Reactions of Diphenyl(phenylethynyl)selenonium Salts with Active Methylene Compounds and Amides: First Isolation of Oxyselenuranes [10-Se-4(C3O)] as a Reaction Intermediate

Article abstract of DOI:10.1021/jo980999x

The reaction of the diphenyl(phenylethynyl)selenonium triflate 1a with active methylene compounds 5 and t-BuOK in THF gave furan derivatives 6. The [10-Se-4(C3O)l selenuranes 8a and 8b could be isolated from the reactions with benzoylacetonitrile 5f and with 1,3-indandione 5g, respectively, as reaction intermediates. The structures of the selenuranes 8 were elucidated by X-ray crystallography and ⁷⁷Se high-resolution solid-state NMR spectroscopy. The selenuranes 8 underwent ligand coupling on standing at room temperature or refluxing in chloroform and gave the furan derivatives 6 and the ring-opened product 9. Similarly, the reaction of 1a with benzamide 13a and pivalamide 13d in the presence of NaH in THF afforded oxazole derivatives 14.

Full text of DOI:10.1021/jo980999x

6382
J . Org. Chem. 1998, 63, 6382-6386
Rea ction s of Dip h en yl(p h en yleth yn yl)selen on iu m Sa lts w ith
Active Meth ylen e Com p ou n d s a n d Am id es: F ir st Isola tion of
Oxyselen u r a n es [10-Se-4(C3O)] a s a Rea ction In ter m ed ia te
Tadashi Kataoka,*,† Shin-ichi Watanabe,† Keiichirou Yamamoto,† Mitsuhiro Yoshimatsu,‡
Genzoh Tanabe,§ and Osamu Muraoka§
Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, J apan, Faculty of
Education, Gifu University, 1-1 Yanagido, Gifu 501-1193, J apan, and Faculty of Pharmaceutical
Sciences, Kinki University, 3-4-1 Kowakae, Higashi-osaka, Osaka 577-8502, J apan
Received May 26, 1998
The reaction of the diphenyl(phenylethynyl)selenonium triflate 1a with active methylene compounds
5 and t-BuOK in THF gave furan derivatives 6. The [10-Se-4(C3O)] selenuranes 8a and 8b could
be isolated from the reactions with benzoylacetonitrile 5f and with 1,3-indandione 5g, respectively,
as reaction intermediates. The structures of the selenuranes 8 were elucidated by X-ray
crystallography and 77Se high-resolution solid-state NMR spectroscopy. The selenuranes 8
underwent ligand coupling on standing at room temperature or refluxing in chloroform and gave
the furan derivatives 6 and the ring-opened product 9. Similarly, the reaction of 1a with benzamide
13a and pivalamide 13d in the presence of NaH in THF afforded oxazole derivatives 14.
Sch em e 1
In tr od u ction
Many kinds of hypervalent organoselenium compounds
have been synthesized, and their detailed structures and
reactivities have been reported.1 In particular, the
haloselenuranes [10-Se-4(C2OHal)]2 and the alkoxyse-
lenuranes [10-Se-4(O4)]3 and [10-Se-4(C2O2)]4 were widely
studied because they bear electronegative ligands and are
stable. The σ-selenuranes with four carbon-selenium
bonds [10-Se-4(C4)] have been extensively studied by
Furukawa’s group.5 Generation of the selenuranes bear-
ing three carbon-selenium bonds and an oxygen-
selenium bond [10-Se-4(C3O)] has been investigated by
1H, 13C, and 77Se NMR spectroscopy of the reaction of bis-
(2,2′-biphenylene)selenurane with various alcohols or
phenol; however, isolation of the σ-selenurane has been
unsuccessful.6
We reported the synthesis of diphenyl(phenylethynyl)-
selenonium triflate 1a and its reactions with sodium
benzenesulfinate (Scheme 1).7 Very recently, the oxyse-
lenuranes [10-Se-4(C3O)] were fortunately obtained from
the reactions of the selenonium salt 1a with active
methylene compounds. Therefore, this paper reports the
reactions of the alkynylselenonium salts with active
methylene compounds and amides and the first isolation
of the [10-Se-4(C3O)] σ-selenuranes.
† Gifu Pharmaceutical University.
‡ Gifu University.
Resu lts a n d Discu ssion
§ Kinki University.
(1) (a) Paulmier, C. Selenium Reagents and Intermediates in Organic
Synthesis; Pergamon Press: Oxford, 1986. (b) Bergman, J .; Engman,
L.; Side´n, J . The Chemistry of Organic Selenium and Tellurium
Compounds; J ohn Wiley & Sons Ltd.: New York, 1986; Vol. 1, pp 517-
558. (c) Back, T. G. The Chemistry of Organic Selenium and Tellurium
Compounds; J ohn Wiley & Sons Ltd.: New York, 1987; Vol. 2, pp 91-
214.
(2) (a) Kataoka, T.; Shimizu, H.; Tomimatsu, K.; Tanaka, K.; Hori,
M.; Kido, M. Chem. Pharm. Bull. 1990, 38, 874-881. (b) Takahashi,
T.; Kurose, N.; Kawanami, S.; Arai, Y.; Koizumi, T. J . Org. Chem. 1994,
59, 3262-3264. (c) Takahashi, T.; Kurose, N.; Koizumi, T. Chem. Lett.
