Highly stereo and chemoselective iron-catalyzed alkenylation of organomagnesium compounds

Article abstract of DOI:10.1055/s-1998-2135

In the presence of Fe(acac)₃, Grignard reagents react readily with alkenyl halides (X = I, Br or Cl) in a THF/NMP mixture to give the cross-coupling products in high yields with an excellent stereoselectivity (≤99.5%). The scope of the reaction is very broad since a vast array of functional groups are tolerated (esters, nitriles, aromatic or aliphatic halides and even ketones). The procedure reported herein is an interesting alternative to the classical Pd- or Ni-catalyzed reactions, especially for preparative organic chemistry.

Full text of DOI:10.1055/s-1998-2135

SYNTHESIS
August 1998
1199
Highly Stereo- and Chemoselective Iron-Catalyzed Alkenylation of Organomagnesium
Compounds
Gérard Cahiez,* Hovsep Avedissian
Ecole Supérieure de Chimie Organique et Minérale, Département de Chimie, 13, boulevard de l'Hautil, F-95092 Cergy-Pontoise, France
Fax: +33(1)30756021
Received 14 March 1998; revised 26 March 1998
Abstract: In the presence of Fe(acac)3, Grignard reagents react
readily with alkenyl halides (X= I, Br or Cl) in a THF/NMP mix-
ture to give the cross-coupling products in high yields with an
excellent stereoselectivity (≥99.5%). The scope of the reaction is
very broad since a vast array of functional groups are tolerated
(esters, nitriles, aromatic or aliphatic halides and even ketones).
The procedure reported herein is an interesting alternative to the
classical Pd- or Ni-catalyzed reactions, especially for preparative
organic chemistry.
It should be noted that the 1-bromoprop-1-ene used above
is very reactive, thus, from a less reactive alkenyl halide
the influence of the NMP is even more striking (Scheme
2).
Key words: iron, organomagnesium compounds, alkenyl halides,
alkenylation, cross-coupling reaction, Z- or E-alkenes
Scheme 2
Recently we reported the first iron-catalyzed alkenylation
of organometallic reagents of preparative interest.1 In-
deed, we have discovered that organomanganese reagents
readily react with alkenyl iodides, bromides and even the
low reactive chlorides in the presence of iron acetylaceto-
nate to give high yields of cross-coupling products provid-
ing that the coupling is performed in the presence of NMP
as cosolvent. The reaction has a large scope of application
since it is highly stereo- and chemoselective.
As shown in Table 1, the addition of various polar cosol-
vents such as sulfolane, diethyl carbonate, DMPU or N,N-
dialkyl amides such as DMF or DMA (entries 1 to 5) and,
to a lesser extent, tetramethylurea or DME (entries 6 and 7)
also improves the yield of undec-2-ene. However, the best
result was obtained in the presence of NMP (Scheme 1).
Table 1. Influence of Various Cosolvents on the Yield of 1
To extend these results we have decided to reinvestigate
the iron-catalyzed alkenylation of Grignard reagents first
described by Kochi et al. in 1971.2 These authors did a very
interesting mechanistic study, however, the alkenyl halides
have to be used in large excess in most cases (3 to 5 equiv)
and the yields based on the Grignard reagents are moderate.
Diverse attempts to vary the nature of the iron salt used as
catalyst or the nature of the solvent have not been able to
circumvent these drawbacks and the reaction has never
been used for preparative organic chemistry until now. In
the light of the results obtained with organomanganese
chlorides,1 we thought that the use of NMP as cosolvent
could have a beneficial influence on the reaction and we
report now our first results in this field.
Entry
Cosolvent
Yield of 1 (%)a
1
2
3
4
5
6
7
DMPUb
80
81
80
78
72
56
59
DMFb
DMAb
diethyl carbonateb
sulfolaneb
tetramethylurea
DME
a Yield of isolated product.
b The use of 2 equivalents of cosolvent led to the same yield.
Our first attempt to perform the reaction in the presence of
NMP was successful. Thus, octylmagnesium chloride re-
acted with 1-bromoprop-1-ene in the presence of 3%
Fe(acac)3 to give 40% of 2-undecene whereas by adding The nature of the iron salts used as catalyst is not essential.
