Onium Transfer Reaction of (β,β-Dialkylvinyl)(phenyl)iodonium Tetrafluoroborates via an Alkylidene Carbene Pathway: Synthesis of Group 15 Alkenyl(triphenyl)- and Group 16 Alkenyl(diphenyl)onium Salts

Article abstract of DOI:10.1021/jo990963k

Group 15 1-alkenyl(triphenyl)onium (P, As, Sb) tetrafluoroborates were prepared via an onium transfer reaction of alkenyl(phenyl)iodonium tetrafluoroborates under mild conditions. The reaction involves base-induced reductive α-elimination of the iodonium salts, followed by nucleophilic trapping of the resulting free alkylidene carbenes with group 15 element-centered nucleophiles. The onium transfer reaction of the alkenyliodonium salts also produced group 16 1-alkenyl-(diphenyl)onium (S, Se, Te) tetrafluoroborates in good yields.

Full text of DOI:10.1021/jo990963k

J . Org. Chem. 1999, 64, 8563-8567
8563
On iu m Tr a n sfer Rea ction of (â,â-Dia lk ylvin yl)(p h en yl)iod on iu m
Tetr a flu or obor a tes via a n Alk ylid en e Ca r ben e P a th w a y: Syn th esis
of Gr ou p 15 Alk en yl(tr ip h en yl)- a n d Gr ou p 16
Alk en yl(d ip h en yl)on iu m Sa lts
Masahito Ochiai,* Takuya Sueda, Rie Noda, and Motoo Shiro
Faculty of Pharmaceutical Sciences, University of Tokushima, 1-78 Shomachi, Tokushima 770-8505, and
Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196, J apan
Received J une 15, 1999
Group 15 1-alkenyl(triphenyl)onium (P, As, Sb) tetrafluoroborates were prepared via an onium
transfer reaction of alkenyl(phenyl)iodonium tetrafluoroborates under mild conditions. The reaction
involves base-induced reductive R-elimination of the iodonium salts, followed by nucleophilic
trapping of the resulting free alkylidene carbenes with group 15 element-centered nucleophiles.
The onium transfer reaction of the alkenyliodonium salts also produced group 16 1-alkenyl-
(diphenyl)onium (S, Se, Te) tetrafluoroborates in good yields.
Sch em e 1
Base treatment of 1-alkenyl(phenyl)iodonium tetraflu-
oroborates under mild conditions leads to reductive
R-elimination of iodobenzene to generate alkylidene
carbenes, because of the very high leaving group ability
of the phenyliodonio group.1,2 We reported that the
alkenyl group of (E)- and (Z)-1-alkenyl(phenyl)iodonium
tetrafluoroborates 1 was selectively transferred to diphe-
nyl sulfide by reaction with diisopropylethylamine to give
a mixture of stereoisomers of the alkenylsulfonium salt
3 (Scheme 1).3 The high degree of stereoconvergence of
the olefin geometry in this onium transfer reaction
confirmed the involvement of free alkylidene carbene 2
via base-induced reductive R-elimination.
Sch em e 2
Complete stereoconvergence for intramolecular 1,5-
carbon-hydrogen insertions of alkenyliodonium salts
yielding cyclopentenes1a and a small Hammett F value
(-0.56) for the cycloaddition reaction of the alkenyliodo-
nium salt 4 to ring-substituted styrenes4 also suggests
the intermediacy of a free alkylidene carbene rather than
a carbenoid. We report herein a new method for synthesis
of group 15 alkenyl(triphenyl)- and group 16 alkenyl-
(diphenyl)onium tetrafluoroborates that involves an on-
ium transfer reaction of alkenyl(phenyl)iodonium tet-
rafluoroborates 4 and 5 under mild conditions via the
intervention of free alkylidene carbenes. In this reaction,
1-alkenyl groups of the iodonium salts 4 and 5 were
selectively transferred in preference to the phenyl group
to group 15 and 16 element-centered nucleophiles
(Scheme 2).
however, use of triphenylphosphine as a nucleophile
results in the formation of alkenyl(triphenyl)phospho-
nium tetrafluoroborate 6b. Thus, exposure of the iodo-
nium salt 4 to 1.2 equiv of triphenylphosphine in the
presence of diisopropylethylamine (1.2 equiv) in dichlo-
romethane at room temperature allows the onium trans-
fer reaction to proceed, yielding the alkenylphosphonium
salt 6b in 56% yield (Table 1, entry 2). Triphenylarsine
and triphenylstibine also react with 2-methyl-1-prope-
nylidene generated from the reaction of the iodonium salt
4 with diisopropylethylamine to give under similar
conditions the alkenylarsonium 6c and alkenylstibonium
salts 6d in 52% and 44% yields, respectively. The lowest
homologue of the trivalent group 15 compound, triph-
enylbismuthine, shows low nucleophilicity compared to
triphenylphosphine, -arsine, and -stibine5 and, in fact,
was recovered unchanged in the reaction with 4. Use of
excess amounts (2 equiv) of As and Sb nucleophiles
increased the yields of the arsonium 6c and the stibonium
salts 6d (Table 1, entries 4 and 6). Reaction of the
No onium transfer between 2-methyl-1-propenyl(phe-
nyl)iodonium tetrafluoroborate (4) and triphenylamine
via alkylidene carbene intermediates was observed;
* To whom correspondence should be addressed. E-mail: mochiai@
ph2.tokushima-u.ac.jp. Tel: 88-633-7281. Fax: 88-633-9504.
(1) (a) Ochiai, M.; Takaoka, Y.; Nagao, Y. J . Am. Chem. Soc. 1988,
110, 6565. (b) Ochiai, M.; Kunishima, M.; Tani, S.; Nagao, Y. J . Am.
Chem. Soc. 1991, 113, 3135.
(2) For a very high leaving group ability of phenyliodonio groups,
see: Okuyama, T.; Takino, T.; Sueda, T.; Ochiai, M. J . Am. Chem. Soc.
1995, 117, 3360.
