Dichloroenol ethers x-ray analysis in the mechanistic elucidation of ynol ethers formation

Article abstract of DOI:10.1007/s10870-011-0045-3

X-ray crystallographic data are provided for dichloroenol ethers (S,E)-2-(1-(1,2-dichlorovinyloxy)ethyl)-1,3,5-triisopropylbenzene (2) and (S,E)-2-(1-(1,2-dichloroprop-1-enyloxy)ethyl)-1,3,5-triisopropylbenzene (3). The former forms colorless crystals (or

Full text of DOI:10.1007/s10870-011-0045-3

J Chem Crystallogr (2011) 41:1053–1059
DOI 10.1007/s10870-011-0045-3
ORIGINAL PAPER
Dichloroenol Ethers X-ray Analysis in the Mechanistic
Elucidation of Ynol Ethers Formation
•
Benjamin Darses Christian Philouze
•
•
Andrew E. Greene Jean-Franc¸ois Poisson
Received: 20 November 2009 / Accepted: 7 March 2011 / Published online: 23 March 2011
Ó Springer Science+Business Media, LLC 2011
Abstract X-ray crystallographic data are provided for di-
chloroenol ethers (S,E)-2-(1-(1,2-dichlorovinyloxy)ethyl)-1,
3,5-triisopropylbenzene (2) and (S,E)-2-(1-(1,2-dichloro-
prop-1-enyloxy)ethyl)-1,3,5-triisopropylbenzene (3). The
former forms colorless crystals (orthorhombic, P212121
space group) and exhibits the following cell parameters:
Introduction
Ynol ethers have long been employed in synthesis, in par-
ticular for the formation of enol ethers [1, 2]. The most
useful method for their preparation begins from dichloroe-
nol ethers II (Scheme 1) [3–5]. These ethers are easily
prepared through the reaction of a potassium alkoxide with
trichloroethylene. Subsequent addition of excess n-butyl-
lithium, followed by an electrophile, then affords the cor-
responding ynol ethers VI. Although used for decades, this
transformation remained mechanistically ambiguous until
our recent study that successfully defined the reaction
pathway [6]. We were able to show that n-butyllithium ini-
tially effects deprotonation of II at -78 °C to give III (the
addition of one equivalent of n-butyllithium, followed by
methyl iodide, leads to IV), which then upon warming suf-
fers syn b-elimination, and not rearrangement, to generate
isolable V. This complete elucidation, however, required
unequivocal knowledge of the stereochemistry of the di-
chloroenol ethers, which was absent in the literature [7, 8];
no dichloroenol ether crystal structure had been reported.1
Dichloroenol ethers 2 [9] and 5 were prepared from
(S)-1-(2,4,6-triisopropylphenyl)ethanol (1) and (S)-trans-2-
phenylcyclohexanol (4), respectively (Scheme 2). Fortu-
nately, on slow evaporation of the solvent (diethyl ether for
2 and ethyl acetate for 5), each afforded colorless prisms
suitable for single crystal X-ray analysis. The resulting
structures established the previously assumed trans
assignment for these enol ethers. Moreover, the dichlo-
roenol ethers 3 and 6, formed from 2 and 5, respectively,
by deprotonation, followed by lithio carbenoid trapping
with methyl iodide, also produced colorless prisms suitable
˚
a = 10.212(5) A; b = 10.359(8) A; c = 18.217(6) A. The
˚
˚
latter also affords colorless crystals (monoclinic, P21 space
˚
group) with a = 13.558(2) A; b = 10.891(1) A; c =
˚
˚
15.260(2) A; b = 115.65(1)°. The data complement those
recently reported for two other dichloroenol ethers, ((1R,2S)-
2-((E)-1,2-dichlorovinyloxy)cyclohexyl)benzene (5) and
((1R,2S)-2-((E)-1,2-dichloroprop-1-enyloxy)cyclohexyl)
benzene (6). The X-ray analyses of these dichloroenol ethers,
the only reported to date, establish unambiguously the trans
stereochemistry of the chlorides in these and, by extension,
similarly prepared enol ethers. This information was
required for the complete mechanistic understanding of ynol
ethers formation from dichloroenol ethers. Structural com-
parison of these dichloroenol ethers with some carbon (dic-
hloroalkene) and nitrogen (dichloroenamine) analogues is
also presented.
