A representative of P,P,P-trihalogenylides: Synthesis and structure

Article abstract of DOI:10.1021/jo0606352

The representative of P,P,P-trichloroylides-5-methyl-2-phenyl-4- (trichlorophosphoranylidene)-2,4-dihydro-3H-pyrazol-3-one-was synthesized. Its constitution was confirmed by ¹H, ¹³C, and ³¹P NMR spectroscopy and by X-ray a

Full text of DOI:10.1021/jo0606352

determined. Despite such huge attention, the sole trichlorophos-
phorus ylide synthesized exists predominantly as a zwitterion
and no X-ray data are available. One of the most serious hurdles
in the synthesis of P-chloroylides is their propensity to 1,2-
P,C-chloro shift resulting in trivalent phosphorus derivatives.
Recently, starting from 4-phosphorylated-5-alkoxypyrazoles, we
have synthesized P-chloro- and P,P-dichloroylides, with the final
stage being vinylogous Arbuzov’s reaction.6 These compounds
appeared to be quite stable, not prone to 1,2-P,C-chloro shift.
The same strategy was used for the synthesis of P,P,P-
trichloroylides. The starting compound 1, described by us earlier,
is a stable and easily accessible one. Chlorination of dichloro-
phosphine 1 affords phosphorane 2, moving liquid, which has
in the 31P NMR spectrum the sole chemical shift of -68.5
consistent with the phosphoranes. The phosphorane 2 can be
stored for a few days at a temperature of 0 °C, but in solution,
both in polar and nonpolar ones, it decomposes promptly. As
the compound is quite labile, we fail to separate it in an
analytically pure state. After numerous attempts, we have
established that phosphorane 2 undergoes very selective rear-
rangement into the targeted trichloroylide 3 under strictly
controlled conditions. The solvent of choice appeared to be
methylene chloride that was thoroughly degassed and purified
from any traces of chloroform. In this solvent at the temperature
of 18-20 °C, the 31P NMR signal of phosphorane 2 completely
transforms into the signal of trichloroylide 3 (Scheme 1).
The trichloroylide 3 is a solid which crystallizes from ether.
It is a quite labile compound which can be kept for a few days
A Representative of P,P,P-Trihalogenylides:
Synthesis and Structure
Anatoliy P. Marchenko, Georgyi N. Koidan,
Aleksandr N. Kostyuk,* Andrei A. Tolmachev,
Evgenij G. Kapustin, and Aleksandr M. Pinchuk
Institute of Organic Chemistry, National Academy of Sciences of
Ukraine, Murmanska 5, KyiV-94, 02094, Ukraine
a.kostyuk@enamine.net
ReceiVed March 23, 2006
The representative of P,P,P-trichloroylidess5-methyl-2-
phenyl-4-(trichlorophosphoranylidene)-2,4-dihydro-3H-pyra-
zol-3-oneswas synthesized. Its constitution was confirmed
by 1H, 13C, and 31P NMR spectroscopy and by X-ray analysis.
Some chemical properties were studied and compared with
ones of P,P,P-trimethylylides5-methyl-2-phenyl-4-(trimeth-
ylphosphoranylidene)-2,4-dihydro-3H-pyrazol-3-one. DFT
calculations of the model molecules were carried out.
