Stereoselective exo-addition to norbornenes of acetic acid generated from vinyl acetate in the presence of rhodium complexes

Article abstract of DOI:10.1134/S1070428010010045

Rhodium complexes catalyzed decomposition of vinyl acetate with liberation of acetic acid and subsequent stereoselective exo-addition of the latter to norbornene and its derivatives under mild conditions.

Full text of DOI:10.1134/S1070428010010045

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 1, pp. 54–58. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © R.I. Khusnutdinov, N.A. Shchadneva, L.F. Mukhametshina, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 1,
pp. 54–58.
Stereoselective exo-Addition to Norbornenes of Acetic Acid
Generated from Vinyl Acetate in the Presence
of Rhodium Complexes
R. I. Khusnutdinov, N. A. Shchadneva, and L. F. Mukhametshina
Institute of Petroleum Chemistry and Catalysis, Russian Academy of Sciences,
pr. Oktyabrya 141, Ufa, 450075 Bashkortostan, Russia
e-mail: ink@anrb.ru
Received March 2, 2009
Abstract—Rhodium complexes catalyzed decomposition of vinyl acetate with liberation of acetic acid and
subsequent stereoselective exo-addition of the latter to norbornene and its derivatives under mild conditions.
DOI: 10.1134/S1070428010010045
We previously found that Wilkinson’s complex
Rh(PPh3)3Cl promotes decomposition of vinyl acetate
with formation of acetic acid, acetylene, benzene, and
ethylidene diacetate [1]. Taking into account that
ethylidene diacetate is the product of addition of acetic
acid at the double bond of vinyl acetate, in the present
work we made an attempt to use the ability of vinyl
acetate to generate acetic acid to effect mild hydroacet-
oxylation of norbornene and its derivatives.
[4], or p-toluenesulfonic acid [5] as catalyst. These
reactions were successful with the use of 1.5–4-fold
excess of acetic acid under fairly severe conditions
(90–140°C), which promoted formation of the corre-
sponding ester as a mixture of exo and endo isomers.
We found that vinyl acetate can be used as synthetic
equivalent of acetic acid in the above reaction. The
reaction of vinyl acetate with norbornene on heating to
80°C (2 h) in the presence of rhodium catalysts, such
as Rh(PPh3)3Cl, [Rh(CO)2Cl]2, and [Rh(C7H8)Cl]2,
gave bicyclo[2.2.1]hept-exo-2-yl acetate (Ib) in 85%
yield (Scheme 1). Analysis of the reaction mixture by
gas–liquid chromatography (after 1 h) showed that
vinyl acetate undergoes complicated transformations
leading to the formation of acetic acid, ethylidene di-
acetate (20–25%), and benzene and that the concentra-
tion of acetic acid at each moment does not exceed 3–
5%; therefore, the given reaction conditions may be
regarded as “mild.” Preliminary activation of rhodium
catalyst by heating in methylene chloride or chloro-
form for 2–3 h at 200°C is necessary, while the reac-
tion of vinyl acetate with norbornene occurred at 80–
120°C in 1–6 h, the molar ratio [Rh]–norbornene–
vinyl acetate being 1:100:120. The addition of acetic
Norbornene (Ia) was selected as substrate due to its
specific place among cyclic olefins. High reactivity in
electrophilic addition processes and the ability to un-
dergo rearrangements in various media make norbor-
nene and its derivatives indispensable subjects for
chemical and physicochemical studies. Increased inter-
est in norbornene derivatives is also related to their
structural similarity to numerous naturally occurring
compounds of the terpene series and their increased
synthetic accessibility as a result of improvement of
procedures for Diels–Alder reactions.
Esters derived from norbornene were synthesized
previously via addition of monocarboxylic acids, in-
cluding acetic acid, to norbornene in the presence of
sulfuric acid [2, 3], boron trifluoride–ether complex
Scheme 1.
