Regioselective silane-terminated intramolecular heck reaction with alkenyl triflates and alkenyl iodides

Article abstract of DOI:10.1002/(SICI)1099-0690(200005)2000:10<1959::AID-EJOC1959>3.0.CO;2-R

One of the main problems of the Heck reaction using acyclic substrates which lead to Pd intermediates with β- and β'-hydrogens is the lack of selectivity in the formation of the double bond as the last step of the catalytic cycle. The use of allylsilanes as the alkene moiety permits control of the elimination step. Thus, the Pd(o)-catalysed reaction of 1a-c and 2 leads exclusively to the corresponding bicyclic compounds 11a-c. In contrast, reaction of 7 yields a mixture of 12a, (E)-12b and (Z)-12b.

Full text of DOI:10.1002/(SICI)1099-0690(200005)2000:10<1959::AID-EJOC1959>3.0.CO;2-R

FULL PAPER
Regioselective Silane-Terminated Intramolecular Heck Reaction with Alkenyl
Triflates and Alkenyl Iodides
Lutz F. Tietze*[a] and Andrea Modi[a]
Dedicated to Professor Bernd Giese on the occasion of his 60th birthday
Keywords: Heck reaction / Palladium / Silanes / Catalysts / Allylsilanes
One of the main problems of the Heck reaction using acyclic
substrates which lead to Pd intermediates with β- and βЈ-hy- leads exclusively to the corresponding bicyclic compounds
ination step. Thus, the Pd0-catalysed reaction of 1a−c and 2
drogens is the lack of selectivity in the formation of the
double bond as the last step of the catalytic cycle. The use of
allylsilanes as the alkene moiety permits control of the elim-
11a−c. In contrast, reaction of 7 yields a mixture of 12a, (E)-
12b and (Z)-12b.
Introduction
The palladium-catalysed arylation and alkenylation of al-
kenes, known as the Heck reaction,[1] is nowadays one of
the most important CϪC bond forming transformations
and has been used in numerous syntheses of natural prod-
ucts.[2] The broad application of this reaction is due to its
excellent functional group tolerance and the possibility of
using chiral ligands.[3] The Heck reaction is not only an
excellent method for the formation of substituted car-
bocyclic systems, but also for heterocyclic ones. However,
one of the main disadvantages is the low selectivity of the
β-hydride elimination to form the double bond as the last
step in the catalytic cycle. Acyclic substrates which form Pd-
intermediates with β- and βЈ-hydrogens always give mixtures
of double bond isomers. Another problem is the readdition
of the eliminated XϪPdLnϪH species to the formed alkene
moiety, which can also lead to a mixture of double bond
isomers. In previous papers we have shown that these short-
comings can be overcome in intramolecular Heck reactions
of iodoarenes by using allylsilanes.[4,5] This permitted the
selective formation of tertiary stereogenic centers starting
from acyclic alkenes. In this paper we report on the exten-
sion of the silane-terminated intramolecular Heck reaction
methodology to alkenyl triflates such as 1a؊c and alkenyl
iodides containing a (Z)-allylsilane moiety, such as 2
(Scheme 1).
Scheme 1. Substrates for the allylsilane-terminated Heck reaction
(Scheme 2).[6] We also prepared the alkenyl triflate 7 with-
out a trimethylsilyl group from 6 by following the same
strategy, in 46% overall yield. 7 was used for comparison to
Results and Discussion
The synthesis of the alkenyl triflates 1a؊c was performed
by alkylation of cyclohexanone 3 with the (Z)-iodides 4a؊c
in 35Ϫ71% yield, followed by the regioselective conversion
into the triflates using LDA and Tf2NPh in 79Ϫ89% yield
[a]
Institute of Organic Chemistry of the Georg-August-
Scheme 2. Synthesis of substrates for the Heck reaction; reagents
and conditions: a) KN(SiMe3)2, THF, Ϫ78 °CǞroom temp.; b)
LDA, THF, Ϫ78 °C, 3 h; c) Tf2NPh, Ϫ78 °CǞ0 °C, 15 h; d)
KN(SiMe3)2, THF, Ϫ78 °CǞroom temp., 58%; e) LDA, THF, Ϫ78
°C, 3 h, Tf2NPh, Ϫ78 °CǞ0 °C, 79%
Universität
Tammannstraße 2, D-37075 Göttingen, Germany
Fax: (internat.) ϩ49-551/399-476
E-mail: ltietze@gwdg.de
Eur. J. Org. Chem. 2000, 1959Ϫ1964
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000
1434Ϫ193X/00/0510Ϫ1959 $ 17.50ϩ.50/0
1959

L. F. Tietze, A. Modi
FULL PAPER
show the importance of the allylsilane moiety for the con- substrate 1b was obtained by using a catalyst system of 10
trol of the XϪPdLnϪH elimination. mol-% of Pd(OAc)2, 20 mol-% PPh3 and 2 equivalents of
The (Z)-iodides 4b؊c were prepared from the protected NEt3 in toluene at 75 °C. The octahydronaphthalene 11b
alkynes 8b؊c by deprotonation with nBuLi and alkylation was formed in 2 h in 90% yield and with a trans/cis diaster-
with Me3SiCH2I, acidic deprotection, (Z)-selective reduc- eoselectivity of 60:40 (Table 1, entry 3). The use of THF
tion of the triple bond with P2ϪNi[7] and iodination follow- instead of toluene led to 11b in 81% yield with a diastereo-
ing the Appel[8] procedure, in 62% (4b) and 47% yield (4c) selectivity of 68:32 (trans:cis) (Table 1, entry 4). Surpris-
over four steps (Scheme 3). The iodide 4a was prepared dif- ingly, the Pd(OAc)2/PPh3/NEt3 catalyst system was not suit-
ferently, starting from the alkyne 10 and oxirane. Sub- able for the cyclisation of the allylsilane 1c; only traces of
sequent P2ϪNi reduction and Appel-iodination gave 4a in the bicycloundecene 11c were detected. The optimised pro-
48% yield over four steps.[4c]
cedure for this system uses 6 mol-% Pd2(dba)3 CHCl3
(dba ϭ dibenzylideneacetone), 12 mol-% dppb [dppb ϭ 1,4-
bis(diphenylphosphano)butane] and 10 equivalents of
KOAc in DMF. The bicycloundecene 11c was exclusively
obtained in 61% yield after 16 h at 90 °C, but with a low
trans/cis diastereoselectivity of 53:47 (Table 1, entry 5). The
silane-terminated Heck cyclisation of the alkenyl iodide 2
was best accomplished with a catalyst system containing
6 mol-% Pd2(dba)3 CHCl3, 12 mol-% dppb and 10 equiva-
lents of KOAc in DMF at 80 °C (Scheme 5). The octahyd-
ronaphthalene was formed after 2 h in 56% yield as the sole
product with a trans/cis diastereoselectivity of 96:4 (Table 1,
entry 6). The use of a silver salt instead of KOAc was unfa-
vourable for the regio- and stereoselectivity of the reaction.
