Synthesis, solid-state structures, and aggregation motifs of phosphines and phosphine oxides bearing one 2-pyridone ring

Article abstract of DOI:10.1021/jo000417n

Three phosphines and their corresponding oxides bearing one 2-pyridone ring and two benzene rings were synthesized. Their single-crystal X-ray analyses exhibited three kinds of molecular aggregation: bimolecular aggregates, chiral one-dimensional structures, and achiral one-dimensional structures. In the bimolecular aggregate of (2-oxo-1,2-dihydro-x-pyridyl)diphenylphosphines (x = 3: 2a and 6: 2c), cyclic dimers that are derived from two 2-pyridone rings are observed. In contrast, (2-oxo-1,2-dihydro-5-pyridyl)diphenylphosphine (2b) molecules form a chiral one-dimensional chain via intermolecular hydrogen bonding. In the case of phosphine oxides, their oxygen always acts as a hydrogen acceptor of the hydrogen bonding. Thus, (2-oxo-1,2-dihydro-x-pyridyl)diphenylphosphine oxides (x = 3: 3a and 5: 3b) form hydrogen bonds intermolecularly between the oxygen atom on the phosphoryl group and the hydrogen atom on nitrogen to construct a chiral or an achiral one-dimensional chain. Interestingly, (2-oxo-1,2-dihydro-6-pyridyl)diphenylphosphine oxide (3c) exists as a 2-hydroxypyridine form (enol form) in a crystalline state, and intermolecular hydrogen bonds between the phosphoryl oxygen and the hydroxy proton construct an achiral one-dimensional chain.

Full text of DOI:10.1021/jo000417n

J . Org. Chem. 2000, 65, 6917-6921
6917
Syn th esis, Solid -Sta te Str u ctu r es, a n d Aggr ega tion Motifs of
P h osp h in es a n d P h osp h in e Oxid es Bea r in g On e 2-P yr id on e Rin g
Motohiro Akazome, Shihomi Suzuki, Yoshiaki Shimizu, Keiichiro Henmi, and
Katsuyuki Ogura*
Department of Materials Technology, Faculty of Engineering, Chiba University, 1-33 Yayoicho,
Inageku, Chiba 263-8522, J apan
katsu@planet.tc.chiba-u.ac.jp
Received March 21, 2000
Three phosphines and their corresponding oxides bearing one 2-pyridone ring and two benzene
rings were synthesized. Their single-crystal X-ray analyses exhibited three kinds of molecular
aggregation: bimolecular aggregates, chiral one-dimensional structures, and achiral one-dimensional
structures. In the bimolecular aggregate of (2-oxo-1,2-dihydro-x-pyridyl)diphenylphosphines (x )
3: 2a and 6: 2c), cyclic dimers that are derived from two 2-pyridone rings are observed. In contrast,
(2-oxo-1,2-dihydro-5-pyridyl)diphenylphosphine (2b) molecules form a chiral one-dimensional chain
via intermolecular hydrogen bonding. In the case of phosphine oxides, their oxygen always acts as
a hydrogen acceptor of the hydrogen bonding. Thus, (2-oxo-1,2-dihydro-x-pyridyl)diphenylphosphine
oxides (x ) 3: 3a and 5: 3b) form hydrogen bonds intermolecularly between the oxygen atom on
the phosphoryl group and the hydrogen atom on nitrogen to construct a chiral or an achiral one-
dimensional chain. Interestingly, (2-oxo-1,2-dihydro-6-pyridyl)diphenylphosphine oxide (3c) exists
as a 2-hydroxypyridine form (enol form) in a crystalline state, and intermolecular hydrogen bonds
between the phosphoryl oxygen and the hydroxy proton construct an achiral one-dimensional chain.
Sch em e 1
In tr od u ction
Crystal engineering to design and control crystal
packing arrangement has emerged as one of the most
active fields in chemistry.1,2 A 2-pyridone ring is known
to play an important role in supramolecular chemistry.
