Aroylspirophosphoranes bearing two naphth-1,8-diyl-8-oxy groups: Synthesis, crystal structure, and np(Oapical)→π*(CO) charge transfer interaction

Article abstract of DOI:10.1016/j.tet.2013.08.004

The reactions of aroyl chlorides with the lithium phosphoranide generated from bis(naphth-1,8-diyl-8-oxy)phosphorane 1 afforded aroylspirophosphoranes 3a-f. The p-anisoyl- and p-tert-butylbenzoylphosphoranes 3a and 3b bearing an electron-donating aryl gro

Full text of DOI:10.1016/j.tet.2013.08.004

Tetrahedron 69 (2013) 9155e9160
Contents lists available at ScienceDirect
Tetrahedron
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Aroylspirophosphoranes bearing two naphth-1,8-diyl-8-oxy groups:
synthesis, crystal structure, and np(Oapical)/
*
p (C]O) charge
transfer interaction
*
Kazumasa Kajiyama , Sayaka Fujimori, Daisuke Yasuoka, Takeshi Otsuka,
Takeshi Ken Miyamoto
Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 June 2013
Received in revised form 2 August 2013
Accepted 4 August 2013
Available online 11 August 2013
The reactions of aroyl chlorides with the lithium phosphoranide generated from bis(naphth-1,8-diyl-8-
oxy)phosphorane 1 afforded aroylspirophosphoranes 3aef. The p-anisoyl- and p-tert-butylbenzoyl-
phosphoranes 3a and 3b bearing an electron-donating aryl group were stable to moisture on silica gel.
The crystal structures of p-anisoyl-, p-tert-butylbenzoyl-, benzoyl-, and p-fluorobenzoylphosphorane
(3a, 3b, 3d, and 3e) elucidated by X-ray structural analysis suggested effective intramolecular
np(Oapical)/
p
*
(C]O) charge transfer stabilization to be operative.
Keywords:
Hypervalent
Ó 2013 Elsevier Ltd. All rights reserved.
Spirophosphorane
Charge transfer
X-ray structure
1. Introduction
equatorial bond if the substituents at the apical and equatorial sites
are identical.
Pentacoordinate phosphorus compounds, 10-P-51 phosphor-
anes, have been under active investigation, since the phosphorane is
a representative hypervalent compound2 and has been considered
to be a key model compound for elucidating the reaction mecha-
nism of biological processes such as phosphoryl transfer and
hydrolysis of phosphates.3 Stable phosphoranes usually assume
trigonal bipyramidal (TBP) structures in which there are two dis-
tinctive sites, the apical and the equatorial sites. A fundamental
feature of the phosphorane is its stereochemical non-rigidity, that is,
the facile inter-exchange of substituents at the apical and equatorial
sites in a TBP structure without bond cleavage, which has been
explained by the Berry pseudorotation (BPR) process.4,5 The equa-
torial bonds can be described as sp2 hybrid orbitals of the P atom.
The apical bond can be explained with the concept of the three-
center four-electron (3c-4e) bond, in which the electrons are
delocalized into the apical substituents to relieve the electron
density of the central atom.2,6 Thus, electronegative substituents
are preferred in the apical sites, a phenomenon leading to the
concept of apicophilicity.2,7 The apical bond is weaker than the
Experimental8 and theoretical9 apicophilicity scales do not
necessarily follow the electronegativity scale and the apicophilicity
of a substituent must be attributed to the combined influence of
multiple factors. For instance, it has been determined experimen-
tally for modified Martin spirophosphoranes that the acetyl group
is less apicophilic (more equatophilic) than the methoxy group
although they have similar electronegativity.8j This result has been
interpreted as a stereoelectronic effect involving the acyl group
in the equatorial position and the two oxygen atoms in the
apical positions, with intramolecular np(Oapical)/
transfer contributing to stabilization (Fig. 1).10 For effective n/
interaction in acylphosphoranes, the acyl group orients to have its
acceptor orbital parallel to the apical bond, or in other words, the
p (C]O) charge
*
p
*
p
acyl carbonyl group tends to be coplanar with the equatorial
plane.9a,b,d,10
O
P
C
O
O
* Corresponding author. Tel.: þ81 42 778 9505; fax: þ81 42 778 9953; e-mail
Fig. 1. Intramolecular np(Oapical)/
phosphoranes bearing apical oxygen atoms.
p (C]O) charge transfer stabilization in the acyl-
*
address: kajiyama@sci.kitasato-u.ac.jp (K. Kajiyama).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.08.004

9156
K. Kajiyama et al. / Tetrahedron 69 (2013) 9155e9160
Table 1
Acylphosphoranes can also be considered as model compounds
Syntheses of aroylspirophosphoranes 3aef
for pentacoordinate phosphorus intermediates in the hydrolysis
reaction of triesters of phosphonoformic acid (PFA), which have
been synthesized as prodrugs of PFA showing antiviral activity
against most retro-viruses.11 The rate acceleration observed in the
base-catalyzed hydrolysis of the PFA triesters via PeO bond cleav-
X
sa
Yieldb/%
1JCPc/Hz
nCOd/cmꢂ1
3a
3b
3c
3d
3e
3f
OMe
t-Bu
SMe
H
F
CN
ꢂ0.27
ꢂ0.20
0.00
0.00
0.06
82
67
53
44
24
29
173.0
173.2
174.4
174.6
176.4
180.6
1649
1655
1649
1660
1655
1668
age11d has been explained by the involvement of n/
p
*
stabiliza-
tion in the pentacoordinate intermediates.10 Although several
acylphosphoranes have previously been synthesized,8j,12 the n/
0.66
p
*
a
Hammett substituent constant from Ref. 15.