[Rh], CH2Cl2
80°C, 2 h
OAc
+
+
OAc
H2C
~85%
Ia
Ib
54

STEREOSELECTIVE exo-ADDITION TO NORBORNENES OF ACETIC ACID
55
Scheme 2.
Rh(PPh3)3Cl
80°C, 2 h
OAc
+
+
OAc
H2C
Me
Me
Me
OAc
IIa
IIb
4:1
IIc
Scheme 3.
12
11
9
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
8
6
7
5
+
OAc
H2C
OAc
3
1
10
2
4
IIIa
IIIb
acid to vinyl acetate was stereoselective, and the prod-
uct was exo-acetoxy derivative Ib whose structure was
unambiguously confirmed by the NMR data. The
13C NMR spectrum of Ib contained signals at δC 41.68
(C1), 77.50 (C2), 39.70 (C3), 35.52 (C4), 28.33 (C5),
24.40 (C6), 35.37 (C7), and 170.9 ppm (C=O) (cf. [6]).
No signals assignable to the corresponding endo
isomer were observed {δC 40.7 (C1), 75.6 (C2), 37.3
(C3), 37.0 (C4), 29.7 (C5), 21.3 (C6), 37.6 (C7) [7]}.
acetoxy group in both isomers followed from the
chemical shifts of C2, δC 76.45 and 77.35 ppm for
compounds IIb and IIc, respectively. In addition,
signals from the bridging C7 atom in the spectra of IIb
and IIc appeared in a strong field (δC 31.05 and
32.17 ppm), in support of the exo orientation of the
substituent [7].
Norbornene derivatives with a complex structure
readily reacted with vinyl acetate under analogous con-
ditions. exo,exo-Tetracyclo[6.2.1.1.3,6.02,7]dodec-4-ene
(IIIa) reacted with vinyl acetate in the presence of
Wilkinson’s catalyst preliminarily activated with
CH2Cl2 at 200°C (2 h) to give 71% of exo,exo-tetra-
cyclo[6.2.1.02,71.3,6]dodec-exo-4-yl acetate (IIIb)
(Scheme 3). The assignment of signals in the 13C NMR
spectrum of IIIb was not difficult, taking into account
high molecular symmetry. The upfield shift of the C12
signal (δC 32.82 ppm) and downfield of the C4 signal
Analogous reaction of exo-5-methylnorbornene IIa
with vinyl acetate in the presence of Rh(PPh3)3Cl
resulted in the formation of two regioisomeric acetoxy-
(methyl)norbornanes IIb and IIc at a ratio of 4 :1
(overall yield 80%; Scheme 2). The chemical shifts of
the methyl carbon atoms in the 13C NMR spectra of
IIb and IIc, δC 22.05 and 21.66 ppm, respectively,
indicated that the original exo orientation of the methyl
group remained unchanged. The exo orientation of the
Scheme 4.
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
OAc
OAc
+
OAc
OAc
OAc
OAc
H2C
H2C
H2C
H2C
IVa
Va
IVb
Vb
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
+
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
+
OAc
OAc
VIa
VIb
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
+
VIIa
VIIb
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 1 2010

KHUSNUTDINOV et al.
56
Scheme 5.
Rh(PPh3)3Cl
CH2Cl2, 90°C, 5 h
OAc
AcO
OAc
+
+
H2C
VIIIa
VIIIb, VIIIc
Rh(PPh3)3Cl
CH2Cl2, 90°C, 5 h
OAc
AcO
AcO
H2C
OAc
IXa
IXb, IXc
Rh(PPh3)3Cl
CH2Cl2, 90°C, 5 h
OAc
+
H2C
OAc
Xa
Xb, Xc
(δC 76.98 ppm) indicated exo orientation of the acetoxy
group. The C4 atom in the corresponding endo isomer
resonates in a stronger field (δC 70.95 ppm) [8].