1995, 379-380.
(3) Denney, D. B.; Denney, D. Z.; Hammond, P. J .; Hsu, Y. F. J .
Am. Chem. Soc. 1981, 103, 2340-2347.
(4) (a) Paetzold, R.; Lindner, U. Z. Anorg. Chem. 1967, 350, 295-
299. (b) Horn, V.; Paetzold, R. Z. Anorg. Chem. 1973, 398, 186-192.
(c) Reich, H. J . J . Am. Chem. Soc. 1973, 95, 964-966. (d) Marino, J .
P.; Larsen, J . R. D. J . Am. Chem. Soc. 1981, 103, 4642-4643. (e)
Nakanishi, W.; Ikeda, Y.; Iwamura, H. J . Org. Chem. 1982, 47, 2275-
2278. (f) Kawashima, T.; Ohno, F.; Okazaki, R. J . Am. Chem. Soc. 1993,
115, 10434.
(5) (a) Hellwinkel, D.; Fahrbach, G. Liebigs Ann. Chem. 1968, 715,
68-73. (b) Ogawa, S.; Sato, S.; Erata, T.; Furukawa, N. Tetrahedron
Lett. 1991, 32, 1915-1918 (c) Ogawa, S.; Sato, S.; Erata, T.; Furukawa,
N. Tetrahedron Lett. 1991, 32, 3179-3182. (d) Ogawa, S.; Sato, S.;
Furukawa, N. Tetrahedron Lett. 1992, 33, 7925-7928. (e) Sato, S.;
Furukawa, N. Tetrahedron Lett. 1995, 36, 2803-2806.
We investigated the reaction of trimethyl(phenylethy-
nyl)silane and diphenyl selenoxide 2a with a Lewis acid
in CH2Cl2 to prepare the alkynyldiarylselenonium salts.
When BF3‚Et2O was used as a Lewis acid, an alkynylse-
lenonium salt was not obtained at all. In contrast, the
reaction with trifluoromethanesulfonic anhydride (Tf2O),
which is extremely strong Lewis acid, afforded diphenyl-
(phenylethynyl)selenonium triflate 1a in 89% yield (Table
1). The reaction with a milder Lewis acid, trimethylsilyl
trifluoromethanesulfonate, in comparison with Tf2O gave
1a in only 20% yield. The structure of 1a was determined
from its spectral data. The 13C NMR spectrum indicated
the presence of the alkynylic carbons at δ 64.7 and 110.9
and the quaternary carbon of CF3SO3- at δ 120.9 (q, J C-F
) 319.8 Hz). An absorption band of the alkynyl group
showed at 2181 cm-1 in the IR spectrum. The FABMS
(6) (a) Sato, S.; Furukawa, N. Chem. Lett. 1994, 889-892. (b) Sato,
S.; Kondo, N.; Furukawa, N. Organometallics 1994, 13, 3393-3395.
(7) Kataoka, T.; Banno, Y.; Watanabe, S.; Iwamura, T.; Shimizu,
H. Tetrahedron Lett. 1997, 38, 1809-1812.
S0022-3263(98)00999-2 CCC: $15.00 © 1998 American Chemical Society
Published on Web 08/07/1998

Reactions of Diphenyl(phenylethynyl)selenonium Salts
J . Org. Chem., Vol. 63, No. 18, 1998 6383
Ta ble 1. Rea ction s of Dia r yl Selen oxid e a n d
Tr im eth yl(p h en yleth yn yl)sila n e w ith Lew is Acid
Sch em e 3
entry
2
Lewis acid time products (% yield)
1a
2
3
2a : Ar ) Ph
2a
2a
BF3‚Et2O
Tf2O
TMSOTf
17 h no reaction
12 h 1a : X ) TfO (89)
4 d
1a (20)
4
2b: Ar ) p-tolyl Tf2O
12 h 1b: X ) TfO (69)
a
Treatment with aqueous NaBF4.
Sch em e 2
Ta ble 2. Rea ction s of 1 w ith Active Meth ylen e
Com p ou n d s 5
products
(% yield)
entry
1
5
T (°C) time
rt 1 d
reflux 1 h
reflux 1 h
reflux 2 h
1
2
3
4
5
6
7
8
9
1a 5a (R1: MeCO, R2: Me)
1a 5a
6a (40) 7a (62)
6a (58) 7a (88)
6b (80) 7a (86)
6c (53) 7a (97)
6d (83) 7a (97)
6e (58) 7a (97)
8a (70)
6f (63) 7a (77)
8b (39)
6 g (2) 7a (24)
8b (30) 9a (8)
8c (63)
spectrum showed fragment ion peaks arising from the
cation moiety of 1a . Di-p-tolyl(phenylethynyl)selenonium
triflate1b was prepared (69%) in a manner similar to that
for 1a . A plausible reaction mechanism for formation of
1 is shown in Scheme 2. The reaction of diaryl selenoxide
2 with Tf2O forms bis(trifluoromethanesulfonyl)selenurane
3 (or their ionic form),4d,8 and then the selenurane 3
reacts with (trimethylsilyl)alkyne to afford an evidently
unstable intermediate 4, which rapidly decomposes to
form 1 and trimethylsilyl triflate.