(3) Sueda, T.; Nagaoka, T.; Goto, S.; Ochiai, M. J . Am. Chem. Soc.
1996, 118, 10141.
(4) Ochiai, M.; Sueda, T.; Uemura, K.; Masaki, Y. J . Org. Chem.
1995, 60, 2624.
(5) (a) Wardell, J . L. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Ed.; Pergamon: Oxford, U.K., 1982; Vol. 2, Chapter 13.
(b) Pearson, R. G.; Sobel, H.; Songstad, J . J . Am. Chem. Soc. 1968, 90,
319. (c) Mente, D. C.; Mills, J . L.; Mitchell, R. E. Inorg. Chem. 1975,
14, 123. (d) Ahrland, S.; Berg, T.; Trinderup, P. Acta Chem. Scand.
Ser. A 1977, 31, 775. (e) Ogawa, T.; Hikasa, T.; Ikegami, T.; Ono, N.;
Suzuki, H. Chem. Lett. 1993, 815. (f) Parris, G. E.; Brinckman, F. E.
J . Org. Chem. 1975, 40, 3801. (g) Hiatt, R.; McColeman, C.; Howe, G.
R. Can. J . Chem. 1975, 53, 559.
10.1021/jo990963k CCC: $18.00 © 1999 American Chemical Society
Published on Web 10/22/1999

8564 J . Org. Chem., Vol. 64, No. 23, 1999
Ochiai et al.
Ta ble 1. Syn th esis of Gr ou p 15 Alk en yl(tr ip h en yl)on iu m
Tetr a flu or obor a tesa
Sch em e 3
entry
iodonium salt
Ph3X
product
% yieldb
1
2
3
4
5
6
7
8
9
4
4
4
4
4
4
4
5
5
5
Ph3Nc
Ph3P
6a
6b
6c
6c
6d
6d
6e
7b
7c
7d
0
56 (70)
52 (74)
69
44 (54)
70
Ph3As
Ph3Asd
Ph3Sb
Ph3Sbd
Ph3Bi
Ph3P
0
85
80
83
Ph3As
Ph3Sb
10
Ta ble 2. Syn th esis of Gr ou p 16 Alk en yl(d ip h en yl)on iu m
Tetr a flu or obor a tesa
a
Reactions were carried out using diisopropylethylamine (1.2
equiv) and Ph3X (1.2 equiv) in CH2Cl2 at room temperature for
entry
iodonium salt
Ph2X
product
% yieldb
b
15 min under N2. Isolated yields. Yields in parentheses were
1
2
3
4
5
6
7
8
4
4
4
4
4
5
5
5
Ph2Oc
Ph2S
6f
6g
6g
6h
6i
7g
7h
7i
0
60 (70)
67 (92)
54 (70)
68 (99)
67
determined by 1H NMR. c 1.5 h at room temperature. Ph3X (2
d
equiv).
Ph2Sd
Ph2Se
Ph2Te
Ph2S
cyclohexylidenemethyliodonium tetrafluoroborate 5 with
triphenylphosphine, -arsine and -stibine afforded a higher
yield (more than 80%) of the alkenylonium salts 7b-d .
Low reactivity of triphenylamine toward 2-methyl-1-
propenylidene can be attributed to a large steric demand-
ing of the amine, evoked probably by the small atomic
size of nitrogen. In fact, reaction of 4 with 2.5 equiv of
triethylamine gave the alkenylammonium salt 8 in 56%
yield, whereas with the more sterically demanding di-
isopropylethylamine no formation of the onium transfer
product 9 was observed. An alternative explanation
might involve the low polarity of triphenylamine. The
dipole moment of the triphenyl derivatives of group 15
elements is as follows: NPh3 (0.26 D), PPh3 (1.45 D),
AsPh3 (1.07 D), SbPh3 (0.57 D), BiPh3 (0 D).6 The donor
ability toward silver perchlorate in dimethyl sulfoxide
largely follows the pattern of polarity.5d
Ph2Se
Ph2Te
75
89
a
Reactions were carried out using diisopropylethylamine (1.2
equiv) and Ph2X (1.2 equiv) in CH2Cl2 at room temperature for
b
15 min under N2. Isolated yields. Yields in parentheses were
d
determined by 1H NMR. c 1 h at room temperature. Ph2S (2
equiv).
proceed at room temperature. One or more of the follow-
ing reaction mechanisms explains the formation of the
2,2-diphenylvinylarsonium salt 13: (1) a direct in-plane
vinylic SN2 substitution,8 (2) an ionic mechanism through
vinylenebenzenium ion intermediate,9 (3) ligand coupling
on hypervalent iodine(III).10
Results of the reaction of the diphenyl derivatives of
group 16 nucleophiles with the free alkylidene carbenes
are summarized in Table 2. Here again, no onium
transfer reaction between the iodonium salt 4 and the
diphenyl derivative of a second-row element, diphenyl
ether, was observed; however, diphenyl sulfide undergoes
clean onium transfer reactions via alkylidene carbene
intermediates and affords the alkenyl(diphenyl)sulfonium
salt 6g in 60% yield (Table 2, entry 2). Similarly, alkenyl-
(diphenyl)selenonium 6h and 7h and alkenyl(diphenyl)-
telluronium tetrafluoroborates 6i and 7i were prepared
via the onium transfer reaction in good yields. Except
for alkenyl(triphenyl)phosphonium salts, synthetic meth-
ods for producing other triphenylonium salts of group 15
elements and of diphenylonium salts of group 16 ele-
ments are very limited.11,12 The present methodology used
for the onium transfer reaction via an alkylidene carbene
intermediate provides a new and convenient route for the
synthesis of â,â-dialkylvinylonium salts of group 15 and
16 elements.
