Synthesis of Fischer-Type (Alkoxy)carbene Complexes Using Diphenylsulfonium Salts with Functionalized Alkyl Groups

Article abstract of DOI:10.1021/jo991549n

A new and general method for preparing Fischer-type alkoxycarbene complexes 1 is reported. This method involves the alkylation of acylate complexes 7 with alkyldiphenylsulfonium salts 10 with a variety of functionalized alkyl groups. The alkylation of tetramethylammonium pentacarbonyl-(1-oxyalkylidene)chromate(0) 7a-c, tetramethylammonium pentacarbonyl(1-oxymethylidene)molybdate(0) 7d, and pentacarbonyl(1-oxymethylidene)tungstate(0) 7e with alkyldiphenylsulfonium salts 10 proceeded smoothly under mild conditions to give the corresponding alkoxycarbene complexes 12-39 in good to high yields. Competitive alkylation of 7a with methyl-11 and isopropyldiphenylsulfonium tetrafluoroborate 40 shows a higher reactivity of the isopropyl group, suggesting the participation of an S-O sulfurane intermediate 41.

Full text of DOI:10.1021/jo991549n

4796
J . Org. Chem. 2000, 65, 4796-4803
Syn th esis of F isch er -Typ e (Alk oxy)ca r ben e Com p lexes Usin g
Dip h en ylsu lfon iu m Sa lts w ith F u n ction a lized Alk yl Gr ou p s
Haruo Matsuyama,* Takako Nakamura, and Masahiko Iyoda*
Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University,
Hachioji, Tokyo 192-0397, J apan
h-matsu@comp.metro-u.ac.jp
Received October 5, 1999
A new and general method for preparing Fischer-type alkoxycarbene complexes 1 is reported. This
method involves the alkylation of acylate complexes 7 with alkyldiphenylsulfonium salts 10 with
a variety of functionalized alkyl groups. The alkylation of tetramethylammonium pentacarbonyl-
(1-oxyalkylidene)chromate(0) 7a -c, tetramethylammonium pentacarbonyl(1-oxymethylidene)mo-
lybdate(0) 7d , and pentacarbonyl(1-oxymethylidene)tungstate(0) 7e with alkyldiphenylsulfonium
salts 10 proceeded smoothly under mild conditions to give the corresponding alkoxycarbene
complexes 12-39 in good to high yields. Competitive alkylation of 7a with methyl-11 and
isopropyldiphenylsulfonium tetrafluoroborate 40 shows a higher reactivity of the isopropyl group,
suggesting the participation of an S-O sulfurane intermediate 41.
Sch em e 1
In tr od u ction
Metal-stabilized carbene complexes, in particular Fis-
cher-type (alkoxy)carbene complexes 1, have attracted
considerable attention as synthetically useful reagents
since the first studies by Fischer et al.1-3 Typical reac-
tions of (alkoxy)carbene complex 1 are shown in Scheme
1. Complex 1 can be regarded as an ester equivalent, and
the oxidation of 1 with molecular oxygen, pyridine
N-oxide, ceric ammonium nitrate (CAN), etc., gives the
corresponding ester in high yield.4 Metal-coordinated
(1) (a) Fisher, E. O.; A. Maasbo¨l, A. Angew. Chem., Int. Ed. Engl.
1964, 3, 580. (b) Fisher, E. O. Angew. Chem. 1974, 86, 651.
(2) For reviews, see: (a) Casey, C. P. In Transition Metal Organo-
metallics in Organic Synthesis; Alper, H., Ed.; Academic Press: New
York, 1976; Vol. 1, p 228. (b) Do¨tz, K. H.; Fischer, H.; Hofmann, P.;
Kreissl, F. R.; Schubert, U.; Weiâ, K. Transition Metal Carbene
Complexes; Seyferth, D., Ed.; Verlag Chemie: Weinheim, 1983. (c) Do¨tz,
K. H. Angew. Chem., Int. Ed. Engl. 1984, 23, 587. (d) Do¨tz, K. H. In
Organometallics in Organic Synthesis; de Meijere, A.; Dieck, H., Eds.;
Springer: Berlin, 1988; p 85. (e) Schore, N. E. Chem. Rev. 1988, 88,
1081. (f) Aumann, R. Angew. Chem., Int. Ed. Engl. 1988, 27, 1456. (g)
Wulff, W. D. In Advances in Metal-Organic Chemistry; Liebeskind, L.
S., Ed.; J AI Press: London, 1989; Vol. 1, p 209. (h) Brookhart, M.;
Liu, Y. In Advances in Metal Carbene Chemistry; Kluwer Academic
publ: Boston, 1989; p.251. (i) Wulff, W. D. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford,
1991; Vol. 5, p 1065. (j) Schmalz, H.-G. Angew. Chem., Int. Ed. Engl.
1994, 33, 303. (k) Hegedus, L. S. Acc. Chem. Res. 1995, 28, 299. (l)
Schobert, R. Chem. Ber. 1996, 129, 595. (m) Do¨tz, K. H.; Ehlenz, R.
Chem. Eur. J . 1997, 3, 1751.
carbene 1 can also be used as a building block for the
synthesis of cyclopropane derivatives.5 Photolytic reaction
of 1 generates a ketene species which reacts with olefins
to afford cyclobutanones as [2 + 2] cycloaddition prod-
ucts.6 The addition of alkynes to complex 1, which
contains an aryl carbene ligand, leads to naphthol
(3) For recent examples, see: (a) Schmeck, C.; Hegedus, L. S. J . Am.
Chem. Soc. 1994, 116, 9927. (b) Duetsch, M.; Vidoni, S.; Stein, F.;
Funke, F.; Noltemeyer, M.; de Meijere, A. J . Chem. Soc., Chem.
Commun. 1994, 1679. (c) Iyoda, M.; Zhao, L.; Matsuyama, H. Tetra-
hedron Lett. 1995, 36, 3699. (d) Watanuki, S.; Mori, M. Organometallics
1995, 14, 5054. (e) Rudler, H.; Audouin, M.; Parlier, A.; Martin-Vaca,
B.; Goumont, R.; Durand-Re´ville, T.; Vaissermann, J . J . Am. Chem.
Soc. 1996, 118, 12045. (f) Hoffmann, M.; Buchert, M.; Reissig, H.-U.
Angew. Chem., Int. Ed. Engl. 1997, 36, 283. (g) Roth, G.; Reindl, D.;
Gockel, M.; Troll, C.; Fischer, H. Organometallics 1998, 17, 1393. (h)
Sierra, M. A.; Manchen˜o, M. J .; Sa´ez, E.; Amo, J . C. J . Am. Chem.
Soc. 1998, 120, 6812. (i) Pfeiffer, J .; Nieger, M.; Do¨tz, K. H. Chem.
Eur. J . 1998, 4, 1843. (j) Wang, H.; Wulff, W. D. J . Am. Chem. Soc.
1998, 120, 10573. (k) Waters, M. L.; Bos, M. E.; Wulff, W. D. J . Am.
Chem. Soc. 1999, 121, 6403. (l) Bernasconi, C. F.; Kittredge, K. W.;
Flores, F. X. J . Am. Chem. Soc. 1999, 121, 6630. (m) Fischer, H.;
Hofmann, P. Organometallics 1999, 18, 2590. (n) Rudler, H.: Parlier,
A.; Martin-Vaca, B.; Garrier, E.; Vaissermann, J . J . Chem. Soc., Chem.
Commun. 1999, 1439.
(4) (a) Silverman, R. B.; Ologson, R. A. J . Chem. Soc., Chem.
Commun. 1968, 1313. (b) Fischer, E. O.; Riedmu¨ller, S. Chem. Ber.
1974, 107, 915. (c) Casey, C. P.; Brunsvold, W. R. J . Organomet. Chem.
1975, 102, 175. (d) Barluenga, J .; Trabanco, A. A.; Flo´rez, J .; Garc´ıa-
Granda, S.; Mart´ın, E. J . Am. Chem. Soc. 1996, 118, 13099.
(5) (a) Brookhart, M.; Studabaker, W. B. Chem. Ber. 1987, 87, 411.
(b) Fischer, E. O.; Do¨tz, K. H. Chem. Ber. 1972, 105, 3966. (c) Herndon,
J . W.; Turner, S. U. J . Org. Chem. 1991, 56, 286. (d) Harvey, D. F.;
Lund, K. P. J . Am. Chem. Soc. 1991, 113, 8916. (e) Buchert, M.;
Hoffmann, M.; Reiâig, H.-U. Chem. Ber. 1995, 128, 605. (f) Hoye, T.
R.; Vyvyan, J . R. J . Org. Chem. 1995, 60, 4184. (f) Barluenga, J .;
Bernad, P. L., J r.; Concello´n, J . M.; Pin˜era-Nicola´s, A.; Grac´ıa-Granda,
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S. J . Org. Chem. 1991, 56, 2209. (d) Reed, A. D.; Hegedus, L. S. J .