This is because the molecules bearing 2-pyridone rings
form intermolecular hydrogen bonds to control the con-
formation and geometry of their aggregation; two ag-
gregation motifs of 2-pyridones were reported: a cyclic
dimer3,4 and a one-dimensional chain5 (Scheme 1). Re-
cently, Wuest et al. utilized the hydrogen-bonding ability
of the 2-pyridone rings to produce molecular tectonics
that construct beautiful three-dimensional assemblies,
molecular aggregate, and self-replication.6
gen bonds of phosphines and phosphine oxides bearing
one 2-pyridone ring, because phosphines are well-known
to be a good ligand for transition metal complexes.
However, introduction of a 2-pyridone ring into phos-
phines and phosphine oxides had received less attention
except for (2-oxo-1,2-dihydro-6-pyridyl)diphenylphos-
phine ligands.7,8 First, we synthesized three phosphines
and three phosphine oxides (Scheme 2), and their ag-
gregation was elucidated in solid state by means of single-
crystal X-ray analyses.
Against this background, we were interested in devel-
oping a three-dimensional packing structure via hydro-
(1) Desiraju, G. R. Crystal Engineering: The Design of Organic
Solids; Elsevier: Amsterdam, 1989.
(2) Comprehensive Supramolecular Chemistry; Lehn, J .-M., Atwood,
J . L., Davies, J . E. D., MacNicol, D. D., Vo¨gtle, F., Eds.; Pergamon
Press: Oxford, 1996; Vol. 6.
(3) (a) Beak, P.; Covington, J . B.; Smith, S. G.; White, J . M.; Zeigler,
J . M. J . Org. Chem. 1980, 45, 1354. (b) Beak, P. Acc. Chem. Res. 1977,
10, 185. (c) Hammes, G. G.; Park, A. C. J . Am. Chem. Soc. 1969, 91,
956. (d) Krackov, M. H.; Lee, C. M.; Mautner, H. G. J . Am. Chem. Soc.
1965, 87, 892.
(4) (a) Held, A.; Pratt, D. W. J . Am. Chem. Soc. 1990, 112, 8629. (b)
Held, A.; Champagnem, B. B.; Pratt, D. W. J . Chem. Phys. 1991, 95,
8732. (c) Held, A.; Pratt, D. W. J . Chem. Phys. 1992, 96, 4869.
(5) (a) Yang, H. W.; Craven, B. M. Acta Crystallogr. 1998, B54, 912.
(b) Penfold, B. R. Acta Crystallogr. 1953, 6, 591.
Resu lts a n d Discu ssion
Syn th eses of P h osp h in es (2a -c) a n d P h osp h in e
Oxid es (3a -c). The synthetic routes leading to phos-
phines 2a -c and phosphine oxides 3a -c are summarized
in Scheme 2. The starting 2-benzyloxy-x-bromopyridines
(6) (a) Su, D.; Wang, X.; Simard, M.; Wuest, J . D. Supramol. Chem.
1995, 6, 171. (b) Dycharme, Y.; Wuest, J . D. J . Org. Chem. 1988, 53,
5787. (c) Simard, M.; Su, D.; Wuest, J . D. J . Am. Chem. Soc. 1991,
113, 4696. (d) Wang, X.; Simard, M.; Su, D.; Wuest, J . D. J . Am. Chem.
Soc. 1994, 116, 12119. (e) Gallant, M.; Viet, M. T. P.; Wuest, J . D. J .
Am. Chem. Soc. 1991, 113, 721. (f) Boucher, EÄ .; Simard, M.; Wuest, J .
D. J . Org. Chem. 1995, 60, 1408. (g) Persica, F.; Wuest, J . D. J . Org.
Chem. 1993, 58, 95. (h) Gallant, M.; Viet, M. T. P.; Wuest, J . D. J .
Org. Chem. Soc. 1991, 56, 2284.
(7) Newkome, G. R.; Hager, D. C. J . Org. Chem. 1978, 43, 947.
(8) 3a as ligands: (a) Mashima, K.; Tanaka, M.; Tani, K.; Nakamura,
A.; Takeda, S.; Mori, W.; Yamaguchi, K. J . Am. Chem. Soc. 1997, 115,
44307. (b) Mashima, K.; Tanaka, M.; Kaneda, Y.; Fukumoto, A.;
Mizumoto, H.; Tani, K.; Nakano, H.; Nakamura, A.; Sekiguchi, T.;
Kamada, K.; Ohta, K. Chem. Lett. 1997, 411. (c) Mashima, K.; Nakano,
H.; Nakamura, A. J . Am. Chem. Soc. 1996, 118, 9083. (d) Nakano, H.;
Nakamura, A.; Mashima, K. Inorg. Chem. 1996, 35, 4007. (e) Mashima,
K.; Nakano, H.; Nakamura, A. J . Am. Chem. Soc. 1993, 115, 11632.
