Preparation and properties of fluorenylidene(phenyl)phosphines bearing bulky groups with electron-donating substituents in the ortho position on the phenyl group

Article abstract of DOI:10.1246/bcsj.78.1082

Huorenylidene(phenyl)phosphines having bulky substituents with an electron-donating group in the o-position on the phenyl group were prepared and their properties were compared. The prepared materials included 2,4-di-t-butyl-6-methoxyphenyl, 2,4-di-t-buty

Full text of DOI:10.1246/bcsj.78.1082

1082 Bull. Chem. Soc. Jpn., 78, 1082–1090 (2005)
Ó 2005 The Chemical Society of Japan
Preparation and Properties of Fluorenylidene(phenyl)phosphines
Bearing Bulky Groups with Electron-Donating Substituents
in the Ortho Position on the Phenyl Group
ꢀ
Subaru Kawasaki, Takuma Fujita, Kozo Toyota, and Masaaki Yoshifuji
Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578
Received September 7, 2004; E-mail: yoshifj@mail.tains.tohoku.ac.jp
Fluorenylidene(phenyl)phosphines having bulky substituents with an electron-donating group in the o-position on
the phenyl group were prepared and their properties were compared. The prepared materials included 2,4-di-t-butyl-6-
methoxyphenyl, 2,4-di-t-butyl-6-(phenoxymethyl)phenyl, 2,4-di-t-butyl-6-(dimethylamino)phenyl, or 2,4-di-t-butyl-6-
(2-phenylethyl)phenyl. The diphosphenes and dithioxophosphoranes bearing the 2,4-di-t-butyl-6-(phenoxymethyl)phen-
yl group that formed were observed by 31P NMR spectroscopy; the effects of the substituent on these multiply bonded
phosphorus species are discussed.
Studies on multiple bonds containing heavier main group
S
S
elements are of interest in modern element chemistry. Many
compounds containing such unusual bonds have been pre-
pared, in many cases, by the aid of kinetic stabilization meth-
odology (so-called steric protection technique).1 In such steri-
cally protected systems, it is of current interest to study the ef-
fect of the introduction of electronically perturbing substitu-
ents. Knowledge of the structure–properties relationships in
the electronically perturbed sterically protecting systems may
lead to designs of novel reagents or materials containing the
heavier main-group element with unusual bonding.
Br
P
R1
R1
R2
R2
1
2
3a: R1 = R2 = t-Bu
3b: R1 = i-Pr, R2 = t-Bu
Among the studies on the multiply bonded phosphorus com-
pounds,2 various exotic species such as diphosphenes,3 phos-
phacumulenes,4 phospharadialenes,5 and dichalcogenoxophos-
phoranes6 have been prepared by the use of sterically protecting
substituents such as a 2,4,6-tri-t-butylphenyl group (abbreviat-
3c: R1 = Me, R2 = t-Bu
3d: R1 = OMe, R2 = t-Bu
3e: R1 = CH2OMe, R2 = t-Bu
3f: R1 = CH2OPh, R2 = t-Bu
3g: R1 = CH2O(4-t-BuC6H4), R2 = t-Bu
3h: R1 = CH2O(4-MeOC6H4), R2 = t-Bu
3i: R1 = CH2O(2-Naphthyl), R2 = t-Bu
3j: R1 = NMe2, R2 = t-Bu
P
ꢀ
R1
ed as Mes ). In the course of our studies on the structure–prop-
erties relationships of dithioxophosphoranes 1 (Chart 1),6,7 we
have developed various sterically hindered substituents. We
prepared bromobenzene derivatives 2 as precursors of the phos-
phorus-containing compounds, and have evaluated the effects
of their electronically perturbing bulky aryl substituents on 1.
Research on the structure–properties relationships of other
essentially reactive species, such as phosphaethenes, is also
important and attractive, because some phosphaethene-based
polymers and reagents have recently been reported and further
applications are under investigation.8,9 Polarization of the
–P=C bond in phosphaethenes would not be expected to be
as large as that of the –P=S bond in dithioxophosphoranes.
Thus, in the two different systems, it is interesting to discover
how the intramolecular donor-stabilization7,10 is operating. We
report here the preparation and properties of fluorenylidene-
(phenyl)phosphines 3b–l with bulky substituents containing
electron-donating alkoxy or dialkylamino groups at the o-posi-
tion.11 The differences between the effects of the o-functional-
ized aryl substituents and those of the p-substituted ones are
also of interest.
R2
3k: R1 = CH2NMe2, R2 = t-Bu
3l: R1 = CH2CH2Ph, R2 = t-Bu
3m: R1 = t-Bu, R2 = OMe
3n: R1 = t-Bu, R2 = NMe2
Chart 1.
Results and Discussion
Preparation of Fluorenylidene(phenyl)phosphines.12
First, fluorenylidene(phenyl)phosphines with bulky substitu-
ents containing ethereal groups in the o-position on the phenyl
group were prepared as follows (Scheme 1). 9-Fluorenyl-
lithium was allowed to react with dichlorophosphine 4d
(R1 ¼ OMe)7b in tetrahydrofuran (THF) at ꢁ78 ꢂC to form
chloro(fluorenyl)phenylphosphine 5d (Method A). Treatment
with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in the pres-
ence of molecular sieves MS4A gave fluorenylidene(phenyl)-
Published on the web June 6, 2005; DOI 10.1246/bcsj.78.1082

S. Kawasaki et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1083
Br
2b: R1 = i-Pr; c: R1 = Me; d: R1 = OMe; e: R1 = CH2OMe;
f: R1 = CH2OPh; g: R1 = CH2O(4-t-BuC6H4);
R1
h: R1 = CH2O(4-MeOC6H4); i: R1 = CH2O(2-Naphthyl);
j: R1 = NMe2; k: R1 = CH2NMe2; l: R1 = CH2CH2Ph
1) n-BuLi
2) PCl3
Li R3
Cl
Cl
Cl
P
P
R1
R3
R1
3
3
R
= H (Method A)
or
R
= SiMe (Method B)
3
5b-l: R3 = H (Method A)
6d,f: R3 = SiMe3 (Method B)
4b-l
DBU (Method A)
or
P
P
KF, 18-crown-6
(Method B)
R1
R1
3b-l
DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene
Scheme 1.
phosphine 3d in 70% yield. When 4d was allowed to react
with 9-(trimethylsilyl)fluoren-9-yllithium, compound 6d was
obtained (Method B). The attempted conversion of 6d to 3d
by addition of either KF, TBAF, or Et3N, however, resulted
in formation of only a trace amount of 3d (the major product
was the desilylated product 5d).
ceeded. The reaction of 2f with butyllithium, followed by
treatment with PCl3, afforded the dichlorophosphine 4f. This
dichlorophosphine is stable at room temperature under an inert
atmosphere and the cyclization reaction did not occur. When
4f was reacted with methanol, compound 8 was obtained in
84% yield without any cyclization product.
Next, the preparation of 3e, bearing the 2,4-di-t-butyl-6-
(methoxymethyl)phenyl group, was attempted in a similar
manner. Although the formation of a trace amount of 3e was
observed by 31P NMR spectroscopy after the successive treat-
ment of dichlorophosphine 4e with 9-fluorenyllithium and
DBU (Method A), our attempted isolation of 3e failed due to
decomposition. A similar result was obtained in the case of
Method B. Moreover, the instability of 4e seemed to limit its
synthetic applications. As we had observed previously,7c a cy-
clization reaction of 4e occurred13 at room temperature to give
7 (Chart 2) with elimination of chloromethane (the cyclization
The reaction of 4f with 9-fluorenyllithium gave chloro-
(fluorenyl)phosphine 5f (Method A). The treatment of 5f with
DBU formed the corresponding fluorenylidene(phenyl)phos-
phine 3f, although an attempted isolation of 3f from the reac-
tion mixture failed because of a decomposition reaction during
the isolation process. However, 3f was successfully isolated in
the reaction of 6f (Method B) with KF (10 molar amount, see
experimental part) in the presence of 18-crown-6 (5 molar
amount) in 83% yield based on 2f, although fluorenylidene-
(phenyl)phosphine 3f itself was moisture-sensitive, gradually
changing to 9 (Scheme 3).
