Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones from Allenyl Ketones and Comparison with Silver(I)-, Palladium(II)- and Bronsted Acid-Catalyzed Reactions

Article abstract of DOI:10.1002/(sici)1521-3897(200001)342:1<40::aid-prac40>3.0.co;2-v

The allenyl p-methoxybenzyl ketone 3a and allenyl p-siloxybenzyl ketones 6b selectively delivered three different products with three different transition metal-catalysts. With Hg(II)-catalysts a spiro[4.5]decene 9, with Ag(I)-catalysts a 2-substituted furan (10/11) and with Pd(II)-catalysts a 2,4-disubstituted furan (8/12) was formed. Only with perchloric acid the intermolecular addition of water to the allene, leading to 1,3-dicarbonyl compounds 7, was observed. While with the corresponding allenyl o-methoxybenzyl ketone 3b the Ag(I)- and Pd(II)-catalysts provided the expected products, the mercury-catalyst led to a new and interesting side-product rac-17 which combined both the furan moiety and the spiro[4.5]decene moiety. Efforts to prepare allenyl hydroxybenzyl ketones failed, in one case a small amount of a 5H-benzo[b]oxepin-4-one 21 was isolated. It also was not possible to extend the spirocyclization to allenyl p-siloxyphenyl ketone 6a or allenyl 2-(p-siloxyphenyl)ethyl ketone 6c.

Full text of DOI:10.1002/(sici)1521-3897(200001)342:1<40::aid-prac40>3.0.co;2-v

FULL PAPER _________________________________________________________________________
Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones from
Allenyl Ketones and Comparison with Silver(I)-, Palladium(II)- and
BrÝnsted Acid-Catalyzed Reactions
A. Stephen K. Hashmi*, Lothar Schwarz, and J. W. Bats
Frankfurt am Main, Institut für Organische Chemie der Johann Wolfgang Goethe-Universität
Received August 02nd, 1999, respectively October 22nd, 1999
Keywords: Allenes, Homogeneous catalysis, Mercury, Palladium, Silver
Abstract. The allenyl p-methoxybenzyl ketone 3a and alle-
nyl p-siloxybenzyl ketones 6b selectively delivered three dif-
ferent products with three different transition metal-catalysts.
With Hg(II)-catalysts a spiro[4.5]decene 9, with Ag(I)-cata-
lysts a 2-substituted furan (10/11) and with Pd(II)-catalysts
a 2,4-disubstituted furan (8/12) was formed. Only with per-
chloric acid the intermolecular addition of water to the al-
lene, leading to 1,3-dicarbonyl compounds 7, was observed.
While with the corresponding allenyl o-methoxybenzyl ke-
tone 3b the Ag(I)- and Pd(II)-catalysts provided the expect-
ed products, the mercury-catalyst led to a new and interest-
ing side-product rac-17 which combined both the furan moi-
ety and the spiro[4.5]decene moiety. Efforts to prepare alle-
nyl hydroxybenzyl ketones failed, in one case a small amount
of a 5H-benzo[b]oxepin-4-one 21 was isolated. It also was
not possible to extend the spirocyclization to allenyl p-si-
loxyphenyl ketone 6a or allenyl 2-(p-siloxyphenyl)ethyl ke-
tone 6c.
The synthesis of the spiro[4.5]decane terpene skeleton
from methoxy [1] and hydroxy [2] substituted arenes
has been stimulated by the interest in naturally occur-
ing sesquiterpenes like spirovetivanes, acorones or al-
askanes [1b,3] and their analogues. Among these meth-
ods is Nagao’s approach [4] that utilizes easily availa-
ble allenyl benzyl ketones and stoichiometric amounts
of Lewis acids (LA) like BF3· Et2O, ZnI2 or AlCl3. One
major synthetic limitation of this method was the need
of at least two methoxy substituents on the aromatic
system. With only one methoxy group, the yield dropped
from more than 80% to 8%.
We were interested in overcoming both limitations
i.e. to use catalytical amounts of lewis acids and only
one methoxy substituent. We also wanted to address the
question of selectivity, since it was known from work
of Marshall’s and our groups [5, 6] that silver or palla-
dium catalysts are able to cause a cycloisomerization of
the allenyl ketone to a furan.
Scheme 1 Synthesis of allenyl methoxybenzyl ketones 3
Starting from phenols 4a–c, the TBDMS-protected
5a –c delivered 6a–c by the same low temperature ad-
dition of 2.
Recently, we published preliminary results concern-
ing the spirocyclization [7]. Here, we now want to re-
port the mercury-catalyzed reactions in full detail and
compare them with silver-, palladium-, and BrÝnsted
acid-catalyzed reactions.
Synthesis of the Substrates
One class of substrates used in this investigation were
the allenyl methoxybenzyl ketones 3a–b. They were
prepared by the addition of allenylmagnesium bromide
(2) to the esters 1a–b at –78 °C.
Scheme 2 Synthesis of allenyl ketones 6 containing p-(t-
butyldimethylsilanyloxy)phenyl groups
40
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J. Prakt. Chem. 2000, 342, No. 1

Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
Catalysis Reactions
ward the hydrogen atom of the trisubstituted double
bond and the methyl group toward the hydrogen atom
at the 5-position. The NOE-data are in accordance with
this being the main conformer, the minor conformer is
the one with the opposite arrangement. There is only
one significant short intermolecular distance, O1 and
H4 of neighbouring molecules are separated by
2.44(1)Å.
The substrate 3a was first subjected to 10 mol% per-
chloric acid in aqueous acetonitrile (MeCN). Under
these conditions only the 1,3-dicarbonyl compound 7a
(in equilibrium with the corresponding enol 7b) was
formed. This mode of reaction is not unexpected, it is
well known that strong acids catalyze the addition of
water to allenes (as well as to the isomeric alkynes) [8].
On the other hand, under similar conditions
PdCl2(MeCN)2 mainly led to 8 (accompanied by small
amounts of 10 as reported previously), and AgNO3 de-
livered 10 as the exclusive product. With Hg(ClO4)2,
again under similar conditions, 80% of 9 and only 6%
of 7a/b were isolated. The mercury-catalyzed addition
of water to allenes and the isomeric alkynes is well doc-
umented in the literature [9]. Both, the structure of 8
(Figure1) [10] and 9 [7] have been proven by X-ray
crystal structure analyses.
Fig. 1 ORTEP diagram of 1-(4-methoxybenzyl)-3-[5-(4-
methoxybenzyl)furan-3-yl]but-2-en-1-one (8)
NMR studies on 8 (1H,1H-COSY, HSQC and NOESY,
see Figure 2) revealed that a similar conformation seems
to be the major conformer in solution. But a second set
of weak cross-peaks indicated that the other conformer
is also populated.
Scheme 3 Reactions of allenyl ketone 3a with different cata-
lysts
Fig. 2 Assignment of the 1H (numbers without brackets) and
13C (numbers in brackets) NMR signals of 8 obtained from
1H,1H-COSY, HSQC and important cross-peaks obtained from
NOESY spectra (arrows)
In the solid state the middle part of 8 (the furan ring,
the double bond and the carbonyl group) is essentially
coplanar [tilts of 8.2(3)° and 9.7(2)°], and the outer phe-
nyl groups are almost orthogonal to that middle part
[81.2(1)° and 60.2(1)°]. The conformation of the α,β-
unsaturated system is, like in other related derivatives
[6c,d], s-cis. And also the relative arrangement of the
vinyl group and the furyl group is identical with the
conformations observed in related derivatives before:
The hydrogen at the 3-position of the furan points to-
With Hg(ClO4)2 the optimal solvent was MeCN con-
taining 2 eqs. of water. In wet ethyl acetate, acetone and
dichloromethane the reaction was slower and lower
yields were obtained. In n-hexane no reaction was ob-
served. Several other mercury salts and Lewis acids that
tolerate water were also tested. The results are shown
J. Prakt. Chem. 2000, 342, No. 1
41

A. St. K. Hashmi et al.
FULL PAPER __________________________________________________________________________
in Table 1. As one can see, Hg(NO3)2, Hg(OAc)2 and
HgSO4 also show some catalytic activity, but Hg(ClO4)2
was the optimal catalyst. Obviously a weakly coordi-
nating ligand at Hg2+ was necessary. In the absence of
water the reaction failed.
higher yield of 9 was observed (84%). This might be
explained by the higher kinetic lability of the O–Si-bond
that might be broken during the reaction. Efforts to ex-
tend this reaction to the synthesis of four- or six-mem-
bered rings, failed. Neither from 6a nor from 6c any
spirocycles were obtained.
Table 1 Reactions of 3a with different Lewis-acids that tol-
erate water
An interesting aspect of the Ag(I)-catalyzed reaction
of 6a is the side product 13 which was isolated in 14%
yield. It is a constitutional isomer of 12a, the product of
the Pd(II)-catalyzed reaction. The formation of 13 is
still under investigation.
Lewis-acid
solvent
yield (%) of 9
5 mol% Hg(ClO4)2
6 mol% Hg(ClO4)2
10 mol% Hg(ClO4)2
10 mol% Hg(ClO4)2
10 mol% Hg(ClO4)2
10 mol% Hg(ClO4)2
10 mol% Hg(NO3)2
10 mol% HgCl2
10 mol% Hg(OAc)2
10 mol% Hg(SCN)2
10 mol% HgSO4
10 mol% InCl3
10 mol% Tl(ClO4)3
10 mol% Sc(SO2CF3)3
MeCN
acetone
CH2Cl2
Et2O
80
45
66
– a)
– b)
– a)
47 c)
– a)
– a)
– a)
55 c)
– a)
– a)
– a)
ethyl acetate
n-hexane
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
Then we investigated the reactivity of 3b. Again with
Pd(II) and Ag(I), the expected furans 14 and 18 were
obtained. With Hg(II) the reaction was slow (120 h in-
stead of 1 h for 3a) and only 24% of the spirocycle could
be isolated. The major product was 16a (32%, again in
equilibrium with small amounts of the corresponding
enol 16b). Quite unexpected was another side product
that combined both structural motives, a spiro[4.5]de-
cane and a furan, the compound rac-17, which was
formed in 15% yield.
b
a) no reaction. ) starting material completely consumed, but only
c
polymeric material was formed. ) slow reaction.