NMP as cosolvent the yield jumped to 87% (Scheme 1). Thus, no difference was observed by replacing Fe(acac)3
Interestingly, two equivalents of NMP (based on OctMgCl) by Fe(dpm)3, Fe(dbm)3 or FeCl3 (Table 2, entries 1–4). In
are enough to obtain a good result (Scheme 1, note a).
fact, it is only necessary to choose an iron salt soluble in
THF, thus, Fe2(SO4)3 only led to 31% of undec-2-ene (en-
try 5). It should be emphasized that these results are clear-
ly different from those obtained in the absence of NMP
since the nature of the catalyst then deeply influences the
course of the reaction. Thus, Kochi has reported that
Fe(dpm)3 and Fe(dbm)3 are more efficient in THF alone
than Fe(acac)3 which is clearly superior to FeCl3.2g In our
case, one of the effects of NMP is probably to stabilize the
iron organometallic species which are the real catalytic in-
Scheme 1

SYNTHESIS
Feature Article
Table 2. Influence of the Nature of the Catalyst on the Yield of 1
1200
Fe(acac)3 whereas by using 0.01% Fe(acac)3 the yield only
decreased to 82%. This is a good illustration of the high
efficiency of this iron-catalyzed procedure since transition
metal-catalyzed cross-coupling reactions generally require
a higher amount of catalyst (very often 3 to 5%).
Entry
Catalyst
Yield of 1 (%)a
1
2
3
4
5
Fe(acac)3b
Fe(dbm)3c
Fe(dpm)3
FeCl3
87
87
88
88
31
Fe2(SO4)3
a Yield of isolated product.
b dbm = dibenzoylmethido.
c dpm = dipivaloylmethido.
Scheme 3
termediates of this reaction by limiting the decomposition
processes (i.e. hydrogen β-elimination). Such a stabilizing
effect is consistent with the results described in the case of
the copper- and iron-catalyzed organomanganese reac-
tions.
It is worthy of note that the reaction gave similar yields
from alkenyl iodides, bromides and even chlorides in spite
of their low reactivity (Table 3, entries 1–3). However,
with the latter it is necessary to add more NMP (9 equiv
instead of 2 equiv) to improve the yield (entry 3). In all
cases the reaction takes place almost instantaneously. The
results presented above were obtained by using 1%
Fe(acac)3 as catalyst. Indeed, with only 0.1% Fe(acac)3
the yields are lower (X=Br, 55% instead of 82%).
From these considerations it was tempting to try to lower
the percentage of catalyst. As shown in Scheme 3, octyl-
magnesium chloride reacted with 1-bromoprop-1-ene to
afford 87% of undec-2-ene in the presence of 3 to 0.1%
Biographical Sketches
Gérard Cahiez was born in 1950 in Paris, France. He received his Ph. D. degree in 1973,
at the University Pierre et Marie Curie (Paris VI) under the supervision of Professor Jean
Normant on the preparation and reactivity of vinylcopper reagents (syn addition of alkyl-
copper to alk-1-ynes); he then joined the CNRS. After a post-doctoral year at the Re-
search Centre of Roussel Uclaf on the chemistry of steroids he returned to the University
of Pierre et Marie Curie and later moved to Ecole Supérieure de Chimie Organique et
Minérale (ESCOM, Cergy-Pontoise) in 1993. He is now the Director of Research at the
CNRS (since 1980) and Professor of Organic and Analytical Chemistry at ESCOM
(since 1993). In addition, he is the Director of the Research Centre of ESCOM (since
1995) and Chairman of the Department of Chemistry (since 1997). His research is fo-
cussed on the use of organometallic reagents in organic synthesis. He has been a pioneer
in the development of organomanganese chemistry. The current interest is always fo-
cussed on organomanganese chemistry but more generally on the search for new highly
selective organometallic reactions, i.e. Mn- or Fe-cross-coupling reactions, involving no
toxic and/or expensive metal or additives. Other fields of research deal with combinato-
rial chemistry and the design of multi-step syntheses for large scale industrial applica-
tions (mainly pharmaceutical and agrochemical).