10.1021/jo000417n CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/21/2000

6918 J . Org. Chem., Vol. 65, No. 21, 2000
Akazome et al.
Ta ble 1. Cr ysta l Str u ctu r e Da ta for 2a -c a n d 3a -c
compounds
2a
2b
2c
3a
3b
3c
mol formula
Mw
crystal system
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C
17H14NOP
C17H14NOP
279.30
orthorhombic
P212121 (No. 19)
11.795(3)
15.010(5)
7.939(2)
90
C17H14NOP
279.30
triclinic
P-1 (No. 2)
8.548(2)
9.172(2)
10.283(2)
69.71(1)
74.93(1)
79.49(1)
726.4(2)
2
C17H14NO2P
295.30
monoclinic
P21/n (No. 14)
14.964(6)
10.398(4)
9.575(4)
90
98.41(3)
90
1474(1)
4
C17H14NO2P
295.30
orthorhombic
P212121 (No. 19)
12.492(6)
12.660(5)
9.181(3)
90
90
90
C17H14NO2P
295.30
orthorhombic
Pcab (No. 61)
14.078(4)
16.280(3)
12.795(3)
90
279.30
triclinic
P-1 (No. 2)
9.381(2)
11.507(4)
14.703(4)
69.91(2)
75.59(2)
88.71(3)
1440.2(8)
4
90
90
90
90
1405.6(7)
4
1542(1)
4
2932.5(9)
8
Z
Dcalc
1.288
5476
4879
4.3
1.319
1342
1204
5.4
1.277
2763
2528
6.4
1.33
2805
2316
4.3
1.350
1370
1293
2.9
1.337
2788
1882
5.6
unique reflecns
of which I > 1.5σ
R
Rw
5.0
5.8
8.9
4.9
3.3
6.0
Ta ble 2. Selected Bon d Len gth s
Sch em e 2
(x ) 3, 5, and 6) were prepared according to the literature
method.6b,f,9 Lithiation of the 2-benzyloxy-x-bromopyri-
dines followed by coupling with chlorodiphenylphosphine
gave 1a -c, which were deprotected with TFA to afford
2a -c. Further oxidation of 2a -c with hydrogen peroxide
gave 3a -c.
Str u ctu r a l F ea tu r e of Th r ee P h osp h in es (2a -c)
a n d Th eir Oxid es (3a -c). The crystal structures of
three phosphines (2a -c) and three phosphine oxides
(3a -c) were analyzed by single-crystal X-ray analyses.
Since three polymorphs are known for triphenylphos-
phine oxide (Ph3PO),10 it is unclear whether polymor-
phism is possible for these compounds. Crystal data and
the selected bond lengths are given in Tables 1 and 2. In
the crystal of 2a , two crystallographically independent
molecules are present in an asymmetric unit. These
molecules, which are labeled as P(A) and P(B), are very
similar to each other in conformation. As is apparent from
Table 2, the selected bond lengths of 2-pyridone rings are
very similar except for 3c, which has a 2-hydroxypyridine
moiety instead of a 2-pyridone ring (vide infra).
All of these phosphines and their oxides, except for 3c,
have propeller-type conformation where one 2-pyridone
ring and two phenyl groups rotate in one direction, more
or less.
several conformational similarities were observed. For
example, the conformations of 2a and 2c are similar to
that of Ph2(2-Py)P (P21/n), and the conformations of 3a
and 2b are similar to that of Ph3PO (Pcab and P21/c) and
Ph3P11 (P21/a). Furthermore, 3b and Ph3PO (P21/c) have
very similar conformation. Regardless of the phosphines
or phosphine oxides, their torsion angles of the similar
conformations are different within ca. 20°.
Among 2a -c, 3a , 3b, Ph3PO,10 triphenylphosphine
(Ph3P),11 and diphenyl(2-pyridyl)phosphine [Ph2(2-Py)P],12
(9) Serio Duggan, A. J .; Grabowski, E. J . J .; Russ, W. K. Synthesis
1980, 573.