Org. Chem. 1995, 60, 3787.
10.1021/jo991549n CCC: $19.00 © 2000 American Chemical Society
Published on Web 07/07/2000

Synthesis of Fischer-Type (Alkoxy)carbene Complexes
J . Org. Chem., Vol. 65, No. 16, 2000 4797
Sch em e 2
Sch em e 4
Sch em e 3
Sch em e 5
derivatives.7 Furthermore, these reactions can be used
for the synthesis of natural products such as vitamins,8
steroids,9 and antibiotics.10
plexes of chromium, molybdenum, and tungsten are still
limited.14,15
The intramolecular reaction of (alkoxy)carbene com-
plexes containing functionalized alkyl or aryl groups is
also useful for preparing key intermediates in organic
synthesis. As shown in Scheme 2, photolysis of (alkenyl-
oxy)(methyl)carbene complex 2 produced the bicyclic
cyclobutanone 3 in good yield,6a whereas thermal in-
tramolecular cyclopropanation of (alkenyl)(phenyl)car-
bene complex 2 gives the bicyclic cyclopropane 4.11
Alkoxycarbene complexes are usually prepared by
alkylating pentacarbonyl(1-oxyalkylidene)chromate(0),
-molybdate(0), or -tungstate(0) with Meerwein oxonium
salt 6.12 However, this method is limited to the prep-
aration of alkoxycarbene complexes containing simple
methoxy and ethoxy groups. The preparation of
Fischer-type carbene complexes containing functionalized
alkyl groups has been reported (Scheme 3).6a,10a,11,13 How-
ever, the methods used to prepare alkoxy carbene com-
In contrast to oxonium salts 6, sulfonium salts with a
variety of functionalized alkyl groups are readily avail-
able16 and react with nucleophiles such as phenolate and
carboxylate ions to produce the corresponding ethers and
esters. As shown in Scheme 4, diphenylsulfonium salts
9, which possess a good leaving group, Ph2S, react with
nucleophiles such as phenol under mild conditions to give
alkylated products in good yields.17 Keeping these results
in mind, we developed a new and general method for
preparing Fischer-type alkoxycarbene complexes 1 using
the alkylation of tetramethylammonium acylate com-
plexes 7 with alkyldiphenylsulfonium salt 10 (Scheme
4). We previously reported our preliminary findings in
the alkylation of tetramethylammonium acylate com-
plexes using sulfonium salt.18 In this paper, we describe
in detail the successful synthesis of alkoxycarbene com-
plexes using a variety of alkyldiarylsulfonium salts,
together with some related reactions.
(7) (a) Do¨tz, K. H. Pure Appl. Chem. 1983, 55, 1689. (b) Gross, M.
F.; Finn, M. G. J . Am. Chem. Soc. 1994, 116, 10921. (c) Aumann, R.;
J asper, B.; Fro¨hlich, R. Organometallics 1995, 14, 231. (d) Choi, Y.
H.; Rhee, K. S.; Kim, K. S.; Shin, G. C.; Shin, S. C. Tetrahedron Lett.
1995, 36, 1871. (e) Gleichmann, M. M.; Do¨tz, K. H.; Hess, B. A. J . Am.
Chem. Soc. 1996, 118, 10551. (f) Hohmann, F.; Siemoneit, S.; Nieger,
M.; Kotila, S.; Do¨tz, K. H. Chem. Eur. J . 1997, 3, 853.
(8) (a) Do¨tz, K. H.; Pruskil, I. J . Organomet. Chem. 1981, 209, C4.
(b) Do¨tz, K. H.; Pruskil, I. Chem. Ber. 1982, 115, 1278.
(9) (a) Bao, J .; Wulff, W. D.; Dragisich, V.; Wenglowsky, S.; Ball, R.
G. J . Am. Chem. Soc. 1994, 116, 7616. (b) Aumann, R.; Meyer, A. G.;
Fro¨hlich, R. J . Am. Chem. Soc. 1996, 118, 10853.
(10) (a) Semmelhack, M. F.; Bozell, J . J .; Sato, T.; Wulff, W.; Spiess,
E.; Zask, A. J . Am. Chem. Soc. 1982, 104, 5850. (b) Borel, C.; Hegedus,
L. S.; Krebs, J .; Satoh, Y. J . Am. Chem. Soc. 1987, 109, 1101. (c)
Semmelhack, M. F.; Ho, S.; Cohen, D.; Steigerwald, M.; Lee, M. C.;
Lee, G.; Gilbert, A. M.; Wulff, W. D.; Ball, R. G. J . Am. Chem. Soc.
1994, 116, 7108. (d) Kender, T. E.; Miller, M. W.; Hegedus, L. S. J .
Org. Chem. 1996, 61, 6121. (e) Hsiao, Y.; Hegedus, L. S. J . Org. Chem.
1997, 62, 3586.
(11) So¨derberg, B. C.; Hegedus, L. S. Organometallics 1990, 9, 3113.
(12) (a) Fisher, E. O.; Maasbo¨l, A. Chem. Ber. 1967, 100, 2445. (b)
Aumann, R.; Fischer, E. O. Chem. Ber. 1968, 101, 954. (c) Fischer, E.
O.; Plabst, D. Chem. Ber. 1974, 107, 3326.
Resu lts a n d Discu ssion
The tetramethylammonium acylate complex 7 was
prepared by treating M(CO)6 (M ) Cr, Mo, W) with
organolithium reagent and then adding tetramethylam-
monium bromide (Me4N+Br-) as described in the litera-
ture12a (Scheme 5). Alkyldiphenylsulfonium tetrafluo-
roborates 10 were obtained in yields of 53-83% by
(14) (a) So¨derberg, B. C.; Turbeville, M. J . Organometallics 1991,
10, 3951. (b) So¨derberg, B. C.; Liu, J .; Ball, T. W.; Turbeville, M. J . J .
Org. Chem. 1997, 62, 5945.
(15) (a) Harvey, D. F.; Brown, M. F. Tetrahedron Lett. 1990, 31,
2529. (b) Harvey, D. F.; Brown, M. F. Tetrahedron Lett. 1991, 32, 5223.
(16) Lowe, P. A. The Chemistry of the Sulfonium Group; Stirling,
C. J . M.; Patai, S., Eds.; J ohn Wiley & Sons: New York, 1981; pp 267-
312.
(17) Badet, B.; J ulia, M.; Ramirez-Munoz, M. Synthesis 1980, 926.
(18) Nakamura, T.; Matsuyama, H.; Iyoda, M. Chem. Lett. 1994,
1537.
(13) Wulff, W. D.; McCallum, J . S.; Kunng, F.-A. J . Am. Chem. Soc.
1988, 110, 7419.

4798 J . Org. Chem., Vol. 65, No. 16, 2000
Matsuyama et al.
Ta ble 1. P r ep a r a tion of Ca r ben e Com p lex 12a fr om
Am m on iu m Sa lt 7a a n d Su lfon iu m Sa lt 11a
reagent makes it possible to obtain the novel biscarbene
complex 20.
The chromium (alkoxy)carbene complexes 12-23 were
1
identified by examining H NMR, 13C NMR, IR, and MS
spectral data. The 13C NMR spectra of complexes 12-23
are particularly informative and show signals due to
carbene carbons in a low-field position from 350 to 370
ppm. Most of the chromium complexes were stable below
-20 °C and can be stored in a freezer. However, com-
plexes 15a -c containing an ether group, and 17c, 19a ,b,
and 23a containing an ester group, slowly decomposed
in a freezer. Complexes 19a -c decomposed when they
were purified by column chromatography on silica gel.
Molybdenum carbene complexes are usually less stable
in a freezer than the corresponding chromium and
tungsten complexes. There are few studies on the prepa-
ration of molybdenum carbene complexes and their
application to organic synthesis.5d,15,20
Alkylation of tetramethylammonium molybdenum (acy-
late) complex 7d with sulfonium salts 10 was attempted
in a manner similar to that for preparing chromium com-
plexes (Table 3). This method gave molybdenum (alkoxy)-
carbene complexes 24-31 containing various function-
alized alkoxy groups in moderate to good yields (Table
3). Although the yields of molybdenum complexes 24-
31 are less than those of chromium compounds 12-23,
molybdenum (alkoxy)carbene complexes with various
functional groups could be obtained using this method.
Molybdenum (alkoxy)carbene complexes 24-31 also
exhibit characteristic carbon signals in a low-field posi-
tion from 340 to 360 ppm. Complexes 29 and 31 were
stable in nonpolar solvents, but decomposed gradually
at room temperature in the absence of solvent. Complexes
26-28 slowly decomposed in a freezer.