Furthermore, fluorenylidene(phenyl)phosphines 3j,k with
bulky substituents containing an amino functional group in
the o-position of phenyl were prepared from dichlorophos-
phines 4j7a and 4k7d (Method A). In these cases, however,
the desired fluorenylidene(phenyl)phosphines were highly re-
active and they decomposed due to reaction with moisture
[MS data of the crude products: 3j: m=z 427 (Mþ);
3k + H2O: m=z 459]. We then tried to prepare [2,4-di-t-bu-
tyl-6-(2-phenylethyl)phenyl](9-fluorenylidene)phosphine (3l),
to compare the properties with those of 3f. Compound 2o
was converted to 10 by a Wittig reaction and then reduced with
ꢂ
was suppressed below 0 C).
In order to overcome the instability of 4e, we prepared
a
2,6-di-t-butyl-6-(phenoxymethyl)phenyl (abbreviated as
Phomx: phenoxymethylxylene derivative) congener 4f as an
alternative, as follows (Scheme 2): A mixture of 2-bromo-1-
bromomethyl-3,5-di-t-butylbenzene (2o),7c phenol, potassium
carbonate, and potassium iodide in DMF was stirred at room
temperature for 28 h to give 2f in 88% yield. When 2f was
treated with butyllithium and water successively, 1,3-di-t-bu-
tyl-5-(phenoxymethyl)benzene was formed; such formation
showed that the halogen–metal exchange reaction had pro-

1084 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Fluorenylidene(phenyl)phosphines
S
S
Cl
(OC)5W
P
P
O
R
P
1a: R = t-Bu; b: R = i-Pr;
7
11a
d: R = OMe; f: R = CH2OPh;
j: R = NMe2; k: R = CH2NMe2
S
P
S
S
MeO
OMe MeO
MeS
O
PH2
P
R
OPh
P
P
R
13
14
15
12a: R = t-Bu; b: R = i-Pr;
f: R = CH2OPh; j: R = NMe2
Chart 2.
O
P
Cl
Cl
H
OMe
OPh
Br
Br
P
Br
OPh
OPh
MeOH
PhOH
1) n-BuLi
K2CO3
KI, DMF
2) PCl3
4f
7
2f
8
1) Ph3P
2) NaN(SiMe3)2
3) PhCHO
Br
Br
Ph
Ph
H2NNHTs, AcONa
DME-H2O
10
2l
Scheme 2.
diimide14 to give 2-bromo-1,5-di-t-butyl-3-(2-phenylethyl)-
benzene (2l, Scheme 2). The bromobenzene 2l was then con-
verted to 3l via 4l and 5l by a method similar to that described
above (Method A); however, our attempted isolation of 3l
failed due to its instability. Similarly, our attempted isolation
of 3b,c (Method A) by column chromatography failed.
effect on the phosphorus atom in 3d–f. However, the elec-
tron-donating effect in 3d–f is not so strong according to the
31P NMR study. The proximity in chemical shifts of 3d and
3e may indicate the contribution of through-space interaction
ꢀ
between the oxygen lone pair and the P=C ꢀ orbital, because
through-bond interaction of the oxygen lone pair is not likely
effective in the case of 3e. To gain more precise insight into
the effect of the aryloxy group in 3f, we carried out 31P NMR
spectroscopic investigations of the related fluorenylidene-
(phenyl)phosphines 3g–i. Bromobenzenes 2g–i were prepared
from 2o and converted to 3g–i by similar methods. The 31P
chemical shifts of 3g–i were very close to that of 3f
(Table 1). This fact suggests that the interaction between the
oxygen atom and the phosphorus atom is not so large and that
Properties
of
Fluorenylidene(phenyl)phosphines.
Table 1 shows 31P and 13C NMR data of various fluorenyli-
dene(phenyl)phosphines. The 31P NMR signal of 3d showed
a higher-field shift, compared with that of the kinetically stabi-
lized molecule 3a,12b while the chemical shift of 3d was very
close to those of 3e and 3f. Although the anisotropic effect
of the aromatic ring in 3f should be taken into account, these
facts indicate that the alkoxy group has an electron-donating

S. Kawasaki et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1085
the perturbation due to the p-substituent of the phenoxy group
is small. In addition, the instability of 3d–f suggests that the
donor groups in these molecules do not sufficiently stabilize
the phosphorus–carbon double bond, while kinetically stabi-
lized 3a is very stable at room temperature even in air.
Contrary to this, amino-substituted 3k showed a considera-
ble high-field shift in 31P NMR spectroscopy. This means that
the conformationally flexible and electron-donating amino
group in 3k interacted with the phosphorus atom more effi-
ciently than the amino group in 3j or the methoxy group in
3e, although the basis for the high reactivity of 3k is unclear
so far.
the p-position seems to affect the nonbonding orbital (mainly
the phosphorus lone pair) rather than the P=C ꢀ orbital, be-
cause the bulky aryl ꢀ-plane and the P=C ꢀ-plane are normal-
ly almost perpendicular in the lowest energy conformer (see,
for example, X-ray crystallographic results in Ref. 11), leading
to a low-field shift.16
ꢀ
It should be noted that the dimethyl amino group at the para
position causes a lower-field shift compared to the methoxy
group at the para position. A similar tendency is observed be-
tween 3d and 3j, probably due to the contribution of through-
bond interaction, although the effect is not so large as through-
space interaction in these cases, because both 3d and 3j
showed a net high-field shift, compared to 3a–c. In the case
of 3b, an inductive effect (through ꢁ bond), which also affects
the n orbital, seems to cause a low-field shift compared to 3c,
while a slightly high-field shift of 3a compared to 3b may be
attributable to steric compression.
Tungsten Carbonyl Complex of Fluorenylidene(phenyl)-
phosphine 3f. As mentioned above, among the fluorenyli-
dene(phenyl)phosphines with an o-substituent 3b–l, only 3d
and 3f were isolated. As 3d was less stable than 3f at room
temperature, group 6 metal complex formation of 3f was ex-
amined as a representative of 3d and 3f, and the results were
compared with those of 3a. When 3f was treated with
The p-functionalized fluorenylidene(phenyl)phosphines 3m
and 3n showed a tendency much different from the corre-
sponding o-substituted derivatives 3d and 3j, respectively. In-
troduction of the electron-donating group at the o-position
caused a high-field shift, while introduction in the p-position
caused a low-field shift compared with 3a. It is likely that
the electron-donating group in the o-position mainly affects
ꢀ
the ꢀ orbital of the P=C bond by through-space interaction,
causing a high-field shift, while the electron-donating group in
O
H2O
[W(CO)5(thf)] in THF at room temperature, a pentacarbonyl-
1
P
PH
tungsten complex 11f [ꢂP (CDCl3) = 193.9, satellite, JWP
¼
H
281:4 Hz] was obtained (the X-ray crystallography of 11f
was reported in a previous communication11). Comparison of
the 31P NMR data for 11f with those for 11a [ꢂP (CDCl3) =
O
O
Ph
Ph
6f
9
1
215.0, satellite d, JWP ¼ 291:2 Hz] shows that the modifica-
tion in the o-substituent affects not only the chemical shift
but also the spin–spin coupling (1JWP), which suggests that
the trans influence or the trans effect of the complexes is tun-
able by the o-substituent. This may lead to tuning of catalytic
ability of appropriate homogeneous catalyst containing sp2-hy-
bridized phosphorus ligands.8 It should be noted that the at-
tempted reactions of 3f with [Cr(CO)5(thf)] or [Mo(CO)5(thf)]
under similar conditions failed. It is likely that group 6 metal
pentacarbonyls with atomic radii shorter than that of tungsten
W(CO)5(thf)
W(CO)5
P
O
Ph
11f
Scheme 3.