Isolated yield.
Coupling constant between phosphorus and the directly bonded carbonyl car-
interaction has not been clearly demonstrated from their structural
aspects. It is worth noting that the average torsion angle of the
carbonyl group from the equatorial plane in a Martin acetylspir-
ophosphorane was shown to be 17.8ꢀ by X-ray structural analysis
(Fig. 2),8j where the deviation from the ideal angle of 0ꢀ for efficient
b
c
bon observed by 13C NMR (CDCl3, 151 MHz).
d
Frequency of the carbonyl absorption observed by IR (KBr).
the other hand phosphoranes 3cef, in which benzoyl substituents
X were not electron-donating (
to give hydrophosphorane 1. Thus, phosphoranes 3cef were ob-
tained in lower yields by purification with PTLC (CH2Cl2/hexane
1:1) followed by recrystallization.
Although aroylphosphoranes 3 were stable in anhydrous organic
solvents, dichloromethane, chloroform, benzene, tetrahydrofuran,
acetonitrile, MeOH, EtOH, or iPrOH, at room temperature, they
slowly hydrolyzed upon long exposure to moisture to give hydro-
phosphorane 1. 1H and 13C NMR (CDCl3) spectroscopic analyses
suggested that the two naphthyl groups were spectroscopically
equivalent due to fast rotation around the carbonyl carbon-
ephosphorus bond on the NMR time scale. Although the 31P
n/
p interaction was attributed to the bulkiness of the tri-
*
sꢁ0), slowly hydrolyzed on silica gel
fluoromethyl groups of the Martin ligands.
F3C
F3C
CF3
O
F3C
O
CF3
17.8
Me
O
O
P
C
C
Me
O
CF3
O
CF3
F3C
Fig. 2. Torsion angle of the carbonyl group from the equatorial plane in a Martin
acetylspirophosphorane.
NMR chemical shift (
13C NMR chemical shift of the carbonyl carbons (
not significantly vary with the benzoyl substituents X, the
d
ꢂ38.6 to ꢂ39.3) of the phosphoranes and the
By utilizing bis(naphth-1,8-diyl-8-oxy)phosphorane 1, we
have succeeded in the syntheses of sterically congested phos-
phoranido complexes.13 It has also been found in the Hor-
nereWadswortheEmmons-type (HWE) reaction that the
phosphorane reagent derived from 1 was more reactive than the
corresponding reagent of the Martin phosphorane system.14 The
naphth-1,8-diyl-8-oxy group derived from 1-naphthol is a flat
bidentate, which is much less sterically demanding than the Martin
ligand. Thus, one could anticipate that the carbonyl group in acyl-
spirophosphoranes bearing two naphth-1,8-diyl-8-oxy groups
would be essentially coplanar with the equatorial plane. Herein, we
report on the syntheses of aroylspirophosphoranes 3, and on the X-
ray crystal structural analyses of 3a, 3b, 3d$0.5CH3CN, and 3e
bearing a p-anisoyl, a p-tert-butylbenzoyl, a benzoyl, and a p-flur-
orobenzoyl group, respectively.
d
191.3e193.0) do
1JCP value for the carbonyl carbon increases as the
s value of X
increases. The frequency (1660 cmꢂ1) for carbonyl absorption in
the IR spectrum of benzoylphosphorane 3d is nearly identical
to that (1659 cmꢂ1) of bis(pinacolate) benzoylphosphorane.12c
The frequencies (1649e1668 cmꢂ1) of nCO in the series of aroyl-
phosphoranes 3 are higher than those of aroyldiphenylphosphanes
(1643e1652
(1639e1655 cmꢂ1).16c,17 These results imply that the np(Oapical)/
(C]O) interaction in the aroylphosphorane is weaker than the
np(P)/ (C]O) and np(OP]O)/ (C]O) interactions in the
cmꢂ1 16
)
and
dialkyl
aroylphosphonates
p
*
p
*
p
*
aroylphosphane and aroylphosphonate, respectively.