The allenyl ketones 6a–c reacted with the Ag(I)- and
Pd(II)-catalysts in the expected manner, leading either
to 11a –c or to 12a–c. When 6b was subjected to Hg(II)
under the optimal conditions mentioned above, an even
yield of
11
12
6,11,12
a
b
c
n = 0
n = 1
n = 2
22%
88%
85%
59%
68%
63%
9
Scheme 4 Reactions of allenyl ketones 6 with different cata-
lysts
Scheme 5 Reactions of allenyl ketone 3b with different cata-
lysts
42
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Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
The structural assignment for rac-17 is based on 1H,
Mechanistic Considerations
1
13C, H,1H-COSY, 13C,1H-COSY, 13C,1H-HMBC and
NOESY spectra [11]. The 1H and 13C assignments and
crucial NOESY-crosspeaks for the assignment of the
relative configuration of the two stereogenic centers in
rac-17 are summarized in Figure 3.
Now the question arose, why these quite simple salts or
complexes of different transition metals led to different
products. This shall be discussed for the reaction of 3a.
The Ag(I)- and Pd(II)-systems have been compared
before [6c], one suggestion for the selective formation
of either 10 or 8 was that only in the case of metal M =
Pd(II) the intermediate 23 lives long enough to react
with a second molecule of 3a, for M = Ag(I) a fast for-
mation of 10 takes place. In both these reactions, the
electrophilic metal first coordinates to the electron-rich
and less substituted terminal double bond of the allene
as shown in 22. This coordination will allow a nucleo-
philic attack by the carbonyl-oxygen only if it takes place
from the face opposite to the carbonyl-substituent on
the allene. Furthermore, the conformation 22a (s-cis for
the enone) is necessary. For the spirocyclization things
look similar, it is exactly the same face of the terminal
double bond that was mentioned above to react with the
nucleophilic oxygen after coordination to the metal that
now will have to react with the (nucleophilic) aromatic
system by an electrophilic attack. Here only the s-trans
conformer 23b can react in the desired manner (con-
necting the central carbon of the allene to the ipso-car-
bon of the arene). For geometrical reasons we favor the
model of a coordination of the soft Hg(II) to the termi-
nal double bond of the allene as shown in 22b which
will yield 24. A coordination to the carbonyl group (as
in 22c) would activate a π-orbital with lobes orthogo-
nal to those of the aromatic ring. A third possibility
would be an ipso-mercuration of the electron-rich aro-
matic ring (22d), followed by a 1,4-addition to the
Michael-acceptor substructure of the allenylketone, but
for simple geometric reasons such an 5-endo-trig cycli-
zation (carbomercuration of the enone) is not favour-
able (Scheme 7).
Fig. 3 Assignment of the 1H (numbers without brackets) and
13C (numbers in brackets) NMR signals of rac-17 obtained
1
from H,1H-COSY, 13C,1H-COSY, HMBC and important
cross-peaks obtained from NOESY spectra (arrows)
In order to test a free hydroxyl-group with a proton
as an even better leaving group for the spirocyclization,
we tried to synthesize allenyl p-hydroxybenzyl ketones.
Efforts to deprotect 6b failed, only the formation of ol-
igomeric or polymeric material was observed. Then we
tried to obtain the allenyl o-hydroxybenzyl ketone 20
following our standard route from 19 and 2. Apart from
polymeric material only 6% of the seven-membered
cyclic vinyl ether 21 were obtained. The structure of 21
has also been proven by an X-ray crystal structure anal-
ysis [7]. Comparable formations of a seven-membered
heterocycle by the intramolecular addition of an O-nu-
cleophile to an allene have been reported before [12].
Then a nucleophilic substitution at the methyl-group
or a nucleophilic attack at the arene-carbon of 24 with
water as the nucleophile will ultimately form methanol,
a proton and the mercury dienolate 25. The proton fi-
nally sets free the product 9 and the transition catalyst.
With the various metals the rates for these processes
seem to be quite different. So with Ag(I) and Pd(II) no
9 was formed. On the other hand, when the spirocycli-
zation was slow, as with the o-methoxybenzyl deriva-
tive 3b, the formation of rac-17 suggests that some of
the furan 27 was also produced with Hg(II).
We now would like to suggest that the different abil-
ities for back-bonding and the charge of the metal ion
are responsible for this behaviour. In the case of Pd(II)
back-donation is feasible, the intermediate 23 is easily
accessible and profits a lot from 23b. In the case of Ag(I)
the intermediate 23 is still accessible, but here 23a might
be more important, the intermediate does not live long
Scheme 6 Formation of 5H-benzo[b]oxepin-4-one 21
J. Prakt. Chem. 2000, 342, No. 1
43

A. St. K. Hashmi et al.
FULL PAPER __________________________________________________________________________
Scheme 7 Possible pathways for the formation of the different products
it. The back-side attack at the methyl groups with small
nucleophiles like Cl– or H2O should not be so sensitive
to sterical hindrance three bonds away but an attack of
H2O at the arene-carbon should be (see 26) .
enough to react with a second molecule of 3a. With the
doubly charged Hg2+-ion an electrophilic attack at the
arene becomes the main pathway, due to the bad ability
for back-donation 23 would be quite unfavourable. If
now, like with 3b, in the subsequent transformations
the σ-complex 26 reacts only slowly with the nucleo-
phile, the reversibility of the electrophilic attack at the
arene allows the formation of some 10 via 22a and 23.
27 might then react with the 2,4-dien-1-one system in
the other product 15 and give rac-17. This reaction
stereoselectively takes place from the less hindered face
of 15 (opposite to the methyl group shielding the diene)
and is regioselective (no C–C bond formation next to
the spiro-carbon), thus the relative configuration of the
stereocenters in the product can be explained. The for-
mation of 13 mentionend above is another evidence for
the ability of furans to react with α,β-unsaturated ke-
tones under the influence of electrophilic metal-cata-
lysts. These reactions are still under investigation.
Scheme 8 Positional selectivity of the loss of the substituent
on the arene
The formation of slightly higher amounts of 16 in
the reaction of 3b (compared to 3a) with Hg(II) also
shows that only when the other reactions, in which the
first step always is intramolecular, are slow, the inter-
molecular addition of water to the allene also becomes
visible.
The slow reaction of 3b (compared to 3a) also ex-
plains why Nagao only saw the product 28 and no 29 in
the reactions of 27. The origin of this positional selec-
tivity is yet unknown, sterical reasons might be part of
Conclusion
By the choice of the transition metal-catalyst it is possi-
ble to obtain selectively one out of three possible prod-
44
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Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
4-N,N-dimethylaminopyridine (DMAP) were added with stir-
ring. Then the reaction mixture was cooled to 0 °C and 1.2
eqs. of tert-butyldimethylchlorosilane (TBDMSCl) were
added. After warming to room temperature, stirring was con-
tinued for one hour. The precipitate was filtered off, the fil-
trate was washed with water, and the aqueous layer was ex-
tracted with Et2O three times. The combined organic layers
were treated as mentioned above (general procedure a).
ucts from the allenyl ketones 3a and 6a –c. While with
Ag(I)- and Pd(II)- this is also true for 3b, the Hg(II)-
catalysis was very slow and delivered several products.
This explains why Nagao in his o,p-disubstituted de-
rivatives observed only the product resulting from the
loss of the p-MeO group but never of the o-MeO group.
The side products 13 and rac-17 suggest that, at least in
electron-rich furans, there exists the possibility to form
new C–C-bonds also in the 5-position of the furan (and
not only in the 4-position as observed in the Pd(II)-cat-
alyzed reactions).
c) Cycloisomerisation to furans by AgI-catalysts. The al-
lenyl ketone was dissolved in acetone (amount given in the
individual experiment). 10–30 mol% AgNO3 were added.
Then the reaction mixture was stirred at room temperature
over night or refluxed for 1 hour. After removing the solvent
in vacuo, the crude product was purified by column chroma-
tography as described below.
This work was supported by the Deutsche Forschungsgemein-
schaft (Ha 1932/3-3 and Ha 1932/3-4) and the Fonds der
Chemischen Industrie. Furthermore we are grateful to the
Degussa AG for the generous donation of palladium and sil-
ver salts.
d) Cycloisomerization/Dimerization by PdII-catalysts. The
starting material was dissolved in MeCN (amount given in
the individual experiment) and PdCl2(MeCN)2 was added at
room temperature. When the reaction was finished (checked
by TLC), the solvent was removed in vacuo and the crude
product was purified by column chromatography as described
below.