Similarly, tungsten complexes 32-39 were successfully
prepared from acylate complex 7e and diphenylsulfonium
salts 10 (Table 4). Most of the tungsten (alkoxy)carbene
complexes 32-39 were stable, like the corresponding
chromium complexes. Compound 38 with a hydroxy
group was very unstable in the absence of solvent.
Complexes 36 and 39 slowly decomposed in a freezer.
For the alkylation of acylate ion from 7 with alkyl-
diphenylsulfonium salts 10, there are at least three
posssible routes: (1) via an SN2 reaction, (2) via an S-O
sulfurane intermediate, and (3) via single-electron trans-
fer (Figure 1).
reacting a large excess of Ph2S with alkyl halides in the
presence of AgBF4 (Scheme 5).19
Reaction of tetramethylammonium pentacarbonyl(1-
oxymethyliden)chromate(0) (7a ) with methyldiphenyl-
sulfonium tetrafluoroborate (11) in CH2Cl2 was carried
out under an argon atmosphere at room temperature,
and the results are summarized in Table 1. Alkylation
of 7a with 11 readily gave pentacarbonyl[(methoxy)-
methylcarbene]chromium (12a ) in high yield (run 1). The
(alkoxy)carbene complexes obtained are unstable under
acidic conditions. We considered that it may be necessary
to control the pH of the reaction solution because the
sulfonium salt 11 is acidic, like the oxonium salt 6, and
the resulting carbene complex 12a may decompose under
these reaction conditions. Therefore, alkylations of 7a
with 11 were attempted in the presence of a base (runs
of 2-4). However, as seen in Table 1, in each case the
use of base decreased the yield of carbene complex 12a .
This result implies that sulfonium salts are mild and
useful alkylating reagents for preparing (alkoxy)carbene
complex 12a . Thus, subsequent alkylation with sulfonium
salts was performed under the conditions used in run 1.
Alkylation of tetramethylammonium chromium (acy-
late) complexes 7a -c was investigated using diphenyl-
sulfonium salt 10 with various alkyl groups. As shown
in Table 2, chromium (alkoxy)carbene complexes 12-23
were obtained in moderate to high yields. For example,
the total yields of carbene complexes by two-steps (yields
for the preparation of sulfonium salts 10 and then
alkylation of 7 with 10) are as follows: 12a , 69%; 14, 68%;
and 22a , 69%. The present method using sulfonium salts
has the following advantages: (1) While a longer reaction
time (12 h) is needed than that in the known method12
using oxonium salts 6, a variety of functionalized alkyl
groups with a secondary carbon can be effectively intro-
duced. (2) This reaction can be carried out at room
temperature, although the known method using acyloxy
intermediate 8 gives enol esters at room temperature
when R-hydrogens next to the carbene carbon atom are
present.14 (3) The present method is particularly useful
for preparing carbene complexes 18 with a hydroxyl
group, since the known method via acyloxy intermediate
8 gives a mixture of 18 and a biscarbene complex like
20. (4) The use of diphenylsulfonium salt as an alkylating
The alkylation of carboxylate anions with alkylsulfo-
nium salts has been suggested to proceed via sulfurane
intermediates on the basis of the relative reactivities of
the alkyl groups in sulfonium salts.21,22 To explore the
mechanism of the alkylation in the present study, the
competitive alkylation of 7a (1 mmol) with methyldiphen-
ylsulfonium tetrafluoroborate 11 (5 mmol) and isopro-
pyldiphenylsulfonium tetrafluoroborate 40 (5 mmol) was
carried out (Scheme 6). From this reaction, the relative
(20) (a) Hegedus, L. S.; Schultze, L. M.; Montgomery, J . Organo-
metallics 1989, 8, 2189. (b) Brandvold, T. A.; Wulff, W. D. J . Am. Chem.
Soc. 1990, 112, 1645.
(21) (a) Matsuyama, H.; Nakamura, T.; Kamigata, N. J . Org. Chem.
1989, 54, 5218. (b) Umemura, K.; Matsuyama, H.; Watanabe, N.;
Kobayashi, M.; Kamigata, N. J . Org. Chem. 1989, 54, 2374.
(22) For the sulfurane intermediates: (a) Martin, J . C.; Porezzi, E.
F. J . Am. Chem. Soc. 1974, 96, 3155. (b) Kapovits, I.; Kalman, A. J .
Chem. Soc., Chem. Commun. 1971, 649. (c) Trost, B. M.; Schinsk, L.;
Chen, F.; Manats, I. B. J . Am. Chem. Soc. 1971, 93, 676. (d) Martin,
J . C.; Balthazer, T. M. J . Am. Chem. Soc. 1977, 99, 152. (e) Takeuchi,
H.; Minato, H.; Kobayashi, M.; Yoshida, M.; Matsuyama, H.; Kamigata,
N. Phosphorus, Sulfur,Silicon 1990, 47, 165.
(19) Nakamura, T.; Matsuyama, H.; Kamigata, N.; Iyoda, M. J . Org.
Chem. 1992, 57, 3783.

Synthesis of Fischer-Type (Alkoxy)carbene Complexes
J . Org. Chem., Vol. 65, No. 16, 2000 4799
Ta ble 2. P r ep a r a tion of Ch r om iu m (Alk oxy)ca r ben e Com p lexes
Ta ble 4. P r ep a r a tion of Tu n gsten (Alk oxy)ca r ben e
Com p lexes
F igu r e 1. Possible alkylation processes of metal acylate ion.
Ta ble 3. P r ep a r a tion of Molybd en u m (Alk oxy)ca r ben e
Com p lexes
Sch em e 6
reactivity of the methyl and isopropyl groups was found
to be 1:9, based on the yields of 12a and 13a . This result
shows that the secondary alkyl group is more reactive
than the primary alkyl group. A similar reactivity (Me:
Bu-s ) 1:2) for the alkylation of carboxylate anions has
been reported in the literature.21a,23 The relative reac-
tivities of the methyl, ethyl, and isopropyl groups in alkyl
halides toward several nucleophiles via an SN2 reaction
have been reported to be 1.0, 0.05, and 0.001, respec-
tively.24 Accordingly, the reaction mechanism of the
present alkylation is not a simple SN2-type reaction, and
(23) Umemura, K.; Matsuyama, H.; Kamigata, N. Bull. Chem. Soc.
J pn. 1990, 63, 2593.

4800 J . Org. Chem., Vol. 65, No. 16, 2000
Matsuyama et al.
Sch em e 7
transfer can also explain the relative reactivities of alkyl
groups in sulfonium salts.
In conclusion, alkylation with diphenylsulfonium salts
was found to be a simple and general method for syn-
thesizing Fischer-type chromium, molybdenum, and tung-
sten (alkoxy)carbene complexes with various functional-
ized alkoxy groups. It may be possible to develop new
intra- and intermolecular reactions of the resulting
carbene complexes using the functional groups in these
complexes.
Exp er im en ta l Section
1H NMR spectra were recorded at 400 MHz and 13C NMR
spectra were recorded at 100 MHz. Mass and high-resolution
mass spectra were determined at an inoizing voltage of 70 eV.
Column chromatography was performed with Daisogel 1001w
containing 10% water. Gel permeation chromatograpy was
performed with two J AIGEL-1H columns (20 mm × 600 mm)
with chloroform as eluent. Dry solvents were purified as
follows. Dichloromethane was distilled over CaH2; ether was
distilled from sodium benzophenone ketyl immediately before
use. Tetramethylammonium pentacarbonyl(1-oxymethylidene)-
chromate(0) (7a ), tetramethylammonium pentacarbonyl(1-
oxybutylidene)chromate(0) (7b), tetramethylammonium pen-
tacarbonyl(1-oxyphenylidene)chromate(0) (7c), tetramethyl-
ammonium pentacarbonyl(1-oxymethylidene)molybdate(0) (7d),
and tetramethylammonium pentacarbonyl(1-oxymethylidene)-
tungstate(0) (7e) were prepared according to the literature.12,13
Alkyl iodides were prepared from commercially available alkyl
bromides and KI (3 equiv) in refluxing acetone.
the reaction may proceed via an S-O sulfurane inter-
mediate 41. One possible explanation for the ratio of
isopropylated and methylated products posutulates a
transition state in which the S-C bond is broken before
alkylation of acylate ion from 7.