1
at room temperature. Its structure was proved by H, 13C, and
31P NMR spectroscopy and finally by X-ray analysis. To
compare peculiarities of structures and properties of trichlo-
roylide, P,P,P-trimethylylide 6 was synthesized. The heating of
phosphonium salt 5 resulted in a mixture of the targeted ylide
6 and N-alkylated byproduct 7. The related trimethyl-substituted
ylide 6 was likewise characterized by X-ray single-crystal
diffraction (Figure 1). The molecular parameters of 3 and 6
mainly correspond to those reported for semi-stabilized and
stabilized phosphorus ylides: the phosphorus atom has the usual
tetrahedral configuration with the shortest P-X bond located
almost in the ylide plane, and the ylide carbon atom C(2) is
planar. The most interesting feature of the molecular structure
of ylide 3 is the noticeable shortening of the formal PdC double
bond of 1.663(7) Å in comparison with all known semi-
stabilized and stabilized phosphorus ylides (PdC ) 1.70-1.76
Å) as well as with the corresponding value of 1.725(3) Å in
the related compound 6.1
DFT calculations of the model molecules (Figure 2) I (X dF),
II (X ) Cl), III (X dH), and IV (X ) CH3) have been carried
out at the B3LYP/6-311++G(3df,3pd) level of theory to under-
stand the nature of the shortening of the PdC double bond. Nature
of the stationary points was verified by analysis of the matrices
of the energy second derivatives. All calculations were performed
with the Gaussian 98W program suite.7 Electronic density distri-
bution of obtained wave functions was interpreted in NBO meth-
od formalism.8 Calculated data are listed in Tables 1 and 2.
The P-X3 moieties are trigonal pyramidal with one atom of
the X group being located in the plane of the heterocyclic ring.
Among the four-coordinated phosphorus trihalides of general
type Hal3PdX (X ) O, S, NR, CR2), the key compounds in
the synthesis of organophosphorus derivatives, P,P,P-trihalo-
genylides (X ) CR2), are mentioned only once. P-Halogenylides
occupy a separate niche in P-ylide chemistry stipulated by the
presence of good leaving groups. Being highly active phospho-
rylating agents, these compounds enter into various reactions,
such as cycloaddition, heterocyclization, and others. They are
very convenient objects for studying theoretical structural
problems and reactivity of organophosphorus compounds. These
compounds have been studied quite well, so that many refer-
ences are known on P-monohalogenylides.1 At the same time,
there are only a few works devoted to P,P-dichloro-2 and
difluoro-3 and one to trihalogenylides.4 In P-ylides, the nature
of the P-Cylide bond is the main point of interest and became
the subject of a great number of intensive debates based on the
experimental data and theoretical calculations.5 A large number
of different X-ray structures of phosphorus ylides have been
(1) Kolodyazhnyi, O. I. Phosphorus Ylides. Chemistry and Application
in Organic Synthesis; Wiley-VCH: Weinheim, Germany, 1999.
(2) (a) Kolodyazhnyi, O. I. Zh. Obsch. Khim. 1977, 47, 2390. (b)
Konovets, A. I.; Kostyuk, A. N.; Pinchuk, A. M.; Tolmachev, A. A.; Fischer,
A.; Jones, P. G.; Schmutzler, R. Heteroat. Chem. 2003, 14, 452. (c) Jones,
C.; Junk, P. C.; Richards, A. F.; Waugh, M. New J. Chem. 2002, 26, 1209.
(3) Kolodiazhnyi, O. I.; Schmutzler, R. Synlett 2001, 1065.
(4) Sviridov, B. D.; Porhun, V. I.; Serdobov, M. B.; Ryabokobylko, Yu.
S.; Adamova, G. M.; Poponova, R. V. Zh. Obsch. Khim. 1986, 56, 1268.
(5) (a) Gilheany, D. G. Chem. ReV. 1994, 94, 1339. (b) Sandblom, N.;
Ziegler, T.; Chievers, T. Can. J. Chem. 1996, 74, 2363. (c) Yufit, D. S.;
Howard, J. A. K.; Davidson, M. G. J. Chem. Soc., Perkin Trans. 2 2000,
249.
(6) Tolmachev, A. A.; Konovets, A. I.; Kostyuk, A. N.; Chernega, A.
N.; Pinchuk, A. M. Heteroat. Chem. 1998, 9, N 1, 41.