Table 1. 31P NMR Data and Selected 13C NMR Data for Fluorenylidene(phenyl)phosphines 3
aÞ
bÞ
Compound
R1
R2
ꢂP
ꢂC (P=C) (1JPC/Hz)
a
b
c
d
e
t-Bu
i-Pr
Me
OMe
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
OMe
NMe2
256.5cÞ
257.2
254.0
247.9
249.7
245.8
246.7
246.7
245.7
252fÞ
170.3 (42.7)
dÞ
dÞ
—
—
171.8 (40.1)eÞ
dÞ
CH2OMe
CH2OPh
CH2O(4-t-BuC6H4)
CH2O(4-MeOC6H4)
CH2O(2-Naphthyl)
NMe2
—
f
173.4 (43.1)
172.9 (43.2)
172.8 (43.1)
173.3 (43.3)
g
h
i
j
k
l
dÞ
dÞ
dÞ
—
—
—
CH2NMe2
153fÞ
CH2CH2Ph
t-Bu
t-Bu
253.9
258.0gÞ
264.8hÞ
m
n
171.2 (43.2)
171.3 (44.2)
a) In CDCl3, relative to external 85% H3PO4. b) In CDCl3. c) Data taken from Ref. 11. See also,
Ref. 12b. d) Attempted purification failed and assignment was unsuccessful. e) Measured in CD2Cl2.
f) Measured in THF–C6D6. g) Data taken from Ref. 15. h) Data taken from Ref. 16.

1086 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Fluorenylidene(phenyl)phosphines
could not coordinate to the phosphorus due to the steric hin-
drance caused by the o-substituents and the conformationally
rigid fluorenylidene moiety close to the phosphorus lone pair.
Other Derivatives Bearing the Phomx Group. Further-
more, some 31P NMR spectroscopic investigations of phospho-
rus compounds containing the Phomx group were carried out.
Thus, diphosphene 12f (Chart 2) was generated from 4f by ad-
dition of magnesium turnings in THF. Dithioxophosphorane
1f was formed by the reaction of a primary phosphine 13
and the fluorenylidene(phenyl)phosphine. The degree of inter-
action turned out to be related to the degree of polarization in
the P=X bonds. The ortho-functional groups and the corre-
sponding para-functional groups seem to exert influence in a
different manner: The ortho-functional groups seem to affect
ꢀ
the ꢀ orbital, while the para-functional group affect the n or-
bital. These findings concerning the structure–properties rela-
tionships of phosphaethenes will help in the design of new cat-
alysts8 or polymeric materials9 containing phosphorus–carbon
double bonds. Further studies on the structure–properties rela-
tionships of the phosphaethenes and application of the sub-
stituents are in progress.
1
[ꢂP (CDCl3) = ꢁ147:5, JPH ¼ 205:1 Hz, prepared by reduc-
tion of 4f] with elemental sulfur in refluxing toluene.
The 31P NMR chemical shift of 12f [ꢂP (C6D6) = 506.5,
ꢂP (CDCl3) = 506.7] showed a low-field shift, compared with
those of 12a [ꢂP (C6D6) = 492.4]3 or 12j [ꢂP (C6D6) =
425.9].7a The chemical shift of 12f is rather close to that of
12b [ꢂP (C6D6) = 510.5];17 thus, the electronic effect of the
oxygen atom on the phosphorus–phosphorus double bond in
12f seems to be small, probably because the P=P bond is
not polar in this case, in contrast to the P=C or P=S bonds.
The high-field shift of 12a compared to 12b,f is likely caused
by steric compression. As the electronic effect in 12f now
turned out to be relatively small, the reason for the large chem-
ical-shift change in 12j becomes unclear. One possible reason
is the contribution of (Z)-form in 12j;17 however, further in-
vestigation including systematic modification and theoretical
calculations for diphosphene derivatives should be carried
out. The diphosphene 12f turned out to be too unstable to be
isolated, while 12a is stable enough to allow isolation in air.
This difference in stability is likely caused by steric effects
rather than electronic effects.
Experimental
Melting points were taken on a Yanagimoto MP-J3 micromelt-
ing point apparatus and are uncorrected. 1H NMR spectra,
13C NMR spectra, and 31P NMR spectra were recorded on a Bruk-
er AC-200P or a Bruker Avance-400 spectrometer using CDCl3 as
a solvent, unless otherwise specified. In some cases, 1H NMR (600
MHz, CDCl3) spectra and 13C NMR (150 MHz, CDCl3) spectra
were obtained on a Bruker AM-600 spectrometer. UV spectra
were measured on a Hitachi U-3210 spectrometer. IR spectra were
obtained on a Horiba FT-300 spectrometer. Mass spectra (70 eV)
were taken on either a JEOL HX-110 or a Hitachi M-2500S spec-
trometer. Dichlorophosphines 4b,18 4c,19 4d,7b 4e,7c 4j,7a and 4k7d
were prepared according to a previously reported method.
Chloro(2,4-di-t-butyl-6-methoxyphenyl)(9-fluorenyl)phos-
phine (5d). To a solution of fluorene (443 mg, 2.67 mmol) in
THF (10 mL) was added 2.7 mmol of butyllithium (1.50 M in hex-
ane, 1 M = 1 mol dmꢁ3) at ꢁ78 ꢂC. This solution was added to a
ꢃ
solution of 4d (prepared from 2.67 mmol of 2d) in THF (15 mL)
at ꢁ78 ꢂC. The resulting mixture was allowed to warm to ambient
temperature and then stirred for 2 h. The solvent was then
removed under reduced pressure and a small amount of hexane
was added to the residue. Inorganic salt was removed by filtration
and the filtrate was concentrated. A small amount of hexane was
added and 634 mg (ca. 53% yield) of crude 5d was obtained by
decantation as a colorless solid. 5d: 31P{1H} NMR (81 MHz,
CDCl3) ꢂ 83.9; MS (70 eV) m=z (rel intensity) 452 (Mþ + 2;
13), 450 (Mþ; 34), 414 (Mþ ꢁ HCl; 16), 285 (MoxPClþ; 100),
and 249 (MoxPþ ꢁ 1; 63).
In contrast, as for the structure–properties relationships
of dithioxophosphoranes, the 31P NMR spectrum of 1f
[ꢂP (C6D6) = 264.0, ꢂP (CDCl3) = 261.3] showed a signifi-
cant high-field shift, compared with those of 1a [ꢂP (CDCl3) =
298.2],6 1b [ꢂP (CDCl3) = 291.3],17 and 1d [ꢂP (C6D6) =
277.6].7b This fact suggests a considerable electron-donating
effect of the oxygen lone pairs to the phosphorus center
of 1f, although the effect is not as large as that of 1j
[ꢂP (CDCl3) = 170.6]7a or 1k [ꢂP (CDCl3) = 149.6].7d Com-
pound 1f was also highly reactive and rapidly decomposed
in air. It should be noted that dithioxophosphorane 14
[ꢂP (C6D6) = 295.2] is not so stable at room temperature
due to rearrangement to 15,7g and attempted preparation of
1e led to the formation of a complex mixture of products,
probably via a similar migration of the methyl group.7f While
1d dimerized on concentration of the solution of 1d,7b mono-
meric 1f was observed by 31P NMR spectroscopy after concen-
tration and re-solvation. Thus, the Phomx group is a substitu-
ent of value as it provides a relatively weak interaction or
tuning on the phosphorus center without migration of the
phenyl group or polymerization.
Chloro(2,4-di-t-butyl-6-methoxyphenyl)[9-(trimethylsilyl)-
9-fluorenyl]phosphine (6d). To a solution of 9-(trimethylsilyl)-
fluorene (467 mg, 1.96 mmol) in THF (20 mL) was added 1.85
mmol of butyllithium (1.42 M in hexane) at ꢁ78 ꢂC. This solution
was added to a solution of 4d (prepared from 1.90 mmol of 2d) in
THF (20 mL) at ꢁ78 ꢂC and the resulting mixture was allowed to
warm to ambient temperature and stirred for 3 h. The solvent was
then removed under reduced pressure and a small amount of hex-
ane was added to the residue. Inorganic salt was removed by fil-
tration, and the filtrate was concentrated. Hexane (10 mL) was
added and 237 mg (23% yield) of 6d was obtained by filtration.