1a 5b (R1: PhCO, R2: Me)
1a 5c (R1: PhCO, R2: Ph)
1a 5d (R1: MeOCO, R2: Me) reflux 1 h
1a 5e (R1: EtOCO, R2: Ph) reflux 1 h
1a 5f (R1: CN, R2: Ph)
1a 5f
rt
reflux 1 h
rt 1 d
reflux 1 h
1 d
1a 5g (1,3-indandione)
1a 5g
10
11
1b 5g
rt
3 h
NMR spectroscopy10 and compared the 77Se NMR chemi-
cal shifts with those in the solutions. Although the cross-
polarization magic-angle spinning (CP/MAS) 77Se NMR
experiment11 of the selenonium salt 1a showed a chemical
shift (δ 467.7) almost similar to that in a CDCl3 solution
(δ 469.6), the chemical shifts of 8a and 8b in the solid
state (8a , δ 454.1; 8b, δ 451.3) were different from those
monitored in CDCl3 solutions (8a , δ 462.2; 8b, δ 476.2)
and shifted to higher field at about 8.1 and 24.9 ppm,
respectively. These high-field shifts in the solid state
might be attributable to the different structure in each
state. Thus, the results suggested that the intermediate
8 in the solid state might be the selenurane form A.12
The crystal structure of the intermediate 8a was
established more clearly by X-ray diffraction analysis
(Figure 1).13 The apical-bond distance of Se-O (2.553
Å) is shorter than the sum of the van der Waals radii
(3.40 Å). The O-Se-Cap bond angle of 173.5° is ap-
proximately collinear and close to those of other se-
lenuranes.2,4 The quadruple average angle of 8a (111.3°)
coincided with the mean values (ca. 112°) in the
The reaction of 1a with 2,4-pentanedione 5a and
t-BuOK in THF gave a furan derivative 6a 9 (40%) and
diphenyl selenide 7a (62%). The yield of this reaction
was much improved by refluxing the reaction mixture.
The reactions with other active methylene compounds
under the refluxing conditions similarly gave the corre-
sponding furan derivatives in high yields except the
reaction with 1,3-indandione 5g affording 6g (2%), 7a
(24%), 8b (30%), and 9a (8%). In sharp contrast, the
reactions with benzoylacetonitrile 5f and 1,3-indandione
5g at room temperature only gave the products 8a and
8b in yields of 70% and 39%, respectively. Similarly the
reaction of 1b with 5g afforded the compound 8c in good
yield (Scheme 3, Table 2). J udging from thermal reac-
tions of the compounds 8a -c as described below, it was
assumed that these products would be the reaction
intermediates to form the furan derivatives 6f and 6g or
a ring-opened coupling product 9a . The structures of
8a -c were characterized by NMR (1H, 13C, 77Se) spec-
troscopy, mass spectrometry, and elemental analysis. In
particular, the olefinic protons of 8a , 8b, and 8c were
observed at δ 5.45, 5.55, and 5.54, respectively, at higher
field than that of the (Z)-(â-phenylsulfonyl)vinylsele-
nonium triflate (δ 7.22).7 This result implied that the
structure of 8 might not be the ionic form. To solve the
question of whether the intermediate is a hypervalent
compound A or a betaine B, we measured the solid-state
(10) Fyfe, C. A. Solid State NMR for Chemists; C. F. C. Press:
Ontario, 1983.
(11) Potrzebowski, M. J .; Blaszczyk, J .; Wieczorek, M. W.; Misiura,
K.; Stec, W. J . J . Chem. Soc., Perkin Trans. 2 1997, 163-168.
(12) (a) Odom, J . D.; Dawson, W. H.; Ellis, P. D. J . Am. Chem. Soc.
1979, 101, 5815-5822. (b) McFarlawe, W.; Wood, R. J . J . Chem. Soc.,
Dalton Trans. 1972, 1397-1402.
(13) Crystallographic data for 8a :
C29H21NOSe, MW ) 478.451,
(8) (a) Okamoto, Y.; Chellappa, K. L.; Homsany, R. J . Org. Chem.
1973, 38, 3172-3175. (b) Nenajdenko, V. G.; Vertelezkij, P. V.;
Balenkova, E. S. Synthesis 1997, 351-355.
(9) Harigya, Y.; Yamamoto, T.; Okawara, M. Chem. Lett. 1974, 2,
101-102.
triclinic, space group P1h (#2), a ) 10.867 (2) Å, b ) 11.553(2) Å, c )
9.634(1) Å, R ) 91.70(1)°, â ) 102.68(1)°, γ ) 103.46(1)°, V ) 1143.4-
(3) Å3, Z ) 2, Dcalcd ) 1.390 g/cm3, µ(Mo KR) ) 16.43 cm-1, R ) 3.8%,
Rw ) 4.2%. Full details of the crystallographic analysis of 8a are
described in the Supporting Information.

6384 J . Org. Chem., Vol. 63, No. 18, 1998
Kataoka et al.