10.1021/jo0606352 CCC: $33.50 © 2006 American Chemical Society
Published on Web 10/05/2006
J. Org. Chem. 2006, 71, 8633-8636
8633

SCHEME 1
The P-C bond length significantly depends on the substi-
tuent X electronegativity (X ) F, Cl, H, CH3; P-C ) 1.635,
1.662, 1.686, 1.711 Å, correspondingly). 13C NMR experi-
mental data of 3 and 6 correspond with natural charge
distributions in the molecules. Thus, the greater magnetic
shielding of the ylidic carbon in molecule 3, δc ) 81.2(1JP-C
FIGURE 1. Sketches of the molecular structures of P,P,P-trichloroylide
3 and P,P,P-trimethylylide 6. 3: PdC(2) 1.663(7), P-Cl(1) 1.961(3),
P-Cl(2) 1.978(3), P-Cl(2) 1.970(4) Å; Cl(1)-P(1)-C(2)-C(1)
-171.4, Cl(2)-P(1)-C(2)-C(1) 69.6, Cl(3)-P(1)-C(2)-C(1) -50.3°;
the pyrazolyl cycle N(1)N(2)C(1-3) is planar within 0.008 Å. 6:
PdC(2) 1.725(3), P-C(11) 1.778(3), P-C(12) 1.786(4), P-C(13)
1.784(3) Å; Cl(1)-P(1)-C(2)-C(1) -177.8, Cl(2)-P(1)-C(2)-C(1)
-57.5, Cl(3)-P(1)-C(2)-C(1) 61.1°; the pyrazolyl cycle N(1)N(2)C-
(1-3) is planar within 0.004 Å.
) 172 Hz), as compared with that of molecule 6, δc
)
67.7(1JP-C ) 126 Hz), manifests itself in more downfield
chemical shift. Moreover, the higher polarity of the P-C bond
in molecule 3 confers greater value of spin-spin coupling
1
constants JP-C as compared to the corresponding value in
molecule 6. Compared to 13C NMR chemical shifts trend, 31P
NMR spectra have a reverse tendency.
The out-of-plane orientation of the P-X bonds with regard
to the pyrazolyl ring leads to the elongation of these bonds,
whereas in the in-plane orientation, this bond is the shortest
one. The P-X bond lengths for the coplanar and noncoplanar
bonds are X ) F, Cl, H, CH3; P-X ) 1.562 and 1.565, 2.023
and 2.051, 1.090 and 1.093, 1.821 and 1.825 Å, correspondingly.
Such difference is due to the strong stereoselective interaction
of n(Cylide) with σ*(P-X). The interaction depends on the
electronegativity of the substituent X and its orbitals’ energy.
These results are in agreement with previous experimental
studies on the rotational dependence of a P-Cl bond length in
a P-chloroylide.9 Strong interactions of the lone pair of the ylidic
carbon atom with π* orbitals of the pyrazolyl moiety stabilized
the molecules (Figure 2). These interactions also depend on the
electronegativity of the substituents X (Table 2). The two
competitive effects are responsible for the stabilization of the
phosphorus ylide systems: (a) n(Cylide)-σ*(P-X) interaction;
(b) n(Cylide)-π*pyrazolyl interaction.
FIGURE 2. Direction of selected donor-acceptor interactions.
TABLE 1. B3LYP/6-311++G(3df,3pd) Results for Compounds
I-IV
total energy
(Hartree)
ZPVE correction
(Hartree/particle)
lowest frequency
molecule
(cm-1
)
I
II
III
IV
-1020.1164097
-2101.1168323
-722.1504039
-840.1883131
0.118803
0.222415
0.147988
0.114239
21.5
28.6
27.2
9.7
The trichloroylide 3 reacts quite actively, but the reaction
does not lead to cleavage of the P-C bond. Most probably, the
reaction runs via a six-membered intermediate followed by
Arbuzov rearrangement, resulting in phosphonic dichloride 8.
Both 1H NMR (7.70 singlet) and 13C NMR (92.7 singlet) spectra
signals of the OCHCl moiety are singlets with typical chemical
shift values. It should be noted that trimethylylide 6 reacts with
aldehydes by typical Wittig reaction, affording phosphine oxide
10 and an alkene compound 9 in high yield.
The trichloroylide 3 is a thermally unstable compound which
undergoes rearrangement into phosphonic dichloride 11 upon
heating at 170 °C (Scheme 3). Its constitution was confirmed
by a set of physicochemical methods and by the reaction with
dimethylamine resulting in phosphonic diamide 12. Trichlo-
roylide 3 reacts with nucleophiles, as well. Thus, it reacts with
methanol, yielding phosphonate 14.