Thus, the addition of an equimolar amount of Ag3PO4 gave
11b in 57% yield with a trans/cis diastereoselectivity of
69:31. In addition, about 9% of the unwanted double bond
isomers were formed. As found for the reaction of 1c, al-
most no transformation was observed when the catalyst sys-
tem Pd(OAc)2/PPh3/NEt3 in toluene was used.
Scheme 3. Synthesis of allylsilanes 4; reagents and conditions: a)
nBuLi, THF, Ϫ30 °CǞ0 °C; b) Me3SiCH2I, 60Ϫ65 °C, 16 h; c)
cat. H2SO4, MeOH, 16 h; d) nBuLi, toluene, Ϫ45 °C, Et2AlCl (1.3
equiv.), oxirane (1.3 equiv.), 69%; e) P2ϪNi/H2, EtOH; f) PPh3,
imidazole, I2, Et2O/MeCN
The synthesis of the alkenyl iodide 2 was accomplished
by a palladium-catalysed reaction of the alkenyl triflate 1b
with hexamethyldistannane followed by iodination with an
excess of iodine in 67% overall yield (Scheme 4).[9]
Scheme 4. Synthesis of vinyl iodide 2; reagents and conditions: a)
Me3SnϪSnMe3, 2 mol-% [Pd(PPh3)4], LiCl, THF, 60 °C, 16 h; b)
I2 (2.0 equiv.), room temp., 20 h, 67%
The silane-terminated Heck reaction of the alkenyl trifl-
ate 1a (Scheme 5) was best accomplished with a catalyst
system containing 10 mol-% of Pd(OAc)2, 20 mol-% PPh3
and two equivalents of NEt3 in toluene at 80 °C, to give
exclusively the trimethylsilyl-substituted hexahydroindene
11a in 93% yield with a trans/cis diastereoselectivity of
90:10 (Table 1, entry 1). The use of THF as solvent gave
Scheme 5. Heck reactions of 1, 2 and 7
To show the significance of the presence of a trimethylsi-
11a in 89% yield with a trans/cis diastereoselectivity of lyl moiety in the substrates for regioselective β-hydride elim-
80:20 (Table 1, entry 2). The best result in the cyclisation of ination, a Heck reaction of 7 was performed under the con-
1960
Eur. J. Org. Chem. 2000, 1959Ϫ1964

Silane-Terminated Intramolecular Heck Reaction
FULL PAPER
Table 1. Intramolecular Heck reactions with alkenyl triflates and alkenyl iodides
Entry
Substrate
Product
Conditions
Temp. [°C]
Time [h]
Yield [%](Diastereoselec.)[a]
1
2
3
4
5
6
7
8
1a
1a
1b
1b
1c
2
11a
11a
11b
11b
11c
11b
Pd(OAc)2/PPh3/NEt3/
toluene
80
65
75
50
90
80
70
65
3
93
(90:10)
89
Pd(OAc)2/PPh3/NEt3/
THF
3
(80:20)
90
Pd(OAc)2/PPh3/NEt3/
toluene
2
(60:40)
81
Pd(OAc)2/PPh3/NEt3/
THF
3
(68:32)
61
Pd2(dba)3 CHCl3/dppb/
KOAc/DMF
16
2
(53:47)
56
Pd2(dba)3 CHCl3/dppb/
KOAc/DMF
(96:4)
12a, 33
12b, 47
12a, 36
12b, 45
7
12a
12b
12a
12b
Pd(OAc)2/PPh3/NEt3/
toluene
4
7
Pd(OAc)2/PPh3/NEt3/
THF
4
[a]
Diastereoselectivity determined by GC.
ditions optimised for compound 1b (Scheme 5). With a ate at δ ϭ 5.52Ϫ5.62 as a doublet of doublets, with J ϭ
catalyst system containing 10 mol-% of Pd(OAc)2, 20 mol- 18.0Ϫ18.5 and 1.0Ϫ1.5 Hz for 2Ј-H, and as a doublet of
% PPh3 and 2 equivalents of NEt3 in toluene at 70 °C, an doublets at δ ϭ 5.76Ϫ6.14 with J ϭ 18.5 and 4.4Ϫ7.0 Hz
inseparable mixture of the double bond isomers 12a (33%), for 1ЈH. The large coupling constants of 18.0Ϫ18.5 Hz cle-
(E)-12b and (Z)-12b (47% together) was obtained. A similar arly indicate that the vinylsilane possesses the E configura-
result was found using THF at 65 °C (Table 1, entry 7Ϫ8). tion. The relative trans-configuration of the substituents at
The results of the Heck reactions of 1 and 2 with an the two stereogenic centres of products 11a and 11b was
1
allylsilane moiety as the terminating group, compared with confirmed by H NMR NOESY experiments.
those of 7 with an alkene, clearly demonstrate the import-
ance of the trimethylsilyl group for the regioselective elim-
Conclusion
ination of the XϪPdLnϪH in the intermediate Pd-complex.