(C5), 134.70 ppm (C6)], bridging carbon atom (C7,
δC 30.76 ppm), and C2 (δC 76.75 ppm) in the 13C NMR
spectrum. Unusual behavior of endo-dicyclopentadiene
(XIIa) in the examined reaction should be noted. This
compound reacted with vinyl acetate exclusively at the
double bond in the norbornene fragment to give two
regioisomeric products, endo-tricyclo[5.2.1.02,6]dec-
3(4)-ene-exo-8-yl acetates XIIb and XIIc at a ratio of
Hexacyclic norbornadiene dimers IVa–VIIa having
two potential reaction centers, double bond and cyclo-
propane ring, reacted with vinyl acetate only at the
norbornene double bond, while the three-membered
ring remained intact (Scheme 4). The yields of acetates
IVb–VIIb were 60–78%. Unlike hexacyclic norborna-
diene dimers IVa–VIIa, pentacyclic dimers VIIIa–Xa
containing two equivalent norbornene fragments took
up acetic acid at both double bonds provided that
4 equiv of vinyl acetate was used (Scheme 5). The re-
actions with pentacyclic compounds VIIIa–Xa in each
case gave both possible regioisomers in approximately
equal amounts; both acetoxy groups in both isomers
had exo orientation.
1
8 :1 (Scheme 7). The H NMR spectrum of isomer
mixture XIIb/XIIc contained a signal at δ 4.65 ppm
due to endo-oriented proton on C8; this suggests exo
orientation of the acetoxy group [6, 7]. The double
bond in the five-membered ring of XIIa remains intact
even under severe conditions (130°C, 10 h).
Scheme 7.
In the reaction of a “pseudoconjugated” diene,
norbornadiene with vinyl acetate in the presence of
Rh(PPh3)3Cl we obtained two products, 3-acetoxynor-
tricyclane (XIb, 72%) and bicyclo[2.2.1]hept-5-en-
exo-2-yl acetate (XIc, 10%) (Scheme 6). The structure
of the latter was confirmed by the presence of charac-
teristic signals from sp2-carbon atoms [δC 129.68
+
OAc
H2C
XIIa
Rh(PPh3)3Cl
CH2Cl2, 90°C, 3 h
OAc
OAc
+
XIIb
8:1
XIIc
Scheme 6.
The structure of the isolated products was con-
firmed by spectral data, as well as by comparing with
authentic samples and published data [6–9].
+
OAc
H2C
XIa
EXPERIMENTAL
Rh(PPh3)3Cl
CH2Cl2, 80°C, 2 h
OAc
OAc
The reaction mixtures and products were analyzed
by GLC on a Khrom-5 chromatograph equipped with
flame ionization detectors and 1.2 m×3-mm and 3 m×
+
XIb
7:1
XIc
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STEREOSELECTIVE exo-ADDITION TO NORBORNENES OF ACETIC ACID
57
3-mm columns; stationary phase 5% of SE-30 on
Chromaton N-AW-HMDS (0.125–0.160 mm); carrier
gas helium, flow rate 50 ml/min; oven temperature
programming from 50 to 220°C. The IR spectra were
recorded in the range from 550 to 3600 cm–1 on
a Specord 75IR spectrometer from samples prepared as
C 71.25; H 9.48. C10H16O2. Calculated, %: C 71.39;
H 9.59.
exo-6-Methylbicyclo[2.2.1]hept-exo-2-yl acetate
1
(IIc). Yield 15%. H NMR spectrum, δ, ppm: 5.17 s
(2-H), 2.45 (2H, 1-H, 4-H), 2.20 d (CH3), 1.30–1.85 m
(4H, 3-H, 5-H, 6-H, 7-H), 1.25 d (CH3). 13C NMR
spectrum, δC, ppm: 44.14 (C1), 74.35 (C2), 40.75 (C3),
36.77 (C4), 34.52 (C5), 33.81 (C6), 37.17 (C7), 169.95
(C8), 20.77 (C9), 21.66 (C10).