2.2. X-ray crystal structural analysis
2. Results and discussion
2.1. Synthesis
The crystal structures of aroylspirophosphoranes 3a, 3b,
3d$0.5CH3CN, and 3e could be elucidated by X-ray crystal structural
analyses. ORTEP drawings [overview and side view along the
PeC(carbonyl) axis] are shown in Fig. 3. Selected bond lengths,
bond angles, and dihedral angles are listed in Table 2, along with
the corresponding data of methylphosphorane 413a,b,18 (Scheme 2,
Fig. 4) also bearing two naphth-1,8-diyl-8-oxy groups. For all of the
compounds, the geometry around the hypervalent phosphorus
atom is trigonal bipyramidal (TBP) structure with the two oxygen
atoms in the apical positions and the sum of the equatorial angles is
360ꢀ, which is the ideal value for TBP structures.
The reaction of the lithium phosphoranide 2 generated from
bis(8-oxy-1-naphthyl)hydrophosphorane 1 with aroyl chlorides,
benzoyl chloride or p-substituted benzoyl chlorides, gave air-stable
aroylspirophosphoranes 3 (Scheme 1, Table 1). In the case of 3a and
3b, in which the benzoyl substituents X were electron-donating
(
s15<0), purification of the crude mixtures could be carried out
by silica gel chromatography to give the products in good yields. On
The presence of intramolecular np(Oapical)/
p (C]O) charge
*
transfer interactions in the solid states of 3a, 3b, 3d, and 3e is highly
suggestive by the conformation of the aroyl groups and the unusual
distortion of the solid state structures of the spirophosphorane
from ideal TBP structure. As for the former, the carbonyl groups are
nearly coplanar with the equatorial plane in spite of steric repulsion
between the aryl groups at the carbonyl carbon and the naphth-1,8-
diyl-8-oxy groups. The repulsion is evident from the equatorial
C1eP1eC21 angles (123.30ꢀe130.55ꢀ), which are much larger than
the ideal equatorial angle of 120ꢀ and the other two equatorial
angles (112.65ꢀe122.49ꢀ) of 3a, 3b, 3d, and 3e. The torsion angles
O
P
O
P
COCl
THF
X
O
E
O
O
X
1; E = H
2; E = Li
3
tBuLi, THF
a) X = OMe, b) X = tBu, c) X = SMe, d) X = H, e) X = F, f) X = CN
Scheme 1.

K. Kajiyama et al. / Tetrahedron 69 (2013) 9155e9160
9157
(a) overview
O1
P1
O1
O1
P1
O1
P1
C1
C1
C1
C1
P1
C11
C11
C11
C11
C22
C21
C21
O3
C21
C22
C21
O3
C22
C22
O3
O3
O2
O2
O2
O2
3d
3a
3b
3e
(b) side view
3a
3b
3d
3e
Fig. 3. ORTEP diagrams of 3a, 3b, 3d$0.5CH3CN, and 3e showing the thermal ellipsoids at the 30% probability level. All hydrogens and CH3CN molecule are omitted for clarity.
Table 2
Selected structural parameters for aroylspirophosphoranes 3b, 3c, 3e, 3f, and
methylphosphorane 4
3a
3b
3d
3e
4
ꢀ
Bond lengths/A
P1eO1
P1eO2
P1eC1
P1eC11
P1eC21
1.7597(12) 1.7763(13) 1.7751(18) 1.7606(15) 1.791(2)
1.7863(12) 1.7619(14) 1.7692(18) 1.7781(14) 1.803(2)
1.8100(19) 1.8066(16) 1.801(3)
1.8009(17) 1.7977(18) 1.792(3)
1.8044(14) 1.814(3)
1.794(3) 1.811(3)
1.8687(18) 1.804(3)
1.8760(18) 1.873(2)
1.863(4)
Bond angles/ꢀ
O1eP1eO2
O1eP1eC1
O1eP1eC21
O2eP1eC11
O2eP1eC21
C1eP1eC11
C1eP1eC21
C11eP1eC21
Fig. 4. ORTEP diagram of 4 showing thermal ellipsoids at the 30% probability level. All
hydrogens are omitted for clarity.
175.13(6) 174.40(8) 175.17(11) 173.04(8)
179.2(1)
88.6(1)
89.9(1)
88.4(1)
90.6(1)
121.6(2)
89.35(7)
87.98(7)
89.29(7)
87.42(7)
88.77(7)
85.92(8)
89.85(7)
89.18(8)
89.34(11) 89.34(7)
86.43(11) 86.05(8)
89.66(11) 89.84(9)
88.78(11) 87.39(8)
oxy group and the bulky Martin ligand. It is also notable that the
aryl group on the aroyl carbon is coplanar to the carbonyl group,
115.98(8) 118.27(9) 122.49(13) 116.97(9)
130.55(8) 129.06(9) 123.30(13) 130.04(10) 117.8(1)
113.47(9) 112.65(8) 114.19(12) 113.00(8)
which can be rationalized by the
with the carbonyl group.