Hovsep Avedissian was born in 1970 in Lebanon. He studied chemistry at the University
Pierre et Marie Curie, France. He received his Ph. D. in 1997 for a thesis on the Fe- and
Co-catalyzed alkenylation of organomagnesium and organozinc reagents under the su-
pervision of Prof. G. Cahiez. He is now a post-doctoral fellow at the Scripps Research
Institute, USA, in the group of Prof. E. Keinan.

SYNTHESIS
August 1998
1201
Table 3. Influence of the Nature of X on the Yield of 2
Table 4. Iron-Catalyzed Alkenylation of Alkylmagnesium Chlorides:
Preparation of Olefins 3 and 7–22
Entry
X
NMP (equiv)
Yield of 2 (%)a
Entry Starting
Alkenyl Halide
Prod-
uct
Ra
Yield
(%)b
1
2
3
I
Br
Cl
2
2
9
83
82b
85
1
3
7
Bu
t-Bu
80
64
a Yield of isolated product.
b Only 55% were obtained by using 0.1% Fe(acac)3 as catalyst.
2
3
8
Bu
s-Bu
83
80
As exemplified below (Scheme 4), the reaction is highly
stereoselective, thus the (Z)- and (E)-1-chlorooct-1-enes
afforded the corresponding Z- and E-olefins 3 and 4 with
a stereoisomeric purity ≥ 99.5%.
3
4
5
8
9
s-Bu
c-Hex
Mec
74
89
87
10
11
12
13
14
Mec
Bu
i-Pr
t-Bu
88
84
73
64
6
7
8
15
C8H17
86
Scheme 4
16
i-Pr
72
Similar results were also obtained from (Z)- and (E)-1-io-
dohex-1-enes (Scheme 5).
9
10
11
17
18
19
Mec
60
82
87
c-Hex
c-Hex
Scheme 5
12
13
14
20
21
22
Mec
Bu
75
75
84
Kochi has evidenced that in THF (E)-1-bromoprop-1-ene
reacts much more rapidly than the corresponding Z-iso-
mer.2a Under our conditions we have observed no differ-
ence of reactivity beetwen the two stereoisomers. Thus,
octylmagnesium chloride when treated with an excess of
a 60:40 mixture of (E)- and (Z)-1-bromoprop-1-ene (2
equiv) in the presence of NMP and 3% Fe(acac)3 gave a
mixture of (E) and (Z)-2-undecene in the same stereoiso-
meric ratio (60:40) (Scheme 6).
C8H17
a 1.1 equivalents of RMgCl were used.
b Yield of distilled product.
The procedure described above has a large scope of appli-
cation. Various alkenyl iodides, bromides or chlorides
have been converted to the corresponding cross-coupling
products in excellent yields (Table 4, entries 1 to 14). In
all cases the stereochemistry of the starting halides was
c When R = Me, the reaction was performed between 15 and 20°C.

SYNTHESIS
Feature Article
1202
This preliminary result prompted us to continue our inves-
tigations in this field. In all the examples described above,
the reaction of organomagnesium reagents with NMP (2
to 9 equiv) was never observed. The chemoselectivity of
the reaction is not limited to amides since more reactive
compounds such as esters and even ketones are tolerated
in spite of the very high reactivity of Grignard reagents
towards these functional groups (Table 6, entries 1 and 2).
In addition, under our reaction conditions the competitive
cross-coupling reactions with alkyl or aryl halides do not
occur (Table 6, entries 3 and 4).
Scheme 6
conserved. Primary and secondary alkyl Grignard re-
agents reacted successfully under standard conditions [1%
Fe(acac)3, –5 to 0°C, 9 equiv NMP] to give 74 to 89% of
the expected olefines (entries 2–4). In some cases, the reac-
tion conditions must be changed. Thus, from the less reac-
tive methylmagnesium chloride or bromide, the reaction
led to more satisfactory results by adding the Grignard re-
agent at 15–20°C (entries 5, 6, 9, and 12, R= Me). On the
other hand, with tert-butylmagnesium chloride the β-elim-
ination process becomes competitive and it is better to use
Fe(dpm)3 as catalyst (entries 1 and 6, R = t-Bu). Thus, in the
Table 6. Chemoselectivity of the Iron-Catalyzed Akenylation of Or-
ganomagnesium Reagents
case of 2-bromostyrene, the yield of alkene 14 increased Entry
from 54 to 64% by replacing Fe(acac)3 by Fe(dpm)3 (entry
R-Fg
Recovered R-Fg
(%)a
Yield of 1
(%)b
6, R = t-Bu). However, with a β,β-disubstituted alkenyl ha-
lide such as Bu2C=CHBr which is less reactive, only the
reduction product Bu2C=CH2 was formed in 42% yield.