Besides, some chemical properties of the ylide 3 were studied.
A typical reaction of phosphorus ylides is the reaction with
aldehydes (Scheme 2).
(7) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A., Jr.;
Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels, A.
D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi,
M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.;
Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Malick,
D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Cioslowski, J.;
Ortiz, J. V.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi,
I.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Gonzalez, C.; Challacombe, M.; Gill, P. M.
W.; Johnson, B. G.; Chen, W.; Wong, M. W.; Andres, J. L.; Head-Gordon,
M.; Replogle, E. S.; Pople, J. A. Gaussian 98, revision A.7; Gaussian,
Inc.: Pittsburgh, PA, 1998.
Experimental Section
(8) Glendening, A. D.; Reed, A. E.; Carpenter, J. E.; Weinhold, F.
Gaussian 98W, revision A.7 (NBO version 3.1); Gaussian Inc.: Pittsburgh,
PA, 1998.
(9) Grutzmacher, H.; Pritzkow, H. Angew. Chem., Int. Ed. Engl. 1992,
31, 99.
5-Ethoxy-3-methyl-1-phenyl-4-(tetrachlorophosphoranyl)-1H-
pyrazole 2. To a stirring solution of 1, 5-ethoxy-3-methyl-1-phenyl-
pyrazol-4-yldichlorophosphine (mp 45-46 °C, ether; 10 mmol), in
8634 J. Org. Chem., Vol. 71, No. 22, 2006

TABLE 2. Atomic Natural Charges and Energy of Interactions n(Cylide) with σ*(P-X) and π*pyrazolyl Antibonding Orbitalsa
q(P),
e
q(C2),
e
n(Cylide)-σ*(P-X)
n(Cylide)-π*(C3-N1)
n(Cylide)-π*(C1-O1)
molecule
kcal/mol
kcal/mol
kcal/mol
I
II
III
IV
2.50
1.34
0.92
1.56
-0.89
-0.80
-0.75
-0.75
57.88
63.23
30.47
26.73
36.59
53.66
63.04
72.24
40.95
67.38
80.98
95.75
a NBO analysis shows the strong π-back-donation from the ylidic lone pair located on the carbon atom on the σ*(P-X) orbitals (Figure 2).
SCHEME 2
Calcd for C10H8Cl3N2OP (MW 309.52): C, 38.81; H, 2.61; Cl,
34.36; N, 9.05; P, 10.01. Found: C, 38.64; H, 2.34; Cl, 34.69; N,
8.85; P, 9.73.
4-(Dimethylphosphino)-5-ethoxy-3-methyl-1-phenyl-1H-pyra-
zole 4. To a stirring solution of dichlorophosphine 1 (13.7 mmol)
in ether (30 mL) cooled to -10 °C was added dropwise a solution
of methylmagnesium iodide (30 mmol) in ether (20 mL) for 10
min. The reaction mixture was allowed to reach room temperature,
then after 1 h, the reaction mixture was cooled to -10 °C and a
saturated solution of aqueous NH4Cl was added. The organic layer
was separated, the solvent was evaporated, and the residue was
distilled. Yield 2.58 g (81%). Mp 61-63 °C. 1H NMR (C6D6, 300
MHz): δ 0.95 (t, 3JHH ) 7.2 Hz, 3H), 1.24 (d, 2JHP ) 3.9 Hz, 6H),
3
3
2.44 (s, 3H), 3.77 (q, JHH ) 7.2 Hz, 2H), 6.94 (t, JHH ) 7.5 Hz,
1H), 7.11 (t, 3JHH ) 7.5 Hz, 2H), 7.89 (d, 3JHH ) 7.9 Hz, 2H). 31
P
SCHEME 3
NMR (C6D6, 121.4 MHz): δp -72.5. Anal. Calcd for C14H19N2OP
(MW 262.29): C, 64.11; H, 7.30; N, 10.69; P, 11.81. Found: C,
63.76; H, 7.03; N, 11.04; P, 11.45.