exo,exo-Tetracyclo[6.2.1.13,6.02,7]dodec-exo-4-yl
acetate (IIIb). Yield 71%, bp 90°C (3 Pa). IR spec-
trum: ν 1740–1745 cm–1 (C=O). 13C NMR spectrum,
δC, ppm: 40.63 (C1, C8), 53.90 (C2), 41.29 (C3), 76.98
(C4), 39.72 (C5), 39.76 (C6), 53.90 (C7), 31.98 (C9,
C10), 35.47 (C11), 32.82 (C12), 170.91 (C13), 20.77
(C14). Found, %: C 76.27; H 9.20. C14H20O2. Calculat-
ed, %: C 76.32; H 9.15.
exo,exo-Hexacyclo[9.2.1.02,10.03,8.04,6.05,9]tetra-
dec-exo-12-yl acetate (IVb). Yield 78%. IR spectrum
ν, cm–1: 1740 (C=O), 1190–1195 (C–O–C). 13C NMR
spectrum, δC, ppm: 11.59 (C6), 16.68 (C4, C5), 20.92
(C16), 33.45 (C7), 36.82 (C14), 38.39 (C8), 39.72 (C13),
39.79 (C1), 41.29 (C11), 46.25 (C3, C9), 52.55 (C2, C10),
76.98 (C12), 168.80 (C15). Found, %: C 78.32; H 8.15.
C16H20O2. Calculated, %: C 78.65; H 8.25.
exo,endo-Hexacyclo[9.2.1.02,10.03,8.04,6.05,9]tetra-
dec-exo-12-yl acetate (Vb). Yield 78%. 13C NMR
spectrum, δC, ppm: 12.66 (C4, C5), 16.95 (C6), 20.89
(C16), 28.09 (C7), 34.63 (C14), 39.48 (C1), 40.64 (C11),
42.90 (C13), 43.73 (C8), 47.25 (C3, C9), 49.15 (C2, C10),
77.45 (C12), 165.70 (C15). Found, %: C 78.45; H 8.19.
C16H20O2. Calculated, %: C 78.65; H 8.25.
endo,exo-Hexacyclo[9.2.1.02,10.03,8.04,6.05,9]tetra-
dec-exo-12-yl acetate (VIb). Yield 64%. 13C NMR
spectrum, δC, ppm: 13.70 (C6), 18.20 (C4, C5), 20.58
(C16), 32.17 (C14), 33.46 (C7), 37.62 (C8), 40.29 (C1),
40.42 (C11), 42.82 (C3, C9), 43.12 (C13), 49.20 (C2,
C10), 76.98 (C12), 165.80 (C15). Found, %: C 78.35;
H 8.19. C16H20O2. Calculated, %: C 78.65; H 8.25.
endo,endo-Hexacyclo[9.2.1.02,10.03,8.04,6.05,9]tetra-
dec-exo-12-yl acetate (VIIb). Yield 60%. 13C NMR
spectrum, δC, ppm: 12.66 (C4, C5), 13.88 (C6), 20.89
(C16), 27.44 (C7), 32.80 (C13), 34.89 (C14), 40.64 (C11),
41.26 (C1), 46.03 (C3, C9), 47.64 (C2, C10), 50.02 (C8),
76.98 (C12), 162.80 (C15). Found, %: C 78.42; H 8.21.
C16H20O2. Calculated, %: C 78.65; H 8.25.
1
KBr pellets or dispersed in mineral oil. The H and
13C NMR spectra were measured on a JEOL FX 90Q
instrument at 90 and 22.5 MHz, respectively, using
CDCl3 as solvent and tetramethylsilane as reference.
The mass spectra (electron impact, 70 eV) were ob-
tained on a Finnigan MAT-112S GC–MS system, ion
source temperature 220°C. The elemental composi-
tions were determined on a Carlo Erba 1106 analyzer.