1
2
3
4
C4H9CO2Et
C3H7COC3H7
PhBr
≥98
≥98
≥98
≥98
85
87
92
88
C7H15Br
Vinyl-vinyl and aryl-vinyl cross-coupling reactions were
also achieved. Thus, 60% of diene 23 was obtained from
2-methylprop-1-enylmagnesium bromide and 2-bro-
mostyrene (Scheme 7).
a GC analysis.
b Yield of distilled undec-2-ene.
The high selectivity of the procedure is underlined by the
examples presented in Table 7.
Table 7. Selective Substitution of Functionalized Alkenyl Halides
Scheme 7
Phenylmagnesium chloride reacted with 2-bromostyrene
to afford 90% of stilbene 24 (Table 5, entry 1). However,
from a less reactive alkenyl halide such as 1-bromoprop-
1-ene the yield was lower (57% of 25, entry 2). These re-
sults are not surprising since aryl- and alkenyl organome-
tallic reagents are less reactive than their alkyl counter-
parts. It is probably possible to improve the yields by
changing the reaction conditions. Thus, by using sulfolane
in place of NMP the coupling of phenylmagnesium chlo-
ride with 1-bromoprop-1-ene led to 82% of olefin 26 in-
stead of 57% (entries 2 and 3).
Entry Functionalized Alkenyl
Halide
Prod- Ra
uct
Yield
(%)b
1
26
27
Bu
i-Pr
80
72
2
3
<?Z02698-18>
28
Bu
80
29
Mec
68
Table 5. Iron-Catalyzed Cross-Coupling Reaction of Phenylmagnesi-
um Chloride with Alkenyl Halides
4
5
30
31
Bu
Bu
79
79
Entry
R
Prod-
uct
X
Cosolvent
Yield (%)a
1
2
3
Ph
Me
Me
24
25
25
0.1%
3%
3%
NMP (2 equiv)
NMP (9 equiv)
sulfolane (9 equiv) 82
90
57
a 1.1 equivalents of RMgCl were used.
b Yield of distilled product.
c The reaction was performed between 15 and 20°C.
a Yield of isolated product.

SYNTHESIS
August 1998
1203
THF was distilled from sodium benzophenone ketyl under a N2 atmo-
sphere and NMP was distilled before use. All products were isolated
by distillation. The most part of the reactions were performed on a
50 mmol scale. GC analyses: Fisons GC 8000, capillary column SGE
Recently, we have tried to extend the reaction to enol es-
ters. We report below our first successful attempt from an
enol phosphate3 (Scheme 8).
1
25QC5/BP1 (25 m × 0.53 mm, 0.5 mm film thickness). H and 13C
NMR spectra: JEOL JNM-EX 270, internal standard TMS, J values
in Hz. IR spectra: FT spectrometer Nicolet Impact 400 (OMNIC soft-
ware). The starting β-substituted alkenyl iodides were prepared by
carbocupration of alk-1-ynes, then iodolysis of the resulting alkenyl
copper (from RC≡CH)6a or cuprates (from HC≡CH)6b and by hy-
droalumination of alk-1-ynes then iodolysis of the resulting alkenyl
alanes.7 The corresponding bromides and chlorides were obtained by
chlorine- or bromine-iodine exchange (CuCl or CuBr, NMP, 120–
150°C).8 2-Bromoolefins were prepared by addition of HBr to alk-1-
ynes (Et4NHBr2, CH2Cl2, 40°C).9 Specific methods were used for the
two halocyclenones mentioned in Table 7 (entries 310 and 411). The
iron complexes were synthesized according to literature.2g The prod-
ucts 1, 10–12, 17, 20, 24 and 25 were compared with commercial
samples. The products 2 and 206a as well as 2912 were compared with
authentic samples. All other cross-coupling products are described in
Table 8.
