl-4-p en ten -2-on e (13a ). Typical
procedure. NaI (180 mg, 1.2 mmol) was added to a solution of
3-butyl-3,4-pentadien-2-one (138 mg, 1 mmol) in HOAc (1 mL)-
CF3COOH (1 mL) at room temperature. The mixture was stirred
at 25 °C for 24 h. After complete conversion of the starting
material, the mixture was diluted with ether and neutralized
with aqueous K2CO3 at 0 °C. The ether layer was separated,
the aqueous layer was extracted with ether, and the combined
ether layers were dried over MgSO4. Evaporation of the solvent
and chromatography on silica gel (petroleum ether-ether ) 100:
(t, J ) 6.96 Hz, 3 H), 1.34-1.54 (m, 4 H), 2.05-2.30 (m, 2 H),
2.18 (s, 3 H), 3.68 (s, 2 H), 5.65 (t, J ) 6.66 Hz, 1 H); MS (m/e)
266 (M+, 0.10), 43 (100); IR (neat) 1716, 1638 cm-1; HRMS calcd
for C9H15IO 266.0169, found 266.0167. In the NMR spectra of
the crude product, the following signals for the E-isomer were
discernible: δ 3.67 (s, 2 H), 6.43 (t, J ) 7.34 Hz, 1 H).
The following compounds were prepared similarly using the
conditions listed in Schemes 3, 4, and 6.
(Z)-4-Br om o-4-n on en -2-on e (9b). Liquid; 1H NMR δ 0.90
(t, J ) 7.01 Hz, 3 H), 1.27-1.50 (m, 4 H), 2.11-2.30 (m, 2 H),
2.19 (s, 3 H), 3.51 (s, 2 H), 5.82 (t, J ) 6.83 Hz, 1 H), MS (m/e)
1
1) afforded 13a in 89% yield (237 mg): liquid; H NMR δ 0.89
(t, J ) 7.10 Hz, 3 H), 1.05-1.44 (m, 4 H), 1.48-1.78 (m, 2 H),
2.19 (s, 3 H), 3.09 (dd, J ) 6.12 and 8.20 Hz, 1 H), 6.02 (s, 1 H),
220 (M+ 81Br), 0.04), 218 (M+ 79Br), 0.05), 43 (100); IR (neat)
( (
1715, 1649 cm-1; HRMS calcd for C9H15BrO 218.0307, found
218.0291. In the NMR spectra of the crude product, the following
signals for the E-isomer were discernible: δ 3.61 (s, 2 H), 6.11
(t, J ) 7.61 Hz, 1 H).
6.33 (s, 1 H); MS (m/e) 266 (M+, 2.19); IR (neat) 1714, 1607 cm-1
;
HRMS calcd for C9H15IO 266.0169, found 266.0155. The follow-
ing compounds were prepared similarly.
4-Br om o-3-bu tyl-4-p en ten -2-on e (13b). Liquid; 1H NMR δ
0.84 (t, J ) 7.05 Hz, 3 H), 1.02-1.38 (m, 4 H), 1.54-1.88 (m, 2
H), 2.17 (s, 3 H), 3.26 (dd, J ) 6.17 and 8.32 Hz, 1H), 5.65 (s,
(E)-4-Ch lor o-4-n on en -2-on e (9c).14 Liquid; 1H NMR δ 0.88
(t, J ) 7.01 Hz, 3H), 1.23-1.50 (m, 4 H), 2.03 (q, J ) 7.24 Hz,
2H), 2.21 (s, 3 H), 3.41 (s, 2 H), 5.84 (t, J ) 7.72 Hz, 1 H); MS
1H), 5.79 (s, 1H); MS (m/e) 220 (M+ 81Br), 5.21), 218 (M+ 79Br),
( (
(m/e) 176 (M+
(
37Cl), 12.34), 174 (M+(35Cl), 33.05), 43 (100); IR
5.36), 43 (100); IR (neat) 1715, 1621 cm-1; HRMS calcd for C9H15
BrO 218.0307, found 218.0276.
-
(neat) 1716, 1650 cm-1
.
(Z)-4-Ch lor o-4-n on en -2-on e (9c).14 Liquid; 1H NMR δ 0.87
(t, J ) 6.99 Hz, 3 H), 1.20-1.50 (m, 4 H), 2.10-2.30 (m, 2 H),
2.12 (s, 3 H), 3.42 (s, 2H), 5.62 (t, J ) 7.03 Hz, 1 H); MS (m/e)
3-Bu tyl-4-ch lor o-4-p en ten -2-on e (13c). Liquid; 1H NMR
0.87 (t, J ) 7.05 Hz, 3 H), 1.06-1.39 (m, 4 H), 1.59-1.85 (m, 2
H), 2.20 (s, 3 H), 3.27 (dd, J ) 6.21and 8.44 Hz, 1 H), 5.36 (s, 1
176 (M+
( (
37Cl), 2.39), 174 (M+ 35Cl), 6.80), 43 (100); IR (neat)
H), 5.41 (s, 1 H); MS (m/e) 176 (M+(37Cl), 3.15), 174 (M+ 35Cl),
(
1717, 1652 cm-1
.
9.14); IR (neat) 1715, 1626 cm-1; HRMS calcd for C9H15ClO
174.0813, found 174.0791.