Other competitive alkylation experiments suggested
another possible mechanism (Scheme 7). In the methy-
lation of 7a (0.5 mmol) with methyldiphenylsulfonium
tetrafluoroborate 11 (1.5 mmol) and methyl(4,4′-dini-
trodiphenyl)sulfonium tetrafluoroborate 42 (1.5 mmol) [or
methyl(4,4′-dimethoxydiphenyl)sulfonium tetrafluorobo-
rate 43 (1.5 mmol)], the relative reactivities of sulfonium
salts were estimated, again based on the yields of the
resulting diaryl sulfides, since the yields of methylation
are almost equal to those of the sulfides. The results are
as follows: 4-NO2C6H4:C6H5:4-MeOC6H4 ) 6.9:1.00:0.38
(M ) Cr) and 4-NO2C6H4:C6H5:4-MeOC6H4 ) 6.3:1.00:
0.26 (M ) W). These results show that sulfonium salts
with an electron-withdrawing substituent (4-NO2C6H4)
react much faster than those with an electron-donating
substituent (4-MeOC6H4). Taking into account the reac-
tivities of 11, 42, and 43 for acylate complexes 7, a
possible pathway for the formation of methoxycarbene
complex may include an electron-transfer reaction.25,26
Thus, the reaction of 7 with sulfonium salts 11, 42, and
43 forms the radical pair 44 via electron transfer,
followed by bond formation to produce the S-O sulfurane
intermediate 41.27,28 Electron transfer from 7 to 42 is
expected to be faster than that from 7 to 11, whereas
electron transfer from 7 to 43 is slow. Although the rho
(F) value of the Hammett relationship might suggest
nucleophilic attack of acylate ion to sulfonium salts (SN2
mechanism), the SN2 reaction can be ruled out from the
results shown in Scheme 6. Since electron transfer
between 7 and 40 might take place to form 41 faster than
that between 7 and 11 due to an isopropyl group, electron
Tet r a m et h yla m m on iu m p en t a ca r b on yl(1-oxym et h -
ylid en e) m olybd a te(0) (7d ): 50% yield; yellow crystals; mp
120.0 °C (dec); 1H NMR (CD2Cl2) δ 2.31 (s, 3H), 3.34 (s, 12H);
13C NMR (CD2Cl2) δ 53.9, 54.5, 199.5, 210.0, 217.3, 296.6; IR
(KBr) 2050, 1888 cm-1
.
Tet r a m et h yla m m on iu m p en t a ca r b on yl(1-oxyb u t yl-
id en e) tu n gsta te(0) (7e): 64% yield; yellow needles; mp
131.8 °C (dec); 1H NMR (CD2Cl2) δ 2.38 (s, 3H), 3.35 (s, 12H);
13C NMR (CD2Cl2) δ 54.5, 56.3, 202.2, 207.2, 282.3; IR (KBr)
2052, 1878, 1071 cm-1
.
Dip h en ylsu lfon iu m Tetr a flu or obor a te 10.16,19 To silver
tetrafluoroborate AgBF4 (2.93 g, 15 mmol), under ice bath
cooling, was added dropwise a mixture of diphenyl sulfide (27.9
g, 0.15 mol) and alkyl halides (18 mmol). The mixture was
covered with aluminum foil and stirred at room temperature
for 3 days. Then the mixture was passed through a short
column of silica gel and eluted with acetone. The eluate was
concentrated in vacuo. After being washed with ether, the
residue was dried under reduced pressure or was recrystallized
from CH2Cl2-ether.
Meth yldiph en ylsu lfon iu m tetr aflu or obor ate: 82% yield;
mp 51.0-53.0 °C; 1H NMR (CD3OD) δ 3.69 (s, 3H), 7.62-7.73
(m, 6H), 7.94-7.96 (m, 4H).
Isop r op yld ip h en ylsu lfon iu m tetr a flu or obor a te: 53%
yield; mp 126.0-127.0 °C; 1H NMR (CD3OD) δ 1.50 (d, J )
6.35 Hz, 6H), 4.91 (m, 1H), 7.72-7.84 (m, 6H), 8.11-8.13 (m,
4H); 13C NMR (CD3OD) δ 19.3, 52.4, 125.9, 133.0, 133.3, 136.7.
1-Octyldiph en ylsu lfon iu m tetr aflu or obor ate: 75% yield;
1
oil; H NMR (CD3OD) δ 0.85 (t, J ) 6.84 Hz, 3H), 1.23-1.30
(m, 8H), 1.55 (quintet, J ) 7.33 Hz, 2H), 1.74 (quintet, J )
7.57 Hz, 2H), 4.20 (t, J ) 7.57 Hz, 2H), 7.69-7.80 (m, 6H),
8.04 (d, J ) 7.33 Hz, 4H); 13C NMR (CD3OD) δ 15.1, 24.2, 26.2,
29.6, 30.5, 33.2, 45.8, 127.0, 132.2, 133.1, 136.2.
(24) Okamoto, K.; Nitta, I.; Imoto, T.; Singu, H. Bull. Chem. Soc.
J pn. 1967, 40, 1905.
(25) Andrieux, C. P.; Robert, M.; Saeva, F. D.; Saveant, J .-M. J . Am.
Chem. Soc. 1994, 116, 7864.
(26) Saeva, F. D.; Brestin, D. T.; Martic, P. A. J . Am. Chem. Soc.
1989, 111, 1328.
(27) Fountain, K. R.; Kamlesh, D. P. J . Org. Chem. 1997, 62, 4795.
(28) Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chro-
mium(0) complexes are oxidized with manganese(III) 2-pyridinecar-
boxylate to generate carbon-centered radicals which react with various
olefins giving the intermolecular addition products. See, Narasaka, K.;
Sakurai, H. Chem. Lett. 1993, 1269.
(2-E t h oxyet h yl)d ip h en ylsu lfon iu m
t et r a flu or ob o-
1
r a te: 79% yield; mp 68.3-69.6 °C; H NMR (CD3OD) δ 1.05
(t, J ) 7.08 Hz, 3H), 3.41 (t, J ) 7.00 Hz, 2H), 3.83 (t, J )
5.37 Hz, 2H), 4.46 (t, J ) 5.37 Hz, 2H), 7.70 (t, J ) 7.82 Hz,
4H), 7.77 (t, J ) 6.84 Hz, 2H), 8.02 (d, J ) 8.30 Hz, 4H); 13C
NMR (CD3OD) δ 15.7, 47.2, 65.1, 68.3, 126.8, 132.2, 132.9,
136.0.
(5-Meth oxycar bon ylpen tyl)diph en ylsu lfon iu m tetr aflu -
1
or obor a te: 80% yield; mp 77.8-78.4 °C; H NMR (CD3OD)

Synthesis of Fischer-Type (Alkoxy)carbene Complexes
J . Org. Chem., Vol. 65, No. 16, 2000 4801
δ 1.59-1.62 (m, 4H), 1.73-1.77 (m, 2H), 2.30 (t, J ) 6.84 Hz,
2H), 3.62 (s, 3H), 4.21 (t, J ) 7.57 Hz, 2H), 7.70-7.81 (m, 6H),
8.01-8.04 (m, 4H); 13C NMR (CD3OD) δ 24.7, 24.9, 27.9, 44.7,
51.9, 125.8, 131.3, 132.2, 135.4, 175.0. Anal. Calcd for C19H23O2-
SBF4: C, 56.67; H, 5.76. Found: C, 56.24; H, 5.54.
of silica gel and concentrated in vacuo. The product was
separated by gel permeation chromatography with chloroform.
The results are summarized in Table 1.
Run 1: The reaction was carried out under the conditions
described above, and carbene complex 12a (0.21 g, 84% yield)
and diphenyl sulfide (0.19 g, 100% yield) were obtained.
Run 2: The reaction was carried out in the presence of
potassium carbonate (0.14 g, 1.0 mmol), and carbene complex
12a (0.18 g, 73% yield) and diphenyl sulfide (0.178 g, 95%
yield) were obtained.
Run 3: The reaction was carried out in the presence of
pyridine (0.1 mL, 1.2 mmol). However, carbene complex 12a
was not obtained. (CO)5Cr-pyridine complex12c [15% yield;
yellow needles; mp 96.5-98 °C; MS m/z 415 (M+)] and diphenyl
sulfide (0.152 g, 81% yield) were obtained.
Run 4: The reaction was carried out in the presence of 2,6-
lutidine (0.14 mL, 1.2 mmol). Carbene complex 12a (0.13 g,
52% yield) and diphenyl sulfide (0.19 g, 100% yield) were
obtained.
(3-Hyd r oxyp r op yl)d ip h en ylsu lfon iu m tetr a flu or obo-
1
r a te: 73% yield; mp 78.1-79.6 °C; H NMR (CD3OD) δ 1.98
(quintet, J ) 6.35 Hz, 2H), 3.77 (t, J ) 5.86 Hz, 2H), 4.25 (t,
J ) 7.08 Hz, 2H), 4.72 (s, 1H), 7.69-7.80 (m, 6H), 7.99-8.01
(m, 4H); 13C NMR (CD3OD) δ 27.9, 42.7, 59.9, 125.8, 130.9,
132.0, 135.1. Anal. Calcd for C15H17OSBF4: C, 54.24; H, 5.16.
Found: C, 54.12; H, 5.14.