Scheme 8
These substrates are less reactive than alkenyl halides and
it is necessary to add more catalyst (6%) and more orga-
nomagnesium reagent (2 equiv) to obtain a satisfactory
yield. However, this preliminary result is interesting since
enol phosphates are readily prepared from ketones.4 In ad-
dition, they are cheaper and much easier to handle than the
corresponding triflates which are generally used to per-
form such cross-coupling reactions since they are more
reactive.
In conclusion, we have shown that organomagnesium re-
agents readily react with alkenyl iodides, bromides and
chlorides in the presence of Fe(acac)3 and NMP (2 to 9
equiv) to give the corresponding cross-coupling products in
high yields. The reaction is highly stereoselective (≥99.5%)
and numerous functional groups are tolerated (alkyl and
aryl bromides, amides, esters and even ketones). The proce-
dure reported herein is the first iron-catalyzed alkenylation
of organomagnesium reagents of actual preparative inter-
est. From an economical and environmental point of view,
it is an interesting alternative to the nickel and palladium-
catalyzed reactions prevalent at present.5 The application to
the synthesis of natural products (e.g. insect pheromones)
and the extension to enol esters, especially to enol phos-
phates, will be reported in due course.
12-Acetoxydodec-5-ene (26); Typical procedure:
To a solution of (E)-8-acetoxy-1-chlorooct-1-ene (25 mmol, 5.11 g)
and 1% Fe(acac)3 (0.088 g) in a mixture of THF (30 mL) and NMP
(25 mL, 9 equiv) was added dropwise (10 min), between –5 and 0°C,
a 1.2 M solution of butylmagnesium chloride in THF (27.5 mmol,
22.9 mL). Stirring was continued for 15 min then the reaction mixture
was hydrolyzed at –10°C with aq 1 M HCl (80 mL). After decanta-
tion, the aqueous layer was extracted with Et2O and the combined
organic phases were washed with satd aq NaHCO3 solution, H2O and
dried (MgSO ). Solvents were removed under vacuo and the product
4
26 was isolated by distillation in 80% yield (4.53 g); bp 120–123°C/
5 Torr (Table 8).
G.C. belongs to the CNRS. We thank the CNRS and the Ecole
Supérieure de Chimie Organique et Minérale (ESCOM) for their
financial support.
Table 8. Characteristic Physical and Spectroscopic Data of Products
Prod- bp
IR (neat)
1H NMR (CDCl3/TMS)
δ, J (Hz)
13C NMR (CDCl3/TMS)
δ
ucta
(°C)/Torr
ν (cm–1)
3
88–92/10
93–97/10
119/12
72/4
1669, 964
1656, 722
1650, 960
1650, 715
0.88–0.95 (m, 6H), 1.20–1.32 (m, 12H), 1.95– 13.93, 14.07, 22.25, 22.71, 28.93, 29.70, 31.85,