6d: Colorless powder, mp 163–165 ꢂC; 1H NMR (600 MHz,
4
CD2Cl2) ꢂ ꢁ0:83 (9H, d, JPH ¼ 0:9 Hz, SiMe3), 1.12 (9H, s,
Conclusion
p-t-Bu), 1.69 (9H, s, o-t-Bu), 2.40 (3H, s, OMe), 6.00 (1H, d, J ¼
1:6 Hz, arom.), 6.74 (1H, d, J ¼ 7:8 Hz, arom.), 6.84 (1H, m, ar-
om.), 6.94 (1H, dd, J ¼ 5:4, 1.7 Hz, arom.), 7.09 (1H, t, J ¼ 7:5
Hz, arom.), 7.35–7.37 (2H, m, arom.), 7.74 (1H, d, J ¼ 7:6 Hz,
arom), 7.87 (1H, m, arom.), and 7.90 (1H, m, arom.);
13C{1H} NMR (150 MHz, CD2Cl2) ꢂ ꢁ2:4 (s, SiMe3), 31.4 (s,
p-CMe3), 34.0 (s, o-CMe3), 35.9 (s, p-CMe3), 38.6 (s, o-CMe3),
In summary, we have evaluated the effects of the Phomx
and some related substituents in fluorenylidene(phenyl)phos-
phines, diphosphenes, and dithioxophosphoranes. Although
the effect of the aryloxy group was small in the case of the di-
phosphene with the non-polar P=P bond, we have observed
significant effects in the cases of the dithioxophosphorane

S. Kawasaki et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1087
54.1 (s, OMe), 105.3 (s, m-arom.), 116.0 (s, m-arom.), 119.6 (s,
arom., CH), 120.4 (s, arom., CH), 125.4 (s, arom., CH), 125.7
(s, arom., CH), 126.1 (s, arom., CH), 126.9 (s, arom., CH);
31P{1H} NMR (81 MHz, CDCl3) ꢂ 99.8; MS (70 eV) m=z (rel
intensity) 524 (Mþ + 2; 17), 522 (Mþ; 40), 507 (Mþ ꢁ Me; 7),
449 (Mþ ꢁ Tms; 3), 414 (Mþ ꢁ TmsCl; 100), 328 (Mþ
ꢁ TmsCl ꢁ MeO ꢁ t-Bu + 2; 19), 285 (MoxPClþ; 48), 249
(MoxPþ ꢁ 1; 51), 237 (Mþ ꢁ MoxPCl; 39), 222 (C13H8Tmsþ;
5), 195 (C13H8Pþ; 13), 179 (MoxPþ ꢁ t-Bu ꢁ Me + 1; 10),
this mixture was added N,N-dimethylformamide (30 mL) and the
resulting mixture was stirred at room temperature for 28 h. The
reaction mixture was then diluted with diethyl ether and the organ-
ic phase was successively washed with water and brine, and dried
over MgSO4. The solvent was removed and the residue was re-
crystallized from hexane–MeOH (20:1) to give 4.40 g (88% yield)
of 2f. Bromobenzenes 2g–i were prepared in a similar manner.
2f: Colorless powder, mp 62–64 ꢂC; 1H NMR (400 MHz,
CDCl3) ꢂ 1.36 (9H, s, p-t-Bu), 1.63 (9H, s, o-t-Bu), 5.22 (2H, s,
CH2O), 7.05 (2H, d, J ¼ 7:5 Hz), 7.10 (1H, t, J ¼ 8:7 Hz), 7.38
(2H, dd, J ¼ 8:7, 7.5 Hz), 7.53 (1H, d, J ¼ 2:4 Hz), and 7.55
(1H, d, J ¼ 2:4 Hz); 13C{1H} NMR (100 MHz, CDCl3) ꢂ 30.6
(p-CMe3), 31.7 (o-CMe3), 35.3 (p-CMe3), 37.8 (o-CMe3), 71.6
(CH2O), 115.5 (arom.), 120.6 (arom.), 121.5 (arom.), 124.7 (ar-
om.), 125.2 (arom.), 129.9 (arom.), 137.7 (arom.), 147.9 (arom.),
150.1 (arom.), and 159.2 (arom.); IR (KBr) 1595, 1495, 1471,
1427, 1387, 1365, 1265, 1174, 1080, 1020, 885, 835, 750, and
692 cmꢁ1; MS (70 eV) m=z (rel intensity) 376 (Mþ + 2; 10),
374 (Mþ; 10), 283 (Mþ ꢁ OPh + 2; 75), 281 (Mþ ꢁ OPh; 76),
187 (Mþ ꢁ Br ꢁ CH2OPh + 1; 6), and 57 (t-Buþ; 100). Found:
m=z 374.1247. Calcd for C21H27BrO: M, 374.1245.
þ
165 (C13H8 + 1; 23), 73 (Tmsþ; 16), and 57 (t-Buþ; 16). Found:
m=z 522.2275. Calcd for C31H40ClOPSi: M, 522.2275.
(2,4-Di-t-butyl-6-methoxyphenyl)(9-fluorenylidene)phosphine
(3d) by Method A. To a solution of crude 5d (264 mg, ca. 0.6
mmol) in THF (3 mL) was added 0.045 mL (0.30 mmol) of DBU
in the presence of MS4A. The resulting mixture was stirred for 10
min and the solvent was removed under reduced pressure. To the
residue was added a small amount of hexane and the insoluble ma-
terials were removed by filtration. The filtrate was concentrated to
give 173 mg (ca. 70% yield based on 5d) of 3d: Yellow powder,
mp 142–145 ꢂC; 1H NMR (600 MHz, CD2Cl2) ꢂ 1.40 (9H, s, p-t-
Bu), 1.41 (9H, s, o-t-Bu), 3.60 (3H, s, OMe), 6.33 (1H, m), 6.82
(1H, m), 6.89 (1H, d, J ¼ 1:3 Hz), 7.19 (1H, m), 7.27–7.33
(3H, m), 7.60 (1H, m), 7.64 (1H, m), and 8.16 (1H, m);
2g: Colorless solid, mp 73–75 ꢂC; 1H NMR (400 MHz, CDCl3)
ꢂ 1.32 (9H, s, t-Bu), 1.33 (9H, s, t-Bu), 1.59 (9H, s, o-t-Bu), 5.16
(2H, s, CH2O), 6.99 (2H, d, J ¼ 8:8 Hz), 7.35 (2H, d, J ¼ 8:8 Hz),
and 7.48 (2H, br. s); 13C{1H} NMR (100 MHz, CDCl3) ꢂ 30.5
(CMe3), 31.7 (CMe3), 31.9 (CMe3), 35.2 (p-CMe3), 37.8 (o-
CMe3), 71.8 (CH2O), 114.9 (arom.), 120.7 (arom.), 124.8 (arom.),
125.2 (arom.), 126.7 (arom.), 137.9 (arom.), 144.1 (arom.), 147.9
(arom.), 150.1 (arom.), and 156.9 (arom.); IR (KBr) 1606, 1512,
1363, 1242, 1182, 1022, and 825 cmꢁ1; MS (70 eV) m=z (rel in-
tensity) 432 (Mþ + 2; 19), 430 (Mþ; 19), 283 (Mþ ꢁ OAr + 2;
96), 281 (Mþ ꢁ OAr; 100), and 57 (t-Buþ; 83).
1
13C{1H} NMR (150 MHz, CD2Cl2) ꢂ 171.8 (d, JPC ¼ 40:1 Hz,
P=C); 31P{1H} NMR (81 MHz, C6D6) ꢂ 246.4; IR (KBr) 1647,
1589, 1442, 1394, 1325, 1207, 1055, 847, 769, and 729 cmꢁ1
;
MS (70 eV) m=z (rel intensity) 414 (Mþ; 100), 249 (MoxPþ ꢁ 1;
75), 233 (MoxPþ ꢁ Me ꢁ 2; 6), 219 (Moxþ; 5), 193 (Mþ
ꢁ Mox ꢁ 2; 20), 165 (C13H9þ; 42), and 57 (t-Buþ; 20). Found:
m=z 414.2115. Calcd for C28H31OP: M, 414.2113.