(3-Ch lor op r op yl)d ip h en ylsu lfon iu m t et r a flu or ob o-
1
r a te: 76% yield; mp 107.3-108.5 °C; H NMR (acetone-d6) δ
2.23 (quintet, J ) 6.84 Hz, 2H), 3.76 (t, J ) 6.35 Hz, 2H), 4.33
(t, J ) 7.33 Hz, 2H), 7.71-7.82 (m, 6H), 8.03-8.05 (m, 4H);
13C NMR (acetone-d6) δ 28.8, 42.7, 43.2, 126.0, 131.8, 132.5,
135.8. Anal. Calcd for C15H16ClSBF4: C, 51.38; H, 4.59.
Found: C, 50.97; H, 4.52.
(4-Meth y-3-p en ten yl)d ip h en ylsu lfon iu m tetr a flu or o-
bor a te: 30% yield; colorless oil; H NMR (CD3OD) δ 1.39 (s,
3H), 1.65 (s, 3H), 2.49-2.52 (m, 2H), 4.24 (t, J ) 7.08 Hz, 2H),
5.18 (m, 1H), 7.66-7.76 (m, 6H), 7.99-8.02 (m, 4H); 13C NMR
(CD3OD) δ 24.1, 27.6, 34.8, 45.7, 119.1, 125.8, 130.1, 131.3,
135.3, 136.5.
(4-pen ten yl)diph en ylsu lfon iu m tetr aflu or obor ate: 79%
yield; colorless oil; NMR (CD3OD) δ 1.86 (quintet, J ) 7.45
Hz, 2H), 2.32 (q, J ) 7.00 Hz, 2H), 4.17 (t, J ) 7.81 Hz, 2H),
5.03 (d, J ) 10.3 Hz, 1H), 5.09 (d, J ) 17.1 Hz, 1H), 5.76 (ddt,
J ) 17.1, 10.3, 6.78 Hz, 1H), 7.71 (t, J ) 7.82 Hz, 4H), 7.78 (t,
J ) 7.33 Hz, 2H), 8.03 (d, J ) 8.30 Hz, 4 H); 13C NMR (CD3-
OD) δ 25.2, 33.0, 45.2, 118.1, 126.2, 131.9, 132.9, 136.1, 137.1.
Bistetr a flu or obor a te sa lt of 1,4-bis(d ip h en ylsu lfon io)-
bu ta n e: 83% yield; colorless oil; 1H NMR (CD3OD) δ 2.02 (br
s,4H), 4.22 (br s, 4H), 7.68 (t, J ) 7.82 Hz, 8H), 7.76 (t, J )
7.33 Hz, 4H), 7.97 (d, J ) 7.32 Hz, 8H); 13C NMR (CD3OD) δ
23.7, 43.7, 125.4, 131.2, 132.2, 135.5.
Gen er a l P r oced u r e for P r ep a r a tion of Ch r om iu m
(Alk oxy)ca r ben e Com p lexes 12-23. A mixture of am-
monium acylate complexes 7a -c (3.0 mmol) and diphenylsul-
fonium tetrafluoroborate 10 (3.0 mmol) in CH2Cl2 (15 mL) was
stirred at room temperature for 12 h under Ar. The solvent
was removed under reduced pressure at 0 °C, and the residue
was dissolved into ether. The ether solution was passed
through a short column of silica gel and concentrated in vacuo.
The product was separated by gel permeation chromatography
using chloroform or by column chromatography on silica gel
using a mixed solvent of hexane and ether as eluent. The
results are summarized in Table 2.
1
12a : 84% yield; yellow needles; mp 33.4-34.0 °C [lit.12a mp
34 °C]; 1H NMR (CDCl3) δ 2.94 (s, 3H), 4.70 (s, 3H); 13C NMR
(CDCl3) δ 49.6, 67.3, 216.5, 223.5, 360.5; MS m/z 250 (M+),
233, 222.
12b: 82% yield; orange oil; 1H NMR (CDCl3) δ 0.91 (s, 3H),
1.34 (s, 2H), 1.46 (s, 2H), 3.30 (s, 2H), 4.76 (s, 3H); 13C NMR
(CDCl3) δ 13.9, 22.5, 28.4, 62.9, 67.6, 216.5, 223.2, 363.9; MS
m/z 292 (M+), 279, 264; HRMS cacld for C11H12O6Cr: 292.0039,
found: 291.9992.
(3-Cya n op r op yl)d ip h en ylsu lfon iu m
tetr a flu or obo-
r a te: 80% yield; colorless oil; 1H NMR (CD3OD) δ 2.14
(quintet, J ) 7.45 Hz, 2H), 2.80 (t, J ) 7.33 Hz, 2H), 4.27 (t,
J ) 7.57 Hz, 2H), 7.68-7.80 (m, 6H), 8.01-8.03 (m, 4H); 13C
NMR (CD3OD) δ 16.7, 22.4, 44.1, 120.5, 125.8, 132.0, 133.0,
136.3.
12c: 85% yield; red needles; mp 47.0-48.3 °C [lit.12a mp 46
1
°C]; H NMR (CDCl3) δ 4.65 (s, 3H), 7.28 (s, 3H), 7.38(s, 2H);
13C NMR (CDCl3) δ 67.2, 123.1, 128.3, 130.4, 153.8, 216.3,
224.2, 351.1; MS m/z 312 (M+), 284, 256.
(Meth oxyca r bon ylm eth yl)d ip h en ylsu lfon iu m tetr a flu -
1
or obor a te: 66% yield; mp 94.0-94.8 °C; H NMR (acetone-
13a : 92% yield; yellow needles; mp 54.0-55.1 °C; 1H NMR
(CDCl3) δ 1.55 (d, J ) 5.37 Hz, 6H), 2.90 (s, 3H), 5.82 (s, 1H);
13C NMR (CDCl3) δ 22.5, 50.3, 87.2, 216.6, 223.5, 352.2; MS
m/z 279 (M+ + 1), 251, 223; HRMS calcd for C10H10O6Cr:
277.9882, found: 277.9882.
d6) δ 3.73 (s, 3H), 5.53 (s, 2H), 7.71 (t, J ) 7.57 Hz, 4H), 7.79
(t, J ) 7.57 Hz, 2H), 8.16 (d, J ) 7.81 Hz, 4H); 13C NMR
(acetone-d6) δ 47.7, 54.7, 125.8, 131.6, 132.4, 135.7, 165.0.
P r ep a r a tion of Dia r ylm eth ylsu lfon iu m Tetr a flu or o-
bor a tes 42 a n d 43. To silver tetrafluoroborate (2.14 g, 11
mmol) was added dropwise a mixture of diaryl sulfide (10
mmol) and methyl iodide (8 mL, 129 mmol) under ice-cooling.
The mixture was covered with aluminum foil and stirred at
room temperature for 3 days. The mixture was passed through
a short column of silica gel and eluted with acetone. The eluate
was concentrated in vacuo. After being washed with ether, the
residue was dried under reduced pressure or was recrystallized
from acetone.
13b: 94% yield; yellow needles; mp 37.9-38.3 °C; 1H NMR
(CDCl3) δ 0.91 (s, 3H), 1.54 (br s, 10H), 3.23 (s, 2H), 5.82 (s,
1H); 13C NMR (CDCl3) δ 13.9, 22.4, 28.3, 63.0, 87.1, 216.6,
223.5, 355.3; MS m/z 320 (M+), 292, 264; HRMS calcd for
C
13H16O6Cr: 320.0352, found: 320.0430.
13c: 90% yield; red needles; mp 39.2-39.7 °C; 1H NMR
(CDCl3) δ 1.55 (s, 6H), 5.63 (s, 1H), 7.35 (s, 5H); 13C NMR
(CDCl3) δ 22.6, 85.8, 122.5, 128.2, 129.8, 153.8, 216.3, 224.5,
345.6; MS m/z 340 (M+), 312, 284; HRMS calcd for C15H12O6-
Cr: 340.0040, found: 340.0078.
Meth yl(4,4′-Din itr od ip h en yl)su lfon iu m tetr a flu or obo-
r a te (42): 60% yield; mp 151.6-154.2 °C; 1H NMR (acetone-
d6) δ 4.20 (s, 3H), 8.51(d, J ) 9.00 Hz, 4H), 8.57(d, J ) 9.00
Hz, 4H). Anal. Calcd for C13H11N2O4SBF4: C, 41.29; H, 2.93;
N, 7.40. Found: C, 40.95; H, 2.84; N, 7.30.
Meth yl(4,4′-Dim eth oxyd ip h en yl)su lfon iu m tetr a flu o-
r obor a te (43): 96% yield; mp 99.0-100.0 °C; 1H NMR
(acetone-d6) δ 3.83 (s, 3H), 3.91 (s, 6H), 7.26 (d, J ) 9.15 Hz,
4H), 8.03 (d, J ) 9.15 Hz, 4H). Anal. Calcd for C15H17O2SBF4:
C, 51.75; H, 4.92. Found: C, 51.68; H, 4.76.