Keywords Dichloroenol ethers ꢀ Ynol ethers ꢀ Crystal
structure ꢀ Mechanism ꢀ Stereochemistry
B. Darses ꢀ C. Philouze ꢀ A. E. Greene ꢀ J.-F. Poisson (&)
´
´
´
Departement de Chimie Moleculaire (SERCO), Universite
Joseph Fourier, UMR-5250, ICMG FR-2607, 38041 Grenoble
Cedex 9, France
1
The structures of dichloroenol ethers 5 and 6, reported without
detailed discussion in ref 3, represented the first examples.
e-mail: jean-francois.poisson@ujf-grenoble.fr
123

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J Chem Crystallogr (2011) 41:1053–1059
35Cl
H
Cl
Me
Cl
RO
O
Cl
IV
MeI
535
Cl
Li
Cl
H
KH;
n-BuLi
ROH
Cl
Cl
H
RO
Cl
n-BuLi (1 eq)
–78 °C
RO
Cl
Cl
II
III
I
35Cl
RO
Li
FBW
β-elim.
syn β-elimination −50 °C
n-BuLi
RO
35Cl
RO
Cl
Cl
Cl
RO
RO
E
E+
V
VI
Scheme 3 Labeling experiment
Scheme 1 Mechanism of formation of ynol ethers VI from dichlo-
roenol ethers II
chloro acetylenic ether (FBW rearrangement) or one with
natural abundance (syn b-elimination) (Scheme 3). The
labeled compound 535 was obtained from the corresponding
chloro acetylenic ether by reaction with H35Cl. On depro-
tonation with one equivalent of n-butyllithium, only the
natural abundance chloro acetylenic ether was produced, as
evidenced by ESI mass spectrometry (triple quadrupole
analyzer) of the derived chloroacetate, thus proving an
exclusive syn b-elimination pathway. Metadynamics ab ini-
tio calculations were fully concordant with this result: the syn
b-elimination was found to be 5 kcal/mol more favorable
than the FBW rearrangement [6].
for single crystal X-ray analysis on slow, controlled
evaporation of ethyl acetate solutions. The structures of
these derivatives provided unambiguous proof that the
trans relationship of the chlorines is retained in the prod-
ucts, indicating a low-temperature configurational stability
for the intermediate lithio carbenoids III. Upon warming,
however, these carbenoids are converted into the chloro
acetylenic ethers V and thence, by reaction with an addi-
tional equivalent of n-butyllithium and an electrophile, into
the acetylenic ethers VI.
A final experiment was required to determine which of
two potential mechanisms (or in what combination) was
operative for the formation of the chloro acetylenic ethers
V from the now established transient lithio carbenoids III: a
well-known Fristch–Buttenberg–Wiechell (FBW) rear-
rangement [10–14] or a relatively uncommon syn (as
opposed to anti) b-elimination. For this purpose, a chlorine-
35 labeled dichloroenol ether 535 was prepared, which would
provide, depending on the mechanism, either a labeled
Experimental
(S,E)-2-(1-(1,2-Dichlorovinyloxy)ethyl)-1,3,5-
triisopropylbenzene (2)
An argon-flushed flask was charged with potassium hydride
(30% suspension in mineral oil, 14.3 g, 107 mmol). The
mineral oil was removed by washing with pentane
Scheme 2 Synthesis of
dichloroenol ethers 2, 3, 5, and
6
H
Cl
Me
Cl
Cl
iPr
n-BuLi (1 eq)
THF, −78 °C;
iPr
iPr
iPr
iPr
Cl
O
O
KH;
OH
iPr
iPr
Cl
Cl
H
MeI, −90 °C
iPr
iPr
Cl
88%
78%
3
2
1
Cl
H
Cl
Me
Cl
n-BuLi (1 eq)
THF, −78 °C;
OH
O
Cl
O
KH;
Cl
H
MeI, −90 °C
Cl
Cl
91%
83%
4
6
5
123

J Chem Crystallogr (2011) 41:1053–1059
1055
(3 9 10 mL), and anhydrous THF (60 mL) was then added.