(Z)-4-Iod o-4-d od ecen -2-on e (9d ). Liquid; 1H NMR δ 0.87
(t, J ) 6.73 Hz, 3 H), 1.15-1.53 (m, 10 H), 2.07-2.27 (m, 2 H),
2.11 (s, 3 H), 3.68 (s, 2 H), 5.65 (t, J ) 6.76 Hz, 1 H); MS (m/e)
308 (M+, 3.21), 43 (100); IR (neat) 1716, 1638 cm-1; HRMS calcd
for C12H21IO 308.0638, found 308.0653. In the NMR spectra of
the crude product, the following signals for the E-isomer were
discernible: δ 3.72 (s, 2 H), 6.49 (t, J ) 7.52 Hz, 1 H).
1
4-Iod o-3-m eth yl-4-p en ten -2-on e (11a ). Liquid; H NMR δ
1.19 (d, J ) 6.72 Hz, 3 H), 2.19 (s, 3 H), 3.32 (q, J ) 6.72 Hz, 1
H), 5.97 (s, 1 H), 6.30 (s, 1 H); MS (m/e) 224 (M+, 10.90), 43
(100); IR (neat) 1710, 1605 cm-1; HRMS calcd for C6H9IO
223.9698, found 223.9695.
(Z)-4-Br om o-4-d od ecen -2-on e (9e). Liquid; 1H NMR δ 0.87
(t, J ) 6.53 Hz, 3 H), 1.18-1.52 (m, 10 H), 2.12-2.30 (m, 2 H),
2.20 (s, 3 H), 3.51 (s, 2 H), 5.82 (t, J ) 6.85 Hz, 1 H); MS (m/e)
1
4-Iod o-3-m eth yl-3-p en ten -2-on e (12a ). Liquid; H NMR δ
2.07 (s, 3H), 2.27 (s, 3H), 2.67 (s, 3H); MS (m/e) 224 (M+, 12.59),
43 (100); IR (neat) 1694, 1601 cm-1; HRMS calcd for C6H9IO
223.9699, found 223.9707.
262 (M+ 81Br), 6.83), 260 (M+ 79Br), 6.83), 43 (100); IR (neat)
( (
1716, 1652 cm-1; HRMS calcd for C12H21BrO 260.0776, found
260.0798. In the NMR spectra of the crude product, the following
signals for the E-isomer were discernible: δ 3.55 (s, 2 H), 6.10
(t, J ) 7.64 Hz, 1 H).
4-Br om o-3-m eth yl-4-p en ten -2-on e (11b). Liquid; 1H NMR
δ 1.27 (d, J ) 6.86 Hz, 3 H), 2.22 (s, 3 H), 3.41 (q, J ) 6.86 Hz,
1 H), 5.66 (s, 1 H), 5.82 (s, 1 H); MS (m/e) 178 (M+(81Br), 1.50),
176 (M+ 79Br), 1.55); IR (neat) 1715, 1617 cm-1; HRMS calcd
(
(Z)-4-Ch lor o-4-d od ecen -2-on e (9f). Liquid; 1H NMR δ 0.87
(t, J ) 6.41 Hz, 3H), 1.14-1.52 (m, 10 H), 2.10-2.30 (m, 2H),
2.20 (s, 3 H), 3.35 (s, 2 H), 5.63 (t, J ) 6.93 Hz, 1 H); MS (m/e)
for C6H9BrO 175.9837, found 175.9825.
4-Ch lor o-3-m eth yl-4-p en ten -2-on e (11c).17 Liquid; 1H NMR
δ 1.29 (d, J ) 6.96 Hz, 3 H), 2.22 (s, 3 H), 3.44 (q, J ) 6.84 Hz,
1 H), 5.37 (s, 1 H), 5.40 (s, 1 H); MS (m/e) 134 (M+(37Cl), 1.95),
218 (M+ 37Cl), 0.02), 216 (M+ 35Cl), 0.04), 43 (100); IR (neat)
( (
1716, 1654 cm-1; HRMS calcd for C12H21ClO 216.1282, found
216.1266.
132 (M+ 35Cl), 5.65), 43 (100); IR (neat) 1716, 1625 cm-1
( .
(E)-4-Ch lor o-4-d od ecen -2-on e (9f). Liquid; 1H NMR δ 0.86
(t, J ) 6.58 Hz, 3 H), 1.15-1.60 (m, 10 H), 2.02 (q, J ) 7.35 Hz,
2 H), 2.21(s, 3 H), 3.41 (s, 2 H), 5.84 (t, J ) 7.73 Hz, 1 H); MS
Ack n ow led gm en t. We thank National Natural
Science Foundation of China, Laboratory of Organome-
tallic Chemistry, Chinese Academy of Sciences, and
Shanghai Municipal Committee of Science and Technol-
ogy for financial support.
(m/e) 218 (M+ 37Cl), 1.94), 216 (M+ 35Cl), 5.85), 43 (100); IR
( (
(neat) 1716, 1650 cm-1; HRMS calcd for C12H21ClO 216.1282,
found 216.1294.
(14) Martin, G. J .; Kirschleger, B. C. R. Hebd. Seances Acad. Sci.,
Ser. C 1974, 279, 363.
(15) Sugita, T.; Ito, H.; Nakajima, A.; Sunami, M.; Kawakatsu, A.;
Suami, M.; Ichikawa, K. Bull. Chem. Soc. J pn. 1987, 60, 721.
(16) Suama, M.; Nakajima, A.; Sugita, T. Chem. Lett. 1981, 1459.
(17) Schelhorn, H.; Hauptmann, S. Z. Chem. 1973, 13, 130. Chem.
Abstr. 1973, 79, 52733s.
1
Su p p or tin g In for m a tion Ava ila ble: The H NMR spec-
tra of the compounds Z-9a -f, E-9c, E-9f, 10a -b, 11a -b, 12a ,
and 13a -c. This material is available free of charge via the
Internet at http://pubs.acs.org.
J O9903205