(5-Ethoxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)(trimethyl)-
phosphonium iodide 5. To a solution of phosphine 4 (10 mmol)
in degassed benzene (15 mL) was added a solution of methyl iodide
in the benzene (15 mL). After 20 h, the precipitated solid was
collected by filtration, washed with benzene (2 × 10 mL), and dried
in vacuo until a constant weight was maintained. Yield 3.28 g
1
(88%). Mp 178-179 °C (dec). H NMR (CDCl3, 300 MHz): δ
1.28 (t, 3JHH ) 7.1 Hz, 3H), 2.48 (s, 3H), 2.59 (d, 2JHP ) 14.3 Hz,
3
9H), 3.99 (q, JHH ) 7.1 Hz, 2H), 7.4-7.6 (m, 5H). 31P NMR
(CDCl3, 121.4 MHz): δp 10.6. Anal. Calcd for C15H22IN2OP (MW
404.23): C, 44.57; H, 5.49; I, 31.39; N, 6.93; P, 7.66. Found: C,
44.12; H, 5.67; I, 30.73; N, 7.34; P, 8.01. MS (API) m/z (%): 249-
(100).
carbon tetrachloride (10 mL) was added a solution of chlorine (10
mmol) in carbon tetrachloride (10 mL) during 5 min, keeping the
temperature at -15((5) °C. After 30 min, the reaction mixture was
filtered to remove admixtures. The solvent was evaporated in vacuo
at 0.02 Torr, keeping the temperature below 25 °C until the weight
of the residue remained constant. The residue is a mobile transparent
liquid. Yield 3.62 g (97%). 31P NMR: δp ) -68.5 ppm. The
product decomposes on storing at 20 °C. Anal. Calcd for C12H13-
Cl4N2OP (MW 374.04): C, 38.53; H, 3.50; Cl, 37.91; N, 7.49; P,
8.28. Found: C, 38.62; H, 3.34; Cl, 37.49; N, 7.64; P, 8.39.
5-Methyl-2-phenyl-4-(trimethylphosphoranylidene)-2,4-dihy-
dro-3H-pyrazol-3-one 6 and 2-Ethyl-3-methyl-5-oxo-1-phenyl-
4-(trimethylphosphoranylidene)-4,5-dihydro-1H-pyrazol-2-
ium iodide 7. Phosphonium salt 5 (0.81 g, 2 mmol) was heated in
vacuo at 180 °C for 3 min with the formation of a melt. Then it
was extracted with boiling benzene (4 × 10 mL). The residue was
identified as compound 7. Yield 0.29 g (30%). Mp 258-259 °C.
1H NMR (CDCl3, 300 MHz): δ 1.15 (t, 3JHH ) 7.1 Hz, 3H), 2.47
(d, 2JHP ) 14.4 Hz, 9H), 2.83 (s, 3H), 3.88 (d, 3JHH ) 7.1 Hz, 2H),
3
7.31 (d, JHH ) 7.5 Hz, 2H), 7.3-7.6 (m, 3H). 31P NMR (CDCl3,
5-Methyl-2-phenyl-4-(trichlorophosphoranylidene)-2,4-dihy-
dro-3H-pyrazol-3-one 3. The solution of 2 (8 mmol) in dry
methylene dichloride (degassed and purified from any admixtures
of chloroform) was kept at the temperature of 18-20 °C for 8 h.
During this time, the 31P NMR signal of the tetrachlorophosphorane
2 (δp ) -68.5) gradually disappeared, and the downfield signal of
the trichloroylide 3 at δp ) 55.9 ppm appeared, which eventually
became the sole signal. The solvent was evaporated in vacuo at
0.02 Torr at a temperature lower than 40 °C and was further kept
in vacuo until the residue weight remained constant. The crystalline
residue was washed with dry hexane and again was kept in vacuo
under the same conditions. Yield 2.23 g (90%). It can be crystallized
121.4 MHz): δp 13.5. Anal. Calcd for C15H22IN2OP (MW
404.23): C, 44.57; H, 5.49; I, 31.39; N, 6.93; P, 7.66. Found: C,
44.18; H, 5.11; I, 30.96; N, 6.61; P, 7.87.