P r ep a r a tion of (Alk oxy)ca r ben e Com p lex 12a . A mix-
ture of ammonium acylate complex 7a (0.311 g, 1.0 mmol) and
methyldiphenylsulfonium tetrafluoroborate 10 (0.288 g, 1.0
mmol) in CH2Cl2 (5 mL) was stirred for 12 h at room
temperature under Ar. The solvent was removed under
reduced pressure at 0 °C, and the residue was dissolved into
ether. The ether solution was passed through a short column
1
14: 91% yield; orange oil; H NMR (CDCl3) δ 0.90 (s, 3H),
1.31(s, 10H), 1.50 (s, 2H), 1.98 (s, 2H), 2.93 (s, 3H), 4.93 (s,
2H); 13C NMR (CDCl3) δ 14.1, 22.7, 25.9, 29.2, 29.3, 31.7, 49.9,
82.0, 216.6, 223.5, 357.4; MS m/z 348 (M+), 320, 292; HRMS
calcd for C15H20O6Cr: 348.0665, found: 348.0637.
15a : 68% yield; orange oil; 1H NMR (CDCl3) δ 1.25 (s, 3H),
2.98 (s, 3H), 3.61 (s, 2H), 3.95 (s, 2H), 5.02 (s, 2H); 13C NMR
(CDCl3) δ 15.1, 49.6, 67.2, 68.4, 80.1, 216.5, 223.5, 359.5; MS
m/z 308 (M+), 252, 224; HRMS calcd for C11H12O7Cr: 307.9988,
found: 308.0046.
15b: 71% yield; orange oil; 1H NMR (CDCl3) δ 0.91 (s, 3H),
1.24 (s, 3H), 1.34 (s, 2H), 1.48 (s, 2H), 3.32 (s, 2H), 3.60 (s,
2H), 3.94 (s, 2H), 5.09 (s, 2H); 13C NMR (CDCl3) δ 13.9, 15.1,
22.4, 28.5, 62.9, 67.0, 68.4, 80.6, 216.4, 223.3, 362.4; MS m/z
350 (M+), 294, 266; HRMS calcd for C14H18O7Cr: 350.0457,
found: 350.0417.

4802 J . Org. Chem., Vol. 65, No. 16, 2000
Matsuyama et al.
15c: 66% yield; dark red oil; 1H NMR (CDCl3) δ 1.24 (s,
3H), 3.60 (s, 2H), 3.95 (s, 2H), 4.92 (s, 2H), 7.26-7.39 (m, 5H);
13C NMR (CDCl3) δ 15.1, 67.0, 68.4, 79.8, 122.9, 128.2, 130.1,
153.5, 216.2, 224.4, 350.2; MS m/z 370 (M+), 314, 286; HRMS
calcd for C16H14O7Cr: 370.0145, found: 370.0088.
16a : 84% yield; yellow crystals; mp 40.8-42.0 °C; 1H NMR
(CDCl3) δ 2.37 (s, 2H), 2.64 (s, 2H), 2.99 (s, 3H), 4.96 (s, 2H);
13C NMR (CDCl3) δ 14.4, 25.5, 49.2, 76.0, 118.5, 216.3, 223.4,
360.6; MS m/z 303 (M+), 275, 247; HRMS calcd for C11H9O6-
NCr: 302.9835, found: 302.9753.
NMR (CDCl3) δ 26.4, 79.7, 122.5, 128.3, 130.2, 153.5, 216.1,
224.1, 350.2; MS m/z 650 (M+), 454, 398; HRMS calcd for
C28H18O12Cr2: 649.9609, found: 649.9522.
1
21: 55% yield; orange oil; H NMR (CDCl3) δ 1.74 (s, 6H),
2.68 (s, 2H), 2.94 (s, 3H), 4.89 (s, 2H), 5.21 (s, 1H); 13C NMR
(CDCl3) δ 17.9, 25.8, 28.3, 49.7, 81.2, 118.1, 136.0, 216.6, 223.4,
357.6; MS m/z 317 (M+ - 1), 287, 271: HRMS calcd for
C
13H14O6Cr: 318.0196, found: 318.0145.
22a :6a 87% yield; orange oil; 1H NMR (CDCl3) δ 2.10 (s, 2H),
2.31 (s, 2H), 2.94 (s, 3H), 4.94-5.12 (m, 4H), 5.86 (s, 1H).
22b: 88% yield; orange oil; 1H NMR (CDCl3) δ 0.91(s, 3H),
1.34 (s, 2H), 1.46 (s, 2H), 2.09 (s, 2H), 2.29 (s, 2H), 3.30 (s,
2H), 4.98 (s, 2H), 5.08 (s, 2H), 5.85 (s, 1H); 13C NMR (CDCl3)
δ 13.9, 22.5, 28.5, 28.6, 30.0, 63.0, 81.1, 116.2, 136.7, 216.5,
223.3, 361.0; MS m/z 346 (M+), 290, 262.
16b: 79% yield; orange oil; 1H NMR (CDCl3) δ 0.92 (s, 3H),
1.36 (s, 2H), 1.47 (s, 2H), 2.37 (s, 2H), 2.61 (s, 2H), 3.33 (s,
2H), 5.07 (s, 2H); 13C NMR (CDCl3) δ 13.8, 14.4, 22.4, 25.6,
28.6, 62.9, 78.3, 118.3, 216.2, 223.0 363.9; MS m/z 345 (M+),
317, 289; HRMS calcd for C14H15O6NCr: 345.0304, found:
345.0271.
22c:11 92% yield; orange oil; 1H NMR (CDCl3) δ 2.10 (s, 2H),
2.31 (s, 2H), 4.80 (s, 2H), 5.05-5.13 (m, 2H), 5.82 (s, 1H), 7.22
(s, 2H), 7.39 (s, 3H).
16c: 67% yield; dark red oil; 1H NMR (CDCl3) δ 2.35 (s,
2H), 2.66 (s, 2H), 4.80 (s, 2H), 7.18 (s, 2H), 7.42 (m, 3H); 13C
NMR (CDCl3) δ 14.3, 25.6, 62.7, 118.3, 122.1, 128.4, 130.2,
153.4, 215.9, 224.1, 351.8; MS m/z 365 (M+), 309, 281; HRMS
calcd for C16H11O6NCr: 364.9992, found: 365.0084.
17a : 89% yield; orange oil; 1H NMR (CDCl3) δ 2.45 (s, 2H),
2.97 (s, 3H), 3.77 (s, 2H), 5.03 (s, 2H); 13C NMR (CDCl3) δ 32.0,
40.7, 49.3, 76.1, 126.4, 223.4, 359.5; MS m/z 312 (M+, 35Cl),
283, 255; HRMS calcd for C10H9O6ClCr: 311.9492, found:
311.9425.
23a : 66% yield; orange oil; 1H NMR (CDCl3) δ 1.57 (s, 2H),
1.75 (s, 2H), 2.02 (s, 2H), 2.38 (s, 2H), 2.94 (s, 3H), 3.68 (s,
3H), 4.92 (s, 2H); 13C NMR (CDCl3) δ 24.5, 25.5, 29.1, 33.8,
49.9, 51.6, 81.7, 173.9, 216.6, 223.4, 357.9; MS m/z 364 (M+),
332, 308; HRMS calcd for C14H16O8Cr: 364.0250, found:
364.0205.
23b: 86% yield; orange oil; 1H NMR (CDCl3) δ 0.91 (s, 3H),
1.34 (s, 2H), 1.45 (s, 2H), 1.55 (s, 2H), 1.75 (s, 2H), 2.01 (s,
2H), 2.37 (s, 2H), 3.29 (s, 2H), 3.68 (s, 3H), 4.98 (s, 2H); 13C
NMR (CDCl3) δ 13.9, 22.4, 24.5, 25.5, 28.4, 29.2, 33.8, 51.6,
63.0, 81.6, 173.8, 216.5, 223.3, 360.9; MS m/z 406 (M+), 350,
322.
17b: 83% yield; orange oil; 1H NMR (CDCl3) δ 0.91 (s, 3H),
1.35 (s, 2H), 1.46 (s, 2H), 2.45 (s, 2H), 3.32 (s, 2H), 3.74 (s,
2H), 5.12 (s, 2H); 13C NMR (CDCl3) δ 13.9, 22.5, 28.5, 32.2,
40.7, 62.9, 77.6, 216.3, 223.2, 362.8; MS m/z 354 (M+, 35Cl),
326, 298; HRMS calcd for C13H15O6ClCr: 353.9962, found:
353.9962.
23c: 93% yield; dark red oil; 1H NMR (CDCl3) δ 1.58 (s,
2H), 1.73 (s, 2H), 2.03 (s, 2H), 2.36 (s, 2H), 3.66 (s, 3H), 4.81
(s, 2H), 7.23 (s, 2H), 7.39 (s, 3H); 13C NMR (CDCl3) δ 24.5,
25.5, 29.3, 33.8, 51.6, 80.8, 122.6, 128.2, 130.1, 153.7, 173.8,
216.2, 224.3, 349.4; MS m/z 426 (M+), 370, 342.