Experimental
All operations with Grignard-reagents were carried out un-
der N2 and in anhydrous solvents; transfers were effected by
means of Schlenk-tube techniques. 2 [13] and PdCl2(MeCN)2
[14] were prepared by literature procedures. All other chemi-
cals were commercially available and used as received. – IR:
Perkin-Elmer 1600. – NMR: Bruker AM 250 (250 and 62.9
MHz for 1H and 13C, respectively) and Bruker AM 270 (270
1-(4-Methoxyphenyl)penta-3,4-dien-2-one (3a)
Following the general procedure a), from 24.3 g (135 mmol)
methyl (p-methoxyphenyl)acetate (1a) in 170 ml Et2O,
94.0 ml (1.6M, 150 mmol) allenylmagnesium bromide (2) in
94 ml of Et2O after HPLC (H/EE, 20:3), 12.5 g (49%) of 3a
were obtained. Rf (H/EE, 5:1) = 0.24. – IR (film, NaCl):
ν/cm–1 = 3 064, 3 033, 2 990, 2 967, 2 935, 2 907, 2 836, 1 958
(C=C=C), 1 933 (C=C=C), 1 678 (C=O), 1 611, 1 513, 1 248,
1
and 67.9 MHz for H and 13C, respectively) Bruker AMX
1
400 (400 MHz for H). CDCl3 as solvent δH/ppm = 7.25;
δC/ppm = 77.0. The degree of substitution of the C atoms was
determined by a combination of DEPT 135 and DEPT 90
spectra. – MS: VG-Instruments-Micro-Mass Tris 2000, EI
70 eV, quadrupole analyser and Finnigan CH7A (80 eV). –
HRMS: Finnigan MAT 711 (EI, 80 eV, 8 kV ion acceleration,
resolution >= 20 000, peak match). – m.p. (uncorrected): Kof-
ler hot-stage. – Column chromatography: Merck Kieselgel
60 using n-hexane/ethyl acetate (H/EA) as eluent. – Elemen-
tal analyses were performed on a Foss-Heraeus CHN-O-Rapid
elemental analyser.
1
1154, 1 035, 857, 804, 774. – H NMR (CDCl3, 250 MHz):
δ/ppm = 3.78 (s, 3H), 3.84 (s, 2H), 5.28 (d, J = 6.5 Hz, 2H),
5.81 (t, J = 6.5 Hz, 1H), 6.82–6.88 (m, 2H), 7.11–7.17 (m,
2H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = 44.97 (t), 55.08
(q), 79.60 (t), 96.21 (d), 113.90 (d, 2C), 126.47 (s), 130.32 (d,
2C), 158.43 (s), 197.81 (s), 216.98 (s). – MS (70 eV):
m/z (%) = 188 (30)[M+], 157 (8), 121 (100).
C12H12O2
(188.22)
Calcd.: C 76.57 H 6.43
Found: C 76.70 H 6.57.
General Procedures
1-(2-Methoxyphenyl)penta-3,4-dien-2-one (3b)
7.44 g (41.3 mmol) methyl 2-methoxyphenylacetate (1b) in
80 ml of Et2O and 31.0 ml (49.6 mmol, 1.6M) 2 in 31 ml of
Et2O were treated according to the general procedure a). Pu-
rification by HPLC (H/MeOAc, 10:0.35+30% DCM) pro-
vided 4.41 mg (57%) of 3b. Rf (H/EE, 2:1) 0.44. – IR (film,
NaCl): ν/cm–1 = 3064, 2988, 2940, 2837, 1957 (C=C=C),
1934 (C=C=C), 1690 (C=O), 1 602, 1496, 1464, 1439, 1336,
1290, 1247, 1156, 1112, 1029, 858, 754. – 1H NMR (CDCl3,
250 MHz): δ/ppm = 3.79 (s, 3H), 3.92 (s, 2H), 5.23 (d, J = 6.5
Hz, 2H), 5.86 (t, J = 6.5 Hz, 1H), 6.85–6.95 (m, 2H), 7.11–
7.15 (m, 1H), 7.22–7.29 (m, 1H). – 13C NMR (CDCl3, 62.9
MHz): δ/ppm = 40.93 (t), 55.22 (q), 79.35 (t), 96.04 (d), 110.35
(d), 120.37 (d), 123.51 (s), 128.23 (d), 131.04 (d), 157.27 (s),
197.62 (s), 216.37 (s). – MS (80 eV): m/z (%) = 188 (62)[M+],
121 (100), 91 (69).
a) Preparation of allenyl ketones from esters. 1.1 eqs. of a
solution of 2 in Et2O (1.6M) were diluted with dry Et2O
(amount given in the individual experiment) and cooled to
–78 °C. 1.0 eq. of the ester was dissolved in Et2O (amount
given in the individual experiment), precooled to –78 °C and
slowly added to the well-stirred solution of 2. After 15 min-
utes of stirring the reaction was quenched with saturated,
NH4Cl solution (still at –78 °C). Then the reaction mixture
was warmed to room temperature, the organic layer separat-
ed and the aqueous solution was extracted with ether twice.
The combined organic layers were dried over MgSO4, the
solvent was removed in vacuo, and the crude product was
purified by column chromatography or HPLC as described
in the individual experiments.
b) Silylation of phenols. To a solution of 1.0 eq. of phenol
in dry THF (10 ml/g phenol) 2.3 eqs. of Et3N and 0.1 eqs.
C12H12O2
(188.22)
Calcd.: C 76.57 H 6.43
Found: C 76.33 H 6.48.
J. Prakt. Chem. 2000, 342, No. 1
45

A. St. K. Hashmi et al.
FULL PAPER __________________________________________________________________________
Methyl 4-(t-butyldimethylsilanyloxy)benzoate (5a)
the general procedure a). Purification by HPLC (H/EE, 5:1)
provided 1.88 g (29%) of 6a. Rf (H/EE, 5:1) = 0.36. – IR
(film, NaCl): ν/cm–1 = 2956, 2930, 2886, 2858, 1963, 1935
(C=C=C), 1654, 1597, 1508, 1272, 1216, 1167, 911, 840,
3.96 g (26.0 mmol) methyl p-hydroxybenzoate (4a), 9.40 g
(31.2 mmol) of a solution containing 50% TBDMSCl in n-
hexane, 6.03 g (8.3 ml, 59.5 mmol) Et3N, 320 mg (2.62 mmol)
DMAP and 400 ml THF were treated according to the gener-
al procedure b). Purification by column chromatography (H/
EE, 25:1) provided 6.69 g (97%) of 5a. Rf (H/EE, 2:1) 0.64. –
IR (film, NaCl): ν/cm–1 = 2954, 2931, 2887, 2859, 1723
(C=O), 1604, 1509, 1435, 1271, 1163, 912, 839, 783. –
1H NMR (CDCl3, 250 MHz): δ/ppm = 0.21 (s, 6H), 0.97 (s,
9H), 3.85 (s, 3H), 6.81–6.87 (m, 2H), 7.90–7.96 (m, 2H). –
13C NMR (CDCl3, 62.9 MHz): δ/ppm = –4.58 (q, 2C), 18.06
(s), 25.42 (q, 3C), 51.62 (q), 119.65 (d, 2C), 123.09 (s), 131.37
(d, 2C), 159.86 (s), 166.64 (s). – MS (70 eV): m/z (%) = 266
(17)[M+], 235 (15), 209 (100), 84 (76), 59 (14), 51 (79).
C14H22O3Si Calcd.: C 63.12 H 8.32
1
783. – H NMR (CDCl3, 250 MHz): δ/ppm = 0.23 (s, 6H),
0.98 (s, 9H), 5.24 (d, J = 6.5 Hz, 2H), 6.44 (t, J = 6.5 Hz, 1H),
6.83–6.89 (m, 2H), 7.83–7.89 (m, 2H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = –4.51 (q, 2C), 18.09 (s), 25.43 (q, 3C),
78.89 (t), 92.68 (d), 119.64 (d, 2C), 130.76 (d, 2C), 130.76
(s), 160.09 (s), 189.01 (s), 216.34 (s). – 13C NMR (DMSO,
67.9 MHz): δ/ppm = –4.62 (q, 2C), 17.90 (s), 25.39 (q, 3C),
79.35 (t), 91.79 (d), 119.71 (d, 2C), 130.55 (s), 130.77 (d,
2C), 159.57 (s), 187.90 (s), 216.02 (s). – MS (70 eV):
m/z (%) = 274 (6)[M+], 235 (100), 217 (44), 150 (9), 73 (72),
67 (88), 57 (39).
C16H22O2Si Calcd.: C 70.03 H 8.08
(274.44)
Found: C 69.75 H 8.07.
(266.41)
Found: C 62.88 H 8.42.
1-[4-(t-Butyl-dimethyl-silanyloxy)phenyl]penta-3,4-dien-2-
one (6b)
Methyl [4-(t-butyldimethylsilanyloxy)phenyl]acetate (5b)
10.0 g (60.2 mmol) methyl p-hydroxyphenylacetate (4b),
19.7 g (65.5 mmol) of a solution containing 50% TBDMSCl
in n-hexane, 13.9 g (19.1 ml, 137 mmol) Et3N, 825 mg
(6.75 mmol) DMAP and 100 ml of THF were treated accord-
ing to the general procedure b). Purification by column chro-
matography (H/EE, 25:1) provided 15.9 g (94%) of 5b. Rf
(H/EE, 20:1) 0.22. – IR (film, NaCl): ν/cm–1 = 2955, 2931,
2888, 2858, 1742 (C=O), 1610, 1511, 1464, 1257, 1156,
916, 840, 781. – 1H NMR (CDCl3, 250 MHz): δ/ppm = 0.17
(s, 6H), 0.96 (s, 9H), 3.53 (s, 2H), 3.67 (s, 3H), 6.75–6.78
(m, 2H), 7.03–7.13 (m, 2H). – 13C NMR (CDCl3, 62.9 MHz):
δ/ppm = –4.58 (q, 2C), 18.03 (s), 25.53 (q, 3C), 40.23 (t),
51.80 (q), 119.96 (d, 2C), 126.50 (s), 130.06 (d, 2C), 154.61
(s), 172.20 (s). – MS (70 eV): m/z (%) = 280 (31)[M+], 223
(100), 163 (50). – C15H24O3Si (280.43): calcd. 280.14947;
found: 280.14920 (MS).
