6926 J . Org. Chem., Vol. 64, No. 18, 1999
Notes
the eluent to afford triphenylbismuthine 6 (300 mg, 68%) and
phenyl 3-benzoyl-4-phenyl-4-oxobutanoate 5 (225 mg, 63%): mp
Sch em e 5
1
114-115 °C; H NMR δ 3.35 (d, 2H, J ) 6.5 Hz), 5.87 (t, 1H, J
) 6.5 Hz), 7.00-7.80 (m, 15H); MS (EI) m/z 105, 94, 77; IR (KBr)
1748 (CdO), 1690 (CdO), 1676 (CdO) cm-1. Anal. Calcd for
C
23H18O4: C, 77.08; H, 5.06. Found: C, 76.83; H, 4.98.
Rea ction of 3a w ith Tr ip h en ylp h osp h in e 7. A mixture of
3a (331 mg, 0.50 mmol), triphenylphosphine 7 (131 mg, 0.50
mmol), and CH2Cl2 (5 mL) was stirred at room temperature for
12 h. Removal of the solvent and subsequent dilution with Et2O
separated the crystals, which were filtered off, washed with
Et2O, and dried in vacuo to give (phenoxycarbonylmethyl)-
triphenylphosphonium tetrafluoroborate 8 (238 mg, 98%). The
filtrate was concentrated under reduced pressure to leave an
oily residue, which was recrystallized from MeOH to give
triphenylbismuthine 6 (195 mg, 89%). Compound 8: mp 160-
162 °C; 1H NMR δ 4.99 (d, 2H, J ) 13.8 Hz), 6.84 (d, 2H, J ) 8
Hz), 7.10-7.30 (m, 3H), 7.60-7.90 (m, 15H); MS (FAB) m/z 397
(M+ - BF4); IR (KBr) 1744 (CdO), 1200-1000 (BF4-) cm-1. Anal.
Calcd for C26H22BF4O2P: C, 64.49; H, 4.58. Found: C, 64.19; H,
4.54.
Rea ction of 3b w ith Sod iu m p-Tolu en esu lfin a te 9. A
mixture of 3b (331 mg, 0.50 mmol), sodium p-toluenesulfinate
tetrahydrate 9 (1.25 g, 5.0 mmol), and DMF (5 mL) was stirred
at room temperature for 24 h and then poured into water (10
mL). The organic layer was extracted with Et2O (10 mL × 3),
and the combined extracts were washed with brine (10 mL ×
3), dried over MgSO4, and concentrated under reduced pressure.
An oily residue was chromatographed on silica gel using hex-
anes-ethyl acetate as the eluent to yield triphenylbismuthine
6 (158 mg, 72%) and 4-methylphenyl p-toluenesulfonyl acetate
10 (85 mg, 56%): mp 112-113 °C; 1H NMR δ 2.33 (s, 3H), 2.45
(s, 3H), 4.31 (s, 2H), 6.89 (d, 2H, J ) 8.6 Hz), 7.15 (d, 2H, J )
8.6 Hz), 7.37 (d, 2H, J ) 8.3 Hz), 7.88 (d, 2H, J ) 8.3 Hz); MS
(EI) m/z 304 (M+); IR (KBr) 1757 (CdO), 1323 (SO2), 1167 (SO2)
cm-1. Anal. Calcd for C16H16O4S: C, 63.14; H, 5.30. Found: C,
63.17; H, 5.29.
Gen er a tion a n d Th er m a l Decom p osition of Bism u th o-
n iu m Ylid e 11c. To a suspension of 3c (628 mg, 1.0 mmol) in
THF (10 mL) was added KO-t-Bu (112 mg, 1.0 mmol) at -78
°C. After 10 min, the suspension turned to a yellow solution,
which was allowed to warm to gradually room temperature.
Evaporation of the solvent gave an oily residue that contained
triphenylbismuthine 6, diisopropyl maleate ((Z)-12), and diiso-
propyl fumarate ((E)-12). An E/ Z mixture of 12 was obtained
in 50% yield (50 mg; E/ Z ) 78/22) by chromatography on silica
gel.
Ba se-P r om oted Rea ction of 3 w ith Ca r bon yl Com -
p ou n d s. Typ ica l P r oced u r e. To a suspension of 3a (662 mg,
1.0 mmol) in THF (10 mL) was added KO-t-Bu (112 mg, 1.0
mmol) at -78 °C. The suspension turned to a yellow solution.
After 10 min, benzaldehyde 13a (0.10 mL, 1.0 mmol) was added,
and the resulting mixture was allowed to warm to room
temperature. Evaporation of the solvent gave an oily residue,
which was taken up with benzene. The benzene solution was
concentrated under reduced pressure to leave an oily residue,
which was subjected to 1H NMR determination to obtain the
isomeric ratio of R,â-epoxy ester 14a . Triphenylbismuthine 6
(361 mg, 82%) and 14a (86 mg, 36%) were isolated by column
chromatography on silica gel using hexanes-ethyl acetate as
the eluent. The stereochemistry of 14 was assigned on the basis
of the coupling constants of epoxy ring protons.
In summary, the Lewis-acid-promoted reaction of
triphenylbismuth difluoride with ketene silyl acetals
provides a general route to bismuthonium salts bearing
an R-ester group, which can be readily converted to the
corresponding ylides at low temperatures. Bismuthonium
R-ester ylides, Ph3BidCHCO2R, exhibit unique reactivity
toward carbonyl compounds, giving different types of
products according to the structure of substrates.