In the reactions of 1a؊c and 2, products 11a؊c with an
(E)-vinylsilane moiety were formed almost exclusively. In
some cases, small amounts (less than 5%) of the products
with a vinyl group were detected, but there was no trace of
products of type 12b under the normal conditions. In our
former investigations employing aryl iodides we have shown
that, in the absence of a silver salt, the product with a vinyl
group is formed almost exclusively, whereas in the presence
of a silver salt the product with an (E)-trimethylsilylvinyl
group is produced. We explained the formation of the prod-
uct with a trimethylsilylvinyl group by the intermediate cre-
ation of a Pdϩ species which would facilitate a fast PdLnHϩ
elimination of the more acidic hydrogen in the α-position
to the trimethylsilyl group. This would correspond with the
reaction of 1, since the PdϪOTf bond is rather weak and
could dissociate to form a Pdϩ species. On the other hand,
employing 2 with a vinyl iodide moiety should result in the
formation of the vinyl-substituted compound. However,
since in general the alkenylϪPdLnϪX species are more re-
active than their arylϪPdLnϪX counterparts, we have to
assume in this case that the PdLnϪH elimination is again
preferred over a formal IPdL2SiMe3 elimination, which
probably proceeds by means of the intermediate formation
of a β-trimethylsilyl carbocation.
The directing ability of the TMS group is demonstrated
by the intramolecular Heck reaction of the substrates 1a؊c
and 2 containing an allylsilane moiety, resulting in the re-
gioselective formation of the products 11a؊c with a trime-
thylsilylvinyl side chain. We assume that an intermediate
Pdϩ species is formed, at least when using substrates 1,
which then undergoes a rapid PdLnHϩ elimination of the
more acidic hydrogen in the α-position to the trimethylsilyl
group.
Experimental Section
General Remarks: Pd-catalysed transformations and reactions of
air sensitive compounds were carried out in an inert atmosphere.
Ϫ
1H NMR and 13C NMR spectra: Varian XL-200, VXR-200,
Bruker AMX-300. Ϫ IR: Bruker IFS-25. Ϫ MS and HMRS:
Varian MAT 311A and MAT 731. Ϫ UV/Vis: PerkinϪElmer
Lambda 2. Ϫ Elemental analyses: Analytical laboratory of the Uni-
versity of Göttingen. Ϫ Column chromatography: Macherey, Nagel
GmbH & Co. KG silica gel (0.063Ϫ0.200 mm). Ϫ Analytical TLC:
Macherey, Nagel GmbH & Co. KG (SIL G/UV254). Ϫ Gas chro-
matography: Varian 3400cx with FID, N2 (3 mL/min), H2
(200 kPa), Integrator Merck-Hitachi D-2000; columns: 1) SGE
BPX-5% phenyl (equiv.) polysilphenylene-siloxane, 50 m; 2) oc-
takis-(6-O-methyl-2,3-di-O-pentyl)-γ-cyclodextrin (50% in OV
1701, w/w), 25 m. Ϫ Solvents (distilled from): Et2O (KOH or Na/
benzophenone), pentane (KOH), EtOAc (CaH2) THF (LiAlH4).
The structures of the new compounds were mainly deter-
1
mined by H NMR spectroscopy. The Z configuration of
the alkene moiety in substrates 1, 2 and 7 was deduced from
the coupling constants of J ϭ 10Ϫ10.5 Hz. The two hydro-
General Procedure I: To a stirred solution of KN(SiMe3)2 (1.5
gens of the vinylsilanyl moiety in the products 11a؊c reson- equivalents, 0.5  in toluene) in dry THF (1 mL/mmol) was added
Eur. J. Org. Chem. 2000, 1959Ϫ1964 1961

L. F. Tietze, A. Modi
cyclohexanone (1.5 equivalents) at Ϫ78 °C, and stirring was con- 2935, 2860 (CH), 1712 (CϭO), 1645 (CϭC), 1449 (CH), 1247, 855
FULL PAPER
tinued at Ϫ78 °C for 2 h. Then the iodide (1.0 equivalents) in THF
(1 mL/mmol) was added and the mixture was stirred for 2 h at
room temperature, diluted with aqueous NaHCO3 (20 mL/mmol)
and extracted with pentane/Et2O (9:1, 50 mL/mmol). The organic
phase was washed with 1  aqueous HCl (20 mL/mmol), aqueous
(SiMe3). Ϫ 1H NMR (200 MHz, CDCl3): δ ϭ 0.00 (s, 9 H, SiMe3),
1.27Ϫ1.41 (m, 4 H, 2Ј-H, 4-H), 1.46 (d, J ϭ 8 Hz, 2 H, 6Ј-H),
1.66Ϫ2.37 (m, 11 H, 2-H, 3-H, 5-H, 6-H, 1Ј-H, 3Ј-H), 5.16Ϫ5.50
(m, 2 H, 4Ј-H, 5Ј-H). Ϫ 13C NMR (50.3 MHz, CDCl3): δ ϭ Ϫ1.8
(SiMe3), 18.4 (C-6Ј), 24.8 (C-5), 27.2 (C-3Ј*), 27.3 (C-2Ј*), 28.0 (C-
NaHCO3 (20 mL/mmol), and brine (50 mL/mmol). The aqueous 1Ј*), 29.2 (C-4), 33.8 (C-3), 41.9 (C-6), 50.7 (C-2), 125.5 (C-5Ј),
phase was extracted with Et2O (3 ϫ 20 mL), the combined organic
phases were dried over Na2SO4, and the solvent was removed in
vacuo. The residue was purified by column chromatography.
127.2 (C-4Ј), 213.4 (C-1). Ϫ MS (70 eV): m/z (%) ϭ 252 (4) [Mϩ],
237 (6), [Mϩ ϪCH3], 209 (28) [Mϩ Ϫ C3H7], 73 (100) [SiMe3ϩ]. Ϫ
C15H28OSi (252.5): calcd. C 71.36, H 11.18; found C 71.36, H
11.14.
