Functional derivatives of (bromomethyl)phosphonic acid

Article abstract of DOI:10.1007/s11176-005-0131-3

Reaction of equimolar amounts of (bromomethyl)phosphonic dichloride and phenol gives phenyl (bromomethyl)chlorophosphonate. Its reactions with heptamethyldisilazane, N,O-bis(trimethylsilyl)acetamide, and potassium thiocyanate, leading respectively to a si

Full text of DOI:10.1007/s11176-005-0131-3

Russian Journal of General Chemistry, Vol. 74, No. 8, 2004, pp. 1168 1170. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004,
pp. 1262 1265.
Original Russian Text Copyright
2004 by Kibardina, M. Pudovik, Kamalov, and A. Pudovik.
Functional Derivatives of (Bromomethyl)phosphonic Acid
L. K. Kibardina, M. A. Pudovik, R. M. Kamalov, and A. N. Pudovik
Arbuzov Institute of Organic and Physical Chemistry, Kazan Research Center,
Russian Academy of Sciences, Kazan, Tatarstan, Russia
Received November 20, 2002
Abstract Reaction of equimolar amounts of (bromomethyl)phosphonic dichloride and phenol gives phenyl
(bromomethyl)chlorophosphonate. Its reactions with heptamethyldisilazane, N,O-bis(trimethylsilyl)acetamide,
and potassium thiocyanate, leading respectively to a silylamidophosphonate, a silyl phosphonate, and an iso-
thiocyanatophosphonate, were studied. (Bromomethyl)(chloromethyl)phosphinoyl isocyanate was synthesized.
Chemical properties of the prepared functionalyzed (bromomethyl)phosphonates were investigated.
Recently we showed that polyfunctional deriva-
O
OSiMe3
tives of four-coordinate phosphorus, containing a
chloromethyl group, can serve as convenient starting
materials for preparing saturated and unsaturated
polyheterophosphacyclanes [1 3]. Developing this
work we have prepared several derivatives of (bromo-
methyl)phosphonic acid and studied some of their
chemical transformations.
N
II + MeC=NSiMe3
PhO P
C Me
Me3SiCl
CH2Br OSiMe3
III
IV
O
a
PhO P N
Me3SiBr
C Me
O
V
O
Heating of equimolar amounts of (bromomethyl)-
phosphonic dichloride (I) and phenol for some hours
leads to formation of phenyl (bromomethyl)chloro-
phosphonate II.
b
BrCH2POSiMe3
MeCN
OPh
O
O
VI
PhOH
HCl
BrCH2PCl2
BrCH2P Cl
OPh
Reaction of chlorophosphonate II with hepta-
methyldisilazane is accompanied by cleavage of one
of the Si N bonds of the latter and gives rise to silyl-
amidophosphonate VII.
I
II
Reaction of chlorophosphonate II with bis(N,O-
trimethylsilyl)acetamide (III) involves liberation of
chlorotrimethylsilane and initial formation of amido-
phosphonate IV. Subsequent cyclization of the latter
with chlorotrimethylsilane might lead to oxazaphos-
pholine V. The reaction between compounds II and
III proceeds easily with heat release, but the final
O Me
II + MeN(SiMe3)2
BrCH2P NSiMe3
OPh
VII
reaction product is silyl phosphonate VI ( 7 ppm).
Its H NMR spectrum contains a singlet of trimethyl-
P
Compound VII easily adds to phenyl isothiocyanate
to form silylurea VIII which undergoes cyclization to
3-methyl-1-phenyl-4-phenoxy-1,3,4 -diazaphospho-
lidin-2-one 4-oxide (IX) ( P 23.4 ppm) with trimethyl-
bromosilane liberation.
1
silyl protons at 0.33 ppm, a doublet of protons of the
methylene group at phosphorus at 3.36 ppm (2JHP
10 Hz), and a broadened singlet of phenyl protons.
Evidently, the subsequent transformation of the initial
phosphorylation product IV includes its -cleavage
with liberation of acetonitrile and formation of silyl
phosphonate VI. The same result was obtained when
the reaction was carried out in ether at 0 C.
5
The IR spectrum of product IX contains a band of
1
1
the carbamide group at 1718 cm . The H NMR
3
spectrum contains a methyl doublet at 3.02 ppm, JHP
7.48 Hz. The methylene group gives two doublets of
1070-3632/04/7408-1168 2004 MAIK Nauka/Interperiodica