1,2-Migration of R-aryl groups of alkylidene carbene
is a low-energy process and proceeds rapidly.7 We found
that attempts at nucleophilic trapping of the alkylidene
carbene 11 with triphenylarsine to lead to onium transfer
cannot compete with the facile 1,2-aryl migration: thus,
the reaction of â,â-diphenylvinyliodonium tetrafluorobo-
rate 10 with triphenylarsine in the presence of diisopro-
pylethylamine in dichloromethane at 0 °C exclusively
results in the 1,2-phenyl migration and affords dipheny-
lacetylene (12) quantitatively with no signs for formation
of the onium transfer product 13 (Scheme 3). Interest-
ingly, however, 2,2-diphenylvinylarsonium tetrafluorobo-
rate 13 was produced in 67% yield when the reaction was
carried out in acetonitrile, without using a base, at 50
°C for 6 h. This nucleophilic vinylic substitution does not
The parent ethenyl(triphenyl)phosphonium and ethe-
nyl(triphenyl)arsonium salts act as good Michael accep-
tors toward carbon nucleophiles, i.e., enolate anions and
lithium dialkyl cuprates.11 Introduction of alkyl substit-
(6) Fieser, L. F.; Fieser, M. Reagents for Organic Synthesis; Wiley:
New York, 1967; Vol. 1, pp 1238-1247.
(8) (a) Ochiai, M.; Oshima, K.; Masaki, Y. J . Am. Chem. Soc. 1991,
113, 7059. (b) Okuyama, T.; Takino, T.; Sato, K.; Ochiai, M. J . Am.
Chem. Soc. 1998, 120, 2275. (c) Okuyama, T.; Takino, T.; Sato, K.;
Oshima, K.; Imamura, S.; Yamataka, H.; Asano, T.; Ochiai, M. Bull.
Chem. Soc. J pn. 1998, 71, 243.
(9) (a) Okuyama, T.; Ochiai, M. J . Am. Chem. Soc. 1997, 119, 4785.
(b) Stang, P. J .; Dueber, T. E. J . Am. Chem. Soc. 1973, 95, 2683.
(10) (a) Oae, S. Acc. Chem. Res. 1991, 24, 202. (b) Ochiai, M.;
Oshima, K.; Masaki, Y. Chem. Lett. 1994, 871. (c) Okuyama, T.; Takino,
T.; Sato, K.; Ochiai, M. Chem. Lett. 1997, 955. (d) Okuyama, T.; Oka,
H.; Ochiai, M. Bull. Chem. Soc. J pn. 1998, 71, 1915.
(7) (a) Newman, M. S.; Kutner, A. J . Am. Chem. Soc. 1951, 73, 4199.
(b) Stang, P. J .; Mangum, M. G.; Fox, D. P.; Haak, P. J . Am. Chem.
Soc. 1974, 96, 4562. (c) Brown, R. F. C.; Eastwood, F. W.; Harrington,
K. J .; McMullen, G. L. Aust. J . Chem. 1974, 27, 2393. (d) Stang, P. J .;
Fox, D. P.; Collins, C. J .; Watson, C. R. J . Org. Chem. 1978, 43, 364.
(e) Gilbert, J . C.; Weerasooriya, U. J . Org. Chem. 1982, 47, 1837. (f)
Ochiai, M.; Kunishima, M.; Nagao, Y.; Fuji, K.; Shiro, M.; Fujita, E. J .
Am. Chem. Soc. 1986, 108, 8281. (g) Ochiai, M.; Uemura, K.; Masaki,
Y. J . Am. Chem. Soc. 1993, 115, 2528.

Onium Transfer Reaction of Iodonium Tetrafluoroborates
J . Org. Chem., Vol. 64, No. 23, 1999 8565
Sch em e 4
uents at their â positions will decrease the reactivity
toward the Michael additions because of the increased
steric hindrance. Thus, the reaction of 2-methyl-1-pro-
penylarsonium salt 6c with the potassium enolate de-
rived from 2-phenyl-1,3-indandione in refluxing dichlo-
romethane-THF (1:2) results in allylation instead of
Michael addition, giving the diketone 14 in 85% yield.
At room temperature, the reaction afforded the onium
enolate 16c (85%) via a ligand exchange. Similarly, the
arsonium salt 7c gave the allylation product 15 (83%) in
refluxing dichloromethane-THF. The allylation probably
proceeds via the base-catalyzed isomerization of the
vinylarsonium salts 6c and 7c to the allylarsonium salts.
Neither allylation nor Michael addition were observed
in the reactions of the phosphonium 6b and stibonium
salts 6d with the enolate under the same conditions (in
refluxing dichloromethane-THF); these reactions gave
the onium enolates 16b,d in good yields (Scheme 4).
The structure of 16c was established by a single-crystal
X-ray analysis.13 The ORTEP representation of Figure 1
clearly illustrates an ionic structure; the arsine has a
tetrahedral geometry with the bond angles C-As-C
107.6(4)-110.9(4)° and the bond lengths 1.87(1)-1.95-
(1) Å. All the atoms attached to the carbon-carbon double
bond are in the same plane, and the bond length of C19-
C20 is 1.34(2) Å.
F igu r e 1. ORTEP representation of the arsonium enolate
16c.
Exp er im en ta l Section
Gen er a l Meth od s. For general experimental details, see
ref 2. Preparative thin-layer chromatography (TLC) was
carried out on precoated plates of silica gel (Merck, silica gel
F-254). Kieselgel 60 (Merck, 230-400 mesh) was used for flash
chromatography. 2-Methyl-1-propenyl(phenyl)iodonium tet-
rafluoroborate (4) was prepared by tin-iodonium exchange
reaction of 2-methyl-1-(trimethylstannyl)prop-1-ene with io-
dosylbenzene in the presence of BF3‚Et2O.4
Syn t h esis of (Cycloh exylid en em et h yl)(p h en yl)iod o-
n iu m Tetr a flu or obor a te (5). (Cyclohexylidenemethyl)trim-
ethylsilane was prepared according to the procedure described
previously.14 To a stirred suspension of iodosylbenzene (487
mg, 2.2 mmol) and the vinylsilane (232 mg, 1.4 mmol) in
dichloromethane (20 mL) was added dropwise BF3‚Et2O (313
mg, 2.2 mmol) at 0 °C in nitrogen, and the mixture was stirred
for 1 h at 0 °C. After the addition of a saturated aqueous
solution of sodium tetrafluoroborate (3.0 g, 28 mmol), the
mixture was stirred for 15 min. Extraction with dichlo-
romethane, filtration, and then concentration under aspirator
vacuum gave an oil, which was washed several times with
hexane by decantation at -78 °C. Recrystallization from
dichloromethane-diethyl ether-hexane gave the iodonium
salt 5 (255 mg, 48%) as colorless needles: mp 97-98 °C; IR
(11) For syntheses of alkenyl(triphenyl)onium salts of group 15
elements, see: (a) Phosphonium salts: Schweizer, E. E.; Bach, R. D.