[2,4-Di-t-butyl-6-(methoxymethyl)phenyl](9-fluorenylidene)-
phosphine (3e) by Method B. To a solution of 2e (375 mg, 1.2
mmol) in THF (4 mL) was added 1.3 mmol of butyllithium (1.50
M solution in hexane) at ꢁ78 ꢂC. The resulting solution was add-
ed to a solution of PCl3 (3.7 mmol) in THF (2 mL) at ꢁ78 ꢂC. The
resulting mixture was allowed to warm to 0 ꢂC and then stirred for
1 h. The solvent and the unreacted PCl3 were then removed under
reduced pressure at 0 ꢂC. The residue was dissolved in THF (4
mL) and a solution of 9-trimethylsilyl-9-fluorenyllithium (1.2
mmol) in THF (8 mL) (prepared from 286 mg of 9-trimethylsilyl-
fluorene and 1.2 mmol of butyllithium) was added at ꢁ78 ꢂC. The
resulting solution was then allowed to warm to 0 ꢂC and stirred for
30 min. KF (0.7 g, 12 mmol) and 18-crown-6 (1.6 g, 6 mmol)
were added and the resulting mixture was allowed to warm to am-
bient temperature. An aliquot of the solution was analyzed by
31P NMR spectroscopy, which indicated formation of 3e. The sol-
vent was then removed under reduced pressure, 20 mL of anhy-
drous hexane was added, and undissolved inorganic salt was fil-
tered off. Solvent of the filtrate was removed under reduced pres-
sure and the residue was quickly analyzed by 31P NMR spectros-
copy. Although the measurement revealed that a signal due to 3e
appeared at ꢂ ¼ 249:7 in CDCl3, the residue was a complex mix-
ture of products. The attempted isolation of 3e was unsuccessful
[silica-gel column chromatography, recrystallization, and recy-
cling GPC (gel permeation column chromatography) were used].
A trapping experiment using MeOH gave a more complicated
mixture of products.
2h: Colorless solid, mp 109–112 ꢂC; 1H NMR (400 MHz,
CDCl3) ꢂ 1.35 (9H, s, p-t-Bu), 1.62 (9H, s, o-t-Bu), 4.00 (3H, s,
MeO), 5.16 (2H, s, CH2O), 6.90 (2H, d, J ¼ 9:1 Hz), 7.01 (2H,
d, J ¼ 9:1 Hz), 7.51 (2H, s); 13C{1H} NMR (100 MHz, CDCl3)
ꢂ 30.6 (p-CMe3), 31.7 (o-CMe3), 35.2 (p-CMe3), 37.8 (o-CMe3),
56.1 (MeO), 72.5 (CH2O), 115.1 (arom.), 116.5 (arom.), 120.5 (ar-
om.), 124.6 (arom.), 125.2 (arom.), 138.0 (arom.), 147.9 (arom.),
150.1 (arom.), 153.4 (arom.), and 154.5 (arom.); IR (KBr) 1593,
1510, 1369, 1238, 1065, and 820 cmꢁ1; MS (70 eV) m=z (rel in-
tensity) 406 (Mþ + 2; 14), 404 (Mþ; 14), 283 (Mþ ꢁ OAr + 2;
51), 281 (Mþ ꢁ OAr; 52), and 57 (t-Buþ; 100). Found: m=z
404.1340. Calcd for C22H29BrO2: M, 404.1351.
2i: Colorless solid, mp 132–134 ꢂC; 1H NMR (400 MHz,
CDCl3) ꢂ 1.36 (9H, s, p-t-Bu), 1.64 (9H, s, o-t-Bu), 5.33 (2H, s,
CH2O), 7.2–7.6 (6H, m), and 7.7–7.9 (3H, m); 13C{1H} NMR
(100 MHz, CDCl3) ꢂ 30.6 (p-CMe3), 31.7 (o-CMe3), 35.3 (p-
CMe3), 37.8 (o-CMe3), 71.7 (CH2O), 107.9 (arom.), 119.5 (ar-
om.), 120.8 (arom.), 124.1 (arom.), 124.8 (arom.), 125.4 (arom.),
126.8 (arom.), 127.3 (arom.), 128.1 (arom.), 129.6 (arom.), 129.9
(arom.), 135.0 (arom.), 137.6 (arom.), 148.0 (arom.), 150.2
(arom.), and 157.1 (arom.); IR (KBr) 1628, 1599, 1512, 1464,
1396, 1380, 1363, 1254, 1213, 1178, 1117, 1007, 883, 839, 812,
and 744 cmꢁ1; MS (70 eV) m=z (rel intensity) 426 (Mþ + 2;
9), 424 (Mþ; 10), 345 (Mþ ꢁ Br; 16), 283 (Mþ ꢁ ONaph + 2;
31), 281 (Mþ ꢁ ONaph; 30), 115 (Mþ ꢁ Br ꢁ CH2ONaph
ꢁ t-Bu ꢁ Me ꢁ 1; 100), and 57 (t-Buþ; 87). Found: m=z
424.1403. Calcd for C25H29BrO: M, 424.1402.
2-Bromo-1,5-di-t-butyl-3-(phenoxymethyl)benzene (2f) and
the Related Bromobenzenes (2g–i). 2-Bromo-1-bromomethyl-
3,5-di-t-butylbenzene (2o, 5.00 g, 13.8 mmol), phenol (1.53 g,
16.3 mmol), potassium carbonate (3.13 g, 22.7 mmol), and potas-
sium iodide (0.26 g, 1.5 mmol) were placed in a 100 mL flask. To
Methyl [2,4-Di-t-butyl-6-(phenoxymethyl)phenyl]phosphi-
nate (8). Bromobenzene 2f (103 mg, 0.27 mmol) in THF (1
mL) was lithiated with 0.31 mmol of butyllithium (1.58 M in hex-

1088 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Fluorenylidene(phenyl)phosphines
ꢂ
ane) at ꢁ78 C; the resulting solution was then added to a THF
Ph), 136.3 (arom.), 151.5 (arom.), and 159.5 (ipso-Ph); IR
(KBr) 1599, 1494, 1473, 1367, 1295, 1238, 1172, 1081, 1014,
879, 829, 752, 713, and 692 cmꢁ1; MS (70 eV) m=z (rel intensity)
297 (Mþ + 1; 100). Found: m=z 296.2132. Calcd for C21H28O:
M, 296.2140.
(0.5 mL) solution of phosphorus trichloride (1.15 mmol) at that
temperature. The resulting mixture was allowed to warm to room
temperature and stirred for 1 h. The solvent and the unreacted
PCl3 were removed under reduced pressure to give 4f. MeOH
(2 mL) was added to the residue and the resulting mixture was
stirred at room temperature for 2 h. The solvent was removed un-
der reduced pressure and the residue was purified by column chro-
matography (SiO2/hexane–EtOAc) to give 8 (85 mg, 84% yield).
4f: Colorless crystals, 1H NMR (400 MHz, CDCl3) ꢂ 1.34 (9H,
[2,4-Di-t-butyl-6-(phenoxymethyl)phenyl](9-fluorenylidene)-
phosphine (3f) by Method B. A freshly prepared solution of (9-
trimethylsilyl-9-fluorenyl)lithium [prepared from 138 mg (0.58
mmol) of 9-trimethylsilylfluorene and 1.1 molar amount of butyl-
ꢂ
lithium in THF (1 mL) at 0 C] was added dropwise to a THF (1
4
s, p-t-Bu), 1.63 (9H, d, JPH ¼ 1:2 Hz, o-t-Bu), 5.79 (2H, s,
mL) solution of 4f [prepared from 200 mg (0.53 mmol) of 2f by
the method described above; the unreacted PCl3 was removed un-
der reduced pressure] at ꢁ78 ꢂC. The resulting solution of 6f was
stirred at 0 ꢂC for 30 min. To the solution were added KF (370 mg,
6.37 mmol) and 18-crown-6 (621 mg, 2.35 mmol) and the result-
ing mixture was stirred at room temperature for 30 min. The sol-
vent was removed under reduced pressure; hexane (50 mL) was
added to the residue, the mixture was filtered, and the filtrate
was concentrated under reduced pressure. Column chromatogra-
phy of the residue provided 215 mg (83% yield) of 3f. When
KF (1 molar amount) and 18-crown-6 (1 molar amount) was used,
the reaction proceeded very slowly and 3f decomposed before
consumption of 6f. Moreover, when KF and 18-crown-6 were
used in 1:1 ratio, separation of 3f from the reaction mixture be-
came troublesome.