Sch em e 5
obtained. The reaction was completed in 8 h under reflux
in chloroform. The reaction of 8b proceeded slowly to
give a furan derivative 6g (13%), 7a (60%), and a ring-
opened product 9a (29%). The structure of the selenide
9a was determined from the result of spectral data. The
1H NMR spectrum of 9a showed a singlet at δ 6.93
assignable to a vinyl proton. The electron impact MS
showed the molecular ion peak at m/z 480 and the base
peak at m/z 323 due to a fragment ion peak of [M -
PhSe]+. The reaction of 8c similarly afforded 6g (52%),
7b (87%), and a small amount of a mixture of (E)- and
(Z)-9b (4%). Two reaction pathways can be considered
for the formation of the furan derivative. If the reactions
proceed via the betaine 11, which is formed by addition
of an alkoxide ion to the vinylselenonium ion and the
subsequent elimination of diphenyl selenide, the selenide
9a cannot be formed. Thus, the addition-elimination
F igu r e 1. ORTEP drawing of 8a .
Ta ble 3. Decom p osition of Selen u r a n es 8
products (%yield)
entry
8
T (°C) time
8a rt 3 d
8a reflux 8 h
8a rt 3 d
1
6f (77) 7a : Ar ) Ph (81)
6f (87) 7a (85)
6f (75) 7a (90)
2
3a
4
8b reflux 3 d
8c reflux 3 d
6g (13) 7a (60)
9a (29)
5
6g (52) 7b: Ar ) p-tolyl (87)b 9b (4)
a
b
Addition of 10 equiv of CH3I. A mixture of (E)- and (Z)-9b.
Sch em e 4
literature.1b The configuration about the selenium atom
is a slightly distorted trigonal bipyramid with two apical
Se-O and Se-Ph bonds and two equatorial Se-Cd and
Se-Ph bonds, and the lone-pair electrons occupy the
third equatorial position. These structural features are
consistent with a σ-selenurane structure.
If the compound 8a has a betaine structure B, the
O-methylation would occur by treatment of 8a with
iodomethane and a methoxy selenonium salt 10 would
be formed. However, the reaction did not give the
mechanism is not feasible for this reaction. The second
route to 6 and 9a is a pathway going through the
selenurane intermediate 8. The ligand coupling reaction
of 8 between the alkoxy group and the alkenyl carbon
and between the alkoxy group and the phenyl group gives
6 and 9a , respectively. We conducted the crossover
reaction of 8b and 8c to examine the possibility that 9a
might be formed via the intermolecular ipso attack of the
alkoxide ion on the phenyl group (Scheme 5). A thermal
reaction of the mixture of 8b and 8c in chloroform gave
6g (36%), 7a (86%), 7b (86%), and a mixture of 9a (8%)
and 9b (2%). If the crossover reaction proceeded, the
crossed products 9c or 9d should be formed. Since the
MS spectra of the concentrated reaction mixture did not
show the molecular ion peaks of 9c and 9d , this reaction
route was ruled out. The intramolecular ipso substitu-
tion must go through a seven-membered cyclic interme-
diate 12, and therefore, the ligand coupling reaction via
the hypervalent intermediate 8 mentioned above is more
favorable for formation of 6 and 9a . It has been reported
that reactions of alkynyliodonium salts with â-ketosul-
fone and â-ketonitrile gave furan derivatives via alky-
selenonium salt 10 but gave the furan derivative 6f (75%)
and the selenide 7a (90%) (entry 3 in Table 3). Further-
more, we chemically observed that the compounds 8a and
8b underwent the ligand-coupling reactions to form 6f,
6g, and 7a (Scheme 4). When a solution of 8a in
chloroform was allowed to stand at room temperature for
3 days, a furan derivative 6f (77%) and 7a (81%) were

Reactions of Diphenyl(phenylethynyl)selenonium Salts
J . Org. Chem., Vol. 63, No. 18, 1998 6385
Sch em e 6
Exp er m en ta l Section
Gen er a l P r oced u r es. Uncorrected melting points were
determined with a micro melting point apparatus. 1H (270 or
400 MHz), 13C (100 MHz), and 77Se (76.1 MHz) NMR spectra
were determined with solutions in CDCl3. Mass spectra (MS
and HRMS) were obtained with electron impact (EI, 70 eV) or
fast atom bombardment (FAB, glycerol or 3-nitrobenzyl alco-
hol) techniques. IR spectra were recorded as solids (KBr) and
liquids (NaCl). Organic solvents used were dried by standard
methods. All chromatographic isolations were accomplished
with Kieselgel 60 PF254 containing gypsum for preparative
TLC.
Ta ble 4. Rea ction s of 1a w ith Am id es 13
Dip h en yl(p h en yleth yn yl)selen on iu m Tr iflu or om eth -
a n esu lfon a te (1a ). Trifluoromethanesulfonic anhydride (1.5
mL, 8.9 mmol) was added dropwise to a stirred solution of
diphenyl selenoxide (1.0 g, 4.0 mmol) and 1-phenyl-2-(trim-
ethylsilyl)ethyne (1.5 g, 8.6 mmol) in dichloromethane (30 mL)
at 0 °C. The mixture was stirred at room temperature for 12
h. After the solvent was evaporated under reduced pressure,
the precipitate was filtered off and washed several times with
ether and benzene. Recrystallization from CH2Cl2/Et2O af-
forded 1.72 g (89%) of 1a as white prisms: mp 117 °C; IR (KBr)
2181, 1270, 1154, 1029 cm-1; 1H NMR (CDCl3) δ 8.06 (d, 4H),
7.77-7.57 (m, 9H), 7.48 (t, 1H); 13C NMR (CDCl3) δ 133.8,
133.4, 132.7, 131.8, 130.8, 130.2, 129.3, 120.9 (q, J ) 319.8
Hz), 118.1, 110.9, 64.7; 77Se NMR (CDCl3) δ 469.6; 77Se CP-
MAS NMR δ 467.7; FAB MS m/z 335 [(M - TfO)+]. Anal.