17c: 83% yield; dark red oil; 1H NMR (CDCl3) δ 2.42-2.45
(m, 2H), 3.78 (t, J ) 6.10 Hz, 2H), 4.89 (s, 2H), 7.20 (br s, 2H),
7.40-7.41 (m, 3H); 13C NMR (CDCl3) δ 32.1, 40.7, 76.7, 122.2,
128.3, 130.1, 153.6, 216.1, 224.3, 351.0; MS m/z 374 (M+,
35Cl), 346, 290; HRMS calcd for C15H11O6ClCr: 373.9649,
found: 373.9726.
Gen er a l P r oced u r e for P r ep a r a tion of Molybd en u m
(Alk oxy)ca r ben e Com p lexes 24-31. A mixture of am-
monium acylate complexe 7d (3.0 mmol) and diphenylsulfo-
nium tetrafluoroborate 10 (3.0 mmol) in CH2Cl2 (15 mL) was
stirred at room temperature for 12 h under Ar. The results
are summarized in Table 3.
18a : 41% yield; orange oil; 1H NMR (CDCl3) δ 2.24 (s, 2H),
2.96 (s, 3H), 3.68 (s, 1H), 3.89 (s, 2H), 5.01 (s, 2H); 13C NMR
(CDCl3) δ 32.0, 49.7, 58.7, 77.7, 216.5, 223.4, 358.4; MS m/z
295 (M+ + 1), 239, 221; HRMS calcd for C10H10O7Cr: 293.9832,
found: 293.9783.
1
24:12b 85% yield; yellow solids; mp 40.5-41.0 °C; H NMR
(CDCl3) δ 2.90 (s, 3H), 4.68 (s, 3H); 13C NMR (CDCl3) δ 50.1,
69.4, 205.7, 213.3, 352.2; MS m/z 294 (M+), 266, 238.
25: 74% yield; yellow solids; mp 57.8-58.5 °C; 1H NMR
(CDCl3) δ 1.53 (d, J ) 6.34 Hz, 6H), 2.85 (s, 3H), 5.67 (m, 1H);
13C NMR (CDCl3) δ 22.2, 50.5, 89.2, 205.7, 213.5, 343.6; MS
m/z 322 (M+), 294, 266.
18b: 31% yield; orange oil; 1H NMR (CDCl3) δ 0.91 (s, 3H),
1.36 (s, 4H), 2.22 (s, 2H), 3.30 (s, 3H), 3.86 (s, 2H), 5.10 (s,
2H); 13C NMR (CDCl3) δ 13.8, 22.3, 28.3, 32.2, 58.8, 62.8, 78.5,
216.4, 223.2, 361.3; IR (neat) 3354, 2052, 1915 cm-1; MS m/z
336 (M+), 294, 280; HRMS calcd for C13H16O7Cr: 336.0301,
found: 336.0241.
1
26: 66% yield; orange oil; H NMR (CDCl3) δ 0.90 (t, J )
19a : 90% yield; orange oil; 1H NMR (CDCl3) δ 3.06 (s, 3H),
3.86 (s, 3H), 5.59 (s, 2H); 13C NMR (CDCl3) δ 49.3, 52.9, 74.7,
166.8, 215.8, 223.1, 363.4; MS m/z 308 (M+), 280, 252; HRMS
calcd for C10H8O8Cr: 307.9624, found: 307.9583.
6.60 Hz, 3H), 1.30-1.38 (m, 8H), 1.46-1.52 (m, 2H), 1.97
(quintet, J ) 7.08 Hz, 2H), 2.89 (s, 3H), 4.89 (br s, 2H); 13C
NMR (CDCl3) δ 14.1, 22.7, 25.9, 29.2, 29.3, 31.8, 50.2, 205.8,
213.4, 348.9; MS m/z 392 (M+), 336, 308.
19b: 93% yield; orange oil; 1H NMR (CDCl3) δ 0.92 (s, 3H),
1.38 (s, 2H), 1.56 (s, 2H), 3.40 (s, 2H), 3.86 (s, 3H), 5.65 (s,
2H); 13C NMR (CDCl3) δ 13.9, 22.5, 28.8, 52.8, 63.4, 75.4, 166.9,
215.8, 222.9, 367.2; MS m/z 350 (M+), 322, 294; HRMS calcd
for C13H14O8Cr: 350.0094, found: 350.0014.
27: 57% yield; orange oil; H NMR (CDCl3) δ 1.25 (t, J )
1
6.84 Hz, 3H), 2.94 (s, 3H), 3.61 (q, J ) 7.00 Hz, 2H), 3.95 (t, J
) 4.40 Hz, 2H), 5.00 (br s, 2H); 13C NMR (CDCl3) δ 15.1, 50.4,
67.0, 68.3, 82.8, 205.7, 213.3, 350.9; MS m/z 352 (M+), 324,
296.
19c: 57% yield; dark red crystals; mp 38.8-39.3 °C; 1H
NMR (CDCl3) δ 3.82 (s, 3H), 5.41 (s, 2H), 7.29-7.40 (m, 5H);
13C NMR (CDCl3) δ 52.8, 73.9, 122.9, 128.3, 130.5, 152.9, 166.9,
215.7, 224.3, 353.0; MS m/z 370 (M+), 342, 314; HRMS calcd
for C15H10O8Cr: 369.9781, found: 369.9704.
28: 42% yield; orange oil; 1H NMR (CDCl3) δ 2.37 (quintet,
J ) 6.47 Hz, 2H), 2.63 (t, J ) 7.08 Hz, 2H), 2.94 (s, 3H), 4.99
(s, 2H); 13C NMR (CDCl3) δ 14.5, 25.5, 50.4, 80.5, 118.4, 205.5,
213.1, 351.9; MS m/z 347 (M+), 319, 291.
29: 67% yield; orange oil; 1H NMR (CDCl3) δ 2.44 (quintet,
J ) 6.11 Hz, 2H), 2.91 (s, 3H), 3.74 (t, J ) 6.35 Hz, 2H), 5.03
(br s, 2H); 13C NMR (CDCl3) δ 32.0, 40.7, 50.3, 79.8, 205.6,
213.3, 350.9; MS m/z 356 (M+, 35Cl), 328, 300.
20a : 60% yield; yellow needles; mp 77.5-80.4 °C; 1H NMR
(CDCl3) δ 2.26 (s, 4H), 2.98 (s, 6H), 5.01 (s, 4H); 13C NMR
(CDCl3) δ 26.2, 49.8, 80.2, 216.5, 223.3, 359.0; MS m/z 526
(M+), 469, 414; HRMS calcd for C18H14O12Cr2: 525.9296,
found: 525.9358.
30: 67% yield; orange oil; 1H NMR (CDCl3) δ 2.08 (quintet,
J ) 6.84 Hz, 2H), 2.28 (q, J ) 7.16 Hz, 2H), 2.89 (s, 3H), 4.90
(br s, 2H), 5.06 (d, J ) 9.28 Hz, 1H), 5.10 (d, J ) 16.1 Hz, 1H),
5.85 (ddt, J ) 17.1, 10.3, 6.78 Hz, 1H); 13C NMR (CDCl3) δ
28.4, 30.0, 50.2, 83.3, 116.1, 136.7, 205.8, 213.4, 349.4; MS m/z
348 (M+), 292, 264.
20b: 61% yield; yellow needles; mp 67.5-69.0 °C; 1H NMR
(CDCl3) δ 0.92 (s, 6H), 1.36 (s, 4H), 1.48 (s, 4H), 2.23 (s, 4H),
3.32 (s, 4H), 5.08 (s, 4H); 13C NMR (CDCl3) δ 13.9, 22.5, 26.3,
28.6, 63.0, 80.6, 216.5, 223.2, 362.2; MS m/z 610 (M+), 418,
414; HRMS calcd for C24H26O12Cr2: 610.0234, found: 610.0204.
20c: 26% yield; red needles; mp 90.5-92.5 °C; 1H NMR
(CDCl3) δ 2.28 (s, 4H), 4.89 (s, 4H), 7.21-7.40 (m, 10H); 13C
31: 65% yield; orange oil; 1H NMR (CDCl3) δ 1.55 (quintet,
J ) 7.81 Hz, 2H), 1.74 (quintet, J ) 7.57 Hz, 2H), 2.00 (quintet,
J ) 7.08 Hz, 2H), 2.38 (t, J ) 7.33 Hz, 2H), 2.89 (s, 3H), 3.68

Synthesis of Fischer-Type (Alkoxy)carbene Complexes
J . Org. Chem., Vol. 65, No. 16, 2000 4803
(s, 3H), 4.89 (br s, 2H); 13C NMR (CDCl3) δ 24.5, 25.5, 29.0,
33.8, 50.3, 51.6, 83.8, 173.8, 205.7, 213.3, 349.3; MS m/z 410
(M+), 354, 326.