5.62 g (20.0 mmol) methyl [4-(t-butyldimethylsilanyloxy)
phenyl]acetate (5b) in 190 ml of Et2O and 22.0 ml (35.2 mmol,
1.6M) 2 in 22 ml of Et2O were treated according to the gener-
al procedure a). Purification by HPLC (H/MeOAc, 10:0.7),
delivered 3.92 mg (68%) of 6b. Rf (H/EE, 5:1) = 0.38. – IR
(film, NaCl): ν/cm–1 = 1956, 2930, 2895, 2858, 1959, 1933
(C=C=C), 1681 (C=O), 1608, 1509, 1261, 1170, 1152, 916,
1
840, 781. – H NMR (CDCl3, 250 MHz): δ/ppm = 0.17 (s,
6H), 0.96 (s, 9H), 3.80 (s, 2H), 5.24 (d, J = 6.4 Hz, 2H), 5.78
(t, J = 6.5 Hz, 1H), 6.72–6.78 (m, 2H), 7.02–7.08 (m, 2H). –
13C NMR (CDCl3, 62.9 MHz): δ/ppm = –4.57 (q, 2C), 18.03
(s), 25.53 (q, 3C), 45.11 (t), 79.54 (t), 96.26 (d), 119.96 (d,
2C), 127.09 (s), 130.26 (d, 2C), 154.43 (s), 197.86 (s), 217.02
(s). – MS (70 eV): m/z (%) = 288 (45)[M+], 231 (26), 221
(64), 203 (48), 73 (100).
C17H24O2Si Calcd.: C 70.78 H 8.39
Methyl 3-[4-(t-butyldimethylsilanyloxy)phenyl]propionate
(5c)
(288.46)
Found: C 70.56 H 8.40.
1-[4-(t-Butyldimethylsilanyloxy)phenyl]hexa-4,5-dien-3-one
(6c)
5.00 g (27.7 mmol) methyl p-hydroxyphenylpropionate (4c),
9.50 g (31.5 mmol) of a solution containing 50% TBDMCl in
n-hexane, 6.53 g (9.00 ml, 65.6 mmol) Et3N, 396 mg
(3.24 mol) DMAP and 100 ml THF were treated according to
the general procedure b). Purification by column chromato-
graphy (H/EE, 25:1), provided 7.50 g (92%) of 5c. Rf (H/EE,
2:1) 0.58. – IR (film, NaCl): ν/cm–1 = 2954, 2930, 2887,
2858, 1741 (C=O), 1610, 1511, 1436, 1256, 1170, 916, 840,
7.30 g (24.8 mmol) 5c in 400 ml of Et2O and 24.0 ml
(38.4 mmol, 1.6M) 2 in 24 ml of Et2O were treated according
to 2.4. Purification by HPLC (H/EE, 10:1) provided 5.86 g
(78%) of 6c. Rf (H/EE, 5:1) = 0.42. – IR (film, NaCl): ν/cm–1
= 2956, 2930, 2895, 2858, 1960, 1934 (C=C=C), 1682
(C=O), 1610, 1510, 1257, 1155, 916, 840, 781. – 1H NMR
(CDCl3, 250 MHz): δ/ppm = 0.18 (s, 6H), 0.98 (s, 9H), 2.85–
2.89 (m, 4H), 5.20 (d, J = 6.5 Hz, 2H), 5.77 (t, J = 6.5 Hz,
1H), 6.71–6.77 (m, 2H), 7.00–7.06 (m, 2H). – 13C NMR
(CDCl3, 62.9 MHz): δ/ppm = –4.57 (q, 3C), 18.04 (s), 25.54
(q, 2C), 29.55 (t), 40.92 (t), 79.36 (t), 96.59 (d), 119.81 (d,
2C), 129.08 (d, 2C), 133.51 (s), 153.76 (s), 199.75 (s), 216.64
(s). – MS (70 eV): m/z (%) = 302 (32)[M+], 245 (88), 221
(25), 139 (66), 97 (45), 73 (100), 67 (38), 57 (77).
1
781. – H NMR (CDCl3, 250 MHz): δ/ppm = 0.19 (s, 6H),
0.99 (s, 9H), 2.57–2.63 (m, 2H), 2.86–2.92 (m, 2H), 3.66 (s,
3H), 6.73–6.79 (m, 2H), 7.02–7.08 (m, 2H). – 13C NMR
(CDCl3, 62.9 MHz): δ/ppm = –4.58 (q, 2C), 18.03 (s), 25.55
(q, 3C), 30.07 (t), 35.84 (t), 51.36 (q), 119.87 (d, 2C), 129.00
(d, 2C), 133.04 (s), 153.88 (s), 173.25 (s). – MS (70 eV):
m/z (%) = 294 (51)[M+], 237 (62), 221 (25), 195 (54), 163
(87), 161 (100), 107 (56), 89 (81), 73 (49), 57 (55).
C18H26O2Si Calcd.: C 71.47 H 8.66
C16H26O3Si Calcd.: C 65.26 H 8.90
(302.49)
Found: C 71.29 H 8.72.
(294.47)
Found: C 65.13 H 8.90.
1-(4-Methoxyphenyl)pentan-2,4-dione (7a) and 4-Hydroxy-
1-(4-methoxyphenyl)pent-3-en-2-one (7b)
1-[4-(t-Butyldimethylsilanyloxy)phenyl]buta-2,3-dien-1-one
(6a)
6.30 g (23.6 mmol) 5a in 390 ml of Et2O and 23.0 ml
(36.8 mmol, 1.6M) 2 in 23 ml Et2O were treated according to
To 102 mg (542 µmol) 3a and 12.4 mg (688 µmol) H2O in
1.34 g (32.6 mmol) MeCN were added 7.60 mg (71.3%,
46
J. Prakt. Chem. 2000, 342, No. 1

Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
53.9 µmol, 9.9 mol%) HClO4 and stirred for 3 h. Purification
of the crude material by column chromatography (H/EE, 5:1)
provided 106 mg (95%) 7a (in equilibrium with a small
amount of 7b).
F2 to R(F) = 0.045 (wR(F2) = 0.134) and S = 1.52 for 5621
(Rint = 0.024) unique reflections [10].
Reactions of Different Lewis-acids with 3a (from Table 1)
a) 7a+b: Rf (H/EE, 5:1) = 0.25. – IR (film, NaCl): ν/cm–1
=
a) Hg(ClO4)2 in Acetone. 132 mg (701 µmol) 3a were dis-
solved in 500 µl [D6]-acetone containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 16.8 mg (42.1 µmol, 6 mol%)
Hg(ClO4)2 were added. The reaction was monitored by
1H NMR. When complete, the mixture was directly purified
by column chromatography as described above. Thus
55.0 mg (45%) of 9 were obtained.
3002, 2955, 2837, 1706, 1613, 1513, 1460, 1359, 1300,
1248, 1179, 1130, 1034, 918, 819, 788. – MS (80 eV):
m/z (%) = 206 (35)[M+], 122 (100), 85 (89).
C12H14O3
(206.24)
1
Calcd.: C 69.89 H 6.84
Found: C 70.07 H 6.96.
b) 7a: H NMR (CDCl3, 250 MHz): δ/ppm = 2.08 (s, 3H),
3.49 (s, 2H), 3.64 (s, 2H), 3.73 (s, 3H), 6.77–6.83 (m, 2H),
7.03–7.12 (m, 2H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm
= 30.60 (q), 49.68 (t), 55.07 (q), 56.33 (t), 114.19 (d, 2C),
130.47 (d, 2C).
b) Hg(ClO4)2 in DCM. 132 mg (701 µmol) 3a were dissolved
in 500 µl [D2]-DCM containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 28.0 mg (70.1 µmol, 10 mol%)
Hg(ClO4)2 were added. The reaction was monitored by
1H NMR. When complete, the mixture was directly purified
by column chromatography as described above. Thus
80.5 mg (66%) of 9 were obtained.
1
b) 7b: H NMR (CDCl3, 250 MHz): δ/ppm = 1.94 (s, 3H),
3.45 (s, 2H), 3.73 (s, 3H), 5.35 (m, 1H), 6.77–6.83 (m, 2H),
7.03–7.12 (m, 2H), 15.33 (br s, 1H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = 24.64 (q), 44.09 (t), 55.09 (q), 99.56 (d),
113.96 (d, 2C), 126.96 (s), 130.20 (d, 2C), 158.55 (s), 191.03
(s), 192.65 (s).
c) Hg(ClO4)2 in Et2O. 132 mg (701 µmol) 3a were dissolved
in 500 µl Et2O containing 15.2 mg (844 µmol, 1.2 eqs.) and
28.0 mg (70.1 µmol, 10 mol%) Hg(ClO4)2 were added. The
1
progress of the reaction was checked by H NMR of small
(E)-4-[5-(4-Methoxybenzyl)furan-3-yl]-1-(4-methoxyphenyl)
pent-3-en-2-one (8)
aliquotes of the Et2O in CDCl3. Even after the addition of
more water and heating to 30 °C no reaction was observed.