Calcd for C21H15F3O3SSe: C, 52.18; H, 3.13. Found: C, 52.08;
H, 3.24.
products (%yield)
entry
13
1
2
3
4
13a (R ) Ph)
13b (R ) H)
13c (R ) Me)
13d (R ) t-Bu)
14a (50)
7 (56)
7 (19)
7 (6)
2a (40)
2a (44)
2a (78)
2a (44)
14b (27)
7 (43)
lidene carbene intermediates.14 Our findings were much
different from these and particularly interesting in terms
of the formation of the hypervalent intermediates.
If amides are used instead of the active methylene
compounds, formation of oxazole derivatives can be
expected. We conducted the reaction of 1a with benza-
mide 13a and NaH in THF and obtained 2,4-dipheny-
loxazole 14a (50%), 7a (56%), and 2a (40%) (Scheme 6,
Table 4). The structure of the compound 14a was
Di-p-tolyl(p h en yleth yn yl)selen on iu m Tr iflu or om eth -
a n esu lfon a te (1b). Trifluoromethanesulfonic anhydride (0.75
mL, 4.5 mmol) was added dropwise to a stirred solution of di-
p-tolyl selenoxide (554 mg, 2.0 mmol) and 1-phenyl-2-(trim-
ethylsilyl)ethyne (750 mg, 4.3 mmol) in dichloromethane (15
mL) at 0 °C. The mixture was stirred at room temperature
for 12 h. After the solvent was evaporated under reduced
pressure, the precipitate was filtered off and washed several
times with ether and benzene. Recrystallization from CH2-
Cl2/Et2O afforded 703 mg (69%) of 1b as white prisms: mp
determined by comparing its H and 13C NMR spectral
1
data with those of an authentic sample in the literature.15
The reactions with formamide 13b and acetamide 13c
did not afford any oxazole derivatives but the complex
mixtures. The selenonium salt 1a reacted with pivala-
mide 13d to give 14b16 in low yield. The oxazole
derivatives would be formed by the ligand-coupling
reaction of the hypervalent intermediate similar to
formation of furans. The amide ion adds to the Câ to the
selenonio group of 1a and produces the Michael adduct
C. The subsequent protonation of the CR and the attack
of the resulting lactim anion -NdC-O- on the selenium
atom form the selenurane intermediate D. The ligand
coupling between the oxygen atom and the alkenyl carbon
affords an oxazole derivative. Diphenyl selenoxide 2a
would be produced by hydrolysis of 1a , probably because
the reactions were slow.
1
116-118 °C; IR (KBr) 2175, 1270, 1155, 1029 cm-1; H NMR
(CDCl3) δ 7.90 (d, 4H), 7.66 (d, 2H), 7.56 (t, 1H), 7.46 (t, 2H),
7.41 (d, 4H), 2.43 (s, 6H); 13C NMR (CDCl3) δ 144.7, 133.1,
132.3, 132.1, 129.9, 129.1, 127.2, 120.7 (q, J ) 319.8 Hz), 118.0,
109.9, 64.8, 21.5; FAB MS m/z 363 [(M - TfO)+]. Anal. Calcd
for C23H19F3O3SSe: C, 54.02; H, 3.74. Found: C, 54.02; H,
3.67.
Gen er a l P r oced u r e for Rea ction s of Alk yn ylselen on -
iu m Sa lts 1 w ith Active Meth ylen e Com p ou n d s 5.
A
Typ ica l Exa m p le (Ta ble 2, En tr y 1): 3-Acetyl-2-m eth yl-
4-p h en ylfu r a n (6a ). To a stirred solution of 2,4-pentanedione
5a (20 mg, 0.20 mmol) in THF (3 mL) was added 90% t-BuOK
(25 mg, 0.20 mmol) at room temperature under argon. After
the mixture was stirred for 30 min, the selenonium triflate
1a (97 mg, 0.20 mmol) was added, and the mixture was stirred
for 1 d at room temperature. The mixture was quenched with
water and extracted with chloroform. The organic phase was
washed with brine, dried over anhydrous MgSO4, and concen-
trated. Preparative TLC (10:1 hexanes-ethyl acetate) of the
crude product gave 7a (29 mg, 62%) and 6a (16 mg, 40%). 6a :
1
colorless oil; IR (neat) 1674 cm-1; H NMR (CDCl3) δ 7.42-
In conclusion, the reactions of alkynylselenonium salts
1 with active methylene compounds and amides gave
furan and oxazole derivatives, respectively, and we have
isolated the first selenuranes with three carbon-sele-
nium bonds and an oxygen-selenium bond [10-Se-
4(C3O)] as reaction intermediates. Their selenurane
structures were established by the 77Se NMR spectros-
copy and X-ray crystallography as well as their chemical
behavior giving the ligand coupling products.