A solution of (S)-1-(2,4,6-triisopropylphenyl)ethanol (1)
(12.0 g, 48.3 mmol) in anhydrous THF (40 mL) was added
dropwise at 0 °C. The mixture was stirred for 2 h at 20 °C,
cooled to -50 °C, and treated dropwise with a solution of
trichloroethylene (4.80 mL, 53.4 mmol) in anhydrous THF
(20 mL). The reaction mixture was allowed to warm to 0 °C
and stirred until TLC (eluent pentane) showed complete
disappearance of starting material, at which time the mix-
ture was carefully treated with methanol and water. The
crude product was extracted with pentane in the usual way
and the combined extracts were washed with water, dried
over Na2SO4, filtered, and concentrated under vacuum at
0 °C. The residue was purified by flash chromatography on
silica gel (pretreated with 2.5% of triethylamine v/v, eluent
pentane) to afford 13.0 g (78%) of dichloroenol ether 2 as a
white solid, which was recrystallized by slow evaporation
of a diethyl ether solution to afford colorless crystals: mp
24.7, 24.5, 23.9, 21.6, 20.8; MS (EI?) m/z 381.4
(M ? Na)?, 359.3 (M ? H)?, 231.2; Anal. calcd. for
C20H30Cl2O: C, 67.23; H, 8.47. Found: C, 67.51; H, 8.50.
((1R,2S)-2-((E)-1,2-Dichlorovinyloxy)
cyclohexyl)benzene (5)
The procedure for 2 was used to obtain 5: (?)-trans-2-
phenylcyclohexanol (4) (2.40 g, 13.6 mmol), potassium
hydride (30% wt in oil, 4.00 g, 30.0 mmol), and THF
(20 mL) afforded 3.08 g (83%) of dichloroenol ether 5 as a
white solid, which was recrystallized by slow evaporation
of an ethyl acetate solution to give colorless crystals: mp
57–57.5 °C; [a]2D0 ?95.3 (c 1.0, CHCl3); IR (neat) t (cm-1
)
3104, 3031, 2941, 2854, 1629, 1452, 1278, 1087; 1H NMR
(400 MHz, CDCl3) d (ppm) 7.33–7.18 (m, 5H), 5.32 (s,
1H), 4.42 (dt, J = 10.6, 4.4 Hz, 1H), 2.84–2.75 (m, 1H),
2.26–2.18 (m, 1H), 1.99–1.88 (m, 2H), 1.80–1.73 (m, 1H),
1.61–1.25 (m, 4H); 13C NMR (100 MHz, CDCl3) d (ppm)
142.8, 142.4, 128.2, 127.7, 126.5, 97.9, 83.2, 49.7, 34.4,
31.6, 25.6, 24.6; MS (ESI) m/z 293.0 (M ? Na)?.
38–41 °C; [a]2D0 -16.2 (c 1.0, CHCl3); IR (film) t (cm-1
)
3086, 1623, 1609, 1078, 1040; 1H NMR (300 MHz, CDCl3)
d 7.05 (s, 2H), 6.00 (q, J = 6.9 Hz, 1H), 5.60 (s, 1H),
3.75–3.15 (br s, 2H), 2.90 (sept, J = 6.9 Hz, 1H), 1.70 (d,
J = 6.9 Hz, 3H), 1.35–1.20 (m, 18H); 13C NMR (75 MHz,
CDCl3) d 148.5 (Cq), 142.9 (Cq), 131.2 (Cq), 122.1 (CH),
98.3 (CH), 76.4 (CH), 34.1 (CH), 29.4 (CH), 24.7 (CH3),
24.5 (CH3), 23.9 (CH3), 20.3 (CH3); MS (EI?) m/z 343 and
341 (M?), 248, 231 (100%); Anal. Calcd. for C19H28ClO:
C, 66.47; H, 8.22. Found: C, 66.63; H, 8.36.