3
4
CH2O), 7.00 (1H, tt, JHH ¼ 7:3 Hz and JHH < 1 Hz, p-Ph),
3
4
7.07 (2H, dd, JHH ¼ 8:5 Hz and JHH < 1 Hz, o-Ph), 7.34 (2H,
3
3
dd, JHH ¼ 8:5 Hz and JHH ¼ 7:3 Hz, m-Ph), 7.49 (1H, dd,
4JPH ¼ 6:6 Hz and JHH ¼ 1:9 Hz, m-Phomx), and 7.78 (1H, d,
4
4JHH ¼ 1:9 Hz, m-Phomx.); 13C{1H} NMR (100 MHz, CDCl3) ꢂ
4
31.4 (s, p-CMe3), 34.5 (d, JPC ¼ 23:5 Hz, o-CMe3), 35.8 (s, p-
CMe3), 38.0 (s, o-CMe3), 67.8 (s, CH2O), 115.5 (s, arom. CH),
3
121.4 (s, arom. CH), 123.0 (d, JPC ¼ 9:0 Hz, m-Phomx), 126.5
1
(s, arom. CH), 130.0 (arom. CH), 133.0 (d, JPC ¼ 83:7 Hz,
2
ipso-Phomx), 144.9 (s, p-Phomx), 155.1 (d, JPC ¼ 33:8 Hz,
o-Phomx), 155.9 (s, o-Phomx), and 159.1 (s, ipso-Ph);
31P{1H} NMR (162 MHz, CDCl3) ꢂ 162.3; MS (70 eV) m=z (rel
intensity) 400 (Mþ + 4; 0.3), 398 (Mþ + 2; 1), 396 (Mþ; 2),
361 (Mþ ꢁ Cl; 17), and 303 (Mþ ꢁ OPh; 100). Found: m=z
396.1204. Calcd for C21H27Cl2OP: M, 396.1177. The melting
point value was ambiguous because thermal decomposition occur-
red on heating.
6f: 31P{1H} NMR (162 MHz, THF–C6D6) ꢂ 95.8.
3f: Yellow oil; 1H NMR (400 MHz, CDCl3) ꢂ 1.44 (9H, s, p-t-
2
Bu), 1.54 (9H, s, o-t-Bu), 4.82 (1H, d, JHH ¼ 12:7 Hz, CHHO),
8: Colorless crystals, mp 77–79 ꢂC; 1H NMR (400 MHz,
CDCl3) ꢂ 1.31 (9H, s, p-t-Bu), 1.57 (9H, s, o-t-Bu), 3.84 (3H,
d, 3JPH ¼ 12:3 Hz, OMe), 5.51 (1H, d, 2JHH ¼ 13:0 Hz, CHH0O),
5.30 (1H, d, JHH ¼ 12:7 Hz, CHHO), 6.10 (1H, dd, J ¼ 8:0,
2
2.6 Hz), 6.8–6.9 (4H, m), 7.16 (2H, m), 7.25 (2H, d, J ¼ 7:5
Hz), 7.35 (2H, dd, J ¼ 7:5, 7.5 Hz), 7.56 (1H, d, J ¼ 1:6 Hz),
7.63 (2H, dd, J ¼ 8:0, 8.0 Hz), 7.68 (1H, br. s), and 8.14 (1H,
dd, J ¼ 8:0, 7.5 Hz); 13C{1H} NMR (100 MHz, CDCl3) ꢂ 31.9
2
5.61 (1H, d, JHH ¼ 13:0 Hz, CHH0O), 6.97 (1H, t, J ¼ 7:5 Hz),
7.05 (2H, d, J ¼ 8:6 Hz), 7.30 (2H, dd, J ¼ 8:6, 7.5 Hz), 7.51 (1H,
1
4
d, J ¼ 6:0 Hz), 7.64 (1H, s), and 8.46 (1H, d, JPH ¼ 569:4 Hz,
(s, p-CMe3), 32.0 (d, JPC ¼ 5:7 Hz, o-CMe3), 35.6 (s, p-CMe3),
PH); 13C{1H} NMR (100 MHz, CDCl3) ꢂ 31.4 (s, p-CMe3),
38.1 (s, o-CMe3), 70.5 (d, JPC ¼ 9:1 Hz, CH2O), 115.5 (s, Ph),
3
3
3
34.1 (s, o-CMe3), 35.6 (s, p-CMe3), 37.2 (d, JPC ¼ 2:6 Hz, o-
119.8 (s, arom. CH), 119.9 (s, arom. CH), 121.2 (d, JPC ¼ 22:8
2
3
CMe3), 53.8 (d, JPC ¼ 6:1 Hz, OMe), 68.5 (d, JPC ¼ 6:4 Hz,
Hz, m-Phomx), 121.4 (s, arom. CH), 124.1 (s, arom. CH), 124.2
(s, arom. CH), 126.2 (d, JPC ¼ 7:7 Hz, arom. CH), 127.6 (d,
3JPC ¼ 3:2 Hz, m-Phomx), 127.7 (d, JPC ¼ 2:3 Hz, arom. CH),
129.1 (d, JPC ¼ 6:6 Hz, arom. CH), 129.4 (d, JPC ¼ 6:1 Hz, arom.
3
CH2O), 115.4 (s, o-Ph), 121.2 (s, p-Ph), 123.3 (d, JPC ¼ 13:4
3
Hz, m-Phomx), 124.4 (d, JPC ¼ 126:9 Hz, ipso-Phomx), 125.0
3
2
(d, JPC ¼ 10:7 Hz, m-Phomx), 129.9 (s, m-Ph), 143.0 (d, JPC
¼
4:9 Hz, o-Phomx), 153.4 (d, 2JPC ¼ 12:3 Hz, o-Phomx), 155.4 (d,
4JPC ¼ 2:3 Hz, p-Phomx), and 159.0 (s, ipso-Ph); 31P NMR (162
MHz, CDCl3) ꢂ 31.9 (d, 1JPH ¼ 569:6 Hz); IR (NaCl) 3060–2870
(br.), 2431, 1727, 1600, 1546, 1496, 1402, 1375, 1240, 1220,
1010, 883, 855, 838, 790, and 692 cmꢁ1; MS (70 eV) m=z (rel
intensity) 374 (Mþ; 8), 356 (Mþ ꢁ O ꢁ H ꢁ 1; 11), and 281
(Mþ ꢁ OPh; 100). Found: m=z 374.2008. Calcd for C22H31O3P:
M, 374.2011.
CH), 129.8 (s, arom. m-Ph), 134.0 (d, JPC ¼ 52:7 Hz, ipso-
1
Phomx), 138.4 (d, JPC ¼ 14:0 Hz, Flu), 138.9 (d, JPC ¼ 17:2
Hz, Flu), 140.1 (s, o-Phomx), 140.3 (d, JPC ¼ 10:2 Hz, Flu),
143.2 (d, JPC ¼ 25:6 Hz, Flu), 153.2 (s, p-Phomx), 154.3 (d,
2JPC ¼ 2:9 Hz, o-Phomx), 159.0 (s, ipso-Ph), and 173.4 (d, 1JPC
¼
43:1 Hz, P=C); 31P{1H} NMR (162 MHz, CDCl3) ꢂ 245.8; UV
(hexane) 256 (log " 4.24), 266 (4.33), 275 (4.38), and 365 nm
(4.08); IR (NaCl) 1722, 1597, 1492, 1444, 1365, 1295, 1234,
1172, 1033, 883, 759, and 690 cmꢁ1; MS (70 eV) m=z (rel inten-
sity) 490 (Mþ; 65), 397 (Mþ ꢁ OPh; 100), 383 (Mþ ꢁ CH2OPh;
34), 341 (Mþ ꢁ OPh ꢁ t-Bu + 1; 41), 165 (C13H9þ; 32), 149
(84), and 57 (t-Buþ; 86). Found: m=z 490.2432. Calcd for
C34H35OP: M, 490.2426.
1,3-Di-t-butyl-5-(phenoxymethyl)benzene.