General Procedure II: To a solution of diisopropylamine (1.2
equivalents) in THF (1 mmol/mL) was added nBuLi (1.2 equiva-
lents, 1.6  in hexane) at Ϫ78 °C. The solution was stirred for 1 h
at Ϫ78 °C, 1 h at 0 °C and then cooled again to Ϫ78 °C. The ketone
(1.0 equivalent) in THF (1 mmol/mL) was added, the mixture was
stirred for 3 h at Ϫ78 °C, and then Tf2NPh (1.1 equivalents) in
THF (1 mmol/mL) was added. The reaction mixture was stirred
for 15 h at 0 °C and then diluted with pentane (50 mL/mmol), and
washed with water (20 mL/mmol) and brine (20 mL/mmol). The
organic phase was dried over Na2SO4, concentrated in vacuo, and
the residue purified by column chromatography.
(6RS)-(Z)-Trifluoromethanesulfonic Acid 6-(4-Hexenyl-6-trimethyl-
silyl)-1-cyclohexenyl Ester (1b): Ketone 5b (400 mg, 1.58 mmol) was
deprotonated with LDA (1.90 mmol) in THF and reacted with
Tf2NPh (622 mg, 1.74 mmol) according to general procedure II.
Chromatographic purification gave 501 mg (1.41 mmol, 89%) of 1b
as a colorless oil. Ϫ Rf ϭ 0. 27 (pentane). Ϫ IR (KBr): ν˜ ϭ 3007
cmϪ1 (CϭCH), 2949 (CH), 1680, 1646 (CϭC), 1417 (CH), 1247,
1
1209 (SO2ϪO), 858 (SiMe3). Ϫ H NMR (500 MHz, CDCl3): δ ϭ
0.00 (s, 9 H, SiMe3), 1.30Ϫ1.44 (m, 3 H, 2Ј-H, 5-Ha), 1.45 (d, J ϭ
8.5 Hz, 2 H, 6Ј-H), 1.51Ϫ1.73 (m, 4 H, 4-Ha, 5-Hb, 1Ј-H),
1.82Ϫ1.90 (m, 1 H, 4-Hb), 1.95Ϫ2.10 (m, 2 H, 3Ј-H), 2.12Ϫ2.16
(m, 2 H, 3-H), 2.42 (mC, 1 H, 6-H), 5.20Ϫ5.26 (m, 1 H, 4Ј-H),
5.35Ϫ5.41 (m, 1 H, 5Ј-H), 5.72 (dt, J ϭ 4, 1 Hz, 1 H, 2-H). Ϫ 13C
NMR (50.3 MHz, CDCl3): δ ϭ Ϫ1.8 (SiMe3), 18.5 (C-6Ј), 19.1 (C-
1Ј), 24.3 (C-3), 26.7 (C-2Ј), 27.0 (C-3Ј), 28.0 (C-4), 31.2 (C-5), 37.3
(C-6), 118.5 (q, J ϭ 319 Hz, CF3), 118.7 (C-2), 125.9 (C-5Ј), 126.8
(C-4Ј), 152.6 (C-1). Ϫ MS (DCI): m/z (%) ϭ 786.4 (0.5) [2 M ϩ
NH4ϩ], 419 (4) [M ϩ NH3 ϩ NH4ϩ], 402 (100) [M ϩ NH4ϩ]. Ϫ
C16H27F3O3SSi (384.5): calcd. C 49.98, H 7.08; found C 50.03, H
6.99.
(2RS)-(Z)-2-(3-Pentenyl-5-trimethylsilyl)cyclohexanone (5a): Reac-
tion of cyclohexenone 3 (0.55 g, 5.60 mmol) with 4a (1.00 g,
3.73 mmol) according to general procedure
I gave 0.308 g
(1.29 mmol, 35%) of the monoalkylated species 5a. Ϫ Rf ؍ 0.36
(pentane/EtOAc ϭ 50:1). Ϫ IR (KBr): ν˜ ϭ 3005 cmϪ1 (CϭCH),
2935, 2860 (CH), 1712 (CϭO), 1645 (CϭC), 1449 (CH), 857
(SiMe3). Ϫ UV (CH3CN): λmax (lg ε) ϭ 277.5 nm (1.670), 256.5
1
(2.651). Ϫ H NMR (200 MHz, CDCl3): δ ϭ 0.00 (s, 9 H, SiMe3),
1.25Ϫ1.28 (m, 2 H, 4-H), 1.46 (d, J ϭ 8.3 Hz, 2 H, 5Ј-H),
1.58Ϫ2.08 (m, 8 H, 1Ј-H, 2Ј-H, 3-H, 5-H), 2.27Ϫ2.38 (m, 3 H, 6-
H, 2-H), 5.14Ϫ5.50 (m, 2 H, 3Ј-H, 4Ј-H). Ϫ 13C NMR (75.5 MHz,
CDCl3): δ ϭ Ϫ1.8 (SiMe3), 18.4 (C-5Ј), 24.5 (C-2Ј*), 24.9 (C-5*),
28.0 (C-1Ј), 29.4 (C-4), 34.0 (C-3), 42.0 (C-6), 50.1 (C-2), 126.0 (C-
4Ј), 127.0 (C-3Ј), 213.4 (C-1). Ϫ MS (70 eV): m/z (%) ϭ 238 (4)
[Mϩ], 183 (46), 140 (28), 73 (100) [SiMe3ϩ]. Ϫ C14H26OSi (238.4):
calcd. C 70.51, H 10.99; found C 70.72, H 11.11.