The benzene extracts were evaporated to 20 mL and left for 2
h. The precipitated trimethylylide 6 was collected by filtration and
dried. Yield 0.32 g (61%). Mp 187-188 °C; bp 200 °C (0.02 Torr).
2
1H NMR (CDCl3, 300 MHz): δ 1.93 (d, JHP ) 13.8 Hz, 9H),
3
3
2.23 (s, 3H), 7.06 (t, JHH ) 7.5 Hz, 1H), 7.34 (t, JHH )7.5 Hz,
2H), 8.01 (d, JHH ) 7.5 Hz, 2H). 13C NMR (CDCl3, 75.4 MHz):
3
1
1
δ 11.8 (d, Jpc ) 62 Hz, CH3), 16.5 (s, CH3), 67.7 (d, Jpc ) 126
Hz, C), 119.1 (s, CH), 123.3 (s, CH), 128.5 (s, CH), 140.3 (s, C),
147.2 (d, Jcp ) 11.5 Hz, C), 167.7 (d, Jcp ) 19.8 Hz, C). 31P
NMR (CDCl3, 121.4 MHz): δp 4.8. Anal. Calcd for C13H17N2OP
(MW 248.27): C, 62.89; H, 6.90; N, 11.28; P, 12.48. Found: C,
62.64; H, 6.71; N, 10.92; P, 12.0.
2
2
1
from dry ether as yellow prisms. H NMR (C6D6, 300 MHz): δ
3
3
1.93 (s, 3H), 6.95 (t, JHH ) 7.4 Hz, 1H), 7.26 (t, JHH ) 8.7 Hz,
2H), 8.57 (d, 3JHH ) 7.5 Hz, 2H). 13C NMR (C6D6, 75.4 MHz): δ
16.0 (s, CH3), 81.2 (d, 1Jpc ) 172 Hz, C), 119.1 (s, CH), 124.3 (s,
CH), 129.0 (s, CH), 140.2 (s, C), 144.7 (d, 2Jcp ) 15.5 Hz, C), 164
(d, 2Jcp ) 33 Hz, C). 31P NMR (C6D6, 121.4 MHz): δp 55.9. Anal.
5-[Chloro(4-chlorophenyl)methoxy]-3-methyl-1-phenyl-1H-
pyrazol-4-ylphosphonic dichloride 8. To a stirring solution of 3
J. Org. Chem, Vol. 71, No. 22, 2006 8635

2
(1.5 mmol) in benzene (2 mL) at room temperature was added a
solution of p-chlorobenzaldehyde (1.45 mmol) in benzene (1 mL).