Exp er im en ta l Section
Gen er a l Meth od s. Triphenylbismuth difluoride15 and ketene
silyl acetals16 were prepared according to the reported proce-
dures. All reactions were carried out under an atmosphere of
argon. Column chromatography was performed on silica gel
(Wako-gel C200).
(Ar yloxyca r bon ylm eth yl)- a n d (Alk oxyca r bon ylm eth -
yl)tr ip h en ylbism u th on iu m Tetr a flu or obor a te (3): Gen -
er a l P r oced u r e. To a solution of triphenylbismuth difluoride
1 (2.39 g, 5.0 mmol) in CH2Cl2 (25 mL) was added at 0 °C BF3‚
OEt2 (0.62 mL, 5.0 mmol). After 1 h, silyl ketene acetal 2 (5.0
mmol) was added, and the resulting mixture was stirred for 12
h at room temperature. Evaporation of the solvent under reduced
pressure left an oily residue, which was passed through a short
silica gel column using CH2Cl2 as the eluent. Removal of the
solvent under reduced pressure gave a crystalline residue, which
was recrystallized from Et2O-CH2Cl2 (10:1) to afford bismu-
thonium salt 3.
(P h en oxyca r bon ylm eth yl)tr ip h en ylbism u th on iu m tet-
r a flu or obor a te (3a ): mp 165-166 °C; 1H NMR δ 4.85 (s, 2H),
6.69 (d, 2H, J ) 6.9 Hz), 7.10-7.30 (m, 3H), 7.50-7.80 (m, 15H);
13C NMR δ 40.5, 121.1, 126.5, 129.5, 132.2, 132.4, 135.8, 138.0,
150.2, 167.7; MS (FAB) m/z 575 (M+ - BF4), 363, 286, 209; IR
(KBr) 1759 (CdO), 1150-1000 (BF4-) cm-1. Anal. Calcd for
C
26H22BBiF4O2: C, 47.16; H, 3.35. Found: C, 47.27; H, 3.39.
(4-M e t h y lp h e n o x y c a r b o n y lm e t h y l)t r i p h e n y lb i s -
m u th on iu m tetr a flu or obor a te (3b): mp 127-129 °C; 1H NMR
δ 2.28 (s, 3H), 4.85 (s, 2H), 6.56 (d, 2H, J ) 8.4 Hz), 7.04 (d, 2H,
J ) 8.4 Hz), 7.50-7.90 (m, 15H); 13C NMR δ 20.8, 40.7, 120.7,
130.0, 132.2, 132.4, 135.9, 136.3, 138.1, 148.0, 167.8; MS (FAB)
m/z 589 (M+ - BF4), 363, 286, 209; IR (KBr) 1759 (CdO), 1150-
1000 (BF4-) cm-1. Anal. Calcd for C27H24BBiF4O2: C, 47.95; H,
3.58. Found: C, 48.06; H, 3.34.
(Isopr opoxycar bon ylm eth yl)tr iph en ylbism u th on iu m tet-
1
r a flu or obor a te (3c): mp 114-115 °C; H NMR δ 1.05 (d, 6H,
J ) 6.3 Hz), 4.71 (s, 2H), 4.83 (sept, 1H, J ) 6.3 Hz), 7.52-7.82
(m, 15H); 13C NMR δ 21.4, 41.8, 71.6, 132.1, 132.3, 135.8, 138.1,
168.1; MS (FAB) m/z 541 (M+ - BF4), 363, 286, 209; IR (KBr)
The products 16 (isomer ratio ) 80/20), 18 (isomer ratio )
78/22), and 20 (isomer ratio ) 72/28) were similarly isolated by
column chromatography, but their stereochemical assignment
was not made.
1732 (CdO), 1200-950 (BF4-) cm-1. Anal. Calcd for C23H24
BBiF4O2: C, 43.97; H, 3.85. Found: C, 44.00; H, 3.83.
-
Rea ction of Sa lt 3a w ith Sod iu m En ola te 4. To a suspen-
sion of 3a (662 mg, 1.0 mmol) in THF (5 mL) cooled to -50 °C
was added a solution of sodium enolate 4, generated from NaH
(24 mg, 1.0 mmol) and dibenzoylmethane (224 mg, 1.0 mmol) in
the same solvent (5 mL). The resulting yellow solution was
allowed to warm to room temperature with stirring and then
concentrated under reduced pressure. The residue was taken
up with Et2O and evaporated to leave an oil, which was
chromatographed on silica gel using hexanes-ethyl acetate as
tr a n s-P h en yl 2,3-ep oxy-3-p h en ylp r op a n oa te (14a ): mp
1
75-76 °C (lit.17 mp 88-90 °C); H NMR δ 3.69 (d, 1H, J ) 1.7
Hz), 4.23 (d, 1H, J ) 1.7 Hz), 7.10-7.50 (m, 10H); MS (EI) m/z
240 (M+); IR (KBr) 1752 (CdO) cm-1. Anal. Calcd for C15H12O3:
C, 74.99; H, 5.03. Found: C, 74.99; H, 5.03.
tr a n s-P h en yl 2,3-ep oxy-3-(4-m eth ylp h en yl)p r op a n oa te
(14b): mp 69-70 °C; 1H NMR δ 2.35 (s, 3H), 3.72 (d, 1H, J )
1.7 Hz), 4.21 (d, 1H, J ) 1.7 Hz), 7.10-7.50 (m, 9H); MS (EI)
(15) Challenger, F.; Wilkinson, J . F. J . Chem. Soc. 1922, 121, 91.
(16) Slougi, N.; Rousseau, G. Synth. Commun. 1987, 17, 1.
(17) Ramakrishnan, V. T.; Kagan, J . J . Org. Chem. 1970, 35, 2898.