(Z)-2-(5-Heptenyl-7-trimethylsilyl)-cyclohexanone (5c): Reaction of
cyclohexanone 3 (0.50 g, 5.1 mmol) with the iodide 4c (1.00 g,
3.38 mmol ) according to the general procedure I gave 0.46 g
(1.72 mmol, 51%) of 5c. Ϫ Rf ϭ 0.32 (pentane/EtOAc 50:1). Ϫ IR
(KBr): ν˜ ϭ 3005 cmϪ1 (CϭCH), 2933, 2858 (CH), 1713 (CϭO),
1645 (CϭC), 1449 (CH), 856 (SiMe3) Ϫ 1H NMR (200 MHz,
CDCl3): δ ϭ 0.00 (s, 9 H, SiMe3), 1.10Ϫ1.38 (m, 6 H, 2Ј-H, 3Ј-H,
4-H), 1.46 (d, J ϭ 7.5 Hz, 2 H, 7Ј-H), 1.60Ϫ2.48 (m, 11 H, 3-H,
5-H, 1Ј-H, 4Ј-H, 6-H, 2-H), 5.17Ϫ5.48 (m, 2 H, 5Ј-H, 6Ј-H). Ϫ 13C
NMR (50.3 MHz, CDCl3): δ ϭ Ϫ1.8 (SiMe3), 18.4 (C-7Ј), 24.8 (C-
5), 27.0 (C-4Ј), 28.0 (C-2Ј), 29.3 (C-1Ј*), 29.3 (C-4*), 29.9 (C-3Ј*),
33.8 (C-3), 42.0 (C-6), 50.7 (C-2), 125.3 (C-6Ј), 127.5 (C-5Ј), 213.5
(6RS)-(Z)-Trifluoromethanesulfonic Acid 6-(3-Pentenyl-5-trimethyl-
silyl)-1-cyclohexenyl Ester (1a): Ketone 5a (230 mg, 0.965 mmol)
was deprotonated with LDA (1.16 mmol) in THF and reacted with
Tf2NPh (414 mg, 1.16 mmol) according to general procedure II.
Chromatographic purification gave 283 mg (0.76 mmol, 79%) of 1a
as a colourless oil. Ϫ Rf ؍ 0.67 (pentane/EtOAc ϭ 50:1). Ϫ IR
(KBr): ν˜ ϭ 3005 cmϪ1 (CϭCH), 2936 (CH), 1681, 1645 (CϭC),
1448 (CH, SO2ϪO), 857 (SiMe3). Ϫ UV (CH3CN): no absorption.
(C-1). Ϫ MS (70 eV): m/z (%) ϭ 266 (18) [Mϩ], 251 (0.5) [Mϩ
Ϫ
CH3], 183 (100). Ϫ C16H30OSi (266.5): calcd. C 72.11, H 11.35;
found C 72.26, H 11.27.
Ϫ
1H NMR (200 MHz, CDCl3): δ ϭ 0.02 (s, 9 H, SiMe3),
(6RS)-(Z)-Trifluoromethanesulfonic Acid 6-(5-Heptenyl-7-trimethyl-
silyl)-1-cyclohexenyl Ester (1c): Reaction of 5c (500 mg, 1.88 mmol)
with LDA (2.26 mmol) and Tf2NPh (806 mg, 2.26 mmol) accord-
ing to general procedure II gave 0.60 g (1.51 mmol, 80%) of 1c as
a colourless oil. Ϫ Rf ϭ 0.72 (pentane/EtOAc 50:1). Ϫ IR (film):
ν˜ ϭ 3007 cmϪ1 (CϭCH), 2939, 2862 (CH), 1680, 1645 (CϭC),
1418, 1210 (SOϪO), 855 (SiMe3). Ϫ 1H NMR (300 MHz, CDCl3):
δ ϭ 0.01 (s, 9 H, SiMe3), 1.27Ϫ1.40 (m, 5 H, 2Ј-H, 3Ј-H, 5-Ha),
1.47 (d, J ϭ 9.0 Hz, 2 H, 7Ј-H), 1.53Ϫ1.72 (m, 4 H, 1Ј-H, 5-Hb, 4-
Ha), 1.80Ϫ1.90 (m, 1 H, 4-Hb), 1.95Ϫ 2.05 (q, J ϭ 7 Hz, 2 H, 4Ј-
H), 2.10Ϫ2.19 (m, 2 H, 3-H), 2.42 (mC, 1 H, 6-H), 5.23Ϫ5.28 (m,
1 H, 5Ј-H), 5.38Ϫ5.43 (m, 1 H, 6Ј-H), 5.75 (dt, J ϭ 4.0, 1.0 Hz, 1
H, 2-H). Ϫ 13C NMR (50.3 MHz, CDCl3): δ ϭ Ϫ1.8 (SiMe3), 18.4
(C-7Ј), 19.1 (C-1Ј), 24.3 (C-3), 26.2 (C-2Ј*), 26.9 (C-3Ј*), 27.9 (C-
4), 29.7 (C-4Ј), 31.3 (C-5), 37.3 (C-6), 118.5 (q, J ϭ 321 Hz, CF3),
1.34Ϫ1.42 (m, 2 H, 5-H), 1.47 (d, J ϭ 8.0 Hz, 2 H, 5Ј-H),
1.51Ϫ2.05 (m, 6 H, 2Ј-H, 1Ј-H, 4-H), 2.07Ϫ2.22 (m, 2 H, 3-H),
2.46 (mC, 1 H, 6-H), 5.12Ϫ5.28 (m, 1 H, 3Ј-H), 5.35Ϫ5.51 (m, 1
H, 4Ј-H), 5.76 (dt, J ϭ 4.0, 1.0 Hz, 1 H, 2-H). Ϫ 13C NMR
(50.3 MHz, CDCl3): δ ϭ Ϫ1.8 (SiMe3), 18.5 (C-5Ј), 19.0 (C-1Ј),
24.1 (C-2Ј), 24.3 (C-3), 27.9 (C-4), 31.4 (C-5), 37.0 (C-6), 118.4 (q,
J ϭ 321 Hz, CF3), 118.7 (C-2), 126.2 (C-4Ј), 126.4 (C-3Ј), 152.5 (C-
1). Ϫ MS (DCI): m/z (%) ϭ 405 (12) [M ϩ NH4ϩ ϩ NH3], 388
(100) [Mϩ], 374 (0.1) [M Ϫ CH3 ϩ NH4ϩ]. Ϫ C15H25F3O3SSi
(370.5).