Compound 2f
(192 mg, 0.51 mmol) in THF (2 mL) was lithiated with 1.7 mmol
of butyllithium (1.57 M in hexane) at ꢁ78 ꢂC. To the solution was
added 1 mL of water. The resulting mixture was stirred at that
temperature for 10 min, and then allowed to warm to room tem-
perature. The mixture was concentrated under reduced pressure
and the residue was purified by column chromatography (SiO2/
hexane) to give 114 mg (75%) of 1,3-di-t-ꢂbutyl-5-(phenoxy-
[2,4-Di-t-butyl-6-(phenoxymethyl)phenyl](9-fluorenyl)phos-
phine Oxide (9) by Method A. A freshly prepared solution of 9-
fluorenyllithium [prepared from 148 mg (0.89 mmol) of fluorene
and 1.1 molar amount of butyllithium in THF (1 mL)] was added
dropwise to a THF (3 mL) solution of 4f [prepared from 300 mg
(0.80 mmol) of 2f by the method described above; the unreacted
PCl3 was removed in vacuo] at ꢁ78 ꢂC. The resulting solution
1
methyl)benzene: Colorless crystals, mp 53–54 C; H NMR (400
MHz, CDCl3) ꢂ 1.36 (18H, s, t-Bu), 5.05 (2H, s, CH2O), 6.99
(1H, t, J ¼ 7:6 Hz), 7.04 (2H, dd, J ¼ 8:8, 1.2 Hz), 7.30–7.35
(4H, m), and 7.43 (1H, t, J ¼ 1:8 Hz); 13C{1H} NMR (100
MHz, CDCl3) ꢂ 31.9 (CMe3), 35.3 (CMe3), 71.2 (CH2O), 115.2
(o-Ph), 116.6 (arom.), 121.2 (p-Ph), 122.7 (arom.), 129.8 (m-
ꢂ
of 5f was stirred at 0 C for 10 min. To the solution was added
DBU (0.14 mL, 0.99 mmol) and the resulting mixture was stirred

S. Kawasaki et al.
Bull. Chem. Soc. Jpn., 78, No. 6 (2005) 1089
at 0 ꢂC for 30 min and then allowed to warm to room temperature.
The 31P NMR spectrum of the solution showed a signal due to 3f.
The solvent was then removed under reduced pressure, and hex-
ane (30 mL) was added to the residue; the mixture was filtered,
and the filtrate was concentrated under reduced pressure. 31P NMR
spectrum of the residue showed that 3f decomposed to 9, which
was isolated (169 mg, 42% yield) by recycling gel permeation
chromatography (Japan Analytical Industry, JAIGEL H1+H2
column, eluent: CHCl3).
16.1 mmol) was added and the solution was refluxed, and aqueous
NaOAc (1.4 g in 7 mL of water) was slowly added. After being
cooled to room temperature, the solution was worked up using
Et2O, saturated aqueous NaHCO3, and brine. The organic phase
was dried over MgSO4 and the solvent was removed under re-
duced pressure. Column chromatography (SiO2) of the residue
provided 488 mg (99% yield) of 2l: Colorless solid, mp 37–39
ꢂC; 1H NMR (400 MHz, CDCl3) ꢂ 1.32 (9H, s, p-t-Bu), 1.62
(9H, s, o-t-Bu), 3.16 (2H, m, CH2), 3.77 (2H, m, CH2), 7.05
(1H, d, J ¼ 2:5 Hz), 7.2–7.4 (5H, m), and 7.40 (1H, d, J ¼ 2:5
Hz); 13C{1H} NMR (100 MHz, CDCl3) ꢂ 30.7 (p-CMe3), 31.7
(o-CMe3), 35.0 (p-CMe3), 36.9 (o-CMe3), 37.9 (CH2), 41.0
(CH2), 122.4 (arom., CBr), 123.8 (arom., CH), 126.2 (arom.,
CH), 126.3 (arom., CH), 128.8 (Ph), 129.0 (Ph), 142.4 (arom.),
142.5 (arom.), 148.0 (arom.), and 149.7 (arom.); IR (KBr) 1454,
1394, 1362, 1014, and 696 cmꢁ1; MS (70 eV) m=z (rel intensity)
374 (Mþ + 2; 58), 372 (Mþ; 73), 359 (Mþ ꢁ Me + 2; 40),
357 (Mþ ꢁ Me; 46), 283 (Mþ ꢁ CH2Ph + 2; 76), 281 (Mþ
ꢁ CH2Ph; 78), 91 (PhCH2þ; 28), and 57 (t-Buþ; 100).
5f: Colorless powder, mp 179–182 ꢂC, 31P{1H} NMR (162
MHz, CDCl3) ꢂ 82.2; MS m=z (rel intensity) 528 (Mþ + 2;
0.8), 526 (Mþ; 2), 490 (Mþ ꢁ HCl; 5), 397 (Mþ ꢁ HCl ꢁ OPh;
10), 325 (Mþ ꢁ Cl ꢁ C13H9 ꢁ 1; 68), and 165 (C13H9þ; 100).
Found: m=z 526.2175. Calcd for C34H36ClOP: M, 526.2192.
9: Colorless powder, mp 206–208 ꢂC; 1H NMR (500 MHz,
CDCl3) ꢂ 1.03 (9H, s, p-t-Bu), 1.43 (9H, s, o-t-Bu), 4.95 (1H,
2
3
2
dd, JPH ¼ 24:5 Hz, JHH ¼ 7:0 Hz, P–CH), 5.35 (1H, d, JHH
¼
11:3 Hz, CHH0O), 6.25 (1H, d, J ¼ 7:5 Hz), 6.41 (1H, d, JHH
¼
2
11:3 Hz, CHH0O), 6.91 (1H, dd, J ¼ 7:5, 7.5 Hz), 6.98 (1H, t, J ¼
1
3
7:3 Hz), 7.08 (1H, dd, JPH ¼ 502:6 Hz and JHH ¼ 7:0 Hz, PH),
7.10 (2H, d, J ¼ 8:0 Hz), 7.26–7.31 (1H, m), 7.30 (2H, dd,
J ¼ 8:0, 7.3 Hz), 7.40 (1H, dd, J ¼ 7:5, 7.5 Hz), 7.47 (1H, dd,
J ¼ 7:5, 7.5 Hz), 7.55 (1H, d, J ¼ 4:5 Hz), 7.69 (1H, s), 7.73
(1H, d, J ¼ 7:5 Hz), 7.81 (1H, d, J ¼ 7:5 Hz), and 8.05 (1H, d,
J ¼ 7:5 Hz); 13C{1H} NMR (125 MHz, CDCl3) ꢂ 31.0 (s, p-
CMe3), 33.0 (s, o-CMe3), 35.2 (s, p-CMe3), 36.8 (s, o-CMe3),
31P NMR Spectroscopic Observation of 3b, 3c, and 3g–l.
Typical Procedure (Method A): To a solution of 2 (1.5 mmol)
in THF (17 mL) was added 1.6 mmol of butyllithium (hexane
solution) at ꢁ78 ꢂC. The resulting mixture was stirred for 10
min and then was added to a THF (17 mL) solution of PCl3
(3.9 mmol) at ꢁ78 ꢂC. The reaction mixture was allowed to warm
to room temperature and then stirred for 1 h. The solvent and the
unreacted PCl3 were removed under reduced pressure and then
THF (18 mL) was added to the residue. In a separate flask,
0.36 g (2.2 mmol) of fluorene inꢂTHF (17 mL) was treated with
butyllithium (2.4 mmol) at ꢁ78 C. The resulting solution of 9-
fluorenyllithium was stirred for 10 min and then added to the
THF solution of 4 at ꢁ78 ꢂC. The reaction mixture was stirred
for 90 min. 31P NMR spectroscopic monitoring of the mixture
showed a signal due to 5. To the resulting solution was added
2.0 mmol of DBU. The solution was then stirred for 1 h. 31P NMR
spectroscopic monitoring of the mixture showed a signal due to 3
(Table 1); however, attempted isolation of 3 by column chro-
matography (Al2O3) or by recrystallization failed due to de-
composition of the desired product. 31P{1H} NMR (162 MHz)
data: 4l, ꢂ (THF–C6D6) 166; 5b, ꢂ (THF–C6D6) 83; 5j, ꢂ
(THF–C6D6) 83; 5k, ꢂ (THF–C6D6) 86; 5i, ꢂ (C6D6) 85.6.
Pentacarbonyl{[2,4-di-t-butyl-6-(phenoxymethyl)phenyl](9-
1
3
50.8 (d, JPC ¼ 56:3 Hz, P(O)–CH), 68.5 (d, JPC ¼ 6:0 Hz,
CH2O), 114.9 (s, o-Ph), 119.9 (s, arom. CH), 120.1 (s, arom.