p-conjugation of the aryl group
120.6(2)
Torsion angles/ꢀ
C1eP1eC21eO3
As for the latter, generally, distortion of the TBP geometry about
the phosphorus atom of spirophosphoranes except for several
metallaphosphoranes13a,b,d,19 is along the Berry pseudorotation
coordinate with the monodentate equatorial group as the pivot.4,20
According to this preference, the O1eP1eC21 angles and the
O2eP1eC21 angles of 3a, 3b, 3d, and 3e should be larger than the
ideal angle of 90ꢀ. However, these angles (85.92ꢀe89.18ꢀ) are
smaller than 90ꢀ, while the structure of methylphosphorane 4 was
quite ordinary. Thus, it is reasonable to assume that the unusual
inclination of the apical bond toward the monodentate carbonyl
170.98(10) 172.42(11) 174.47(17) ꢂ174.72(11)
C1eP1eC21eC22 ꢂ9.79(17) ꢂ9.95(18) ꢂ3.1(3)
4.9(2)
4.69(17)
C11eP1eC21eO3 ꢂ9.94(14) ꢂ9.29(15) ꢂ3.9(3)
C11eP1eC21eC22 169.29(11) 168.35(12) 178.48(17) ꢂ175.67(13)
Average torsion
anglea
9.87
9.62
3.5
4.8
a
Average torsion angle from the equatorial plane.
O
O
P
MeI
THF
group is induced by intramolecular n/
p interaction (Fig. 1). The
*
P
E
Me
ꢀ
shorter apical PeO bonds (1.760e1.786 A) of the aroylphosphor-
O
O
ꢀ
anes compared with those (1.791e1.803 A) of methylphosphorane
4 can also be rationalized to be a consequence of such interactions.
1; E = H
2; E = Li
4
tBuLi, THF
3. Conclusions
Scheme 2.
The reaction of the lithium phosphoranide 2 generated from
bis(8-oxy-1-naphthyl)hydrophosphorane 1 with aroyl chlorides
afforded air-stable aroylspirophosphoranes 3. Phosphoranes 3 hy-
drolyzed upon long exposure to moisture but were stable in an-
(3.5ꢀe9.9ꢀ) of the carbonyl groups from the equatorial plane are
much smaller than that of the reported Martin acetylspir-
ophosphorane (Fig. 2).8j This difference can be attributed to the
difference in steric demands between the flat naphth-1,8-diyl-8-
hydrous solutions. Intramolecular np(Oapical)/
p (C]O) charge
*

9158
K. Kajiyama et al. / Tetrahedron 69 (2013) 9155e9160
transfer interactions are highly suggested according to the X-ray
structural analyses of 3a, 3b, 3d, and 3e. In the crystal structure, the
carbonyl groups are essentially coplanar with the equatorial plane
and the apical bond is titled toward the presumably interacting
carbonyl group, a distortion opposite of what is usually observed
for spirophosphoranes with TBP geometry. Since novel phosphor-
anes 3 can be considered to be analogues of pentacoordinate
phosphorus intermediates in the hydrolysis reaction of triesters of
PFA, which are potentially useful as antiviral drugs, it can be said
that we have provided experimental structural support for the
theoretically proposed stereoelectronic effect in this reaction.11
(CH2Cl2/hexane 1:1) to give 3b as yellow powder. Yield 101 mg
(67%); mp 250e252 ꢀC. Anal. Calcd for C31H25O3P: C 78.14, H 5.29.
Found: C 78.04, H 5.31; 1H NMR (CDCl3, 600 MHz)
d
¼8.30 (dd,
J¼12.0 and 7.2 Hz, 2H), 8.02 (dd, J¼8.4 and 3.0 Hz, 2H), 7.79 (d,
J¼8.4 Hz, 2H), 7.66 (dt, J¼7.2 and 6.6 Hz, 2H), 7.47 (t, J¼8.4 Hz, 2H),
7.37 (dd, J¼8.4 and 1.8 Hz, 2H), 7.30 (dd, J¼8.4 and 1.8 Hz, 2H), 6.96
(d, J¼7.8 Hz, 2H),1.23 (s, 9H); 13C NMR (CDCl3, 151 MHz)
¼192.3 (d,
d
J¼173.2 Hz), 158.0, 156.3, 133.2 (d, J¼8.3 Hz), 132.5 (d, J¼74.7 Hz),
132.2 (d, J¼14.3 Hz), 131.5 (d, J¼4.4 Hz), 129.6, 129.5, 129.3, 128.5 (d,
J¼16.5 Hz), 126.0, 124.2 (d, J¼149.0 Hz), 116.8, 105.4, 35.2, 30.9; 31
P
NMR (CDCl3,162 MHz)
d
¼ꢂ38.6; IR (KBr, cmꢂ1
¼3053, 2962, 2868,
)
n
1655,1626,1601,1576,1491,1454,1419,1408,1367,1340,1248,1205,
1182, 1147, 1101, 1043, 1016, 960, 935, 920, 845e754; HRMS (APCI):
[MþH]þ, found 477.1620. C31H26O3P requires 477.1614.
4. Experimental section
4.1. General
4.2.3. 2-(40-Methylthiobenzoyl)-2,20 5-spirobi[2H-naphth[1,8-cd]-
l
All reactions were carried out under a nitrogen atmosphere.