(10) (a) Brock, C. P.; Schweizer, W. B.; Dunitz, J . D. J . Am. Chem.
Soc. 1985, 107, 6964. (b) Bondoli, G.; Bortolozzo, G.; Clemente, D. A.;
Croatto, U.; Panattoni, C. J . Chem. Soc. A 1970, 2778-2780. (c) Ruban,
G.; Zabel, V. Cryst. Struct. Comm. 1976, 5, 671. (d) Spek, A. L. Acta
Crystallogr. 1987, C43, 1233.
(11) Daly, J . J . J . Chem. Soc. 1964, 3799.
(12) Charland, J .-P.; Roustan, J .-L.; Ansari, N. Acta Crystallogr.
1989, C45, 680.

Phosphines and with a 2-Pyridone Ring
J . Org. Chem., Vol. 65, No. 21, 2000 6919
Figu r e 2. Hydrogen-bonding columnar structure of 2b (chiral).
Hydrogen atoms are omitted for clarity.
which has been reported to afford the crystals (P212121)
with 21 helical columns via hydrogen bonds (Scheme 1).5
Molecu la r Aggr ega tion of P h osp h in e Oxid es (3a -
c) by Hyd r ogen Bon d in g betw een 2-P yr id on es a n d
P h osp h in e Oxid es. Crystals of 3a have a 21 helical
chain, which comprises intermolecular hydrogen bonds
between the phosphoryl oxygen and the pyridone N-
proton (Figure 3a). In this case, the oxygen atom of the
phosphoryl groups worked as a good hydrogen accep-
tor13,14 to disrupt self-aggregation of the 2-pyridone rings.
One-dimensional hydrogen-bonding chains of the P-form
and M-form of 3a align side by side so that the crystals
become achiral (space groups P21/n).
In a manner similar to that of 2b, the crystals of its
oxide 3b have a space group of P212121, and chiral 21
helical chains were constructed by means of hydrogen
bonds (Figure 3b).
In crystals (space groups Pcab) of 3c, a 21 helical chain
via hydrogen bonds was also formed, and the helical
chains paired with the opposite 21 helical chain and, in
result, became achiral (Figure 4).
F igu r e 1. Two molecular aggregation by hydrogen bonds. (a)
Crystal structure of 2a . (b) Crystal structure of 2c. Hydrogen
atoms are omitted for clarity.
F ixa tion of th e En ol F or m of 3c in Solid Sta te. It
should be noted that 3c adopts an enol form in solid state,
but a keto form predominates in solution. The bond
distances in Table 2 strongly supported the hydroxy-
pyridine skeleton. The C-O bond (1.340(3) Å) is fairly
longer than other C-O bonds (1.229(2)-1.244(2) Å), and
the C-N bond (1.322(3) Å) is shorter than other C-N
bonds (1.373(1)-1.382(2) Å).
The IR spectra of 2a -c, 3a , and 3b in crystalline state
show an absorption peak in the range between 1631 and
1684 cm-1, which corresponds with absorption of 2-pyri-
done carbonyl. The absorption is similar to that (1650
cm-1) of 2-pyridone in solid state.15 Although 3c in solid
state exhibited no absorption in this range, a chloroform
solution of 3c showed a strong absorbent peak at 1665
cm-1. Etter et al. reported a quite similar phenomenon,
namely, that triphenylphosphine oxide compels an eno-
lizable amide into an enol form by the hydrogen bond.14
The present tautomerism was also detected by 13C NMR
spectra as summarized in Figure 5. Most of the com-
pounds listed herein show that the chemical shifts of
their solid states are comparable with those of their
From these results, replacement of the phenyl or
pyridyl group by one 2-pyridone ring did not influence
the typical propeller-type conformation. More surpris-
ingly, even intermolecular hydrogen bonding between the
2-pyridone rings did not compel their conformation to
change. The intriguing conformation of 3c may be based
on a unique hydrogen network and/or packing (shown in
Figure 4).
Molecu la r Aggr ega tion of P h osp h in es (2a -c) by
Hyd r ogen Bon d in g betw een 2-P yr id on es. In crystals
of 2a and 2c, the molecules aggregate by bimolecular
hydrogen bonds to form a dimeric structure (Figure 1).