After 5 min, the solvent was evaporated in vacuo, and the residue
was recrystallized from n-hexane. Yield 0.46 g (70%). Mp 126-
MHz): δ 14.5 (s, CH3), 35.9 (d, Jpc ) 3.9 Hz, CH3), 106.8 (d,
1Jpc ) 106.8 Hz, C), 125.4 (s, CH), 128.6 (s, CH), 128.8 (s, CH),
2
2
130.9 (d, Jcp ) 15.2 Hz, C), 137.6 (s, C), 154.4 (d, Jcp ) 10.8
Hz, C). 31P NMR (CDCl3, 121.4 MHz): δp 21.6. Anal. Calcd for
C14H20ClN4OP (MW 326.77): C, 51.46; H, 6.17; Cl, 10.85; N,
17.15; P, 9.48. Found: C, 51.11; H, 6.55; Cl, 11.04; N, 17.02; P,
9.79. MS (API) m/z (%): (M+ + 1) 327 (100).
1
127 °C (transparent prisms). H NMR (C6D6, 300 MHz): δ 2.33
(s, 3H), 6.9-7.1 (m, 3H), 6.91 (d, 3JHH ) 9 Hz, 2H), 7.21 (d, 3JHH
3
) 9 Hz, 2H), 7.48 (d, JHH )7.2 Hz, 2H), 7.70 (s, 1H). 13C NMR
(C6D6, 75.4 MHz): δ 14.70 (s, CH3), 92.7 (s, CHCl), 102.01 (d,
1Jpc ) 190.8 Hz, C), 124.64 (s, CH), 128.46 (s, CH), 128.59 (s,
CH), 129.02 (s, CH), 129.15 (s, CH), 135.64 (s, C), 136.37 (s, C),
3-Methyl-1-phenyl-4-(tetrachlorophosphoranyl)-1H-pyrazol-
5-ol 13. To a stirring solution of 3 (1.45 mmol) in benzene (10
mL) cooled with an ice bath was added dropwise an ethereal
solution of hydrogen chloride (3 mL, 0.5 N). After 4 h, the
precipitated solid was collected by filtration, washed with benzene
(2 × 5 mL), and dried in vacuo at 50-60 °C. Yield 0.38 g (76%).
2
2
137.53 (s, C), 150.04 (d, Jcp ) 13 Hz, C), 152.33 (d, Jcp ) 32.9
Hz, C). 31P NMR (C6D6, 121.4 MHz): δp 19.4. Anal. Calcd for
C17H13Cl4N2O2P (MW 450.09): C, 45.37; H, 2.91; Cl, 31.51; N,
6.22; P, 6.88. Found: C, 44.92; H, 3.32; Cl, 32.01; N, 6.75; P,
7.15.
1
Mp 124-125 °C. H NMR (CDCl3, 300 MHz): δ 2.73 (s, 3H),
3
3
7.28 (t, JHH ) 10.5 Hz, 1H), 7.46 (t, JHH ) 10.5 Hz, 2H), 7.84
4-(4-Chlorobenzylidene)-5-methyl-2-phenyl-2,4-dihydropyra-
zol-3-one 9. A mixture of trimethylylide 6 (0.12 mmol) and
p-chlorobenzaldehyde (0.12 mmol) in benzene (0.5 mL) was heated
in a sealed tube at 150 °C for 10 h. The benzene was removed in
vacuo. Then, the residue was heated in vacuo at 0.05 Torr at 100
°C, affording trimethylphosphineoxide. Mp 136-137 °C (0.11
mmol), 90%. 1H NMR (CDCl3, 300 MHz): δ 1.53 (d, 2JHP ) 12.6
Hz, CH3). 31P NMR (CDCl3, 121.4 MHz): δp 40.3. The residue
was extracted with n-hexane (3 × 3 mL), then the hexane was
evaporated to 1/3 volume. The solution was cooled to -10 °C and
allowed to crystallize to the targeted product 9 as an orange powder.
Yield 0.03 g (84%). Mp 101-102 °C. 1H NMR (CDCl3, 300
(d, JHH )7.8 Hz, 2H), 13.05 (s, 1H). 13C NMR (CDCl3, 75.4
3
1
MHz): δ 14.6 (s, CH3), 84.2 (d, Jpc ) 191.8 Hz, C), 120.9 (s,
2
CH), 126.6 (s, CH), 129.0 (s, CH), 135.6 (s, C), 148.1 (d, Jcp
)
21.6 Hz, C), 160.5 (d, 2Jcp ) 27.5 Hz, C). 31P NMR (CDCl3, 121.4
MHz): δp 69.2. On addition of triethylamine in an NMR tube, the
signal δp 69.2 disappeared and the sole signal δp 55.7 of trichlo-
roylide 3 formed. Anal. Calcd for C10H9Cl4N2OP (MW 345.98):
C, 34.72; H, 2.62; Cl, 40.99; N, 8.10; P, 8.95. Found: C, 34.33;
H, 3.02; Cl, 41.52; N, 8.53; P, 9.33.