3
CH), 121.4 (s, p-Ph), 124.0 (d, JPC ¼ 11:4 Hz, m-Phomx),
126.5 (d, JPC ¼ 2:9 Hz, arom. CH), 126.6 (d, JPC ¼ 2:9 Hz, arom.
CH), 127.3 (d, JPC ¼ 3:4 Hz, arom. CH), 127.4 (s, m-Phomx),
127.4 (d, JPC ¼ 2:9 Hz, arom. CH), 127.9 (d, JPC ¼ 2:3 Hz, arom.
1
CH), 128.0 (d, JPC ¼ 1:6 Hz, arom. CH), 129.5 (d, JPC ¼ 72:1
Hz, ipso-Phomx), 129.6 (s, arom. m-Ph), 137.3 (s, o-Phomx),
140.8 (d, JPC ¼ 4:0 Hz, Flu), 141.0 (d, JPC ¼ 4:5 Hz, Flu),
141.9 (d, JPC ¼ 6:9 Hz, Flu), 142.1 (d, JPC ¼ 5:1 Hz, Flu),
2
4
153.8 (d, JPC ¼ 8:6 Hz, o-Phomx), 155.3 (d, JPC ¼ 2:3 Hz, p-
Phomx), and 158.3 (s, ipso-Ph); 31P NMR (162 MHz, CDCl3) ꢂ
1
2
30.8 (dd, JPH ¼ 502:6 Hz and JPH ¼ 24:5 Hz); IR (KBr)
3133, 2998, 1596, 1485, 1448, 1230, 1180, 1008, 800, and 748
cmꢁ1; MS (70 eV) m=z (rel intensity) 508 (Mþ; 10), 415
(Mþ ꢁ OPh; 13), 343 (Mþ ꢁ C13H9; 51), 325 (Mþ ꢁ C13H10
ꢁ OH; 11), 249 (Mþ ꢁ C13H10 ꢁ OPh; 42), and 165 (C13H9
;
100). Found: m=z 508.2502. Calcd for C34H37O2P: M, 508.2531.
fluorenylidene)phosphine}tungsten (11f).
A solution of
þ
[W(CO)5(thf)] [prepared from 160 mg, 0.45 mmol of [W(CO)6]
in THF (20 mL)] was added to 3f (72 mg, 0.15 mmol). The result-
ing mixture was stirred at room temperature for 3 days and then
the solvent was removed under reduced pressure. Column chroma-
tography of the residue (SiO2, hexane–toluene 20:1) provided 26
mg (28% yield) of 11f: Orange prisms, mp 167 ꢂC (decomp);
1H NMR (400 MHz, CDCl3) ꢂ 1.43 (9H, s, p-t-Bu), 1.57 (9H, s,
2-Bromo-1,5-di-t-butyl-3-(2-phenylethyl)benzene (2l).
A
mixture of 7 (3.1 g, 8.56 mmol) and triphenylphosphine (2.4 g,
9.16 mmol) in toluene (20 mL) was stirred at 90 ꢂC for 3 h.
The mixture was allowed to cool to room temperature and the sol-
vent was evaporated under reduced pressure. To the residue was
added THF (40 mL), and then were added 10 mmol of sodium
bis(trimethylsilyl)amide (ꢂ1 M solution in THF) and benzaldehyde
(1 mL, 9.84 mmol) at 0 C; the resulting solution was stirred at
room temperature for 4 h. The solution was then worked up using
Et2O and brine; the organic phase was dried over MgSO4 and the
solvent was removed under reduced pressure. Column chromatog-
raphy (SiO2) of the residue provided 1.3 g (41% yield) of 10.
Compound 10 (490 mg, 1.32 mmol) was then dissolved in 1,2-di-
methoxyethane (35 mL) and p-tolylsulfonylhydrazide (3.0 g, 16.1
mmol) was added. The resulting solution was refluxed and aque-
ous NaOAc (1.4 g in 7 mL of water) was slowly added. The result-
ing mixture was refluxed for an additional 1 h and then allowed to
cool to room temperature. Again, p-tolylsulfonylhydrazide (3.0 g,
2
4
o-t-Bu), 5.17 (1H, dd, JHH ¼ 12:3 Hz and JPH ¼ 1:6 Hz,
2
4
CHH0O), 5.52 (1H, dd, JHH ¼ 12:3 Hz and JPH ¼ 2:2 Hz,
CHH0O), 6.44 (1H, dd, J ¼ 8:0, 3.6 Hz), 6.64–6.66 (2H, m),
6.83–6.90 (2H, m), 7.08–7.11 (2H, m), 7.24 (1H, ddd, J ¼ 7:4,
7.4, 2.4 Hz), 7.34 (1H, dd, J ¼ 7:8, 7.8 Hz), 7.41 (1H, ddd,
J ¼ 7:4, 7.4, 2.0 Hz), 7.62 (1H, d, J ¼ 7:2 Hz), 7.67 (1H, d, J ¼
7:6 Hz), 7.72–7.78 (2H, m), and 8.69 (1H, dd, J ¼ 7:6, 4.0 Hz);
13C{1H} NMR (100 MHz, CDCl3) ꢂ 69.7 (d, JPC ¼ 8:6 Hz,
3
1
2
CH2O), 168.2 (d, JPC ¼ 40:4 Hz, P=C), 195.9 (d, JPC ¼ 9:6
1
2
Hz, satellite JWC ¼ 125:7 Hz, COeq), and 198.8 (d, JPC ¼ 31:7
Hz, COax); 31P{1H} NMR (162 MHz, CDCl3) ꢂ 193.9 (satellite,
1JWP ¼ 281:4 Hz); UV (hexane) 211 (log " 4.90), 337 (3.88),

1090 Bull. Chem. Soc. Jpn., 78, No. 6 (2005)
Fluorenylidene(phenyl)phosphines
and 474 nm (4.38); IR (KBr) 2071, 1957, 1919, 1597, and 1232
cmꢁ1; MS (70 eV) m=z (rel intensity) 814 (Mþ; 6), 730
(Mþ ꢁ 3CO; 8), 674 (Mþ ꢁ 5CO; 8), 490 (Mþ ꢁ W(CO)5;
42), 397 (Mþ ꢁ OPh ꢁ W(CO)5; 63), 341 (Mþ ꢁ t-Bu
ꢁ OPh ꢁ W(CO)5; 23), 165 (Fluþ + 1; 34), 57 (t-Buþ; 89),
and 28 (COþ; 100).
S. Kawagishi, M. Hiraoka, S. Ikeda, T. Minami, S. Ito, and M.
Yoshifuji, Chem. Lett., 2001, 972; T. Minami, H. Okamoto, S.
Ikeda, R. Tanaka, F. Ozawa, and M. Yoshifuji, Angew. Chem.,
Int. Ed., 40, 4501 (2001); F. Ozawa, H. Okamoto, S. Kawagishi,
S. Yamamoto, T. Minami, and M. Yoshifuji, J. Am. Chem. Soc.,
124, 10968 (2002); O. Daugulis, M. Brookhart, and P. S. White,
Organometallics, 21, 5935 (2002); M. Yoshifuji, J. Synth. Org.
Chem., Jpn., 61, 1116 (2003); A. Ionxin and W. Marshall, Chem.
Commun., 2003, 710; See also: L. Weber, Angew. Chem., Int. Ed.,
41, 563 (2002), and references cited therein.
This work was supported in part by the Grants-in-Aid for
Scientific Research on Priority Area (Nos. 09239104 and
12020205) from the Ministry of Education, Culture, Sports,
Science and Technology.
9
For phosphaethene based polymers, see: N. Yamada, K.
Toyota, and M. Yoshifuji, Chem. Lett., 2001, 248; V. A. Wright
and D. P. Gates, Angew. Chem., Int. Ed., 41, 2389 (2002); R. C.
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Soc., 125, 1480 (2003); R. C. Smith and J. D. Protasiewicz,
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Kawasaki, K. Abe, N. Yamada, and M. Yoshifuji, Tetrahedron
Lett., 45, 7609 (2004).
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