From 57.0 mg (303 µmol) 3a and 2.0 mg (7.7 µmol, 2.5 mol%)
Pd(MeCN)2Cl2 in 400 mg MeCN, 41.2 mg (72%) of 8 were
obtained according to the general procedure d). – Column
with (H/EE, 5:1). – Rf (H/EE, 2:1) = 0.38. – m.p. 89 °C. –
IR (neat, KBr): ν/cm–1 = 3032, 3000, 2954, 2934, 2908,
2835, 1676, 1610, 1588, 1512, 1463, 1248, 1178, 1034,
d) Hg(ClO4)2 in Ethyl Acetate. 132 mg (701 µmol) 3a were
dissolved in 500 µl ethyl acetate containing 15.2 mg
(844 µmol, 1.2 eqs.) and 28.0 mg (70.1 µmol, 10 mol%)
Hg(ClO4)2 were added. The progress of the reaction was
checked by 1H NMR of small aliquots of the Et2O in CDCl3.
The starting material was completely consumed, but in the
spectra only broad signals were visible and the TLC showed
a baseline spot.
1
819, 770. – H NMR (CDCl3, 250 MHz): δ/ppm = 2.40 (d,
J = 1.1 Hz, 3H), 3.71 (s, 2H), 3.80 (s, 3H), 3.81 (s, 3H), 3.89
(s, 2H), 6.12 (d, J = 0.9 Hz, 1H), 6.39 (d, J = 1.1 Hz, 1H),
6.85–6.92 (m, 4H), 7.12–7.18 (m, 4H), 7.55 (d, J = 0.8 Hz,
e) Hg(ClO4)2 in n-Hexane. 132 mg (701 µmol) 3a were dis-
solved in 500 µl n-hexane containing 15.2 mg (844 µmol,
1.2 eqs.) and 28.0 mg (70.1 µmol, 6 mol%) Hg(ClO4)2 were
added. The progress of the reaction was checked by 1H NMR
of small aliquotes of the Et2O in CDCl3. No reaction was
observed, even when heated to 40 °C.
1
1H). – H NMR (CDCl3, 400 MHz): δ/ppm = 2.40 (d, J =
1.1 Hz, 3H), 3.70 (s, 2H), 3.79 (s, 3H), 3.80 (s, 3H), 3.88 (s,
2H), 6.12 (d, J = 0.9 Hz, 1H), 6.39 (d, J = 1.0 Hz, 1H), 6.86–
6.89 (m, 4H), 7.13–7.18 (m, 4H), 7.55 (d, J = 0.6 Hz, 1H). –
13C NMR (CDCl3, 62.9 MHz): δ/ppm = 16.81 (q), 33.48 (t),
50.66 (t), 55.12 (q, 2C), 103.63 (d), 113.91 (d), 113.99 (d,
2C), 120.05 (d, 2C), 126.91 (s), 129.10 (s), 129.22 (s), 129.58
(d, 2C), 130.32 (d, 2C), 141.90 (d), 145.92 (s), 156.72 (s),
158.33 (s), 158.40 (s), 198.31 (s). – MS (70 eV): m/z (%) =
376 (18)[M+], 255 (100), 212 (69).
f) Hg(NO3)2 in MeCN. 132 mg (701 µmol) 3a were dissolved
in 500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 22.8 mg (70.1 µmol, 10 mol%)
Hg(NO3)2 were added. The reaction was monitored by
1H NMR. When complete (approximately 40 h), the mixture
was directly purified by column chromatography as described
above. Thus 57.3 mg (47%) of 9 were obtained.
C24H24O4
(376.45)
Calcd.: C 76.57 H 6.43
Found: C 76.30 H 6.46.
g) HgCl2 in MeCN. 132 mg (701 µmol) 3a were dissolved in
500 µl [D3]-MeCN containing 15.2 mg (844 µmol, 1.2 eqs.)
in a NMR tube and 19.0 mg (70.1 µmol, 10 mol%) HgCl2
Crystal Structure Determination of (E)-4-[5-(4-Methoxy-
benzyl)furan-3-yl]-1-(4-methoxyphenyl)pent-3-en-2-one
(8)
1
were added. The reaction was monitored by H NMR. But
only starting material was visible.
X-ray crystal data for C24H24O4: triclinic, P (–1), a = 5.4743
(6) Å, b = 12.685 (2) Å, c = 15.210 (2) Å, α = 108.29 (2)°,
β = 97.35 (1)°, γ = 98.33 (1)°, V = 975.2 (3) Å3, Z = 2,
Dcalc = 1.282 g cm–3, MoKα radiation (λ = 0.71073 Å), µ =
0.086 mm–1, T = –140 °C. 15773 reflections were collected
on a SIEMENS CCD three-circle diffractometer for 3° < 2θ
< 65°. The data were corrected for absorption effects using
the program SADABS [15]. The structure was solved by di-
rect methods and refined by full-matrix least-square against
h) Hg(OAc)2 in MeCN. 132 mg (701 µmol) 3a were dissolved
in 500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 22.3 mg (70.1 µmol, 10 mol%)
Hg(OAc)2 were added. The reaction was monitored by
1H NMR. But only starting material was visible.
i) Hg(SCN)2 in MeCN. 132 mg (701 µmol) 3a were dissolved
in 500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 22.2 mg (70.1 µmol, 10 mol%)
J. Prakt. Chem. 2000, 342, No. 1
47

A. St. K. Hashmi et al.
FULL PAPER __________________________________________________________________________
Hg(SCN)2 were added. The reaction was monitored by
1H NMR. But only starting material was visible.
tained according to the general procedure c). – Column with
(H/EE, 5:1). – Rf (H/EE, 5:1) = 0.48. – IR (film, NaCl):
ν/cm–1 = 3032, 3000, 2955, 2934, 2907, 2835, 1611, 1513,
j) HgSO4 in MeCN. 132 mg (701 µmol) 3a were dissolved in
500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 18.6 mg (70.1 µmol, 10 mol%)
HgSO4 were added. The reaction was monitored by 1H NMR.
When complete (approximately 26 h), the mixture was di-
rectly purified by column chromatography as described above.
Thus 67.3 mg (45%) of 9 were obtained.
1
1463, 1248, 1176, 1035, 1010, 931, 804, 761. – H NMR
(CDCl3, 250 MHz): δ/ppm = 3.81 (s, 3H), 3.93 (s, 2H), 6.00
(dd, J = 3.1 Hz, 0.8 Hz, 1H), 6.30 (dd, J = 3.2 Hz, 1.8 Hz,
1H), 6.84–6.90 (m, 2H), 7.15–7.20 (m, 2H), 7.34 (dd, J =
1.8 Hz, 0.7 Hz, 1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm
= 33.48 (t), 55.12 (q), 105.82 (d), 110.07 (d), 113.80 (d, 2C),
129.54 (d, 2C), 130.09 (s), 141.27 (d), 154.92 (s), 158.15 (s).
– MS (70 eV): m/z (%) = 188 (100)[M+], 159 (25), 157 (19),
144 (21), 115 (22).
k) InCl3 in MeCN. 132 mg (701 µmol) 3a were dissolved in
500 µl [D3]-MeCN containing 15.2 mg (844 µmol, 1.2 eqs.)
in a NMR tube and 15.5 mg (70.1 µmol, 10 mol%) InCl3
C12H12O2
(188.22)
Calcd.: C 76.57 H 6.43
Found: C 76.33 H 6.56.
1
were added. The reaction was monitored by H NMR. But
only starting material was visible, even after the addition of a
large excess of water.
Reaction of 6a with Ag(I)
l) Tl(ClO4)3 in MeCN. 132 mg (701 µmol) 3a were dissolved
in 500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 35.2 mg (70.1 µmol, 10 mol%)
Tl(ClO4)3 were added. The reaction was monitored by
1H NMR. But only starting material was visible, even after
the addition of a large excess of water.
65.0 mg (237 µmol) 6a and 1.9 mg (11.2 µmol, 5 mol%)
AgNO3 in 305 mg acetone were treated according to the gen-
eral procedure c). Purification by column chromatography
(H/EE, 50:1) provided 14.5 mg (22%) t-butyl-(4-furan-2-
ylphenoxy)dimethylsilane (11a) and 9.3 mg (14%) 4-{5-[4-
(t-butyldimethylsilanyloxy)benzyl]furan-2-yl}-1-[4-(t-bu-
tyldimethylsilanyloxy)phenyl]pentan-2-one (13).
m) Sc(SO2CF3)2 in MeCN. 132 mg (701 µmol) 3a were dis-
solved in 500 µl [D3]-MeCN containing 15.2 mg (844 µmol,
1.2 eqs.) in a NMR tube and 31.1 mg (70.1 µmol, 10 mol%)
Sc(SO2CF3)3 were added. The reaction was monitored by
1H NMR. But only starting material was visible, even after
the addition of a large excess of water.
a) 11a: Rf (H/EE, 20:1) = 0.54. – IR (film, NaCl): ν/cm–1
=
2956, 2930, 2886, 2858, 1613, 1589, 1514, 1484, 1266,
1169, 1007, 912, 841, 781. – 1H NMR (CDCl3, 250 MHz):
δ/ppm = 0.22 (s, 6H), 1.00 (s, 9H), 6.44 (dd, J = 1.8 Hz,
3.3 Hz, 1H), 6.52 (d, J = 3.3 Hz, 1H), 6.85–6.89 (m, 2H),
7.42–7.43 (m, 1H), 7.52–7.58 (m, 2H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = –4.54 (q, 2C), 18.11 (s), 25.54 (q, 3C),
103.32 (d), 111.38 (d), 120.21 (d, 2C), 124.45 (s), 125.02 (d,
2C), 141.24 (d), 153.97 (s), 155.04 (s). – MS (70 eV):
m/z (%) = 274 (55)[M+], 217 (100), 161 (4), 115 (7). –
C16H22O2Si: calcd. 274.13891, found 274.13884 (MS).