Dimethyl 5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-ylphos-
phonate 14. To a solution of trichloroylide 3 (0.82 g, 2.65 mmol)
in benzene (10 mL) was added a mixture of methanol (8 mmol)
and triethylamine (8.6 mmol) in benzene (10 mL) at 0 °C with
stirring. The reaction mixture was allowed to reach room temper-
ature, and after 1 h, the precipitated solid was removed by filtration.
The mother liquor was evaporated; the residue was dissolved in
ether (10 mL) and cooled to -15 °C. The precipitated oil was
separated and dried in vacuo. Yield 0.44 g (60%). Upon distillation,
the product decomposes. 1H NMR (CDCl3, 300 MHz): δ 2.24 (s,
3H), 3.41 (d, 3JHP ) 11.7 Hz, 6H), 6.9 (t, 3JHH ) 6.9 Hz, 1H), 7.4
(t, 3JHH ) 8.1 Hz, 2H), 7.73 (d, 3JHH ) 8.1 Hz, 2H), 10.27 (s, 1H).
13C NMR (CDCl3, 75.4 MHz): δ 13.8 (s, CH3), 52.7 (d, 2Jpc ) 4.0
3
MHz): δ 2.33 (s, 3H), 7.19 (t, J ) 7.5 Hz, 1H), 7.26 (s, 1H),
7.35-7.5 (m, 4H), 7.39 (d, 3J ) 7.8 Hz, 2H), 8.46 (d, 3J ) 7.8 Hz,
2H). 13C NMR (CDCl3, 75.4 MHz): δ 13.4 (s, CH3), 119.2 (s,
CH), 125.1 (s, CH), 128.2 (s, C), 128.9 (s, CH), 129.2 (s, CH),
131.4 (s, C), 135.0 (s, CH), 138.4 (s, C), 139.4 (s, C), 145.2 (s,
CH), 150.8 (s, C), 161.8 (s, C). Anal. Calcd for C17H13ClN2O (MW
296.76): C, 68.81; H, 4.42; N, 9.44. Found: C, 68.44; H, 4.03; N,
9.34. MS (API) m/z (%): (M+ +1) (297.2, 100%), (298.4, 50%),
(299.2 35%).
5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-ylphosphonic dichlo-
ride 11 and P-(5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-
N,N,N′,N′-tetramethylphosphonic diamide 12. Trichloroylide 3
(1.13 g, 3.65 mmol) was distilled from a Claisen flask. Yield 1.0
g (88%). Colorless liquid, bp 170 °C/0.02 Torr. 31P NMR (CDCl3,
121.4 MHz): δ 16.9. Thus prepared dichlorophosphonate 11 (3.23
mmol) was dissolved in ether (10 mL), cooled to - 20 °C, and to
the solution was added a solution of dimethylamine (1 g, 22 mmol)
in ether (10 mL). The reaction mixture was allowed to reach room
temperature, and after 1 h, precipitated solid was removed by
filtration. The mother liquor was evaporated in vacuo. The resulting
solid was recrystallized from n-hexane. Yield 0.55 g (52%). Mp
1
Hz, CH3), 82.4 (d, Jpc ) 219.0 Hz, C), 121.3 (s, CH), 126.6 (s,
2
2
CH), 137.6 (s, C), 149.4 (d, Jcp ) 9.6 Hz, C), 159.6 (d, Jcp
)
21.9 Hz, C). 31P NMR (CDCl3, 121.4 MHz): δp 24.6. Anal. Calcd
for C12H15N2O4P (MW 282.24): C, 51.07; H, 5.36; N, 9.93; P,
10.97. Found: C, 51.44; H, 5.75; N, 9.41; P, 11.44. MS (API) m/z
(%): (M+ + 1) 283 (100).
Supporting Information Available: CIF files of both ylides 3
and 6. This material is available free of charge via the Internet at
http://pubs.acs.org.
1
75-76 °C. H NMR (CDCl3, 300 MHz): δ 2.5 (s, 3H), 2.71 (d,
3JHP ) 10.5 Hz, 12H), 7.3-7.6 (m, 5H). 13C NMR (CDCl3, 75.4
JO0606352
8636 J. Org. Chem., Vol. 71, No. 22, 2006