Tetr a m eth yla m m on iu m p en ta ca r bon yl(1-oxym eth yli-
d en e)tu n gsta te(0) (7e) w ith 11 a n d 42 (or 43). (a) A mix-
ture of ammonium acylate complex 7a (0.5 mmol), methyl-
diphenylsulfonium tetrafluoroborate 11 (1.5 mmol), and meth-
yl(4,4′-dinitrodiphenyl)sulfonium tetrafluoroborate 42 (1.5
mmol) in CH2Cl2 (5 mL) was stirred at room temperature for
24 h under Ar, and a mixture of 12a (62%), diphenyl sulfide
(10%), and 4,4′-dinitrodiphenyl sulfide (69%) was obtained (see
Scheme 7).
(b) Similarly, a mixture of ammonium acylate complex 7a
(0.5 mmol), methyldiphenylsulfonium tetrafluoroborate 11 (1.5
mmol), and methyl(4,4′-dimethoxydiphenyl)sulfonium tetrafluo-
roborate 43 (1.5 mmol) in CH2Cl2 (5 mL) was stirred at room
temperature for 24 h under Ar. The product was separated by
gel permeation chromatography, and a mixture of 12a (67%),
diphenyl sulfide (66%), and 4,4′-dimethoxydiphenyl sulfide
(25%) was obtained (see Scheme 7).
(c) Similarly, a mixture of ammonium acylate complex 7e
(0.5 mmol), methyldiphenylsulfonium tetrafluoroborate 11 (1.5
mmol), and methyl(4,4′-dinitrodiphenyl)sulfonium tetrafluo-
roborate 42 (1.5 mmol) in CH2Cl2 (5 mL) was stirred at room
temperature for 24 h under Ar, and a mixture of 32 (87%),
diphenyl sulfide (13%), and 4,4′-dinitrodiphenyl sulfide (82%)
was obtained (see Scheme 7).
(d) Similarly, a mixture of ammonium acylate complex 7e
(0.5 mmol), methyldiphenylsulfonium tetrafluoroborate 11 (1.5
mmol), and methyl(4,4′-dimethoxydiphenyl)sulfonium tetraflu-
oroborate 43 (1.5 mmol) in CH2Cl2 (5 mL) under Ar was stirred
at room temperature for 24 h, and a mixture of 32 (85%),
diphenyl sulfide (74%), and 4,4′-dimethoxydiphenyl sulfide
(19%) was obtained (see Scheme 7).
Gen er a l P r oced u r e for P r ep a r a t ion of Tu n gst en
(Alk oxy)ca r ben e Com p lexes 32-39. A mixture of am-
monium acylate complexe 7e (3.0 mmol) and diphenylsulfo-
nium tetrafluoroborate 10 (3.0 mmol) in CH2Cl2 (15 mL) was
stirred at room temperature for 12 h under Ar. The results
are summarized in Table 4.
32: 93% yield; yellow needles; mp 52.3-53.0 °C [lit.13 mp
52 °C]; 1H NMR (CDCl3) δ 2.89 (s, 3H), 4.59 (s, 3H); 13C NMR
(CDCl3) δ 52.1, 70.3, 197.2, 203.5, 333.3; MS m/z 382 (M+),
354, 339.
1
33: 95% yield; yellow needles; mp 67.1-67.8 °C; H NMR
(CDCl3) δ 1.52 (d, J ) 6.34 Hz, 6H), 2.86 (s, 3H), 5.60-5.67
(m, 1H); 13C NMR (CDCl3) δ 22.2, 52.6, 89.9, 197.1, 203.5,
325.5; MS m/z 410 (M+), 365, 337.
1
34: 85% yield; orange oil; H NMR (CDCl3) δ 1.25 (t, J )
6.84 Hz, 3H), 2.92 (s, 3H), 3.61 (q, J ) 7.00 Hz, 2H), 3.94 (t, J
) 4.64 Hz, 2H), 4.90 (br s, 2H); 13C NMR (CDCl3) δ 15.1, 52.5,
67.0, 68.2, 83.5, 197.3, 203.5, 332.0; MS m/z 440 (M+), 412,
384.
35: 69% yield; orange oil; 1H NMR (CDCl3) δ 2.35 (quintet,
J ) 6.47 Hz, 2H), 2.62 (t, J ) 6.84 Hz, 2H), 2.90 (s, 3H), 4.88
(br s, 2H); 13C NMR (CDCl3) δ 14.5, 25.3, 52.3, 81.3, 118.4,
197.0, 203.4, 332.5; MS m/z 435 (M+), 407, 379.
36: 90% yield; orange oil; 1H NMR (CDCl3) δ 2.44 (quintet,
J ) 6.11 Hz, 2H), 2.89 (s, 3H), 3.75 (t, J ) 6.11 Hz, 2H), 4.93
(br s, 2H); 13C NMR (CDCl3) δ 31.9, 40.7, 52.3, 80.5, 197.1,
203.5, 331.8; MS m/z 444 (M+, 35Cl), 416, 388.
37: 91% yield; orange oil; 1H NMR (CDCl3) δ 2.08 (quintet,
J ) 6.84 Hz, 2H), 2.28 (q, J ) 7.00 Hz, 2H), 2.88 (s, 3H), 4.80
(br s, 2H), 5.05-5.12 (m, 2H), 5.84 (ddt, J ) 17.1, 10.3, 6.65
Hz, 1H); 13C NMR (CDCl3) δ 28.2, 30.0, 52.3, 84.0, 116.1, 136.7,
197.3, 203.5, 330.7; MS m/z 436 (M+), 380, 352.
According to the results described above, we calculated the
relative reactivities of sulfonium salts 11, 42, and 43 based
on the yields of the resulting diaryl sulfides, since the yields
of the methylation of the acylate ion from 7 are almost equal
to those of the diaryl sulfides. The results are as follows:
toward ammonium acylate complexe 7a (M ) Cr), 4-NO2C6H4
(6.9):C6H5 (1.0):4-MeOC6H4 (0.38); toward ammonium acylate
complex 7e (M ) W), 4-NO2C6H4 (6.3):C6H5 (1.0):4-MeOC6H4
(0.26).
38: 48% yield; orange oil; 1H NMR (CDCl3) δ 2.13 (br s, 1H),
2.23 (quintet, J ) 6.11 Hz, 2H), 2.89 (s, 3H), 3.88 (t, J ) 6.10
Hz, 2H), 4.93 (br s, 2H); 13C NMR (CDCl3) δ 31.9, 52.3, 58.9,
81.4, 197.3, 203.6, 331.0; MS m/z 426 (M+), 398, 370.
39: 85% yield; orange oil; 1H NMR (CDCl3) δ 1.52-1.58 (m,
2H), 1.74 (quintet, J ) 7.57 Hz, 2H), 1.99 (quintet, J ) 7.08
Hz, 2H), 2.37 (t, J ) 7.32 Hz, 2H), 2.88 (s, 3H), 3.68 (s, 3H),
4.80 (br s, 2H); 13C NMR (CDCl3) δ 24.5, 25.5, 28.9, 33.8, 51.6,
52.3, 84.5, 173.8, 197.3, 203.5, 330.6; MS m/ z 496 (M+), 440,
412.
Ack n ow led gm en t. Financial support by a Grant-
in-Aid (No. 06227257) for Scientific Research on Priority
Areas from the Ministry of Education, Science, Culture,
and Sports, J apan is gratefully acknowledged. We thank
Dr. Masato Yoshida for helpful discussions, and Mr.
Yuhki Yamaguchi and Mr. Takeshi Aizawa for helping
the preparation of 42 and 43.
Com p etitive Alk yla tion of Tetr a m eth yla m m on iu m
p en ta ca r bon yl(1-oxym eth ylid en e)ch r om a te(0) (7a ) w ith
11 a n d 40. A mixture of ammonium acylate complexe 7a (1
mmol) and methyldiphenylsulfonium tetrafluoroborate 11 (5
mmol) and isopropyldiphenylsulfonium tetrafluoroborate 40
(5 mmol) in CH2Cl2 (30 mL) was stirred at room temperature
for 12 h under Ar. The product was separated by gel perme-
ation chromatography, and 12a (8%) and 13a (72%) were
obtained (see Scheme 6).
Su p p or tin g In for m a tion Ava ila ble: Characterization
data for all new compounds (1H and/or 13C NMR spectra and
IR data of sulfonium salts 10 and carbene complexes 12-39).
This material is available free of charge via the Internet at
http://pubs.acs.org.
Com p etitive Meth yla tion of Tetr a m eth yla m m on iu m
p en ta ca r bon yl(1-oxym eth ylid en e)ch r om a te(0) (7a ) or
J O991549N