4-Methyl-spiro[4.5]deca-3,6,9-trien-2,8-dione (9) from 3a
To 203 mg (1.17 mmol) 3a in 265 mg MeCN containing
21.6 mg (1.20 mmol) H2O at 0 °C under stirring 2.4 mg
(6.0 µmol, 0.5 mol%) Hg(ClO4)2 were added, and stirring
was continued at room temperature for 6h. Then the solvent
was removed in vacuo, and the residue was purified by col-
umn chromatography on silica gel. Thus 163 mg (80%) of 9
were obtained. – Column with (H/EE, 1:1). – Rf (H/EE, 1:1)
0.20. – m.p. 269 °C. – IR (neat, KBr): νcm–1 = 3069, 3043,
2970, 1720, 1698, 1661, 1621, 1434, 1404, 1289, 1253,
b) 13: Rf (H/EE, 10:1) = 0.26. – IR (film, NaCl): ν/cm–1
=
2955, 2930, 2885, 2858, 1648, 1598, 1507, 1486, 1420,
1
1363, 1268, 1219, 1165, 1043, 911, 841, 806. – H NMR
(CDCl3, 250 MHz): δ/ppm = 0.24 (s, 6H), 0.26 (s, 6H), 1.01
(s, 18H), 2.53 (d, J = 1.0 Hz, 3H), 6.64 (d, J = 3.6 Hz, 1H),
6.81 (d, J = 3.6 Hz, 1H), 6.88–6.96 (m, 4H), 7.51 (d, J =
1.1 Hz, 1H), 7.62–7.68 (m, 2H), 7.95–8.01 (m, 2H). –
13C NMR (CDCl3, 62.9 MHz): δ/ppm = –4.54 (q, 2C), –4.51
(q, 2C), 15.37 (s), 18.01 (s), 25.41 (q), 25.46 (q, 3C), 25.50
(q, 3C), 106.28 (d), 114.45 (d), 115.66 (d), 119.73 (d, 2C),
120.38 (d, 2C), 123.49 (s), 125.60 (d, 2C), 130.08 (d, 2C),
133.36 (s), 141.00 (s), 153.54 (s), 155.38 (s), 155.95 (s), 159.49
(s), 189.96 (s).
1
1200, 1083, 860. – H NMR (CDCl3, 250 MHz): δ/ppm =
1.90 (d, J = 1.3 Hz, 3H), 2.64 (s, 2H), 6.20 (q, J = 1.3 Hz,
1H), 6.41–6.47 (m, 2H), 6.61–6.67 (m, 2H). – 13C NMR
(CDCl3, 62.9 MHz): δ/ppm = 15.01 (q), 45.11 (t), 52.37 (s),
130.68 (d, 2C), 132.37 (d), 149.51 (d, 2C), 176.63 (s), 184.54
(s), 204.27 (s). – MS (80 eV): m/z (%) = 147 (100)[M+], 146
(94), 131 (36), 117 (28), 78 (53).
C11H10O2
(174.19)
Calcd.: C 75.84 H 5.79
Found: C 75.53 H 5.83.
t-Butyl-(4-furan-2-ylmethylphenoxy)dimethylsilane (11b)
9 from 6b. To 2.01 mg (6.97 mmol) 6b in 4.0 ml MeCN
containing 130 mg (7.22 mmol) H2O at 0 °C under stirring
13.9 mg (34.7 µmol, 0.5 mol%) Hg(ClO4)2 were added and
stirring was continued at room temperature for 6 h. Then the
solvent was removed in vacuo and the residue was purified
by column chromatography on silica gel. Thus 1.02 g (84%)
of 9 were obtained.
50.0 mg (173 µmol) 6b, 5 mg (29.4 µmol, 17 mol%) AgNO3,
2 ml of acetone were treated according to the general proce-
dure c). Purification by column chromatography (H/EE, 20:1)
provided 44 mg (88%) of 11b. Rf (H/EE, 5:1) = 0.66. – IR
(film, NaCl): ν/cm–1 = 2956, 2930, 2896, 2858, 1609, 1510,
1472, 1261, 1169, 1010, 916, 839, 781. – 1H NMR (CDCl3,
250 MHz): δ/ppm = 0.19 (s, 6H), 0.99 (s, 9H), 3.90 (s, 2H),
5.96 (dd, J = 0.8 Hz, 3.1 Hz, 1H), 6.28 (dd, J = 1.9 Hz,
3.1 Hz, 1H), 6.75–6.81 (m, 2H), 7.06–7.11 (m, 2H), 7.32 (dd,
J = 0.8 Hz, 1.9 Hz, 1H). – 13C NMR (CDCl3, 62.9 MHz):
δ/ppm = –4.55 (q, 2C), 18.07 (s), 25.57 (q, 3C), 33.56 (t),
2-(4-Methoxybenzyl)furan (10)
From 28.0 mg (149 µmol) 3a, 8.00 mg (47.1 µmol, 32 mol%)
AgNO3 and 3 ml of acetone 24.8 mg (89%) of 10 were ob-
48
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Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
105.85 (d), 110.07 (d), 119.89 (d, 2C), 129.49 (d, 2C), 130.65
(s), 141.23 (d), 154.11 (s), 154.96 (s). – MS (70 eV):
m/z (%) = 288 (24)[M+], 231 (36), 81 (100).
MHz): δ/ppm = –4.54 (q, 4C), 16.80 (s, 2C), 18.06 (q), 25.56
(q, 6C), 33.54 (t), 50.82 (t), 103.64 (d), 120.00 (d, 2C), 120.05
(d), 120.10 (d, 2C), 127.58 (s), 129.11 (s), 129.52 (d, 2C),
129.83 (s), 130.29 (d, 2C), 141.88 (d), 145.83 (s), 154.31 (s),
154.41 (s), 156.71 (s), 198.37 (s). – MS (70 eV): m/z (%) =
576 (10)[M+], 355 (100), 221 (26), 73 (9). – C34H48O4Si: cal-
cd. 576.30911, found 576.30953 (MS).
C17H24O2Si Calcd.: C 70.78 H 8.39
(288.46)
Found: C 70.56 H 8.42.
t-Butyl-[4-(2-furan-2-ylethyl)phenoxy]dimethylsilane (11c)
30.0 mg (99.2 µmol) 6c, 4.00 mg (23.5 µmol, 24 mol%)
AgNO3, 400 mg of acetone were treated according to the gen-
eral procedure c). Purification by column chromatography
(H/EE, 20:1) provided 25.4 mg (85%) of 11c. Rf (H/EE, 5:1)
= 0.62. – IR (film, NaCl): ν/cm–1 = 2956, 2930, 2896, 2858,
1610, 1510, 1463, 1257, 1170, 1013, 917, 840, 780. – 1H
NMR (CDCl3, 250 MHz): δ/ppm = 0.20 (s, 6H), 0.99 (s, 9H),
2.90 (s, 4H), 5.95 (d, J = 3.2 Hz, 1H), 6.28 (dd, J =
1.9 Hz, 3.1 Hz, 1H), 6.75–6.79 (m, 2H), 7.00–7.06 (m, 2H),
7.32 (dd, J = 0.8 Hz, 1.9 Hz, 1H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = –4.57 (q, 2C), 18.06 (s), 25.56 (q, 3C),
30.02 (t), 33.46 (t), 104.96 (d), 109.95 (d), 119.75 (d, 2C),
129.05 (d, 2C), 133.81 (s), 140.65 (d), 153.70 (s), 155.40 (s).
– MS (70 eV): m/z (%) = 302 (5)[M+], 245 (2), 221 (100), 81
(20), 73 (43).
(E)-1-[4-(t-Butyldimethylsilanyloxy)phenyl]-5-(5-{2-[4-(t-
butyldimethylsilanyloxy)phenyl]ethyl}furan-3-yl)hex-4-en-3-
one (12c)
50.7 mg (167.6 µmol) 6c, 1.20 mg (4.63 µmol, 3 mol%)
Pd(MeCN)2Cl2 and 400 mg of MeCN were treated according
to the general procedure d). Purification by column chroma-
tography (H/EE, 20:1) provided 31.9 mg (63%) of 12c Rf
(H/EE, 5:1) = 0.44. – IR (film, NaCl): ν/cm–1 = 2955, 2929,
2895, 2858, 1682, 1608, 1593, 1510, 1472, 1257, 1169,
916, 840, 781. – 1H NMR (CDCl3, 250 MHz): δ/ppm = 0.18
(s, 6H), 0.19 (s, 6H), 0.98 (s, 18H), 2.41 (d, J = 1.1 Hz, 3H),
2.75–2.92 (m, 8H), 6.13 (s, 1H), 6.34 (d, J = 1.1 Hz, 1H),
6.72–6.78 (m, 4H), 6.79–7.08 (m, 4H), 7.56 (d, J = 0.7 Hz,
1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = –4.57 (q, 4C),
16.79 (q), 18.05 (s, 2C), 25.55 (q, 6C), 29.35 (t), 29.97 (t),
33.16 (t), 46.43 (t), 102.87 (d), 119.82 (d, 4C), 120.60 (d),
129.04 (d, 4C), 133.36 (s), 133.87 (s), 141.37 (d), 144.97 (s),
153.64 (s), 153.81 (s, 2C), 157.07 (s), 200.18 (s). – MS
(70 eV): m/z (%) = 604 (5)[M+], 221 (100), 73 (31). –
C36H52O4Si2: Calcd. 604.34041, found 604.34012 (MS).
C18H26O2Si Calcd.: C 71.47 H 8.66
(302.48)
Found: C 71.28 H 8.97.