Hydrophosphorane 1 was prepared according to a published pro-
cedure.21 Dry solvents used in the reactions and recrystallization
were purchased from Wako Pure Chemical Industries, Ltd. Pre-
parative thin layer chromatography (PTLC) was carried out on
1,2-oxaphosphole] (3c). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.59 M n-pentane solu-
tion, 0.22 mL, 0.35 mmol) at room temperature. The solution was
stirred for 10 min and then a solution of 4-methylthiobenzoyl
chloride (64.9 mg, 0.348 mmol) in 5 mL of THF was added. The
reaction mixture was stirred at room temperature for 30 min and
then the solvents were removed under reduced pressure. Purifi-
cation of the residue was carried out by PTLC (CH2Cl2/hexane 1:1)
followed by recrystallization from CH2Cl2/hexane to give 3c as
yellow crystals. Yield 77.8 mg (53%); mp 248e250 ꢀC. Anal. Calcd
for C28H19O3PS: C 72.09, H 4.11. Found: C 72.35, H 4.15; 1H NMR
plates coated with Merck silica gel 60 GF254
.
Melting points were measured with a Yanaco micro melting
point apparatus and are uncorrected. 1H (600 MHz), 13C (151 MHz),
and 31P (243 MHz) NMR spectra were recorded on a Brucker
AVANCE-II (600 MHz) spectrometer. Elemental analyses were
performed on a PerkineElmer 2400 CHN elemental analyzer. IR
spectra were recorded on a JASCO FT/IR-610 spectrometer. High-
resolution mass spectra (HRMS) were measured on a Thermo Sci-
entific Exactive Plus FTMS using atmospheric-pressure chemical
ionization (APCI).
(CDCl3, 600 MHz)
d
¼8.30 (dd, J¼12.0 and 7.2 Hz, 2H), 8.03 (dd, J¼7.8
and 2.4 Hz, 2H), 7.73 (d, J¼8.4 Hz, 2H), 7.66 (q, J¼7.2 Hz, 2H), 7.47 (t,
J¼8.4 Hz, 2H), 7.37 (dd, J¼8.4 and 1.8 Hz, 2H), 7.07 (dd, J¼8.4 and
1.2 Hz, 2H), 6.96 (d, J¼7.2 Hz, 2H), 2.40 (s, 3H); 13C NMR (CDCl3,
151 MHz)
d
¼191.9 (d, J¼174.4 Hz), 156.3, 147.6, 133.3 (d, J¼8.3 Hz),
4.2. Aroylspirophosphoranes 3
132.2 (d, J¼14.2 Hz), 131.6 (d, J¼4.2 Hz), 131.3 (d, J¼75.5 Hz), 129.8,
129.5, 129.3, 128.5 (d, J¼16.4 Hz), 125.1, 124.1 (d, J¼149.3 Hz), 116.8,
4.2.1. 2-(40-Methoxybenzoyl)-2,20
l
5-spirobi[2H-naphth[1,8-cd]-1,2-
105.4, 14.5; 31P NMR (CDCl3, 162 MHz)
d
¼ꢂ38.8; IR (KBr, cmꢂ1
)
oxaphosphole] (3a). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.55 M n-pentane solu-
tion, 0.22 mL, 0.34 mmol) at room temperature. The solution was
stirred for 10 min and then 4-methoxybenzoyl chloride (0.044 mL,
0.32 mmol) was added. The reaction mixture was stirred at room
temperature for 30 min and then the solvents were removed under
reduced pressure. Purification of the residue was carried out by
PTLC (CH2Cl2) to give 3a as pale yellow powder. Yield 117 mg (82%);
mp 259e261 ꢀC. Anal. Calcd for C28H19O4P: C 74.66, H 4.25. Found:
n
¼3051, 2922, 1649, 1626, 1581, 1549, 1489, 1454, 1419, 1400, 1369,
1340, 1325, 1250, 1232, 1213, 1182, 1146, 1105, 1090, 1043, 1016, 953,
933, 916, 818e727; HRMS (APCI): [MþH]þ, found 467.0873.
C
28H20O3PS requires 467.0865.
4.2.4. 2-Benzoyl-2,20 5 -spirobi[2H-naphth[1,8-cd]-1,2-
l
oxaphosphole] (3d). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.59 M n-pentane solu-
tion, 0.22 mL, 0.35 mmol) at room temperature. The solution was
stirred for 10 min and then benzoyl chloride (0.040 mL, 0.35 mmol)
was added. The reaction mixture was stirred at room temperature
for 30 min and then the solvents were removed under reduced
pressure. Purification of the residue was carried out by PTLC (CH2Cl2/
hexane 1:1) followed by recrystallization from CH2Cl2/hexane to
give 3d as pale yellow crystals. Yield 58.0 mg (44%); mp 214e215 ꢀC.