Reactions of norbornenes Ia–XIIa with vinyl
acetate in the presence of rhodium catalyst. A 17-ml
stainless steel high-pressure microreactor was charged
under argon with 0.1 mmol of Rh(PPh3)3Cl in 3 ml of
methylene chloride or chloroform. The reactor was
hermetically sealed and heated for 2–3 h at 200°C.
After cooling, the reactor was opened, 10 mmol of
compound Ia–XIIa and 12 mmol (in the reactions with
Ia–VIIa) or 24 mmol (in the reactions with VIIIa–
XIIa) of vinyl acetate were added under argon. The
reactor was hermetically sealed, and the mixture was
heated under continuous stirring for 2–5 h at 80–100°C
(depending on the substrate structure). The reactor was
then cooled to room temperature and opened, the mix-
ture was filtered through a layer of Al2O3, the sorbent
was additionally washed with hexane–diethyl ether
(1:1), the solvent was distilled off under reduced pres-
sure, and the residue was distilled under reduced pres-
sure or separated by column chromatography on Al2O3.
Bicyclo[2.2.1]hept-exo-2-yl acetate (Ib). Yield
85%, bp 60°C (8 Pa); published data [6]: bp 64–66°C
(10 Pa). IR spectrum, ν, cm–1: 1740 (C=O), 1200
1
(C–O–C). H NMR spectrum, δ, ppm: 4.75 s (2-H),
2.45 s (2H, 1-H, 4-H), 2.18 d (CH3), 1.30–1.90 m (4H,
3-H, 5-H, 6-H, 7-H). 13C NMR spectrum, δC, ppm:
41.68 (C1), 77.50 (C2), 39.70 (C3), 35.52 (C4), 28.33
(C5), 24.40 (C6), 35.37 (C7), 170.91 (C8), 20.94 (C9).
Found, %: C 69.88; H 9.05. C9H14O2. Calculated, %:
C 70.10; H 9.15.
exo-5-Methylbicyclo[2.2.1]hept-exo-2-yl acetate
(IIb). Yield 65%, bp 80°C (10 Pa); published data [5]:
1
bp 105–106°C (30 Pa). H NMR spectrum, δ, ppm:
4.70 (2-H), 2.47 s (2H, 1-H, 4-H), 2.20 d (CH3), 1.26–
1.90 m (4H, 3-H, 5-H, 6-H, 7-H), 1.19 d (CH3).
13C NMR spectrum, δC, ppm: 42.40 (C1), 76.45 (C2),
39.64 (C3), 42.22 (C4), 35.64 (C5), 34.45 (C6), 31.05
(C7), 169.70 (C8), 21.32 (C9), 22.25 (C10). Found, %:
exo,trans,exo-Pentacyclo[8.2.1.14,7.02,9.03,8]tetra-
decane-exo-5(6),exo-11-diyl diacetate (VIIIb/VIIIc).
Yield 53% (VIIIb), 12% (VIIIc). 13C NMR spectrum,
δC, ppm: VIIIb: 35.96 (C13, C14), 21.32 (C16, C18),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 1 2010

KHUSNUTDINOV et al.
58
39.55 (C1, C7), 40.63 (C4, C10), 41.96 (C6, C12), 44.15
(C3, C8), 44.21 (C2, C9), 75.66 (C5, C11), 170.91 (C15,
C17); VIIIc: 21.32 (C16, C18), 35.96 (C14), 39.55 (C1,
C4), 35.96 (C13), 40.63 (C7, C10), 41.96 (C5, C12), 44.15
(C3, C8), 44.21 (C2, C9), 75.66 (C6, C11), 170.91 (C15,
C17). Found, %: C 70.92; H 7.68. C18H24O4. Calculat-
ed, %: C 71.02; H 7.95.
endo,trans,exo-Pentacyclo[8.2.1.14,7.02,9.03,8]tetra-
decane-exo-5(6),exo-11-diyl diacetate (IXb/IXc).