(2RS)-(Z)-2-(4-Hexenyl-6-trimethylsilyl)-cyclohexanone (5b): Reac-
tion of cyclohexenone 3 (0.130 g, 1.33 mmol) with 4b (250 mg,
0.886 mmol) according to general procedure
I gave 159 mg
(0.630 mmol, 71%) of the monoalkylated species 5b. Ϫ Rf ؍ 0.34
(pentane/EtOAc ϭ 70:1). Ϫ IR (KBr): ν˜ ϭ 3005 cmϪ1 (CϭCH), 118.6 (C-2), 125.6 (C-6Ј), 127.2 (C-5Ј), 152.7 (C-1). Ϫ MS
1962
Eur. J. Org. Chem. 2000, 1959Ϫ1964

Silane-Terminated Intramolecular Heck Reaction
FULL PAPER
(DCI): m/z (%) ϭ 814 (0.1) [2 ϫ M ϩ NH4ϩ], 433 (2) [M ϩ NH3 0.94Ϫ1.06, 1.28Ϫ1.40, 1.40Ϫ1.50, 1.72Ϫ2.10 (m, 10 H, 2-H, 3-H,
ϩ NH4ϩ], 416 (100) [M ϩ NH4ϩ]. Ϫ C17H29F3O3SSi (398.6).
4-H, 5-H, 6-H), 2.10Ϫ2.20 (m, 1 H, 3a-H), 3.00 (mC, 1 H, 1-H),
5.35 (mC, 1 H, 7-H), 5.54 (dd, J ϭ 18.5, 1.5 Hz, 1 H, 2Ј-H), 5.90
(dd, J ϭ18.5, 7.0 Hz, 1 H, 1Ј-H). Ϫ 13C NMR (125.7 MHz,
CDCl3): trans diastereomer: δ ϭ Ϫ1.1 (SiMe3), 22.5 (C-6), 25.3 (C-
5*), 29.1 (C-4*), 31.3 (C-2*), 33.0 (C-3*), 41.3 (C-3a), 50.3 (C-1),
119.1 (C-7), 127.3 (C-2Ј), 146.8 (C-7a), 150.4 (C-1Ј). Ϫ cis diastere-
omer: δ ϭ Ϫ1.1 (SiMe3), 22.5 (C-6), 25.1 (C-5*), 29.5 (C-4*), 30.5
(C-2*), 31.4 (C-3*), 40.5 (C-3a), 49.6 (C-1), 117.7 (C-7), 129.1 (C-
2Ј), 147.4 (C-7a), 149.4 (C-1Ј). Ϫ MS (70 eV): m/z (%) ϭ 220 (28)
[Mϩ], 205 (12) [Mϩ Ϫ CH3], 146 (84) [Mϩ Ϫ HSiMe3], 73 (100)
[SiMe3ϩ]. Ϫ C14H24Si (220.4): calcd. 220.1647, found 220.1647
(HRMS).
(6RS)-(Z)-1-Iodo-6-(4-hexenyl-6-trimethylsilyl)-1-cyclohexene (2): A
degassed solution of 1b (358 mg, 1.00 mmol), hexamethyldistan-
nane (362 mg, 1.10 mmol), LiCl (268 mg, 6.32 mmol) and
Pd(PPh3)4 (23.2 mg, 0.020 mmol) in 5 mL of dry THF was stirred
at 60 °C for 16 h. Then the mixture was cooled to room temper-
ature and iodine (0.51 g, 2.00 mmol) in 2 mL of dry THF was ad-
ded. After additional stirring for 20 h at room temperature, the
mixture was diluted with saturated aqueous Na2S2O3 (5 mL) and
extracted with diethyl ether (10 mL). The combined organic phases
were washed with brine (5 mL) and concentrated in vacuo. Chro-
matographic purification (pentane) gave 243 mg (0.67 mmol, 67%)
of 2. Ϫ Rf ϭ 0.66 (pentane). Ϫ IR (film): ν˜ ϭ 3005 cmϪ1 (CϭCH),
2934, 2858 (CH), 1645 (CϭC), 1455 (CH), 1247, 857 (SiMe3). Ϫ
UV (CH3CN): λmax (lg ε) ϭ 256.0 nm (2.978). Ϫ 1H NMR
(200 MHz, CDCl3): δ ϭ Ϫ0.01 (s, 9 H, SiMe3), 1.12Ϫ1.44 (m, 3
H, 2Ј-H, 5-Ha), 1.47 (d, J ϭ 8.0 Hz, 2 H, 6Ј-H), 1.50Ϫ1.87 (m, 5
H, 4-H, 5-Hb, 1-H), 1.87Ϫ2.12 (m, 4 H, 3-H, 3Ј-H), 2.18Ϫ2.37 (m,
1 H, 6-H), 5.20Ϫ5.50 (m, 2 H, 4Ј-H, 5ЈH), 6.36 (dt, J ϭ 4.0, 1.5 Hz,
1 H, 2-H). Ϫ 13C NMR (50.3 MHz, CDCl3): δ ϭ Ϫ1.7 (SiMe3),
18.5 (C-6Ј), 27.0 (C-2Ј), 27.1 (C-3Ј, C-4), 28.1 (C-3), 29.6 (C-1Ј),
34.5 (C-5), 44.8 (C-6), 107.1 (C-1), 125.6 (C-5Ј), 127.2 (C-4Ј), 138.4
(C-2). Ϫ MS (70 eV): m/z (%) ϭ 362 (1) [Mϩ], 235 (28) [Mϩ Ϫ I],
161 (24) [Mϩ Ϫ I Ϫ SiMe3], 73 (100) [SiMe3ϩ]. Ϫ C15H27ISi (362.4):
calcd. 362.0926, found 362.0926 (HRMS).