2.10 (m, 4H), 5.35–5.45 (m, 2H) 31.91, 32.36, 32.69, 130.28, 130.36
4
5
6
0.88–0.95 (m, 6H), 1.15–1.33 (m, 12H), 1.85– 13.99, 14.10, 22.42, 22.77, 26.98, 27.26, 29.35,
2.05 (m, 4H), 5.38–5.50 (m, 2H) 29.83, 31.99, 32.06, 129.79, 129.87
0.89 (t, 3H, J = 4.9), 0.92 (t, 3H, J = 4.9), 1.20– 13.95, 14.10, 22.20, 22.69, 29.19 (2C), 29.33 (2C),
1.35 (m, 16H), 1.95–2.05 (m, 4H), 5.41 (m, 2H) 29.50 (2C), 31.85 (2C), 31.91, 130.29, 130.37
0.84–0.92 (m, 6H), 1.25–1.36 (m, 16H), 1.9 (m, 13.98, 14.10, 22.35, 22.69, 25.75, 26.91, 27.20,
4H), 5.34 (t, 2H, J = 4.7)
29.33 (2C), 29.65, 29.78, 31.97, 32.82, 129.82,
129.89
7
8
72–73/10
72–73/10
1652, 965
1651, 962
0.88 (t, 3H, J = 4.8), 1.01 (s, 9H), 1.25–1.35 (m, 14.10, 22.67, 28.83, 29.76, 29.85 (3C), 31.79,
8H), 1.97 (dt, 2H, J = 5.1, 0.5), 5.33 (dt, 1H, J = 32.70, 124.80, 141.45
15.6, J = 6.6), 5.45 (d, 1H, J = 15.6)
0.87 (t, 3H, J = 5.1), 0.91 (t, 3H, J = 4.6), 0.98 (d, 11.79, 14.11, 20.51, 22.69, 28.84, 29.72 (2C),
3H, J = 4.6), 1.25–1.40 (m, 12H), 1.95–2.05 (m, 29.91, 31.79, 38.44, 128.70, 136.13
4H), 5.27 (dd, 1H, J = 10.3, 5.1), 5.37 (dt, 1H, J
= 10.3, 4.32)

SYNTHESIS
Feature Article
1204
Table 8. continued
Prod- bp
IR (neat)
1H NMR (CDCl3/TMS)
δ, J (Hz)
13C NMR (CDCl3/TMS)
δ
ucta
(°C)/Torr
ν (cm–1)
9
64–65/2
1650, 725
0.93 (t, 3H, J = 5.1), 1.08–1.36 (m, 10H), 1.55– 14.10, 22.45, 26.12 (2C), 26.20, 27.26, 32.32,
1.80 (m, 4H), 1.95–2.05 (m, 2H), 2.15–2.25 (m, 33.51 (2C), 36.30, 128.10, 136.09
1H), 5.18–5.30 (m, 2H)
13
67–72/10
1695, 1594,
1493, 1456,
966, 747,
693
1.23 (d, 6H, J = 4.5), 2.50 (hept, 1H, J = 4.5), 6.24 22.18 (2C), 31.27, 125.70 (2C), 126.47, 126.67,
(dd, 1H, J = 16.2, 6.75), 6.40 (d, 1H, J = 16.2), 128.16 (2C), 137.45, 137.60
7.13–7.40 (m, 5H)
14
15
16
18
19
22
23
70/5
1690, 1590,
1480, 960,
740, 690
1.15 (s, 9H), 6.33 (d, 1H, J = 10.8), 6.39 (d, 1H, J 29.59 (3C), 33.31, 124.59, 126.01 (2C), 126.71,
= 10.8), 7.22–7.45 (m, 5H)
128.43 (2C), 138.04, 141.78
55/6
1649, 886
0.88 (t, 3H, J = 6.7), 1.25–1.35 (m, 10H), 1.41 (m, 14.10, 22.37, 22.71, 27.67, 29.18, 29.38 (2C),
2H), 1.70 (s, 2H), 1.99 (t, 2H, J = 4.5), 4.67 (m, 29.56, 31.95, 37.86, 109.50, 146.27
2H)
74/10
62–64/10
142/10
85/10
1640, 880
0.88 (t, 3H, J = 7.5), 1.02 (d, 6H, J = 9.2), 1.26– 14.20, 21.98 (2C), 28.23, 29.31, 31.90, 33.78,
1.53 (m, 8H), 2.01 (t, 2H, J = 9.1), 2.22 (hept, 1H, 34.51, 106.01, 156.38
J = 9.2), 4.66 (s, 1H), 4.72 (s, 1H)
1680, 1447,
1372, 887