Anal. Calcd for C27H17O3P: C 77.14, H 4.08. Found: C 77.42, H 4.06; 1H
C 74.82, H 4.25; 1H NMR (CDCl3, 600 MHz)
d
¼8.30 (ddd, J¼12.0, 7.2,
and 0.6 Hz, 2H), 8.03 (dd, J¼7.8 and 2.4 Hz, 2H), 7.82 (d, J¼9.0 Hz,
2H), 7.66 (ddd, J¼8.4, 7.2, and 6.6 Hz, 2H), 7.47 (dd, J¼8.4 and 7.8 Hz,
2H), 7.37 (dd, J¼8.4 and 1.8 Hz, 2H), 6.96 (d, J¼7.2 Hz, 2H), 6.76 (dd,
J¼9.0 and 1.8 Hz, 2H), 3.76 (s, 3H); 13C NMR (CDCl3, 151 MHz)
d
¼191.3 (d, J¼173.0 Hz), 164.3, 156.4, 133.2 (d, J¼8.2 Hz), 132.2 (d,
J¼14.0 Hz), 131.9 (d, J¼1.8 Hz),131.5 (d, J¼4.2 Hz), 129.5, 129.3,128.4
(d, J¼16.5 Hz), 128.0 (d, J¼76.9 Hz), 124.3 (d, J¼148.7 Hz), 116.7,
NMR (CDCl3, 600 MHz)
d
¼8.31 (dd, J¼12.0 and 7.2 Hz, 2H), 8.04 (dd,
114.3, 105.3, 55.5; 31P NMR (CDCl3, 162 MHz)
d¼ꢂ38.7; IR (KBr,
J¼8.4 and 3.0 Hz, 2H), 7.84 (d, J¼8.4 Hz, 2H), 7.67 (dt, J¼7.2 and
6.6 Hz, 2H), 7.49e7.46 (m, 3H), 7.38 (dd, J¼8.4 and 1.8 Hz, 2H), 7.28 (t,
J¼7.8 Hz, 2H), 6.96 (d, J¼7.2 Hz, 2H); 13C NMR (CDCl3, 151 MHz)
cmꢂ1
)
n
¼3060, 2958, 2837, 1649, 1626, 1591, 1508, 1489, 1454, 1419,
1369, 1340, 1323, 1309, 1269, 1250, 1236, 1215, 1205, 1163, 1147,
1105, 1041, 1028, 962, 935, 839e754; HRMS (APCI): [MþH]þ, found
451.1099. C28H20O4P requires 451.1094.
d
¼193.0 (d, J¼174.6 Hz), 156.3, 135.2 (d, J¼74.0 Hz), 133.9, 133.3 (d,
J¼8.6 Hz),132.2 (d, J¼14.2 Hz),131.6 (d, J¼4.2 Hz),129.5,129.4,129.3,
128.8, 128.5 (d, J¼16.5 Hz), 124.0 (d, J¼149.8Hz), 116.8, 105.4; 31P
4.2.2. 2-(40-tert-Butylbenzoyl)-2,20
l
5-spirobi[2H-naphth[1,8-cd]-1,2-
NMR (CDCl3,162 MHz)
d
¼ꢂ38.7; IR (KBr, cmꢂ1
)
n¼3049,1660,1626,
oxaphosphole] (3b). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.59 M n-pentane solu-
tion, 0.22 mL, 0.35 mmol) at room temperature. The solution was
stirred for 10 min and then 4-tert-butylbenzoyl chloride (0.63 mL,
0.35 mmol) was added. The reaction mixture was stirred at room
temperature for 30 min and then the solvents were removed under
reduced pressure. Purification of the residue was carried out by PTLC
1593, 1576, 1491, 1454, 1419, 1367, 1338, 1248, 1219, 1203, 1180, 1147,
1105, 1041, 1018, 999, 962, 931, 804e750; HRMS (APCI): [MþH]þ,
found 421.0987. C27H18O3P requires 421.0988.
4.2.5. 2-(40-Fluorobenzoyl)-2,20 5-spirobi[2H-naphth[1,8-cd]-1,2-
l
oxaphosphole] (3e). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.59 M n-pentane

K. Kajiyama et al. / Tetrahedron 69 (2013) 9155e9160
9159
solution, 0.22 mL, 0.35 mmol) at room temperature. The solution
was stirred for 10 min and then 4-fluorobenzoyl chloride (0.041 mL,
0.35 mmol) was added. The reaction mixture was stirred at room
temperature for 30 min and then the solvents were removed under
reduced pressure. Purification of the residue was carried out by
PTLC (CH2Cl2/hexane 1:1) followed by recrystallization from CH3CN
to give 3e as yellow crystals. Yield 33.0 mg (24%); mp 185e186 ꢀC;
Anal. Calcd for C27H16FO3P: C 73.97, H 3.68. Found: C 73.86, H 3.67;
J¼8.8 Hz), 132.0 (d, J¼14.3 Hz), 130.9 (d, J¼4.2 Hz), 129.21 (d,
J¼25.1 Hz), 129.19, 128.0 (d, J¼15.9 Hz), 125.7 (d, J¼156.4 Hz), 115.6,
103.9, 22.4 (d, J¼124.6 Hz); 31P NMR (CDCl3, 162 MHz)
¼ꢂ28.7; IR
d
(KBr, cmꢂ1
)
n
¼3053, 2920, 1626, 1576, 1491, 1456, 1419, 1367, 1338,
1300, 1255, 1207, 1171, 1147, 1113, 1043, 1020, 970, 933, 893, 868,
814e735; HRMS (APCI): [MþH]þ, found 331.0884. C21H16O2P re-
quires 331.0882.