7.35 (m, 3H), 7.32 (d, 2H), 7.23 (s, 1H), 2.56 (s, 3H), 2.05 (s,
3H); 13C NMR (CDCl3) δ 195.1, 158.6, 138.0, 132.4, 129.2,
128.4, 127.7, 126.7, 122.2, 30.9, 14.3; MS m/z (relative inten-
sity) 200 (71, M+), 185 (100); HRMS calcd for C13H12O2 (M+)
200.0837, found 200.0840.
The mixture of 2,4-pentanedione 5a (20 mg, 0.20 mmol),
90% t-BuOK (25 mg, 0.20 mmol), and the selenonium triflate
1a (97 mg, 0.20 mmol) in THF (3 mL) was refluxed for 1 h in
a manner similar to that of the above experiment. Preparative
TLC (5:1 hexanes-ethyl acetate) of the crude products gave
7a (41 mg, 88%) and 6a (23 mg, 58%).
The products and their yields are listed in Table 2.
3-Ben zoyl-2-m eth yl-4-p h en ylfu r a n (6b): colorless oil; IR
(neat) 1652 cm-1; 1H NMR (CDCl3) δ 7.72 (d, 2H), 7.44 (s, 1H),
7.39 (t, 1H), 7.26 (t, 2H), 7.16-7.12 (m, 5H), 2.37 (s, 3H); 13C
NMR (CDCl3) δ 192.5, 157.2, 138.1, 137.6, 132.7, 131.4, 129.5,
(14) Ochiai, M.; Kunishima, M.; Nagao, Y.; Fuji, K.; Shiro, M.; Fujita,
E. J . Am. Chem. Soc. 1986, 108, 8281-8283.
(15) Prager, R. H.; Smith, J . A.; Weber, B.; Williams, C. M. J . Chem.
Soc., Perkin Trans. 1 1997, 2665-2672.
(16) Vernin, G.; Treppendahl, S.; Metzger, J . V. Helv. Chim. Acta
1977, 60, 284-297.

6386 J . Org. Chem., Vol. 63, No. 18, 1998
Kataoka et al.
128.2, 128.1, 128.0, 127.5, 126.9, 120.5, 31.8; MS m/z (relative
intensity) 262 (100, M+), 261 (95), 185 (14); HRMS calcd for
C18H14O2 (M+) 262.0994, found 262.1001.
Decom p osition of 8a . (a) A solution of compound 8a (96
mg, 0.20 mmol) in chloroform (3 mL) was stirred at room
temperature for 3 d. After the solution was concentrated, the
residue was purified by preparative TLC (5:1 hexanes-ethyl
acetate) to give 7a (38 mg, 81%) and 6f (38 mg, 77%). (b) A
solution of compound 8a (128 mg, 0.27 mmol) in chloroform
(10 mL) was refluxed for 8 h and similarly worked up as above
to give 7a (53 mg, 85%) and 6f (57 mg, 87%).
Tr ea tm en t of 8a w ith Iod om eth a n e. Compound 8a (96
mg, 0.20 mmol) was stirred with 95% iodomethane (300 mg,
2.0 mmol) in chloroform (3 mL) at room temperature for 3 d.
After the solution was concentrated, the residue was purified
by preparative TLC (5:1 hexanes-ethyl acetate) to give 7a (42
mg, 90%) and 6f (37 mg, 75%).
3-Ben zoyl-2,4-d ip h en ylfu r a n (6c): colorless oil; IR (neat)
1
1660 cm-1; H NMR (CDCl3) δ 7.85 (d, 2H), 7.67 (s, 1H), 7.58
(d, 2H), 7.42 (t, 1H), 7.28-7.17 (m, 10H); 13C NMR (CDCl3) δ
193.8, 153.4, 138.6, 137.4, 133.5, 131.1, 129.8, 129.7, 128.9,
128.5, 128.4, 127.8, 127.4, 126.4, 120.3; MS m/z (relative
intensity) 324 (100, M+), 247 (25), 105 (67); HRMS calcd for
C
23H16O2 (M+) 324.1150, found 324.1160.
Meth yl 2-m eth yl-4-p h en yl-3-fu r a n ca r boxyla te (6d ): col-
1
orless oil; IR (neat) 1716 cm-1; H NMR (CDCl3) δ 7.36-7.30
(m, 5H), 7.26 (s, 1H), 3.71 (s, 3H), 2.60 (s, 3H); 13C NMR
(CDCl3) δ 164.5, 160.3, 138.3, 131.9, 129.1, 127.8, 127.4, 127.3,
112.5, 51.0, 14.3; MS m/z (relative intensity) 216 (100, M+),
185 (64), 184 (60), 128 (47), 127 (33). Anal. Calcd for
Decom p osition of 8b. A solution of compound 8b (62 mg,
0.13 mmol) in chloroform (10 mL) was treated in a manner
similar to that for 8a and gave 7a (18 mg, 60%), 6g (4 mg,
13%), and 9a (18 mg, 29%).