(1RS,4aRS)-(E)-1-(2-Trimethylsilylvinyl)-1,2,3,4,4a,5,6,7-octahydro-
naphthalene (11b): (Cyclisation of 1b). ؊ A: Reaction of 1b
(95 mg, 0.25 mmol) in 5 mL of toluene at 75 °C for 2 h according
to general procedure III gave 53 mg (0.23 mmol, 90%) of the octah-
ydronaphthalene 11b. The diastereoselectivity was determined by
GC as 60:40 (trans:cis).
B: Reaction of 1b (100 mg, 0.260 mmol) in 3 mL of THF for 3 h
at 50 °C according to general procedure III gave 48 mg (0.21 mmol,
81%) of the octahydronaphthalene 11b. The diastereoselectivity was
determined by GC: 68:32 (trans:cis). Rf ؍ 0. 81 (pentane). Ϫ GC
(column 1, 130Ϫ230 °C, 5 °C/min): tR1 ϭ 10.55 min (trans), tR2
12.07 min (cis). Ϫ IR (film): ν˜ ϭ 2931 cmϪ1, 2860 (CϭCH, CH),
1667 (CϭC), 1447 (CH), 1248, 839 (SiMe3).
1H NMR
ϭ
Ϫ
General Procedure III (Heck Reactions): A mixture of Pd(OAc)2
(10 mol-%) and PPh3 (20 mol-%) in dry THF or toluene was stirred
at 45 °C for about 30 min to produce a homogeneous slurry. NEt3
(2.0 equivalents) and the allylsilane were added and the mixture
was heated at the indicated temperature until the reaction was com-
pleted (TLC). After cooling to room temperature and filtration
through a short column of silica gel with Et2O as eluent, the solu-
tion was concentrated in vacuo and the residue purified by chroma-
tography on silica gel (pentane).
(500 MHz, CDCl3): δ ϭ 0.03 (s, 9 H, SiMe3, cis), 0.05 (s, 9 H,
SiMe3, trans), 1.14Ϫ1.51, 1.54Ϫ1.81 (m, 21 H, 7-Ha, cis, 6-H, 5-H,
4-H, 3-H, 2-H, cis and trans), 1.95Ϫ1.98 (m, 3 H, 7-H, trans, 4a-
H, cis), 2.03Ϫ2.10 (m, 2 H, 4a-H, trans, 7-Hb, cis), 2.48Ϫ2.55 (m,
1 H, 1-H, cis), 2.85Ϫ2.89 (m, 1 H, 1-H, trans), 5.28 (mC, 1 H, 8-
H, cis), 5.43 (mC, 1 H, 8-H, trans), 5.62 (dd, J ϭ 18.5, 2.0 Hz, 1 H,
2Ј-H, trans), 5.62 (dd, J ϭ 18.5, 1.0 Hz, 1 H, 2Ј-H, cis), 6.03 (dd,
J ϭ 18.5, 7.6 Hz, 1 H, 1Ј-H, cis), 6.05 (dd, J ϭ 18.5, 4.4 Hz, 1 H,
1Ј-H, trans). Ϫ 13C NMR (50.3 MHz, CDCl3): trans diastereomer:
δ ϭ Ϫ1.0 (SiMe3), 21.7 (C-2*), 21.8 (C-3*), 25.8 (C-7*), 31.4 (C-
4*), 32.4 (C-6*), 33.8 (C-4a), 35.4 (C-5), 48.9 (C-1), 122.0 (C-8),
128.7 (C-2Ј), 141.7 (C-8a), 150.4 (C-1Ј). Ϫ cis diastereomer: δ ϭ
Ϫ1.0 (SiMe3), 21.3 (C-2*), 25.8 (C-7), 25.9 (C-3*), 31.3 (C-4*), 33.8
(C-6*), 35.3 (C-5), 37.8 (C-4a), 50.4 (C-1), 118.8 (C-8), 129.7 (C-
2Ј), 143.2 (C-8a), 149.4 (C-1Ј). Ϫ MS (70 eV): m/z (%) ϭ 234 (40)
[Mϩ], 219 (8) [Mϩ Ϫ CH3], 160 (68) [Mϩ Ϫ HSiMe3], 73 (100)
[SiMe3ϩ]. Ϫ C15H26Si (234.5): calcd. 234.1804, found 234.1803
(HRMS).
General Procedure IV (Heck Reactions):
A
mixture of
Pd2(dba)3 CHCl3 (6Ϫ7 mol-%) and 1,4-bis(diphenylphosphano)bu-
tane (dppb) (12Ϫ14 mol-%) was stirred under Ar in DMF or di-
methylacetamide (DMAA) at 45 °C for about 45 min to produce a
homogeneous orange solution. Then KOAc (10 equivalents) and
the allylsilane were added and the mixture was heated at the indic-
ated temperature until completion (TLC). After cooling to room
temperature, the mixture was diluted with Et2O (20 mL/mmol) and
washed with water and brine. The combined organic layers were
dried over Na2SO4, concentrated in vacuo, and the residue was
purified by column chromatography (pentane).
(2RS,7RS)-(E)-2-(2-Trimethylsilylvinyl)-bicyclo[5.4.0]undec-1(11)-
ene (11c) (Cyclisation of 1c): Reaction of 1c (63 mg, 0.16 mmol) in
3 mL of DMF for 16 h at 90 °C according to general procedure
IV gave 24 mg (0.097 mmol, 61%) of bicycloundecene 11c. The
diastereoselectivity was determined by GC as 53:47. Rf ϭ 0.78
(1RS,3aRS)-(E)-1-(2-Trimethylsilylvinyl)-2,3,3a,4,5,6-hexahydro-
1H-indene (11a) (Cyclisation of 1a): A: Reaction of 1a (80 mg,
0.22 mmol) in 5 mL of toluene for 3 h at 80 °C according to general
procedure III gave 45 mg (0.20 mmol, 93%) of the hexahydroindene
11a. The diastereoselectivity was determined by GC as 90:10
(trans:cis).