1H NMR (CDCl3, 600 MHz)
d
¼8.30 (dd, J¼12.6 and 7.2 Hz, 2H), 8.03
4.4. X-ray structure determination
(dd, J¼8.4 and 3.0 Hz, 2H), 7.86 (dd, J¼9.0 and 5.4 Hz, 2H), 7.66 (dt,
J¼7.8 and 6.6 Hz, 2H), 7.48 (t, J¼8.4 Hz, 2H), 7.38 (dd, J¼8.4 and
1.8 Hz, 2H), 6.96 (d, J¼7.8 Hz, 2H), 6.94 (dd, J¼8.4 and 1.8 Hz, 2H);
Yellow crystals of 3a (plates), 3b (prisms), 3d$0.5CH3CN
(prisms), and 3e (plates) were grown by recrystallization from
CH3CN (for 3a, 3d, and 3e) or CH2Cl2/hexane (for 3b). The dif-
13C NMR (CDCl3, 151 MHz)
d¼191.6 (d, J¼176.4 Hz), 166.1 (d,
J¼257.3 Hz), 156.2, 133.4 (d, J¼8.3 Hz), 132.19 (d, J¼14.6 Hz), 132.16
(d, J¼10.0 Hz), 131.8 (d, J¼4.2 Hz), 131.6 (dd, J¼75.8 and 2.9 Hz),
129.41 (d, J¼23.6 Hz), 129.38, 128.5 (d, J¼16.6 Hz), 123.7 (d,
J¼149.9 Hz), 116.9, 116.2 (d, J¼22.2 Hz), 105.5; 31P NMR (CDCl3,
fraction data were measured on a Rigaku AFC-7R diffractometer
ꢀ
using graphite monochromated Mo K
a
radiation (
l
¼0.71069 A).
The data were collected at 296 K using MSC/AFC diffractometer
control software. The structure was solved by direct methods using
SIR92. All non-hydrogen atoms were refined anisotropically. All
hydrogen atoms were refined using a riding model.
162 MHz)
d
¼ꢂ38.9; IR (KBr, cmꢂ1
)
n
¼3062, 1655, 1626, 1591, 1577,
1502, 1489, 1454, 1410, 1367, 1338, 1250, 1228, 1205, 1153, 1103,
1041, 1018, 1009, 964, 953, 935, 849e735; HRMS (APCI): [MþH]þ,
found 439.0898. C27H17FO3P requires 439.0894.
4.4.1. Crystal/refinement data for 3a. C28H19O4P, M¼450.43, triclinic,
ꢀ
ꢀ
ꢀ
P1, a¼9.9957(9) A, b¼10.738(2) A, c¼11.456(1) A,
a
¼77.51(1)ꢀ,
4.2.6. 2-(40-Cyanobenzoyl)-2,20 5-spirobi[2H-naphth[1,8-cd]-1,2-
l
3
ꢀ
ꢂ3
ꢀ
b
¼65.709(7)ꢀ,
g
¼75.93(1) , V¼1077.7(3) A , Z¼2, Dc¼1.388 g cm
,
m
(Mo K
a
)¼1.620 cmꢂ1, F(000)¼468.00, 4938 unique reflections, 317
oxaphosphole] (3f). To a solution of 1 (100 mg, 0.316 mmol) in
20 mL of THF was added dropwise t-BuLi (1.59 M n-pentane solu-
tion, 0.22 mL, 0.35 mmol) at room temperature. The solution was
stirred for 10 min and then a solution of 4-cyanobenzoyl chloride
(57.6 mg, 0.348 mmol) in 10 mL of THF was added. The reaction
mixture was stirred at room temperature for 30 min and then the
solvents were removed under reduced pressure. Purification of the
residue was carried out by PTLC (CH2Cl2/hexane 1:1) followed by
recrystallization from CH2Cl2/CH3CN to give 3f as yellow crystals.
Yield 41.0 mg (29%); mp 199e201 ꢀC. Anal. Calcd for C28H16NO3P: C
75.50, H 3.62, N 3.14. Found: C 75.47, H 3.67, N 3.22; 1H NMR (CDCl3,
parameters, R1 (I>2
s
(I))¼0.0381, wR2 (all data)¼0.1099, GOF 1.039.