0.76–1.40 (m, 6H), 1.51 (s, 3H), 1.57 (s, 3H), 17.75, 25.84, 26.09 (2C), 32.89, 33.37 (2C), 37.00,
1.47–1.65 (m, 4H), 1.82–2.05 (m, 1H), 4.85 (d, 121.22, 131.15
1H, J = 8.9)
1670, 850
1670, 810
0.86 (t, 3H, J = 4.8), 0.89 (t, 3H, J = 4.8), 1.00– 14.42 (2C), 22.84, 23.26, 26.55 (3C), 30.32, 30.92,
1.32 (m, 14H), 1.50–1.70 (m, 4H), 1.88 (t, 2H, J 31.52, 34.22 (2C), 36.85, 37.12, 131.42, 137.96
= 5.2), 1.97 (t, 2H, J = 5.0), 4.88 (d, 1H, J = 4.0)
0.91 (t, 3H, J = 4.7), 1.20–1.45 (m, 10H), 1.57 (d, 13.20, 14.10, 22.70, 23.65, 27.81, 29.34, 29.60
3H, J = 4.4), 1.67 (s, 3H), 2.04 (t, 2H, J = 4.8), (2C), 31.37, 31.93, 118.62, 136.45
5.22 (dt, 1H, J = 4.4, 3.37)
105–107/
5
1644, 1595,
1490, 1448,
984, 954,
1.87 (s, 3H), 1.89 (s, 3H), 6.03 (d, 1H, J = 11.1), 19.25, 26.35, 106.45, 121.33, 125.60, 126.45,
6.39 (dd, 1H, J = 15.1, 11.1), 6.75 (d, 1H, J = 126.93, 128.06, 128.19, 128.73, 129.43, 137.08
14.0), 6.95–7.44 (m, 5H)
870, 747
26
27
28
30
31
32
120–123/
5
1742, 968,
729
0.95 (t, 3H, J = 5.6), 1.25–1.50 (m, 8H), 1.66– 13.53, 20.39, 21.83, 25.44, 28.26, 28.39, 29.13,
1.68 (m, 2H), 2.03–2.11 (m, 6H), 2.11 (s, 3H), 31.46, 31.93, 32.13, 64.06, 129.65, 130.08, 170.38
4.10–4.15 (m, 2H), 5.43–5.45 (m, 2H)
108–110/
10
1742, 970,
724
2.38 (d, 6H, J = 6.9), 2.74 to 2.80 (m, 4H), 2.99– 20.68, 22.46, 25.59, 28.39, 28.51, 29.29, 30.08,
3.06 (m, 2H), 3.36–3.40 (m, 2H), 3.45 (s, 3H), 32.22, 64.31, 126.72, 137.46, 170.76
5.47 (t, 2H, J = 6.6), 6.77 (m, 2H)
82–85/6
85–87/6
92–95/7
115/4
–
0.95 (d, 6H, J = 6.9), 1.63 (tt as a quint, 2H), 1.96 22.01 (2C), 25.78, 29.18, 30.40, 31.25, 42.12,
(m, 2H), 2.20 (m, 1H), 2.13 (s, 3H), 2.42 (t, 2H, J 125.51, 137.86, 207.82
= 7.3), 5.30 to 5.36 (m, 2H)
1717, 969
0.92 (t, 3H, J = 4.3), 1.32–1.37 (m, 4H), 1.66 (tt 13.83, 22.08, 23.45, 29.83, 31.62, 31.79, 32.13,
as a quint, 2H, J = 7.6), 1.98–2.05 (m, 4H), 2.16 42.84, 128.98, 131.55, 209.05
(s, 3H), 2.45 (t, 2H, J = 7.3), 5.37 to 5.45 (m, 2H)
1644, 888,
731, 651
1.00 (t, 3H, J = 6.9), 1.33–1.55 (m, 8H), 1.88 13.96, 22.46, 26.59, 26.97, 29.95, 32.52, 35.67,
(quint, 2H, J = 3.3), 2.06–2.13 (m, 4H), 3.62 (t, 35.77, 44.99, 108.68, 149.70
2H, J = 6.6), 4.79 (m, 2H)
1645, 887,
718
0.99 (t, 3H, J = 6.6), 1.02 (t, 3H, J = 6.6), 1.38– 14.01, 14.12, 22.55, 22.73, 27.87, 29.41, 29.52
1.56 (m, 18H), 2.08–2.13 (m, 2H), 4.79 (s, 2H)
(2C), 29.63, 29.70, 30.06, 31.97, 35.81, 36.12,
108.33, 150.33
a All products gave satisfactory microanalyses: C ± 0.25, H ± 0.28.

SYNTHESIS
August 1998
1205
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