Hydrogen bonding distances are summarized in Table 2.
Since these have a space group of P-1, two phosphine
molecules in the dimer are a mirror image of each other
and are centrosymmetric. The stacking of the dimeric
aggregates constructs these crystals.
In contrast, 2b forms a one-dimensional chain of
hydrogen bonds between 2-pyridone rings, which is 21
helical columnar (shown as P-form of 2b in Figure 2).
Since the space group of 2b crystal is P212121 (chiral),
the 21 helical columns stacked side by side in opposite
direction. This is similar to the case of 2-pyridone itself,
(13) Etter, M. C.; Baures, P. W. J . Am. Chem. Soc. 1988, 110, 639.
(14) Etter, M. C.; Gillard, R. D.; Gleason, W. B.; Rasmussen, J . K.;
Duerst, R. W.; J ohnson, R. B. J . Org. Chem. 1986, 51, 5405.
(15) Mason, S. F. J . Chem. Soc. 1957, 4874.

6920 J . Org. Chem., Vol. 65, No. 21, 2000
Akazome et al.
F igu r e 3. (a) Hydrogen-bonding columnar structure of 3a
(achiral). (b) Hydrogen-bonding columnar structure of 3b
(chiral). Hydrogen atoms are omitted for clarity.
F igu r e 5. Chemical shift (ppm) of 13C NMR spectra of 1c,
2c, 3c, and related compounds in solid and solution. Coupling
constants (J CP, Hz) are shown in parentheses.
2-hydroxypyridine structure (marked underlines in Fig-
ure 5), the enol form in solid 3c was supported again. A
similar change in chemical shift was reported in the
parent 2-pyridone ring as depicted in Figure 5.16
Con clu sion
Three phosphines (2a -c) and their corresponding
oxides (3a -c) bearing one 2-pyridone ring and two
benzene rings were synthesized, and their crystal struc-
tures and aggregation motifs by means of hydrogen bonds
were elucidated by single-crystal X-ray analyses. In the
cases of the phosphines 2a and 2c, two molecules of
2-pyridones aggregate so as to construct a cyclic dimer.
The crystals of 2b showed a one-dimensional chain like
those of 2-pyridone.
In case of the phosphine oxides (3a -c), the oxygen
atom of the phosphoryl groups serves as a good acceptor
of hydrogen bonding to link a neighboring molecule. As
a result, the phosphine oxides have a chiral or an achiral
one-dimensional chain by means of hydrogen bonds. The
phosphine oxide 3c showed a keto-enol tautomerism:
F igu r e 4. Crystal structure of (2-hydroxy-6-pyridyl)diphen-
ylphosphine oxide as a tautomer of 3c; b-c plane. Hydrogen
atoms except for the hydroxy group are omitted for clarity.
solution states. However, the 13C NMR spectrum of 3c
in solid state was different from that in a solution. Since
the chemical shifts of the 3- and 6-carbons of the
2-pyridone ring are quite different from those of the
(16) Vo¨geli, U.; von Philipsborn, W. Org. Magn. Reson. 1973, 5, 551.

Phosphines and with a 2-Pyridone Ring
J . Org. Chem., Vol. 65, No. 21, 2000 6921
114.0, 119.2, 129.5, 132.0, 133.3, 135.3, 140.6, 145.2, 166.4;
IR (KBr) 1643 cm-1; IR (CHCl3) 1654 cm-1. Anal. Calcd for
C17H14NOP: C, 73.11; H, 5.05, N, 5.02. Found: C, 73.21; H,
4.99; N, 4.96.
the keto form was observed in solution, but the enol form
was found in solid state.
Now we are investigating the application of these
phosphines as ligands of transition metals.