J . Org. Chem. 1964, 29, 1764. Schweizer, E. E.; Wehman, A. T. J .
Chem. Soc. C 1971, 343. Howe, R. K. J . Am. Chem. Soc. 1971, 93, 3457.
Schweizer, E. E.; De Voe Goff, S.; Murray, W. P. J . Org. Chem. 1977,
42, 200. Kowalski, M. H.; Hinkle, R. J .; Stang, P. J .; J . Org. Chem.
1989, 54, 2783. Hinkle, R. J .; Stang, P. J .; Kowalski, M. H. J . Org.
Chem. 1990, 55, 5033. Minami, T.; Sako, H.; Ikehira, T.; Hanamoto,
T.; Hirao, I. J . Org. Chem. 1983, 48, 2569. Minami, T.; Shikita, S.; So,
S.; Nakayama, M.; Yamamoto, I. J . Org. Chem. 1988, 53, 2937. Birum,
G. H.; Matthews, C. N. J . Chem. Soc., Chem. Commun. 1967, 137.
Bestmann, H.-J .; Saalfrank, R. W. Angew. Chem., Int. Ed. Engl. 1970,
9, 367. McIntosh, J . M.; Goodbrand, H. B.; Masse, G. M. J . Org. Chem.
1974, 39, 202. Ohmori, H.; Takanami, T.; Masui, M. Tetrahedron Lett.
1985, 26, 2199. J ust, G.; O′Connor, B. Tetrahedron Lett. 1985, 26, 1799.
Okuma, K.; Koike, T.; Yamamoto, S.; Yonekura, K. Chem. Lett. 1989,
1953. Larpent, C.; Meignan, G.; Patin, H. Tetrahedron Lett. 1991, 32,
2615. Posner, G. H.; Lu, S.-B. J . Am. Chem. Soc. 1985, 107, 1424. (b)
Arsonium salts: Forbes, M. H.; Heinekey, D. M.; Mann, F. G.; Millar,
I. T. J . Chem. Soc. 1961, 2762. Manske, R.; Gosselck, J . Tetrahedron
1975, 31, 2121. Nesmeyanov, N. A.; Mikulshina, V. V.; Kharitonov, V.
G.; Petrovsky, P. V.; Reutov, O. A. Izv. Akad. Nauk USSR 1988, 908.
(c) Bismuthonium salts: Matano, Y.; Yoshimune, M.; Azuma, N.;
Suzuki, H. J . Chem. Soc., Perkin Trans. 1 1996, 1971. Matano, Y.;
Begum, S. A.; Miyamatsu, T.; Suzuki, H. Organometallics 1998, 17,
4332.
(KBr) 1609, 1443, 1060 (br), 747 cm-1 1H NMR (400 MHz,
;
CDCl3) δ 7.92 (d, J ) 7.6 Hz, 2H), 7.63 (t, J ) 7.6 Hz, 1H),
7.49 (t, J ) 7.6 Hz, 2H), 6.67 (s, 1H), 2.58-2.53 (m, 4H), 1.72-
1.53 (m, 6H); HRMS (FAB) calcd for C13H16I [(M - BF4)+]
299.0297, found 299.0270. Anal. Calcd for C13H16BF4I: C,
40.45; H, 4.18. Found: C, 40.15; H, 4.37.
Syn th esis of 2,2-Dip h en yleth en yl(p h en yl)iod on iu m
Tetr a flu or obor a te (10). To a stirred solution of 1-bromo-2,2-
diphenylethene15 (900 mg, 3.5 mmol) in THF (30 mL) was
added 1.43 M tert-butyllithium solution in pentane (5.1 mL,
7.3 mmol) dropwise at -78 °C in argon, and the mixture was
stirred for 2 h. Trimethyl borate (361 mg, 3.5 mmol) was added,
and the mixture was stirred at -78 °C for 1 h and at 0 °C for
1 h. After the addition of a 10% aqueous HCl solution (30 mL)
at 0 °C, the mixture was stirred for 1 h. The mixture was
extracted with diethyl ether, and the combined organic phase
(12) For syntheses of alkenyl(diphenyl)onium salts of group 16
elements, see: (a) Sulfonium salts: LaRochelle, R. W.; Trost, B. M. J .
Am. Chem. Soc. 1971, 93, 6077. Stasko, A.; Rapta, P.; Brezova, V.;
Nuyken, O.; Vogel, R. Tetrahedron 1993, 49, 10917. (b) Selenonium
salts: Kataoka, T.; Banno, Y.; Watanabe, S.; Iwamura, T.; Shimizu,
H. Tetrahedron Lett. 1997, 38, 1809. Watanabe, Y.; Ueno, Y.; Toru, T.
Bull. Chem. Soc. J pn. 1993, 66, 2042. (c) Telluronium salts: Matano,
Y.; Suzuki, H.; Azuma, N. Organometallics 1996, 15, 3760.
(14) Barluenga, J .; Fernandez-Simon, J . L.; Concellon, J . M.; Yus,
M. Synthesis 1988, 234.
(15) Suarez, A. R.; Mazzieri, M. R. J . Org. Chem. 1987, 52, 1145.
(13) The author has deposited atomic coordinates for this structure
with the Cambridge Crystallographic Data Centre.