C
13H12O3: C, 72.21; H, 5.59. Found: C, 72.28; H, 5.78.
Eth yl 2,4-d ip h en yl-3-fu r a n ca r boxyla te (6e): colorless
Decom p osition of 8c. A solution of compound 8c (92 mg,
0.18 mmol) in chloroform (10 mL) was treated in a manner
similar to that for 8a and gave 7b (41 mg, 87%), 6g (23 mg,
52%), and a mixture of (E)- and (Z)-3-p-methylphenoxy-2-[1-
phenyl-2-(p-tolylseleno)ethenyl]inden-1-one 9b (4 mg, 4%).
oil; IR (neat) 1720 cm-1; 1H NMR (CDCl3) δ 7.82 (d, 2H), 7.49
(s, 1H), 7.46-7.32 (m, 8H), 4.18 (q, 2H), 1.07 (t, 3H); 13C NMR
(CDCl3) δ 164.6, 156.5, 139.0, 131.7, 129.9, 129.1, 128.7, 128.5,
128.2, 128.1, 127.7, 127.5, 113.9, 60.8, 13.7; MS m/z (relative
intensity) 292 (100, M+), 247 (53), 105 (83); HRMS calcd for
1
9b: pale yellow oil; IR (neat) 1707 cm-1; H NMR (CDCl3) δ
C
19H16O3 (M+) 292.1099, found 292.1107.
7.99 (m, 0.5H), 7.90 (m, 2H), 7.81 (m, 0.5H), 7.74 (m, 2H), 7.
49 (d, 2H), 7.28-7.01 (m, 17H), 6.95 (d, 0.5H), 6.88 (s, 0.25H),
6.57 (s, 1H), 2.29 (s, 6H), 2.27 (s, 0.75H), 2.19 (s, 0.75H); MS
m/z (relative intensity) 508 (35, M+), 506 (18), 337 (100), 309
(20), 265 (45); HRMS calcd for C31H24O2Se (M+) 508.0941,
found 508.0936.
5-Cya n o-2,2,4,6-tetr a p h en yl-1,2-oxa selen in (8a ) was ob-
tained as a pale yellow powder. This compound was pure
enough to use its analysis and reactions: mp 139-141 °C dec;
1
IR (KBr) 2185 cm-1; H NMR (CDCl3) δ 7.64 (d, 4H), 7.58-
7.49 (m, 7H), 7.43-7.36 (m, 5H), 7.28-7.24 (m, 4H), 5.45 (s,
1H); 13C NMR (CDCl3) δ 186.0, 157.0, 141.01, 140.97, 132.7,
131.8, 130.5, 129.7, 129.5, 129.30, 129.27, 129.0, 128.4, 127.6,
127.5, 124.7, 95.6, 79.7; 77Se NMR (CDCl3) δ 462.2; 77Se CP-
MAS NMR δ 454.1; FAB MS m/z 480 (M + 1)+. Anal. Calcd
for C29H21NOSe: C, 72.80; H, 4.42; N, 2.93. Found: C, 72.67;
H, 4.42; N, 2.84.
Cr ossover Rea ction of 8b a n d 8c. A solution of the
mixture of 8b (73 mg, 0.15 mmol) and 8c (77 mg, 0.15 mmol)
in chloroform (10 mL) was refluxed for 3 d. After the solution
was concentrated, the residue was purified by preparative TLC
(5:1 hexanes-ethyl acetate) to give a mixture of 7a (31 mg,
87%) and 7b (34 mg, 86%), 6g (27 mg, 36%), a mixture of 9a
(7 mg, 8%) and 9b (1 mg, 2%), and an unidentified product
(27 mg). The ratio of the products in a mixture was deter-
3-Cya n o-2,4-d ip h en ylfu r a n (6f): white powder; mp 89 °C;
1
IR (neat) 2231 cm-1; H NMR (CDCl3) δ 8.03 (d, 2H), 7.63 (d,
2H), 7.62 (s, 1H), 7.51-7.43 (m, 5H), 7.38 (t, 1H); 13C NMR
(CDCl3) δ 161.0, 138.3, 130.2, 129.2, 129.0, 128.7, 128.5, 128.0,
126.9, 125.5, 115.2, 91.5; MS m/z (relative intensity) 245 (100,
M+), 216 (35), 189 (15); HRMS calcd for C17H11NO (M+)
245.0841, found 245.0848.
1
mined by H NMR.
Gen er a l P r oced u r e for Rea ction s of Alk yn ylselen on -
iu m Sa lts 1a w ith Am id es 13. A Typ ica l Exa m p le (Ta ble
4, En tr y 1). To a stirred solution of benzamide 13a (24 mg,
0.20 mmol) in THF (3 mL) was added 60% NaH (8 mg, 0.20
mmol) at room temperature under argon. After the mixture
was stirred for 30 min, the selenonium triflate 1a (97 mg, 0.20
mmol) was added, and then the mixture was refluxed for 3 h.