4.4.2. Crystal/refinement data for 3b. C31H25O3P, M¼476.51, triclinic,
ꢀ
ꢀ
ꢀ
P1, a¼11.418(3) A, b¼13.401(3) A, c¼8.549(2) A,
a
¼108.42(2)ꢀ,
3
ꢀ
ꢂ3
ꢀ
b
¼97.34(2)ꢀ,
g
¼82.19(2) , V¼1224.6(4) A , Z¼2, Dc¼1.292 g cm
,
m
(Mo K
a
)¼1.435 cmꢂ1, F(000)¼500.00, 5634 unique reflections, 341
parameters, R1 (I>2
s
(I))¼0.0474, wR2 (all data)¼0.1581, GOF 1.056.
4.4.3. Crystal/refinement data for 3d$0.5CH3CN. C28H18.5N0.5O3P,
ꢀ
ꢀ
M¼440.93, monoclinic, C2/c, a¼32.133(2) A, b¼9.478(2) A,
3
ꢀ
ꢂ3
600 MHz)
d
¼8.31 (dd, J¼12.6 and 7.2 Hz, 2H), 8.07 (dd, J¼7.8 and
ꢀ
ꢀ
c¼16.083(3) A,
b
¼114.658(8) , V¼4451(2) A , Z¼8, Dc¼1.316 g cm
,
m
(Mo K
a
)¼1.528 cmꢂ1, F(000)¼1832.00, 5115 unique reflections, 317
3.0 Hz, 2H), 7.89 (d, J¼8.4 Hz, 2H), 7.69 (dt, J¼7.8 and 6.6 Hz, 2H),
7.57 (dd, J¼9.0 and 1.8 Hz, 2H), 7.49 (dd, J¼8.4 and 7.2 Hz, 2H), 7.41
(dd, J¼8.4 and 2.4 Hz, 2H), 6.97 (d, J¼7.8 Hz, 2H); 13C NMR (CDCl3,
parameters, R1 (I>2
s
(I))¼0.0478, wR2 (all data)¼0.1540, GOF 0.991.
151 MHz)
d
¼192.2 (d, J¼180.6 Hz), 155.9, 138.6 (d, J¼74.0 Hz), 133.7
4.4.4. Crystal/refinementdatafor3e. C27H16FO3P, M¼438.39, triclinic,
(d, J¼8.6 Hz), 132.6, 132.2 (d, J¼14.5 Hz), 132.0 (d, J¼4.2 Hz), 129.5,
129.42, 129.36, 128.6 (d, J¼16.6 Hz), 123.0 (d, J¼151.0 Hz), 117.6,
ꢀ
ꢀ
ꢀ
P1, a¼10.082(2) A, b¼10.052(2) A, c¼12.415(3) A,
a
¼80.57(2)ꢀ,
3
ꢀ
ꢂ3
ꢀ
b
¼80.76(2)ꢀ,
g
¼59.80(2) , V¼1068.2(4) A , Z¼2, Dc¼1.363 g cm
,
117.2, 116.9, 105.6; 31P NMR (CDCl3, 162 MHz)
d
¼ꢂ39.3; IR (KBr,
m
(Mo K
a
)¼1.645 cmꢂ1, F(000)¼452.00, 4888 unique reflections, 305
cmꢂ1
)
n
¼3055, 2227, 1668, 1624, 1576, 1491, 1454, 1417, 1406, 1363,
parameters, R1 (I>2
s
(I))¼0.0412, wR2 (all data)¼0.1158, GOF 0.993.
1338, 1290, 1247, 1211, 1172, 1149, 1103, 1043, 1016, 976, 958, 931,
914, 854e754; HRMS (APCI): [MþH]þ, found 446.0946. C28H17NO3P
requires 446.0941.
CCDC-944085 (3a), CCDC-944086 (3b), CCDC-944087
(3d$0.5CH3CN), and CCDC-944088 (3e) contain the supplemen-
tary crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
l
4.3. 2-Methyl-2,20 5-spirobi[2H-naphth[1,8-cd]-1,2-
oxaphosphole] (4)
Supplementary data
To a solution of 1 (100 mg, 0.316 mmol) in 20 mL of THF was
added dropwise t-BuLi (1.59 M n-pentane solution, 0.22 mL,
0.35 mmol) at room temperature. The solution was stirred for
10 min and then an excess amount of iodomethane (0.50 mL,
8.0 mmol) was added. After 30 min of stirring at room temperature
water (20 mL) was added and the mixture was extracted with Et2O
(50 mLꢃ3). The collected organic layer was dried over MgSO4 and
the volatiles were removed under reduced pressure. Purification of
the residue was carried out by PTLC (CH2Cl2/hexane 1:1) followed
by recrystallization from CH2Cl2/hexane to give 4 as pale crystals.
Yield 87.0 mg (84%); mp 178e180 ꢀC. Anal. Calcd for C21H15O2P: C
76.36, H 4.57. Found: C 76.20, H 4.46; 1H NMR (CDCl3, 600 MHz)
Copies of 1H NMR and 13C NMR spectra of aroylphosphoranes 3
and methylphosphorane 4. Supplementary data associated with
this article can be found in the online version, at http://dx.doi.org/
10.1016/j.tet.2013.08.004. These data include MOL files and InChi-
Keys of the most important compounds described in this article.
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