8566 J . Org. Chem., Vol. 64, No. 23, 1999
Ochiai et al.
was washed with water and brine and dried over anhydrous
Na2SO4. Concentration under aspirator vacuum gave (2,2-
diphenyl-1-ethenyl)boronic acid, which was used without
further purification. To a stirred solution of the crude vinyl-
boronic acid in dichloromethane (5 mL) was added dropwise
BF3‚Et2O (595 mg, 4.2 mmol) at 0 °C in nitrogen, and the
mixture was stirred for 10 min at 0 °C. After the addition of
a solution of diacetoxyiodobenzene (1.4 g, 4.2 mmol) in dichlo-
romethane (5 mL), the mixture was stirred for 30 min at 0
°C. A saturated aqueous solution of sodium tetrafluoroborate
(7.7 g, 70 mmol) was added, and the mixture was stirred for
15 min. Extraction with dichloromethane, filtration, washing
with water, and then concentration under aspirator vacuum
gave an oil, which was washed several times with hexane and
diethyl ether by decantation at -78 °C to give the vinyliodo-
nium salt 10 (1.41 g, 86%). Further purification of the
iodonium salt by recrystallization from dichloromethane-
diethyl ether-hexane gave colorless needles: mp 125-126 °C
(m, 15H), 6.12 (s, 1H), 2.76 (t, J ) 6.1 Hz, 2H), 2.11 (t, J ) 6.1
Hz, 2H), 1.91-1.74 (m, 2H), 1.61-1.50 (m, 2H), 1.42-1.23 (m,
2H); HRMS (FAB) calcd for C25H26As [(M - BF4)+] 401.1250,
found 401.1260. Anal. Calcd for C25H26AsBF4: C, 61.51; H,
5.37. Found: C, 61.74; H, 5.41.
(Cycloh exylid en em eth yl)tr ip h en ylstibon iu m tetr a flu -
or obor a te (7d ): colorless prisms; mp 140-141 °C (recrystal-
lized from dichloromethane-hexane); IR (KBr) 1601, 1437,
1
1060 (br), 744, 690 cm-1; H NMR (400 MHz, CDCl3) δ 7.7-
7.59 (m, 15H), 6.28 (s, 1H), 2.65 (t, J ) 6.2 Hz, 2H), 2.22 (t, J
) 6.2 Hz, 2H), 1.83-1.74 (m, 2H), 1.62-1.51 (m, 2H), 1.51-
1.42 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 173.4, 134.8, 133.5,
131.1, 122.6, 99.6, 38.8, 28.0, 27.8, 24.8; HRMS (FAB) calcd
for C25H26Sb [(M - BF4)+] 447.1073, found 447.1089. Anal.
Calcd for C25H26BF4Sb: C, 56.12; H, 4.90. Found: C, 56.30;
H, 4.94.
Syn th esis of (2-Meth yl-1-p r op en yl)tr ieth yla m m on iu m
Tetr a flu or obor a te (8). To a stirred solution of the iodonium
salt 4 (35 mg, 0.1 mmol) in dichloromethane (1 mL) was added
triethylamine (25 mg, 0.25 mmol) under nitrogen at room
temperature, and the mixture was stirred for 30 min. The
organic solvent was evaporated off in vacuo to give an oil,
which was washed several times with hexane by decantation.
Yield of the ammonium salt 83 was determined by 1H NMR
(56%).
Rea ction of (Dip h en yleth en yl)iod on iu m Sa lt 10 w ith
Tr ip h en yla r sin e. (A) In th e P r esen ce of Diisop r op yl-
eth yla m in e. To a stirred solution of the iodonium salt 10 (140
mg, 0.30 mmol) and triphenylarsine (184 mg, 0.60 mmol) in
dichloromethane (25 mL) was added dropwise diisopropyl-
ethylamine (47 mg, 0.36 mmol) under nitrogen at 0 °C, and
the mixture was stirred for 1 h at 0 °C and for 30 min at room
temperature. After addition of water, the mixture was ex-
tracted with dichloromethane. Filtration and concentration
under aspirator vacuum gave an oil, which was purified by
preparative TLC (hexane) to give diphenylacetylene (12) (56
mg, 100%) and triphenylarsine (172 mg, 94%).
dec; IR (KBr) 1579, 1060 (br), 740, 700 cm-1 1H NMR (300
;
MHz, acetone-d6) δ 8.09 (s, 1H), 8.00 (d, J ) 7.5 Hz, 2H), 7.76
(t, J ) 7.5 Hz, 1H), 7.68-7.30 (m, 12H); HRMS (FAB) calcd
for C20H16I [(M - BF4)+] 383.0297, found 383.0314. Anal. Calcd
for C20H16BF4I: C, 51.10; H, 3.43. Found: C, 50.86; H, 3.63.
Gen er a l P r oced u r e for Syn th esis of Gr ou p 15 Alk en yl-
(tr ip h en yl)on iu m Tetr a flu or obor a tes 6 a n d 7 (Ta ble 1).
To a stirred solution of an alkenyl(phenyl)iodonium tetrafluo-
roborate (0.1 mmol) and a group 15 heteroatom nucleophile
(Ph3X, 0.12 mmol) in dichloromethane (1 mL) was added
dropwise diisopropylethylamine (16 mg, 0.12 mmol) under
nitrogen at room temperature, and the mixture was stirred
for 15 min. After addition of water, the mixture was extracted
with dichloromethane. Filtration and concentration under
aspirator vacuum gave an oil, which was washed several times
with hexane by decantation to give the group 15 onium salt.
Further purification of the onium salt was accomplished by
recrystallization from dichloromethane-hexane.