P r ep a r a t ion of t h e P h osp h in e Oxid e 3a . A Typ ica l
P r oced u r e. Hydrogen peroxide (30%, 1 mL) was added to a
solution of 2a (28 mg, 0.10 mmol) in chloroform/diethyl ether
(1:1, 30 mL) and stirred at room temperature. After 3 h, water
and chloroform were added. The aqueous layer was removed
and further extracted with chloroform. The combined organic
layer was dried (Na2SO4) and concentrated in vacuo. A
colorless solid 3a (27 mg, 0.09 mmol) was obtained in 90%
yield: mp 147.6 °C (TG-DTA); 1H NMR (d4-MeOH) δ 6.58 (ddd,
Exp er im en ta l Section
Gen er a l Meth od s. Melting points are measured on a hot
stage or TG-DTA and are uncorrected. 1H and 13C NMR spectra
of CDCl3 solution were recorded at 300 and 75 MHz, respec-
tively. 13C CP/MAS NMR spectra were recorded at a frequency
of 75.50 MHz, rotor spinning speed of 3.5 or 4.0 kHz, 1024
scans, pulse interval of 10 s, contact time of 5 ms, and spectral
width of 29 940 Hz. Elemental analyses were performed at
Chemical Analysis Center, Chiba University, J apan.
3
4
3J HH ) 7.1 Hz, J HH ) 6.4 Hz, J HP ) 1.9 Hz, 1H), 7.48-7.83
(m, 11H), 8.23 (ddd, 3J HP ) 14.4 Hz, 3J HH ) 7.1 Hz, 4J HP ) 2.2
Hz, 1H); IR (KBr) 1667, 1640 cm-1. Anal. Calcd for C17H14
-
2-Benzyloxy-3-bromopyridine,6b,9 2-benzyloxy-5-bromopyri-
dine,6f,9 and 2-benzyloxy-6-bromopyridine6b,9 were prepared
according to the literature procedures.
NO2P: C, 69.15; H, 4.78; N, 4.74. Found: C, 68.96; H, 4.57;
N, 4.73.
P h osp h in e oxid e 3b: colorless solid; mp 229.4 °C (TG-
DTA); 1H NMR (CDCl3) δ 6.60 (dd, 3J HH ) 10.1 Hz, 4J HP ) 2.3
Hz, 1H), 7.27-7.71 (m, 12H), 13.0 (s(br), 1H); IR (KBr) 1673,
Syn th esis of th e P h osp h in e 1a . A Typ ica l P r oced u r e.
n-Butyllithium (1.6 M in hexane, 2.0 mL, 3.2 mmol) was added
dropwise to a stirred solution of 2-benzyloxy-3-bromopyridine
(0.62 g, 2.3 mmol) in dry THF (10 mL) at -78 °C under N2
and stirred for 30 min. Then chlorodiphenylphosphine (0.6 mL,
3.3 mmol) was added to the solution, which was stirred at -78
°C for 30 min and warmed to room temperature. After 1 h,
water was added and further extracted with chloroform. The
combined organic layer was dried (Na2SO4) and concentrated
in vacuo. Purification by column chromatography on silica gel
(hexane/chloroform 1:3) gave 1a (0.28 g, 0.76 mmol, 33%) as a
colorless solid: mp 142.1-146.1 °C (hot stage); 1H NMR
(CDCl3) δ 5.34 (s, 2H), 6.80 (dd, 3J HH ) 7.3 Hz, 3J HH ) 5.1 Hz,
1650 cm-1; IR (CHCl3) 1680, 1656 cm-1. Anal. Calcd for C17H14
-
NO2P: C, 69.15; H, 4.78; N, 4.74. Found: C, 69.11; H, 4.75; N
4.98.
P h osp h in e oxid e 3c: colorless solid; mp 204 °C (TG-DTA),
3
4
1H NMR (CDCl3) δ 6.36 (ddd, J HH ) 6.3 Hz, J HH ) 1.2 Hz,
3
4
3J HP ) 9.2 Hz, 1H), 6.68 (dd, J HH ) 9.3 Hz, J HH ) 1.2 Hz,
3
3
4
1H), 7.38 (ddd, J HH ) 9.3 Hz, J HH ) 6.3 Hz, J HP ) 4.2 Hz,
1H), 7.50-7.76 (m, 10H), 9.81 (s(br), 1H); 13C NMR (CDCl3) δ
113.9 (d, 2J CP ) 11.3 Hz), 125.5, 129.8 (d, 2J CP ) 12.3 Hz), 130.1
1
3
4
(d, J CP ) 107.6 Hz), 132.9 (d, J CP ) 10.3 Hz), 133.9 (d, J CP
3
1
) 2.7 Hz), 139.9 (d, J CP ) 12.4 Hz), 141.3 (d, J CP ) 104.4
3
4
Hz), 163.7 (d, J CP ) 7.0 Hz); 13C NMR (solid) δ 111.3, 118.1,
3
1H), 6.97-7.40 (m, 16H), 8.13 (dd, J HH ) 4.9 Hz, J HH ) 1.9
Hz, 1H). Anal. Calcd for C24H20NOP‚0.5H2O: C, 76.18; H, 5.59;
N, 3.70. Found: C, 76.45; H 5.46; N, 3.32.