Yield 58% (IXb), 10% (IXc). 13C NMR spectrum, δC,
ppm: IXb: 20.77 (C18), 21.29 (C16), 33.42 (C14), 39.62
(C6, C12), 40.09 (C1, C7), 41.26 (C13), 41.39 (C3, C8),
42.69 (C2, C9), 43.95 (C4, C10), 76.88 (C5, C11), 169.95
(C17), 170.85 (C15); IXc: 20.93 (C16), 21.29 (C18),
33.42 (C14), 39.62 (C5, C12), 40.09 (C1, C4), 41.26
(C13), 41.39 (C3, C8), 42.69 (C2, C9), 43.95 (C7, C10),
76.88 (C6, C11), 169.95 (C15), 170.85 (C17). Found, %:
C 70.69; H 7.78. C18H24O4. Calculated, %: C 71.02;
H 7.95.
endo-Tricyclo[5.2.1.02,6]dec-3(4)-en-exo-8-yl
acetate (XIIb/XIIc). Yield 75%, bp 95°C (2 Pa). IR
spectrum, ν, cm–1: 1740 (C=O), 1380 (CH3), 1200–
1250 (C–O–C). 13C NMR spectrum, δC, ppm: XIIb:
20.90 (C12), 34.22 (C10), 34.76 (C5), 35.93 (C7), 37.19
(C8), 38.22 (C1), 40.50 (C6), 42.81 (C2), 74.22 (C9),
125.82 (C3), 131.53 (C4), 166.36 (C11); XIIc: 20.85
(C12), 36.05 (C5), 39.62 (C9), 40.09 (C7), 41.32 (C6),
41.26 (C10), 43.95 (C1), 54.80 (C2), 74.48 (C8), 131.80
(C4), 132.61 (C3), 166.58 (C11). Found, %: C 74.25;
H 7.99. C12H16O2. Calculated, %: C 74.97; H 8.39.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 08-03-97005), by the President of the Russian
Federation (Program for Support of Leading Scientific
Schools, project no. NSh 7470.2006.3), and by the
Department of Chemistry and Materials Science of the
Russian Academy of Sciences (program no. 8).
endo,trans,endo-Pentacyclo[8.2.1.14,7.02,9.03,8]-
tetradecane-exo-5(6),exo-11-diyl diacetate (Xb/Xc).
Yield 41% (Xb), 9% (Xc). 13C NMR spectrum, δC,
ppm: Xb: 20.77 (C18), 21.29 (C16), 39.72 (C6, C12),
40.18 (C1, C7), 43.00 (C13, C14), 43.79 (C2, C3), 43.79
(C8, C9), 43.95 (C4, C10), 76.85 (C5, C11), 169.99 (C17),
170.85 (C15); Xc: 21.29 (C16, C18), 37.52 (C7), 37.96
(C14), 39.62 (C5), 39.72 (C12), 40.18 (C1, C4), 43.00
(C13), 43.79 (C2, C3), 43.79 (C9), 43.95 (C10), 44.15
(C8), 74.35 (C6), 76.85 (C11), 170.85 (C15), 170.85
(C17). Found, %: C 70.93; H 7.84. C18H24O4. Calculat-
ed, %: C 71.02; H 7.95.
Tricyclo[2.2.1.02,6]hept-exo-3-yl acetate (XIb).
Yield 72%, bp 65–66°C (10 Pa). 13C NMR spectrum,
δC, ppm: 11.74 (C6), 13.21 (C1), 14.24 (C2), 20.79 (C9),
30.73 (C5), 30.76 (C7), 33.90 (C4), 52.55 (C10), 80.74
(C3), 169.51 (C8). Found, %: C 70.92; H 7.69.
C9H12O2. Calculated, %: C 71.02; H 7.95.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 1 2010