(2-Meth yl-1-p r op en yl)tr ip h en ylp h osp h on iu m tetr a flu -
or obor a te (6b): colorless plates; mp 244-245 °C (recrystal-
lized from dichloromethane-hexane); IR (KBr) 1616, 1060 (br),
(B) In th e Absen ce of a Ba se. A solution of the iodonium
salt 10 (47 mg, 0.1 mmol) and triphenylarsine (306 mg, 1
mmol) in acetonitrile (1 mL) was heated at 50 °C for 6 h under
nitrogen. Concentration under aspirator vacuum gave an oil,
which was washed several times with hexane by decantation
to give (2,2-diphenylethenyl)triphenylarsonium tetrafluorobo-
rate (13) (38 mg, 66%), contaminated with a small amount of
impurity. Preparative TLC (ethyl acetate) gave the pure salt:
colorless needles; mp 221-222 °C (recrystallized from dichlo-
romethane-diethyl ether-hexane); IR (KBr) 1619, 1060 (br),
751, 721 cm-1
;
1H NMR (400 MHz, CDCl3) δ 7.84-7.60 (m,
2
4
15H), 6.24 (d, J PH ) 23.2 Hz, 1H), 2.37 (s, 3H), 1.74 (d, J PH
) 2.3 Hz, 3H); HRMS (FAB) calcd for C22H22P [(M - BF4)+]
317.1458, found 317.1443. Anal. Calcd for C22H22BF4P: C,
64.73; H, 5.43. Found: C, 64.76; H, 5.28.
(2-Met h yl-1-p r op en yl)t r ip h en yla r son iu m t et r a flu o-
r obor a te (6c): colorless crystals; mp 206-208 °C (recrystal-
lized from dichloromethane-hexane); IR (KBr) 1623, 1060 (br),
1
1
749 cm-1; H NMR (400 MHz, CDCl3) δ 7.78-7.62 (m, 15H),
745 cm-1; H NMR (400 MHz, CD2Cl2) δ 7.86 (t, J ) 7.7 Hz,
6.22 (br s, 1H), 2.33 (d, J ) 0.9 Hz, 3H), 1.82 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ 167.7, 134.2, 132.2, 131.2, 122.5, 103.6,
28.4, 24.9; HRMS (FAB) calcd for C22H22As [(M - BF4)+]
361.0937, found 361.0944. Anal. Calcd for C22H22AsBF4: C,
58.96; H, 4.95. Found: C, 58.68; H, 4.96.
3H), 7.71 (t, J ) 7.7 Hz, 6H), 7.55 (t, J ) 7.7 Hz, 1H), 7.48 (d,
J ) 7.7 Hz, 6H), 7.37 (br t, J ) 7.7 Hz, 2H), 7.36 (br t, J ) 7.7
Hz, 1H), 7.28 (s, 1H), 7.25 (t, J ) 7.7 Hz, 2H), 7.11 (d, J ) 7.7
Hz, 2H), 7.07 (d, J ) 7.7 Hz, 2H); HRMS (FAB) calcd for
C
32H26As [(M - BF4)+] 485.1250, found 485.1222. Anal. Calcd
(2-Met h yl-1-p r op en yl)t r ip h en ylst ib on iu m t et r a flu o-
r obor a te (6d ): colorless prisms; mp 172-174 °C (recrystal-
lized from dichloromethane-hexane); IR (KBr) 1609, 1060 (br),
for C32H26AsBF4‚1/4H2O: C, 66.63; H, 4.54. Found: C, 66.56;
H, 4.56.
Gen er a l P r oced u r e for Syn th esis of Gr ou p 16 Alk en yl-
(d ip h en yl)on iu m Tetr a flu or obor a tes 6 a n d 7 (Ta ble 2).
To a stirred solution of an alkenyl(phenyl)iodonium tetrafluo-
roborate (0.1 mmol) and a group 16 heteroatom nucleophile
(Ph2X, 0.12 mmol) in dichloromethane (1 mL) was added
dropwise diisopropylethylamine (16 mg, 0.12 mmol) under
nitrogen at room temperature, and the mixture was stirred
for 15 min. After addition of water, the mixture was extracted
with dichloromethane. Filtration and concentration under
aspirator vacuum gave an oil, which was washed several times
with hexane by decantation to give the group 16 onium salt.
Further purification of the onium salt was accomplished by
recrystallization.
Dip h en yl(2-m et h yl-1-p r op en yl)su lfon iu m t et r a flu o-
r obor a te (6g): colorless needles; mp 206-207 °C (recrystal-
lized from dichloromethane-diethyl ether-hexane); IR (KBr)
1621, 1060 (br), 747 cm-1; 1H NMR (200 MHz, CDCl3) δ 8.00-
7.81 (m, 4H), 7.78-7.57 (m, 6H), 6.77 (br s, 1H), 2.27 (br s,
3H), 2.24 (d, J ) 1.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
165.3, 134.0, 131.5, 129.8, 127.5, 107.5, 26.4, 21.8; HRMS
1
748 cm-1; H NMR (200 MHz, CDCl3) δ 7.83-7.57 (m, 15H),
6.26 (br s, 1H), 2.29 (s, 3H), 1.96 (s, 3H); 13C NMR (75 MHz,
CDCl3) δ 167.1, 134.8, 133.6, 131.2, 122.2, 102.8, 28.0, 27.3;
HRMS (FAB) calcd for C22H22Sb [(M - BF4)+] 407.0760, found
407.0786. Anal. Calcd for C22H22BF4Sb: C, 53.39; H, 4.48.
Found: C, 53.06; H, 4.45.
(Cycloh exylid en em eth yl)tr ip h en ylp h osp h on iu m tet-
r a flu or obor a te (7b): pale yellow crystals; mp 182-183 °C
(recrystallized from dichloromethane-hexane); IR (KBr) 1610,
1060 (br), 743, 720 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.95-
2
7.50 (m, 15H), 6.15 (d, J PH ) 24.0 Hz, 1H), 2.69 (t, J ) 5.7
Hz, 2H), 2.15-1.97 (m, 2H), 1.87-1.70 (m, 2H), 1.64-1.45 (m,
2H), 1.40-1.20 (m, 2H); HRMS (FAB) calcd for C25H26P [(M -
BF4)+] 357.1772, found 357.1789. Anal. Calcd for C25H26
BF4P: C, 67.59; H, 5.90. Found: C, 67.34; H, 5.79.