131.0, 132.0, 134.7, 140.4, 153.7, 164.4; IR (CHCl3) 1665 cm-1
.
Anal. Calcd for C17H14NO2P: C, 69.15; H, 4.78; N, 4.74.
Found: C, 69.23; H, 4.71; N, 4.75.
P h osp h in e 1b: colorless solid; mp 66.8-68.2 °C (hot stage);
3
1H NMR (CDCl3) δ 5.38 (s, 2H), 6.80 (d, J HH ) 8.5 Hz, 1H),
(2-Ben zyloxy-6-p yr id yl)d ip h en ylp h osp h in e oxid e: col-
3
3
orless solid; mp 142.1-146.1 °C (EtOH/hexane, hot stage); 1H
7.27-7.47 (m, 15H), 7.51 (ddd, J HH ) 8.5 Hz, J HP ) 5.9 Hz,
4J HH ) 2.3 Hz, 1H), 8.13 (dd, J HP ) 4.7 Hz, J HH ) 2.3 Hz,
1H). Anal. Calcd for C24H20NOP‚0.1H2O: C, 77.66; H, 5.48;
N, 3.78. Found: C, 77.51; H, 5.40; N, 3.76.
3
4
3
5
NMR (CDCl3) δ 5.27 (s, 2H), 6.91 (ddd, J HH ) 8.4 Hz, J HP
)
4
1.8 Hz, J HH ) 0.9 Hz, 1H), 7.26-7.33 (m, 6H), 7.37-7.44 (m,
3
3
3H), 7.49-7.54 (m, 2H), 7.73 (ddd, J HH ) 8.4 Hz, J HH ) 7.1
4
3
P h osp h in e 1c: colorless solid; mp 69.4-70.4 °C (hot stage);
Hz, J HP ) 4.1 Hz, 1H), 7.75-7.83 (m, 4H), 7.89 (ddd, J HH
)
3
4
1H NMR (CDCl3) δ 5.26 (s, 2H), 6.66 (dd, J HH ) 8.2 Hz, J HH
7.1 Hz, J HP ) 6.2 Hz, J HH ) 0.9 Hz, 1H); 13C NMR (CDCl3)
δ 68.6, 115.1, 123.2 (d, 2J CP ) 18.9 Hz), 128.5, 128.7, 129.2 (d,
3
4
3
4
3
) 0.8 Hz, 1H), 6.78 (ddd, J HH ) 7.1 Hz, J HH ) 0.8 Hz, J HP
) 2.3 Hz, 1H), 7.25-7.49 (m, 16H); 13C NMR (CDCl3) δ 68.3,
2J CP ) 26.5 Hz), 129.2, 132.6 (d, J CP ) 2.2 Hz), 132.9 (d, J CP
4
3
2
1
3
111.3, 122.9 (d, J CP ) 22.6 Hz), 128.5, 129.1, 129.2, 129.5 (d,
) 9.4 Hz), 133.1 (d, J CP ) 104.5 Hz), 137.9, 139.7 (d, J CP
)
2J CP ) 32.9 Hz), 135.1 (d, 3J CP ) 19.4 Hz), 137.4 (d, J CP ) 9.7
1
10.8 Hz), 153.5 (d, 1J CP ) 132.6), 163 (d, 3J CP ) 19.5); 13C NMR
(solid) δ 69.7, 114.8, 124.7, 128.7, 130.9, 133.1, 134.1, 135.0,
Hz), 138.3, 139.1 (d, 3J CP ) 4.8 Hz), 160.9,163.9 (d, 1J CP ) 10.7
Hz); 13C NMR (solid) δ 66.0, 111.1, 121.8, 128.8, 129.7, 134.7,
137.4, 138.5, 140.9, 158.1, 162.1. Anal. Calcd for C24H20NOP:
C, 78,04; H, 5.46; N, 3.79. Found: C, 77.66; H, 5.39; N, 4.00.