((1R,2S)-2-((E)-1,2-Dichloroprop-1-
enyloxy)cyclohexyl)benzene (6)
The procedure for 3 was used to obtain 6: dichloroenol
ether 5 (262 mg, 0.97 mmol), n-BuLi (2.5 M in hexanes,
0.425 mL, 1.1 mmol), and MeI (0.120 mL, 1.93 mmol)
gave 252 mg (91%) of dichloroenol ether 6 as a white
solid, which was recrystallized by slow evaporation of an
ethyl acetate solution to provide colorless crystals: mp
(S,E)-2-(1-(1,2-Dichloroprop-1-enyloxy)ethyl)-1,3,5-
triisopropylbenzene (3)
43–43.5 °C; [a]2D0 ?76.8 (c 1.0, CHCl3); IR (neat) t (cm-1
)
To a solution of dichloroenol ether 2 (841 mg, 2.45 mmol)
in anhydrous THF (11 mL) at -78 °C was added dropwise
n-BuLi (2.5 M in hexanes, 1.08 mL, 2.7 mmol). After
5 min, the mixture was cooled to -90 °C and MeI
(0.31 mL, 4.98 mmol, prefiltered through a pad of basic
alumina) and distilled HMPA (2.5 mL) were added. The
solution was allowed to warm to -50 °C over 1 h and then
at 20 °C before being treated with water. The crude
product was isolated with pentane in the usual manner and
purified by flash chromatography on silica gel (pretreated
with 2.5% of triethylamine v/v, eluent pentane) to afford
770 mg (88%) of dichloroenol ether 3 as a white solid,
which was recrystallized by slow evaporation of an ethyl
acetate solution to afford colorless crystals: mp
3028, 2930, 2858, 1658, 1448, 1181, 1000; 1H NMR
(400 MHz, CDCl3) d (ppm) 7.32–7.16 (m, 5H), 4.33 (dt,
J = 10.6, 4.3 Hz, 1H), 2.81–2.72 (m, 1H), 2.22–2.13 (m,
1H), 1.98 (s, 3H), 1.96–1.86 (m, 2H), 1.79–1.71 (m, 1H),
1.61–1.29 (m, 4H); 13C NMR (100 MHz, CDCl3) d (ppm)
143.1, 137.5, 128.1, 127.6, 126.3, 110.7, 82.5, 49.7, 34.5,
31.4, 25.7, 24.6, 21.3; MS (ESI) m/z 291.0 (M ? Li)?;
Anal. calcd. for C15H18Cl2O: C, 63.17; H 6.37. Found: C
63.55; H 6.49.
For compound 2, a prismatic colorless crystal was chosen
of 0.34* 0.23* 0.17 mm3 dimensions, which was mounted
on a glass fiber using paraffin. The crystal was then centred
on a Bruker-AXS-Enraf–Nonius Kappa-CCD diffractome-
ter, working at 150°K and at the monochromated (graphite)
40.5–41 °C; [a]2D0 -26.9 (c 1.0, CHCl3); IR (film) t (cm-1
)
MoKa radiation k = 0.71073 A. Data reduction, cell
˚
2961, 2359, 1659, 1459, 1379, 1169, 1050; 1H NMR
(400 MHz, CDCl3) d (ppm) 7.02 (s, 2H), 5.85 (q,
J = 6.8 Hz, 1H), 4.20–2.98 (m, 2H), 2.87 (sept,
J = 6.9 Hz, 1H), 2.17 (s, 3H), 1.64 (d, J = 6.8 Hz, 3H),
1.35–1.19 (m, 18H); 13C NMR (100 MHz, CDCl3) d (ppm)
148.2, 146.7, 138.5, 131.8, 122.1, 111.1, 76.3, 34.1, 29.4,
determination, and refinement were performed using Eval-
CCD. 22204 reflections measured from u and x scans were
recorded for 1.12 \ h \ 30.0° and merged into 5625 unique
reflections, including Friedel-pairs. Even though the Flack
parameter is too small, it nicely corroborates the chemically
known S configuration at C-6.
123

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J Chem Crystallogr (2011) 41:1053–1059
For compound 3, a monocrystalline block of 0.38* 0.36*
anisotropically by the full matrix least-squares method. H
atoms were set geometrically and recalculated before the
last refinement cycle. Figures were created using ORTEP
[19]. Crystal data are summarized in Table 1.
22 mm3 dimensions was mounted on a glass fiber and cen-
tered on a Bruker-AXS-Enraf–Nonius Kappa-CCD diffrac-
tometer, working at 200°K and at the monochromated
˚
(graphite) MoKa radiation k = 0.71073 A. Data reduction,
cell determination, and refinement were performed using
EvalCCD. 43784 reflections measured from u and x scans
were recorded for 1.48 \ h \ 27.5° and merged into 10103
unique reflections, including Friedel-pairs. For this com-
pound, the Flack parameter (0.00(2)) unambiguously
allowed to establish the S configuration at C-7, in agreement
with the chemically known configuration [15, 16].
For compounds 5 and 6, see ref. [6].
Results and Discussion
All four compounds display four molecules inside the
cell and whereas 2, 5 and 6 display one molecule in
the asymmetric unit, 3 display two molecules (3a, b) in the
asymmetric unit. Compounds 2 and 5 crystallize in the
orthorhombic P212121 space group, while 3 and 6 crys-
tallize in monoclinic systems (P21 and C2 space groups,
respectively). Since there is no hydrogen bonding, the
secondary structures may come from phenyl-group p-
stacking Fig. 1.
In all cases, the data were corrected for the Lorentz and
polarization effects.