-
(Cycloh exylid en em eth yl)tr ip h en yla r son iu m tetr a flu -
or obor a te (7c): pale yellow crystals; mp 168-172 °C (re-
crystallized from dichloromethane-hexane); IR (KBr) 1621,
1
1060 (br), 749 cm-1; H NMR (200 MHz, CDCl3) δ 7.81-7.63

Onium Transfer Reaction of Iodonium Tetrafluoroborates
J . Org. Chem., Vol. 64, No. 23, 1999 8567
(FAB) calcd for C16H17S [(M - BF4)+] 241.1051, found 241.1058.
C15H9O2)+] 317.1459, found 317.1474. Anal. Calcd for C37H31O2P‚
H2O: C, 79.84; H, 5.61. Found: C, 79.63; H, 5.83.
Anal. Calcd for
C16H17BF4S‚1/2H2O: C, 56.99; H, 5.08.
Found: C, 57.29; H, 5.18.
Ar son iu m en ola te 16c: 84%; reddish needles; mp 190-
Dip h en yl(2-m eth yl-1-p r op en yl)selen on iu m tetr a flu o-
r obor a te (6h ): colorless needles; mp 180-184 °C(recrystal-
lized from dichloromethane-diethyl ether-hexane); IR (KBr)
1620, 1060 (br), 743 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.85-
7.51 (m, 10H), 6.43 (br s, 1H), 2.21 (br s, 6H); 13C NMR (75
MHz, CDCl3) δ 161.4, 133.2, 131.5, 130.2, 128.2, 110.5, 26.2,
23.2; HRMS (FAB) calcd for C16H17Se [(M - BF4)+] 287.0503,
found 287.0534. Anal. Calcd for C16H17BF4Se: C, 51.24; H,
4.57. Found: C, 51.16; H, 4.55.
193 °C (recrystallized from dichloromethane-hexane); IR
(KBr) 1603, 1539, 1497 cm-1 1H NMR (400 MHz, CDCl3) δ
;
8.55 (d, J ) 7.7 Hz, 2H), 7.67 (t, J ) 7.3 Hz, 3H), 7.57 (t, J )
7.3 Hz, 6H), 7.43 (d, J ) 7.3 Hz, 6H), 7.25-7.20 (m, 2H), 7.18-
7.12 (m, 2H), 7.09 (t, J ) 7.7 Hz, 2H), 6.78 (t, J ) 7.7 Hz, 1H),
6.02 (s, 1H), 2.20 (s, 3H), 1.62 (s, 3H); HRMS (FAB) calcd for
C
22H22As [(M - C15H9O2)+] 361.0937, found 361.0936. Anal.
Calcd for C37H31O2As: C, 76.28; H, 5.36. Found: C, 76.07; H,
5.30.
Dip h en yl(2-m eth yl-1-p r op en yl)tellu r on iu m tetr a flu o-
r obor a te (6i): colorless plates; mp 94-96 °C (recrystallized
from dichloromethane-diethyl ether-hexane, lit.12b mp 92-
93 °C); IR (KBr) 1614, 1573, 1060 (br), 785, 736 cm-1; 1H NMR
(200 MHz, CDCl3) δ 7.70 (br d, J ) 7.6 Hz, 4H), 7.63-7.45
(m, 6H), 6.28 (br s, 1H), 2.20 (d, J ) 1.0 Hz, 3H), 2.17 (s, 3H);
HRMS (FAB) calcd for C16H17Te [(M - BF4)+] 339.0393, found
339.0377.
(Cycloh exylid en em eth yl)d ip h en ylsu lfon iu m tetr a flu -
or obor a te (7g): colorless crystals; mp 165-166 °C (recrystal-
lized from dichloromethane-diethyl ether-hexane); IR (KBr)
1606, 1075 (br), 747 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.97-
7.79 (m, 4H), 7.74-7.52 (m, 6H), 6.70 (s, 1H), 2.70 (t, J ) 5.7
Hz, 2H), 2.59 (t, J ) 5.7 Hz, 2H), 1.82-1.51 (m, 6H); HRMS
(FAB) calcd for C19H21S [(M - BF4)+] 281.1274, found 281.1392.
Anal. Calcd for C19H21BF4S: C, 61.97; H, 5.75. Found: C,
61.93; H, 5.75.
Stibon iu m en ola te 16d : 100%; reddish plates; mp 145-
149 °C (recrystallized from dichloromethane-benzene); IR
(KBr) 1606, 1591, 1520, 759, 739, 692 cm-1 1H NMR (400
;
MHz, CDCl3) δ 7.89 (br d, J ) 7.5 Hz, 2H), 7.69 (d, J ) 7.3
Hz, 6H), 7.53 (t, J ) 7.3 Hz, 3H), 7.45 (t, J ) 7.3 Hz, 6H), 6.97
(t, J ) 7.5 Hz, 2H), 6.98-6.92 (m, 2H), 6.85 (t, J ) 7.5 Hz,
1H), 6.72-6.66 (m, 2H), 6.10 (s, 1H), 1.89 (s, 3H), 1.58 (s, 3H);
HRMS (FAB) calcd for C22H22Sb [(M - C15H9O2)+] 407.0760,
found 407.0777. Anal. Calcd for C37H31O2Sb: C, 70.61; H, 4.96.
Found: C, 70.28; H, 4.93.