The mixture was quenched with NH4Cl (aq) and extracted with
chloroform. The organic phase was washed with brine, dried
over anhydrous MgSO4, and concentrated. Preparative TLC
(5:1 hexanes-ethyl acetate and 10:1 chloroform-methanol) of
the crude product gave 2,4-diphenyloxazole 14a (22 mg, 50%),
7a (26 mg, 56%), and 2a (20 mg, 40%). 14a : a white powder;
2,2,4-Tr ip h en yl-5H-in d en o[1,2-e]-1,2-oxa selen in (8b):
1
yellow powder; mp 146-148 °C dec; IR (KBr) 1660 cm-1; H
NMR (CDCl3) δ 7.67 (d, 4H), 7.60-7.51 (m, 6H), 7.50-7.46
(m, 2H), 7.43-7.31 (m, 7H), 5.55 (s, 1H); 13C NMR (CDCl3) δ
190.4, 156.3, 139.9, 139.4, 133.3, 131.8, 130.9, 130.5, 130.0,
129.3, 129.2, 128.8, 127.9, 119.4, 104.4, 96.2; 77Se NMR (CDCl3)
δ 476.2; 77Se CP-MAS NMR δ 451.3; MS m/z 480 (M+). Anal.
Calcd for C29H20O2Se‚1/2H2O: C, 71.31; H, 4.33. Found: C,
71.06; H, 4.54.
1
mp 101-102 °C; H NMR (CDCl3) δ 8.15-8.11 (m, 2H), 7.97
4-P h en yl-2,2-d i-p -t olyl-5H -in d en o[1,2-e]-1,2-oxa sele-
n in (8c): yellow powder: mp 119-123 °C dec; IR (neat) 1680
cm-1; 1H NMR (CDCl3) δ 7.53 (d, 4H), 7.49-7.46 (m, 2H), 7.41
(d, 2H), 7.39-7.36 (m, 2H), 7.35-7.31 (m, 7H) 5.54 (s, 1H),
2.42 (s, 6H); 13C NMR (CDCl3) δ 190.4, 155.7, 142.5, 140.0,
139.9, 139.4, 131.2, 130.9, 122.9, 129.8, 129.2, 128.7, 127.9,
119.3, 104.3, 97.3, 21.3; MS m/z 508 (M+). Anal. Calcd for
C13H12O3: C, 72.21; H, 5.59. Found: C, 72.28; H, 5.78.
3-P h en yl-4H-in d en o[1,2-b]fu r a n -4-on e (6g): yellow pow-
der; mp 129-130 °C; IR (neat) 1706 cm-1; 1H NMR (CDCl3) δ
7.88 (d, 2H), 7.78 (s, 1H), 7.51 (d, 1H), 7.43 (t, 2H), 7.33 (t,
2H), 7.22 (t, 1H), 7.16 (d, 1H); 13C NMR (CDCl3) δ 184.9, 176.0,
143.6, 138.4, 133.7, 133.0, 129.9, 129.2, 128.9, 128.2, 126.8,
126.0, 123.9, 121.6, 117.2; MS m/z (relative intensity) 246 (100,
M+), 189 (50); HRMS calcd for C17H10O2 (M+) 246.0681, found
246.0686.
(s, 1H), 7.83 (d, 2H), 7.51-7.46 (m, 3H), 7.43 (t, 2H), 7.34 (t,
1H); 13C NMR (CDCl3) δ 161.9, 142.0, 133.4, 133.4, 131.1,
130.4, 128.7, 128.1, 127.5, 126.5, 125.6; MS m/z (relative
intensity) 221 (100, M+), 193 (83). The melting point and
spectral data were identical with those of an authentic sample
in the literature.15
2-ter t-Bu tyl-4-p h en yloxa zole (14b):16 colorless oil; IR
(neat) 1566 cm-1; 1H NMR (CDCl3) δ 7.79 (s, 1H), 7.73 (d, 2H),
7.38 (t, 2H), 7.28 (t, 1H), 1.43 (s, 9H); 13C NMR (CDCl3) δ 171.5,
140.2, 132.7, 131.5, 128.6, 127.7, 125.6, 33.8, 28.6; MS m/z
(relative intensity) 201 (100, M+), 186 (73); HRMS calcd for
C13H15NO (M+) 201.1154, found 201.1150.
Ackn owledgm en t. The authors thank Central Glass
Co., Ltd, (Tokyo, J apan) for a generous gift of trifluo-
romethanesulfonic anhydride.
3-P h en oxy-2-[1-ph en yl-2-(ph en ylselen o)eth en yl]in den -
1-on e (9a ): pale yellow oil: IR (neat) 1707 cm-1 1H NMR
;
Su p p or tin g In for m a tion Ava ila ble: Details of the crys-
tallographic analysis of 8a (10 pages). This material is
contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
(CDCl3) δ 8.01 (m, 2H), 7.82 (m, 2H), 7.37-7.31 (m, 4H), 7.21-
7.07 (m, 11H), 6.93 (s, 1H); 13C NMR (CDCl3) δ 198.4, 143.2,
142.4, 135.7, 135.5, 132.2, 131.8, 129.4, 129.2, 128.5, 128.4,
127.9, 127.7, 127.6, 127.5, 127.3, 126.7, 123.9, 70.5; 77Se NMR
(CDCl3) δ 395.4; MS m/z (relative intensity) 480 (37, M+), 323
(100), 247 (40); HRMS calcd for C29H20O2Se (M+) 480.0628,
found 480.0622.
J O980999X