(pentane). Ϫ GC (column 1, 100Ϫ250 °C, 5 °C/min): tR1
ϭ
18.81 min, tR2 ϭ 19.76 min. Ϫ IR (Film): ν˜ ϭ 2926 cmϪ1, 2856
1
(CϭCH), (CH), 1668 (CϭC), 1453, 1378 (CH), 866 (SiMe3). Ϫ H
NMR (500 MHz, CDCl3): δ ϭ 0.01 (s, 9 H, SiMe3, isomer 1), 0.04
(s, 9 H, SiMe3, isomer 2), 0.78Ϫ0.88, 1.25Ϫ1.80, 1.82Ϫ2.07 (m, 28
H, 3-H, 4-H, 5-H, 6-H, 8-H, 9-H, 10-H), 2.12 (mC, 1 H, 7-H, iso-
mer 1), 2.24 (mC, 1 H, 7-H, isomer 2), 2.77 (mC, 1 H, 2-H, isomer
B: Reaction of 1a (70 mg, 0.19 mmol) in 3 mL of THF for 3 h at
65 °C according to general procedure III gave 37 mg (0.17 mmol,
89%) of the hexahydroindene 11a. The diastereoselectivity was de-
termined by GC as 80:20 (trans:cis). Rf ϭ 0.88 (pentane). Ϫ GC 1), 2.89 (mC, 1 H, 2-H, isomer 2), 5.36 (mC, 2 H, 11-H, both iso-
(column 2, 50Ϫ150 °C, 3 °C/min): tR1 ϭ 19.43 min (trans), tR2
ϭ
mers), 5.52 (dd, J ϭ18.0, 2.0 Hz, 1 H, 2Ј-H, isomer 1), 5.58 (dd,
J ϭ 18.0, 2.0 Hz, 1 H, 2Ј-H, isomer 2), 5.97 (dd, J ϭ 18.0, 6.0 Hz,
20.07 min (cis), tR3 ϭ 20.19 min (cis). Ϫ IR (film): ν˜ ϭ 2952 cmϪ1
,
2858 (CϭCH, CH), 1674, 1615 (CϭC), 1449 (CH), 1249, 841 1 H, 1Ј-H, isomer 1), 6.14 (dd, J ϭ 18.0, 6.0 Hz, 1 H, 1Ј-H, isomer
(SiMe3). Ϫ UV (CH3CN): λmax (lg ε) ϭ 253.5 (4.476). Ϫ 1H NMR 2). Ϫ 13C NMR (50.3 MHz, CDCl3): δ ϭ Ϫ0.99 (SiMe3 isomer 1),
(500 MHz, CDCl3): trans diastereomer: δ ϭ 0.00 (s, 9 H, SiMe3), Ϫ1.02 (SiMe3, isomer 2), 18.8, 20.5, 25.4, 25.5, 25.8, 27.0, 27.9,
Eur. J. Org. Chem. 2000, 1959Ϫ1964
1963

L. F. Tietze, A. Modi
FULL PAPER
Miyazaki, K. Uotsu, M. Shibasaki, Tetrahedron 1998, 54,
29.9, 31.2, 31.7, 32.9, 34.3, 34.8, 36.6 (C-3, C-4, C-5, C-6, C-8, C-
9, C-10), 34.9, 38.6 (C-7), 49.1, 53.1 (C-2), 122.5, 123.8 (C-11),
126.3, 126.5 (C-2Ј), 143.6, 144.1 (C-1), 151.1, 151.4 (C-1Ј). Ϫ MS
(70 eV): m/z (%) ϭ 248 (60) [Mϩ], 233 (28) [Mϩ Ϫ CH3], 174 (100)
[Mϩ Ϫ HSiMe3], 73 (100) [SiMe3ϩ]. Ϫ C16H28Si (248.5): calcd.
248.1960, found 248.1960 (HRMS).
[2d]
13073Ϫ13078. Ϫ
L. F. Tietze, H. Schirok, Angew. Chem.
1997, 109, 1159Ϫ1160; Angew. Chem. Int. Ed. Engl. 1997, 36,
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1124Ϫ1125. Ϫ
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Cyclisation of 2: Reaction of 2 (30 mg, 0.083 mmol) in 3 mL of
DMF for 2 h at 80 °C according to general procedure IV gave
11 mg (0.047 mmol, 56%) of the octahydronaphthalene 11b. The
diastereoselectivity was determined by GC as 96:4 (trans:cis).
[2h]
1996, 118, 2843Ϫ2859. Ϫ
T. Ohshima, K. Kagechika, M.
Adachi, M. Sodeoka, M. Shibasaki, J. Am. Chem. Soc. 1996,
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118, 7108Ϫ7116. Ϫ
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H. Muratake,
Cyclisation of Compound 7.
؊ A: Reaction of 7 (100 mg,
I. Abe, M. Natsume, Chem. Pharm. Bull. 1996, 44, 67Ϫ79. Ϫ
0.320 mmol) in 5 mL of toluene for 4 h at 70 °C according to gen-
eral procedure III gave 43 mg of a mixture of the compounds 12a,
(E)-12b and (Z)-12b. The yield of the compounds was determined
by GC: (1RS,4aRS)-(E/Z)-1-vinyl-1,2,3,4,4a,5,6,7-octahydronaph-
thalene (12a): 33%, (4aRS)-(E/Z)-1-ethylidene-1,2,3,4,4a,5,6,7-oc-
tahydronaphthalene 12b: 47%.
[2l]
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65 °C according to general procedure III gave 42 mg of an insepar-
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This work was supported by the state of Niedersachsen and the
Fonds der Chemischen Industrie. We thank BASF AG Ludwigs-
hafen, Degussa AG Frankfurt and Wacker Chemie GmbH,
München, for generous gifts of chemicals.
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1964
Eur. J. Org. Chem. 2000, 1959Ϫ1964