Allyla tion of 2-P h en yl-1,3-in d a n d ion e w ith Alk en yl-
(tr ip h en yl)a r son iu m Tetr a flu or obor a tes 6c a n d 7c. To a
stirred solution of potassium tert-butoxide (9 mg, 0.08 mmol)
in THF (1 mL) was added a solution of 2-phenyl-1,3-indandione
(17 mg, 0.08 mmol) in THF (1.4 mL) under nitrogen at room
temperature, and the mixture was stirred for 1 h. A solution
of alkenyl(triphenyl)arsonium tetrafluoroborate 6c (30 mg,
0.07 mmol) in dichloromethane (0.7 mL) was added, and the
mixture was refluxed for 40 h. After addition of water, the
mixture was extracted with dichloromethane, and the com-
bined organic phase was washed with water and brine. The
solution was dried over anhydrous Na2SO4 and concentrated
to give an oil, which was purified by preparative TLC (hex-
anes-ethyl acetate 8:2) to give 2-(2-methyl-2-propenyl)-2-
phenyl-1,3-indandione (14) (16 mg, 85%): colorless crystals;
mp 94-95 °C (recrystallized from dichloromethane-hexane);
(Cycloh exyliden em eth yl)diph en ylselen on iu m tetr aflu -
or obor a te (7h ): pale brown powder; mp 124-126 °C; IR (KBr)
1
1614, 1060 (br), 744 cm-1; H NMR (400 MHz, CDCl3) δ 7.75
(d, J ) 6.8 Hz, 4H), 7.67-7.54 (m, 6H), 6.30 (s, 1H), 2.63-
2.50 (m, 4H), 1.78-1.60 (m, 6H); HRMS (FAB) calcd for C19H21
-
Se [(M - BF4)+] 329.0808, found 329.0820. Anal. Calcd for
C
19H21BF4Se: C, 54.97; H, 5.10. Found: C, 54.82; H, 5.05.
(Cycloh exyliden em eth yl)diph en yltellu r on iu m tetr aflu -
or obor a te (7i): colorless oil; IR (film) 1607, 1060 (br), 740
1
cm-1; H NMR (400 MHz, CDCl3) δ 7.71 (d, J ) 7.3 Hz, 4H),
IR (KBr) 1744, 1709, 1639, 1591, 1247, 915, 778, 759, 701 cm-1
;
7.62-7.50 (m, 6H), 6.18 (s, 1H), 2.56-2.45 (m, 4H), 1.77-1.56
(m, 6H); HRMS (FAB) Calcd for C19H21Te [(M - BF4)+]
379.0706, found 379.0781. Anal. Calcd for C19H21BF4Te‚1/
2H2O: C, 48.27; H, 4.48. Found: C, 48.65; H, 4.58.
1H NMR (400 MHz, CDCl3) δ 8.04-7.98 (m, 2H), 7.88-7.80
(m, 2H), 7.44 (d, J ) 7.5 Hz, 2H), 7.30 (t, J ) 7.5 Hz, 2H),
7.24 (t, J ) 7.5 Hz, 1H), 4.68 (s, 1H), 4.65 (s, 1H), 3.06 (s, 2H),
1.54 (s, 3H); MS m/z (relative intensity) 276 (M+, 100), 261
Liga n d Exch a n ge of Alk en yl(tr ip h en yl)on iu m Tet-
r a flu or obor a tes 6b-d w ith En ola te An ion . To a stirred
solution of potassium tert-butoxide (12 mg, 0.11 mmol) in THF
(1 mL) was added a solution of 2-phenyl-1,3-indandione (24
mg, 0.11 mmol) in THF (1 mL) under nitrogen at room
temperature, and the mixture was stirred for 1 h. A solution
of an alkenyl(triphenyl)onium tetrafluoroborate 6b-d (0.1
mmol) in dichloromethane (1 mL) was added, and the mixture
was stirred for 5-35 min at room temperature. After addition
of water, the mixture was extracted with dichloromethane.
Filtration and concentration under aspirator vacuum gave an
oil, which was washed several times with hexane by decanta-
tion to give the group 16 onium enolate.
(17), 221 (24), 165 (14); HRMS calcd for
276.1150, found 276.1163.
C
19H16O2 (M+)
2-[(1-Cycloh exen yl)m et h yl]-2-p h en yl-1,3-in d a n d ion e
(15): 83%; colorless oil; IR (CHCl3) 1735, 1700, 1590, 1220
cm-1; 1H NMR (400 MHz, CDCl3) δ 8.04-7.97 (m, 2H), 7.87-
7.81 (m, 2H), 7.43 (d, J ) 7.4 Hz, 2H), 7.30 (t, J ) 7.4 Hz,
2H), 7.23 (t, J ) 7.4 Hz, 1H), 5.41 (br s, 1H), 2.98 (s, 2H), 1.80-
1.60 (m, 4H), 1.33-1.13 (m, 4H); MS m/z (relative intensity)
316 (M+, 14), 222 (100), 165 (25), 95 (50), 84 (50); HRMS calcd
for C22H20O2 (M+) 316.1463, found. 316.1473.
No allylation was observed in the reactions of the phospho-
nium 6b and the stibonium salts 6d with the enolate anion of
2-phenyl-1,3-indandione in refluxing dichloromethane-THF,
and these reactions gave the onium enolates 16b,d .
P h osp h on iu m en ola te 16b: 81%; reddish needles; mp
162-164 °C (recrystallized from dichloromethane-hexane); IR
(KBr) 1604, 1538, 1108, 769 cm-1; 1H NMR (300 MHz, CDCl3)
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Areas
(A) “The Chemistry of Inter-element Linkage” (No.
09239102) from the Ministry of Education, Science,
Sports, and Culture, J apan.
3
5
3
δ 8.53 (d, J HH ) 7.5 Hz, 2H), 7.69 (dt, J PH ) 2.1 Hz, J HH
)
4
3
7.5 Hz, 3H), 7.56 (dt, J PH ) 3.4 Hz, J HH ) 7.5 Hz, 6H), 7.40
3
3
(dd, J PH ) 13.4 Hz, J HH ) 7.5 Hz, 6H), 7.31-7.22 (m, 2H),
3
3
7.19-7.11 (m, 2H), 7.10 (t, J HH ) 7.5 Hz, 2H), 6.79 (t, J HH
)
7.5 Hz, 1H), 6.02 (d, 2J PH ) 22.9 Hz, 1H), 2.23 (s, 3H), 1.53 (d,
4J PH ) 2.2 Hz, 3H); HRMS (FAB) calcd for C22H22P [(M -
J O990963K