Structure Determination and Refinement
From a structural point of view, the alkyl substituent on
the oxygen atom (2,4,6-triisopropylphenylethyl in 2 and
3a, b, and trans-2-phenylcyclohexyl in 5 and 6) has little
The structures were solved using SIR-92 [17] and refined
using TeXsan [18]. Cl, C, N, and O atoms were refined
Table 1 Crystal data and structure refinement
Compound
Name
2
3
(S,E)-2-(1-(1,2-dichlorovinyloxy)ethyl)
-1,3,5-triisopropylbenzene
(S,E)-2-(1-(1,2-dichloroprop-1-enyloxy)ethyl)-
1,3,5-triisopropylbenzene
CCDC deposit no. or code
Color/shape
742825
742824
Colorless/block
Colorless/platelet
C20H30Cl2O
357.36
Chemical formula
C19H28Cl2O
Formula weight (g.mol-1
Temperature (K)
Crystal system
)
343.34
150
200
Orthorhombic
P212121
Monoclinic
P21
Space group
˚
a = 10.212(5) A
˚
a = 13.558(2) A
Unit-cell dimensions
˚
b = 10.359(5) A
˚
b = 10.891(1) A
˚
c = 18.217(6) A
˚
c = 15.260(2) A
b = 115.65(1)°
2031.3(5)
4
3
Unit-cell volume (A )
˚
1927.2(8)
4
Z
Density (calculated) (g/cm3)
Absorption coefficient (mm-1
Diffractometer/scans
1.183
0.337
1.168
)
0.322
Bruker–Enraf–Nonius Kappa
CCD/phi and omega
Bruker–Enraf–Nonius Kappa CCD/phi
and omega
˚
Wavelength (A)
0.71073
0.71073
h range for data collection (°)
Reflections measured
1.12–30.00
1.48–27.50
22204
43784
Independent/observed reflections
Data/restraints/parameters
Goodness of fit on F
5625 (Rint = 0.114)/4424 [I [ 2r(I)]
4424/0/199
10103 (Rint 0.104)/8512 [I [ 1.5r(I)]
8512/0/415
0.933
1.908
Final R indices [I [ 2r(I)]
R indices (all data)
R1 = 0.0501, wR2 = 0.0773
R1 = 0.0683, wR2 = 0.0864
R1 = 0.0509, wR2 = 0.0686
R1 = 0.0585, wR2 = 0.0706
123

J Chem Crystallogr (2011) 41:1053–1059
1057
Fig. 1 Ortep drawing of
compounds 2 and 3a
plane as the chlorine atom (Cl3) (Table 3, last column),
most probably to minimize steric interactions due to 1,3-
allylic strain [21, 22]. Two related enol ethers with reported
crystallographic structures show similar solid-state confor-
mations, with the corresponding a-hydrogen of the sec-
ondary alkyl groups sitting nearly in the same plane as the
double bond (dihedral angles of 8.61 and 5.46°) [23, 24].
While the dichlorovinyloxyl and dichloropropenyloxyl
groups display roughly comparable distances and angles,
when the oxygen atom is replaced by a nitrogen atom [25,
26] or a carbon atom [27, 28], noticeable differences are
found (Table 4). However, it should be noted that there are
exceedingly few reported structures of such derivatives and
therefore generalizations are somewhat perilous.
Cl3
1
H1
2
Cl3
1
5 Me
2
H2
H4
O5
Cl4
O6
Cl4
9
8
6
7
8
7
Fig. 2 Numbering for the dichloroenol ethers
influence on the pendant dichlorovinyloxyl or dichlorop-
ropenyloxyl portion of the molecule: the distances and
angles are very similar, and not different from those
expected [20].
As seen in Fig. 2 and Table 2, the six atoms of the
dichlorovinyloxyl and dichloropropenyloxyl groups are
nearly in the same plane. In the methylated dichloroenol
ethers 3a, b and 6, the out of plane deformation is slightly
greater than in 2 and 5, but small.
2 and 3 are enantiopure, and their absolute configurations
could be assigned by X-ray crystallography [15, 16]. Addi-
tionally, the absolute configurations of 2, 3, 5 and 6 follow
from those of the starting materials, which are known.
Overall, compounds 2, 5 and 3a, b, 6 have very similar
sp3–O bond distances and dihedral angles (see Table 3).