Syn th esis of th e P h osp h in e 2a . A Typ ica l P r oced u r e.
A solution of 1a (0.11 g, 0.30 mmol) in TFA (5 mL) was stirred
at room temperature for 1.5 h. The reaction mixture was
neutralized by saturated aqueous NaHCO3 and then extracted
with chloroform. The combined organic layer was dried (Na2-
SO4) and concentrated in vacuo. Purification by column
chromatography on silica gel (hexane/ethyl acetate 1:2) gave
2a (0.07 g, 0.27 mmol, 90%) as a colorless solid: mp 198 °C
136.3, 142.3, 152.4, 136.5. Anal. Calcd for
0.5C2H6O: C, 73.50; H, 5.68; N, 3.43. Found: C, 73.20; H, 5.40;
N, 3.38.
C24H20NO2P‚
Cr ysta l Str u ctu r e An a lysis. Single crystals of 2a -c and
3a -c were prepared by recrystallization from ethanol/hexane.
Data collection was performed on a four-circle diffractometer
with monochromated Cu KR (λ ) 1.54178 Å) radiation, and
the X-ray intensities were measured up to 2θ ) 140° at 298
K. The structures were solved and refined on direct methods
(SIR 9217 on a computer program package; maXus ver. 1.1 from
Mac Science Co. Ltd.)
1
3
3
(TG-DTA); H NMR (CDCl3) δ 6.13 (t, J HH ) J HP ) 6.7 Hz,
3
3
4
1H), 6.86 (ddd, J HH ) 6.7 Hz, J HH ) 3.5 Hz, J HP ) 2.1 Hz,
1H), 7.26 (m, 1H), 7.30-7.37 (m, 10H), 13.1 (s(br), 1H); IR
Ack n ow led gm en t. This work was supported by
Grant-in-Aids for Research for the Future Program
(J SPS-RFTF96P00304) and Encouragement of Young
Scientists (11750733) from The J apan Society for the
Promotion of Science.
(KBr) 1631 cm-1; IR (CHCl3) 1634 cm-1. Anal. Calcd for C17H14
-
NOP: C, 73.11; H, 5.05; N, 5.02. Found: C, 72.57; H, 4.82; N,
4.95.
P h osp h in e 2b: colorless solid; mp 152 °C (TG-DTA); 1H
3
NMR (CDCl3) δ 6.56 (d, J HH ) 9.2 Hz, 1H), 7.26-7.41 (m,
12H), 13.2 (s(br), 1H); IR (KBr) 1684, 1662 cm-1; IR (CHCl3)
1675, 1652 cm-1. Anal. Calcd for C17H14NOP: C, 73.11; H, 5.05;
N, 5.02. Found: C, 72.83, H, 4.95, N, 4.93.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and thermal parameters, bond lengths and angles,
and ORTEP views of 2a -c and 3a -c. This material is
available free of charge via the Internet at http://pubs.acs.org.
1
P h osp h in e 2c: colorless solid; mp 195.5 °C (TG-DTA); H
3
3
4
NMR (CDCl3) δ 6.21 (ddd, J HH ) 6.6 Hz, J HP ) 5.6 Hz, J HH
3
4
J O000417N
) 1.0 Hz, 1H), 6.48 (dd, J HH ) 9.3 Hz, J HH ) 1.0 Hz, 1H),
7.29-7.44 (m, 11H), 9.22 (s(br), 1H); 13C NMR (CDCl3) δ 114.2
(d, 2J CP ) 19.9 Hz), 121.8, 130.0 (d, 3J CP ) 7.5 Hz), 130.9, 133.6
(17) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J . Appl. Crystallogr. 1994, 27,
435.
1
2
3
(d, J CP ) 9.7 Hz), 134.7 (d, J CP ) 19.9 Hz), 141.0 (d, J CP
)
6.5 Hz), 147.2 (d, J CP ) 24.7 Hz), 164.9; 13C NMR (Solid) δ
1