(E)-1-[4-(t-Butyldimethylsilanyloxy)phenyl]-3-{5-[4-(t-
butyldimethylsilanyloxy)phenyl]furan-3-yl}-but-2-en-1-one
(12a)
110 mg (401 µmol) 6a, 0.8 mg (3.1 µmol, 1 mol%)
Pd(MeCN)2Cl2 and 360 mg MeCN were treated according to
2.9. Purification by column chromatography (H/EE, 50:1)
provided 65.0 mg (59%) 12a. Rf (H/EE, 10:1) = 0.34. –
IR (film, NaCl): ν/cm–1 = 2956, 2930, 2886, 2858, 1651,
1599, 1495, 1257, 1221, 1165, 1049, 912, 840, 805. –
1H NMR (CDCl3, 250 MHz): δ/ppm = 0.23 (s, 6H), 0.25 (s,
6H), 1.00 (s, 18H), 2.49 (d, J = 1.1 Hz, 3H), 6.78 (d, J =
0.7 Hz, 1H), 6.86–6.93 (m, 4H), 7.14 (d, J = 1.1 Hz, 1H),
7.55– 7.61 (m, 2H), 7.69 (s, 1H), 7.91–7.96 (m, 2H). –
13C NMR (CDClt, 62.9 MHz): δ/ppm = –4.49 (q, 2C), –4.52
(q, 2C), 17.25 (q), 18.10 (s), 18.12 (s), 25.48 (q, 3C), 25.53
(q, 3C), 100.74 (d), 119.01 (d), 119.77 (d, 2C), 120.29 (d,
2C), 123.62 (s), 125.34 (d, 2C), 130.21 (d, 2C), 130.49 (s),
133.00 (s), 141.16 (d), 144.95 (s), 155.30 (s), 155.64 (s),
159.65 (s), 190.35 (s). – MS (70 eV): m/z (%) = 548 (51)[M+],
491 (14), 341 (13), 301 (12), 299 (13), 235 (100), 217 (16),
195 (27). – C32H44O4Si2: calcd. 548.27781, found 548.27761
(MS).
4-[5-(2-Methoxybenzyl)furan-3-yl]-1-(2-methoxyphenyl)
pent-3-en-2-one (14)
150 mg (797 µmol) 3b, 2.00 mg (7.71 µmol, 1 mol%)
Pd(MeCN)2Cl2 and 207 mg MeCN were treated according to
the general procedure d). Purification by column chromatog-
raphy (H/EE, 7:1) provided 116 mg (77%) of 14. Rf (H/EE,
2:1) = 0.40. – IR (film, NaCl): ν/cm–1 = 3065, 3003, 2939,
2836, 1768, 1681, 1590, 1494, 1463, 1439, 1369, 1325,
1290, 1247, 1176, 1129, 1111, 1050, 1029, 951, 754. –
1H NMR (CDCl3, 250 MHz): δ/ppm = 2.38 (d, J = 1.2 Hz,
3H), 3.76 (s, 2H), 3.77 (s, 3H), 3.83 (s, 3H), 3.94 (s, 2H),
6.06 (d, J = 0.9 Hz, 1H), 6.43 (d, J = 1.1 Hz, 1H), 6.85–6.95
(m, 2H), 7.11–7.17 (m, 2H), 7.20–7.27 (m, 2H), 7.53 (d, J =
0.8 Hz, 1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = 16.67
(q), 28.29 (t), 46.02 (t), 55.18 (q), 55.31 (q), 103.63 (d), 110.38
(d), 110.44 (d), 120.32 (d), 120.41 (d), 120.51 (d), 123.92 (s),
125.76 (s), 127.93 (d), 128.11 (d), 129.23 (s), 130.01 (d),
131.01 (d), 141.52 (d), 145.17 (s), 156.18 (s), 157.12 (s),
157.25 (s), 198.40 (s). – MS (70 eV): m/z (%) = 376 (38)[M+],
255 (100), 147 (54), 121 (71), 91 (56). – C24H24O4: Calcd.
376.16746, found 376.16345 (MS).
(E)-4-{5-[4-(t-Butyldimethylsilanyloxy)benzyl]furan-3-yl}-1-
[4-(t-butyl-dimethylsilanyloxy)phenyl]pent-3-en-2-one (12b)
110 mg (381 µmol) 6b, 5.00 mg (19.3 µmol, 5 mol%)
Pd(MeCN)2Cl2 and 5 ml MeCN were treated according to
the general procedure d). Purification by column chromatog-
raphy (H/EE, 20:1) provided 74.9 mg (68%) of 12b. Rf
(H/EE, 10:1) = 0.36. – IR (film, NaCl): ν/cm–1 = 2956, 2300,
2895, 2858, 1678, 1608, 1591, 1509, 1 472, 1261, 1169,
916, 839, 781. – 1H NMR (CDCl3, 250 MHz): δ/ppm = 0.19
(s, 6H), 0.20 (s, 6H), 0.98 (s, 9H), 1.00 (s, 9H), 2.39 (d, J =
1.1 Hz, 3H), 3.68 (s, 2H), 3.86 (s, 2H), 6.09 (d, J = 0.9 Hz,
1H), 6.37 (d, J = 1.1 Hz, 1H), 6.77–6.81 (m, 4H), 7.07–7.10
(m, 4H), 7.55 (d, J = 0.8 Hz, 1H). – 13C NMR (CDCl3, 62.9
C24H24O4
(376.44)
Calcd.: C 76.57 H 6.43
Found: C 76.34 H 6.46.
Reaction of 3b with Hg(II)
215 mg (1.14 mmol) 3b and 20.5 mg (11.4 mg) H2O were
mixed with 1.3 g MeCN at 0 °C. 16.4 mg (41.0 µmol,
3.6 mol%) Hg(ClO4)2 were added. After 5 days at room tem-
perature column chromatography (H/EE, 2:1) provided
47.3 mg (24%) of 4-methylspiro[4.5]deca-3,7,9-trien-2,6-di-
one (15), 75.4 mg (32%) of a mixture of 4-hydroxy-1-(2-
J. Prakt. Chem. 2000, 342, No. 1
49

A. St. K. Hashmi et al.
FULL PAPER __________________________________________________________________________
methoxyphenyl)pent-3-en-2-one (16a, major) and 1-(2-
methoxyphenyl)pentan-2,4-dione (16b, minor) as well as
30.9 mg (15%) of 8-[5-(2-methoxybenzyl)furan-2yl]-4-
methylspiro[4.5]deca-3,9-diene-2,6-dione (rac-17).
δ/ppm = 3.84 (s, 3H), 3.99 (s, 2H), 5.97–6.00 (m, 1H), 6.29
(dd, J = 1.9 Hz, 3.2 Hz, 1H), 6.87–6.93 (m, 2H), 7.09–7.10
(m, 1H), 7.12–7.25 (m, 1H), 7.32 (dd, J = 0.8 Hz, 1.9 Hz,
1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = 28.20 (q),
55.29 (t), 105.90 (d), 110.09 (d), 110.35 (d), 120.37 (d), 126.63
(s), 127.62 (d), 129.90 (d), 140.98 (d), 154.36 (s), 157.12 (s).
– MS (80 eV): m/z (%) = 188 (100)[M+], 173 (21), 159 (18),
145 (15), 128 (18), 115 (15), 91 (10).
a) 15: Rf (H/EE, 2:1) = 0.12. – IR (film, NaCl): ν/cm–1
=
3046, 2 979, 2922, 2848, 2922, 1721, 1695, 1662, 1632,
1621, 1558, 1433, 1414, 1376, 1287, 1201, 1137, 966, 854.
– 1H NMR (CDCl3, 250 MHz): δ/ppm = 1.83 (s, 3H), 2.35 (d,
J = 18.0 Hz, 1H), 2.73 (d, J = 18.1 Hz, 1H), 6.04–6.6 (m,
1H), 6.13–6.19 (m, 2H), 6.39–6.45 (m, 1H), 7.12–7.19 (m,
1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = 15.20 (q),
46.78 (q), 62.36 (q), 122.87 (q), 126.34 (q), 131.85 (q), 142.37
(q), 142.66 (q), 176.14 (q), 200.39 (q), 206.37 (q).
C12H12O2
(188.23)
Calcd.: C 76.57 H 6.43
Found: C 76.58 H 6.43.
2-Methyl-5H-benzo[b]oxepin-4-one (21)
4.86 g (36.2 mmol) 2-cumaranone (19) in 410 ml of Et2O and
36.0 ml (57.6 mmol, 1.6M) 2 in 36 ml Et2O were reacted ac-
cording to the general procedure a). Purification by column
chromatography and HPLC provided 369 mg (6%) of 21.
Rf (H/EE, 2:1) = 0.38. – m.p. 57 °C. – IR (neat, KBr):
ν/cm–1 = 3046, 3008, 2952, 2913, 1666 (C=O), 1628. –
1H NMR (CDCl3, 250 MHz): δ/ppm = 2.13 (s, 3H), 3.70 (s,
2H), 5.46 (s, 1H), 7.05–7.22 (m, 4H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = 23.37 (q), 48.08 (t), 110.72 (d), 119.86
(d), 124.78 (s), 126.47 (d), 127.92 (d), 130.00 (d), 155.09 (s),
168.87 (s), 190.79 (s). – MS (70 eV): m/z (%) = 174 (48)[M+],
145 (32), 131 (61), 115 (18), 89 (57), 78 (100), 63 (55), 51
(75).
b) 16a+b: Rf (H/EE, 2:1) = 0.44. – IR (film, NaCl): ν/cm–1
=
3065, 3004, 2940, 2837, 1727, 1707, 1602, 1538, 1495,
1464, 1247, 1112, 1050, 1029. – MS (80 eV): m/z (%) = 206
(40)[M+], 148 (19), 122 (73), 91 (59), 85 (100).