C
Methylation of 2 and 5 to produce 3 and 6, respectively, is
attended by a small shortening of the Csp3–O bonds. Inter-
estingly, the conformation of the O-alkyl dichloroenol
ethers is similar in all four compounds: The a-hydrogen of
the alkyl groups (H2 or H4) is located in nearly the same
Conclusion
Through X-ray analysis, the trans relationship of the
chlorines in dichloroenol ethers prepared by a popular
Table 2 Table of Least-squares planes
Compound
2
3a
3b
5
6
˚
Distance to plane (A)
Atoms defining planes
Cl3
-0.0016
0.0175(10)
0.0171(10)
-0.0132(10)
-0.0167(9)
0.0379(15)
-0.0308(23)
0.0056(25)
0.1282
-0.0168
-0.0246
0.0398
-0.0175(10)
-0.0153(9)
0.0447(13)
-0.0252(18)
0.0280(19)
0.1874(28)
0.0530
Cl4
0.0036
O5 (2, 5) or O6 (3, 6)
C1
C2
-0.0191
0.0296
-0.0484(16)
0.0389(24)
-0.0176(26)
-0.1588(31)
0.0497
-0.0377
-0.0008
0.0402
0.0033
H1 (2, 5) or C5 (3, 6)
-0.0157
0.0121
˚
Mean deviation from plane (A)
0.0387
0.0266
123

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J Chem Crystallogr (2011) 41:1053–1059
Table 3 Distances and dihedral angles of the Csp3-O bond
˚
C–O distance (A)
Compound
Dihedral angle (°)
(X = H/Me)
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
H
H
H
H
H
H
O
Cl
O
Cl
O
Cl
O
Cl
O
Cl
O
Cl
2 (X = H)
1.475(2)
1.463(3)
1.466(3)
1.472(6)
1.460(2)
-154.4(2)
-165.9(2)
-166.7(2)
-157.7(4)
-161.8(1)
79.2(2)
67.5(3)
66.7(2)
79.1(5)
76.1(2)
-38
-51
-51
-40
-44
70.0(2)
58.1(2)
64.3(2)
67.2(5)
61.6(2)
22.94
2.86
3a (X = Me)
3b (X = Me)
5 (X = H)
7.62
19.68
12.67
6 (X = Me)
Table 4 Angles and distances of dichlorovinyl derivatives
Structures
X
X0
Cl
X' Cl
X' Cl
Cl
X'
Cl
X' Cl
X' Cl
X' Cl
X' Cl
X'
Cl
X'
Cl
X'
Cl
X'
X Cl
Distances in A
X
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
X
Cl
˚
Angles in °
FEHRIT
C
C
N
N
O
O
H
H
H
H
H
H
1.54(2)
1.5091
1.7546
1.30(2)
1.3178
0.96
1.09
0.93
0.95
0.95
0.95
1.72(3)
1.7113
116(2)
112.97
124.66
117.99
112.1(5)
119.89
128.93
142.1(9)
120.10
118.66
125.8(6)
120.33
118.57
125.8(6)
112.02
120.2
120(2)
MCVCHO
AGUXAB
RAGKUG
2 (742825)
1.7625
122.74
108.3(7)
1.373(6)
1.937(7)
1.097(9)
1.859(10) 105.7(7)
1.4081(17) 1.7341(15) 1.323(2)
1.7096(17) 119.76(11) 115.62(10) 124.62(14) 119.02
121.96(12)
119.6(2)
121.2(5)
1.340(2)
1.325(6)
1.737(2)
1.741(6)
1.322(3)
1.316(8)
1.724(4)
1.681(7)
118.3(2)
118.3(5)
115.8(1)
116.1(4)
125.7(2)
125.3(6)
120.2
119.4
EGOREY
(5)
119.4
3a (742824)
3b (742824)
EGORIC (6)
O
O
O
C
C
C
1.341(3)
1.334(3)
1.339(2)
1.732(3)
1.738(3)
1.748(2)
1.326(3)
1.322(3)
1.318(3)
1.479(4)
1.471(4)
1.477(3)
1.730(3)
1.737(3)
1.728(2)
119.7(2)
118.9(2)
118.8(1)
115.9(2)
115.2(2)
115.1(1)
124.0(2)
125.6(2)
125.8(2)
127.3(3)
128.6(3)
128.1(2)
115.7(2)
115.0(2)
114.8(2)
117.0(2)
116.3(2)
117.0(1)
Acknowledgments We thank Prof. P. Dumy (UJF) for his interest
in our work and the French Ministry of Education, Research and
Technology (MENRT) for a fellowship (to B.D.).
procedure has been unambiguously proven. This informa-
tion has been used in fully delineating the mechanism of
the formation of ynol ethers from dichloroenol ethers.
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