C12H14O3
(206.24)
1
Calcd.: C 69.89 H 6.84
Found: C 70.12 H 6.69.
c) 16b: H NMR (CDCl3, 250 MHz): δ/ppm = 1.89 (s, 3H),
3.53 (s, 2H), 3.72 (s, 3H), 5.31 (s, 1H), 6.78–6.87 (m, 2H),
7.02–7.18 (m, 1H), 7.20–7.22 (m, 1H), 15.35 (br, 1H). –
13C NMR (CDCl3, 62.9 MHz): δ/ppm = 24.73 (q), 40.15 (t),
55.82 (q), 99.89 (d), 111.04 (d), 121.03 (d), 124.11 (s), 128.93
(d), 131.47 (d), 157.88 (s), 189.77 (s), 194.67 (s).
C11H10O2
(174.20)
Calcd.: C 75.84 H 5.79
Found: C 76.12 H 5.76.
d) 16a: 1H NMR (CDCl3, 250 MHz): δ/ppm = 2.06 (s, 3H),
3.46 (s, 2H), 3.64 (s, 2H), 3.71 (s, 3H), 6.78–6.87 (m, 2H),
7.02–7.18 (m, 1H), 7.20–7.22 (m, 1H). – 13C NMR (CDCl3,
62.9 MHz): δ/ppm = 30.91 (q), 45.92 (t), 55.68 (q), 57.11 (t),
110.93 (d), 212.23 (d), 123.09 (s), 129.35 (d), 131.79 (d),
157.69 (s), 202.57 (s), 202.73 (s).
References
[1] a) R. P. Gajewski, Tetrahedron Lett. 1976, 4125; b) R. A.
Haack, K. R. Beck, Tetrahedron Lett. 1989, 30, 1605;
c) F. T. Boyle, Z. S. Masusiak, O. Hares, D. A. Whiting, J.
Chem. Soc., Chem. Commun. 1990, 518; d) F. T. Boyle, O.
Hares, Z. S. Matusiak, W. Li, D. A. Whiting, J. Chem. Soc.,
Perkin Trans. 1 1997, 2707
e) rac-17: Rf (H/EE, 2:1) = 0.20. – IR (film, NaCl): ν/cm–1
=
3067, 2962, 2939, 2915, 2837, 1721, 1715, 1697, 1623,
1601, 1558, 1494, 1464, 1439, 1376, 1292, 1247, 1176,
1
1106, 1050, 1028, 756. – H NMR (CDCl3, 250 MHz):
δ/ppm = 1.98 (d, J = 1.3 Hz, 3H), 2.33 (d, J = 18.3 Hz, 1H),
2.70 (d, J = 18.3 Hz, 1H), 2.83 (d, J = 1.7 Hz, 1H), 2.86 (s,
1H), 3.83 (s, 3H), 3.92 (s, 2H), 3.95–3.99 (m, 1H), 5.63 (dd,
J = 2.0 Hz, 9.8 Hz, 1H), 5.85–5.87 (m, 1H), 5.95 (d, J =
3.0 Hz, 1H), 6.07 (q, J = 1.3 Hz, 1H), 6.22 (dd, J = 3.7 Hz,
9.8 Hz, 1H), 6.86–6.92 (m, 2H), 7.05–7.08 (m, 1H), 7.18–
7.26 (m, 1H). – 13C NMR (CDCl3, 62.9 MHz): δ/ppm = 16.05
(q), 28.18 (t), 36.33 (d), 43.86 (t), 48.10 (t), 55.25 (q), 59.84
(s), 105.88 (d), 106.59 (d), 110.31 (d), 120.32 (d), 126.25 (s),
127.67 (d), 129.77 (d), 130.24 (d), 130.95 (d), 132.39 (d),
152.63 (s), 154.18 (s), 157.05 (s), 176.60 (s), 205.75 (s), 208.00
(s). – MS (70 eV): m/z (%) = 362 (100)[M+], 320 (44), 255
(10), 214 (30), 187 (29), 171 (26), 121 (43), 91 (40). –
C23H22O4: Calcd. 362.151809, found 362.15378 (MS).
[2] J. S. Swenton, A. Callinan, Y. Chen, J. J. Rohde, M. L. Kerns,
G. W. Morrow, J. Org. Chem. 1996, 61, 1267
[3] For a review see: C. H. Heathcock, S. L. Graham, M. C.
Pirrung F. Plavac, C. T. White in The Total Synthesis of Nat-
ural Products; J. ApSimon (Ed.); Wiley-Interscience: New
York 1983; Vol. 5, pp 264
[4] Y. Nagao, W. S. Lee, I.-L. Jeong, M. Shiro, Tetrahedron Lett.
1995, 36, 2799
[5] a) J. A. Marshall, E. D. Robinson, J. Org. Chem. 1990, 55,
3450; b) J. A. Marshall, X. Wang, J. Org. Chem. 1991, 56,
960; c) J. A. Marshall, X. Wang, J. Org. Chem. 1992, 57,
3387; d) J. A. Marshall, G. S. Barteley, J. Org. Chem. 1994,
59, 7169; e) J. A. Marshall, E. M. Wallace, P. S. Coan, J.
Org. Chem. 1995, 60, 796; f) J. A. Marshall, C. A. Sehon, J.
Org. Chem. 1995, 60, 5966; g) J. A. Marshall, J. Liao, J.
Org. Chem. 1998, 63, 5962
[6] a) A. S. K. Hashmi, Angew. Chem. 1995, 107, 1749; An-
gew. Chem. Int. Ed. Engl. 1995, 34, 1581; b) A. S. K. Hash-
mi, L. Schwarz, Chem. Ber./Recueil 1997, 130, 1449; c) A.
S. K. Hashmi, T. L. Ruppert, T. Knöfel, J. W. Bats, J. Org.
Chem. 1997, 62, 7295; d) A. S. K. Hashmi, J.-H. Choi, J. W.
Bats, J. Prakt. Chem. 1999, 341, 342
[7] A. S. K. Hashmi, L. Schwarz, M. Bolte, Tetrahedron Lett.
1998, 39, 8969
[8] M. Mühlstädt, J. Graefe, Chem. Ber. 1967, 100, 223; P. Cram-
er, T. T. Tidwell, J. Org. Chem. 1981, 46, 2683; for the anal-
ogous reaction with alkynes, see: J. F. Arens, Adv. Org. Chem.
2-(2-Methoxybenzyl)furan (18)
150 mg (797 µmol) 3b in 1.99 g MeCN and 21.7 mg
(128 µmol, 16 mol%) AgNO3 in 97 mg MeCN were reacted
according to the general procedure c). Purification by col-
umn chromatography (H/EE, 7:1) provided 132 mg (88%) of
18. Rf (H/EE, 2:1) 0.60. – IR (film, NaCl): ν/cm–1 = 3115,
3026, 3003, 2956, 2938, 2907, 2836, 1601, 1590, 1502,
1494, 1464, 1438, 1289, 1246, 1176, 1106, 1050, 1030,
1009, 935, 834, 805, 753, 730. – 1H NMR (CDCl3, 250 MHz):
50
J. Prakt. Chem. 2000, 342, No. 1

Mercury(II)-Catalyzed Synthesis of Spiro[4.5]decatrienediones
___________________________________________________________________________ FULL PAPER
1960, 2, 163
[12] Y. Nagao, I.-Y. Jeong, W. S. Lee, S. Sano, J. Chem. Soc.,
Chem. Commun. 1996, 19
[13] a) L. Brandsma, Preparative Acetylenic Chemistry, Elsevi-
er, Amsterdam 1988, 35; b) H. Hopf, I. Böhm, J. Kleinschroth,
Org. Synth. 1981, 60, 41
[14] L. S. Hegedus in Organometallics in Synthesis (Ed. M.
Schlosser), John Wiley, Chichester 1994, p. 448
[15] G. Sheldrick, Universität Göttingen 1996
[9] Hg(II)-catalyzed H2O addition to allenes: a) M. Murray in
Methoden der Organischen Chemie (Houben-Weyl); Thieme
Verlag: Stuttgart 1977; Vol. V/2a, pp 1065; b) H. Stetter in
Methoden der Organischen Chemie (Houben-Weyl); Thieme
Verlag: Stuttgart 1973; Vol. VII/2a, pp 842. Hg(II)-catalyzed
H2O addition to alkynes: c) V. Jäger, H. G. Viehe in Meth-
oden der Organischen Chemie (Houben-Weyl); Thieme Ver-
lag: Stuttgart 1977; Vol. VII/2a, pp 726; J. S. Reichert, J. H.
Bailey, J. A. Nieuwland, J. Am. Chem. Soc. 1923, 45, 1552;
R. O. C. Norman, W. J. E. Parr, C. B. Thomas, J. Chem.
Soc., Perkin Trans. I 1976, 1983
[10] Crystallographic data (excluding structure factors) for 8 have
been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-132399.
Copies of the data can be obtained free of charge on applica-
tion to The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: Int. code + (1223)36-033; e-mail: deposit@
chemcrys.cam.ac.uk).
[11] a) A. Bax, M. F. Summers, J. Am. Chem. Soc. 1986, 108,
2093; b) H. Kessler, M. Gehrke, C. Griesinger, Angew. Chem.
1988, 100, 507; Angew. Chem. Int. Ed. Engl. 1988, 27, 490
Address for correspondence:
Dr. A. Stephen K. Hashmi
Johann Wolfgang Goethe-Universität Frankfurt
Institut für Organische Chemie
Marie-Curie-Str. 11
D-60439 Frankfurt am Main
Fax: Internat. code (0) 69 798 29464
e-mail: hashmi@chemie.uni-frankfurt.de
J. Prakt. Chem. 2000, 342, No. 1
51