FUNCTIONAL DERIVATIVES OF (BROMOMETHYL)PHOSPHONIC ACID
1169
O
Me
O
NHCNEt2
S
VII + PhNCO
PhO P NC(O)NPh
CH2Br SiMe3
VIII
X + Et2NH
PhOP
CH2Br
XI
O
Me
O
N C NEt2
Et2NH
P
PhO P N
Et2NH HBr
Me3SiBr
PhO
S
C=O
XII
N
Ph
IX
in the intramolecular alkylation of the thiocarbonyl
group of the phosphorylated thiourea, leading to a
cyclic structure, we prepared (bromomethyl)(chloro-
methyl)phosphinoyl isocyanate (XIV) from (bromo-
methyl)(chloromethyl)phosphinoyl chloride (XIII)
and sodium cyanate.
VI
doublets (AB part of the ABX system),
4,03,
3.96 ppm, JAB 13.60, JPA 13.76, and JPBA16.76 Hz.
The signal of the trimethylsilyl group is absent. These
data show that in the first stage of the reaction phos-
phorylation proceeds by the most basic nitrogen atom
bound with the methyl group. Along with the main
reaction pathway, a minor process takes place, that
includes 1,3-N,O migration of the trimethylsilyl group
followed by decomposition of the intermediate to silyl
phosphonate VI ( P 7 ppm). Comparative study of the
reactions of phenyl isothiocyanate with silylamido-
phosphonate VII and its chloromethyl analog showed
that the bromomethyl derivative reacts much faster:
The reaction completes within 7 days. According to
31P NMR data, about 50% of the chloromethyl deri-
vative remains unreacted by this time.
B
2
2
2
O
O
BrCH2
ClCH2
BrCH2
ClCH2
NaOCN
NaCl
PCl
PNCO
XIII
XIV
Addition of one mole of diethylamine to the reac-
tion product gives phosphorylated urea XV. We
previously showed that prosphorylated ureas con-
taining a chloromethyl group on phosphorus undergo
cyclization to 2-amino-4-(chloromethyl)-4,5-dihydro-
5
1,3,4 -oxazaphosphole 4-oxides with liberation of
hydrogen chloride or, in the case of N-silylated
derivatives, chlorotrimethylsilane [3].
Reaction of chlorophosphonate II with potassium
thiocyanate in acetonitrile gives (bromomethyl)iso-
thiocyanatophosphonate X.
O
BrCH2
ClCH2
Et2NH
XIV
P NH C NEt2
O
O
O
KSCN
N C NEt2
II
BrCH2PNCS
KCN
ClCH2P
O
OPh
Et2NH
XVI
X
Et2NH HBr,
Et2NH HCl
O
N C NEt2
Reaction of isothiocyanate X with 2 mol of diethyl-
amine under mild conditions (solvent, 20 C) provides
2-(diethylamino)-4-phenoxy-4,5-dihydro-1,3,4
thiazaphosphole 4-oxide (XII). The IR spectrum of
this product contains absorption bands at 925 (P N),
980 1000, 1190 1200 (POC6H5), 1545 (C=N), and
BrCH2P
5
O
-
XVII
In the case in hand, urea XV can cyclize via the
chloromethyl or bromomethyl group. Recent theo-
retical calculations of model compounds showed that
the process can involve both these groups with equal
probability. The 31P NMR spectrum of the reaction
mixture of urea XV with diethylamine contains a
broadened signal at 60.0 ppm, that provides evidence
for the simultaneous formation of two cyclic com-
pounds XVI and XVII. The same evidence comes
1
1600 (P=O) cm .
The process involved addition of one amine
molecule to isothiocyanate X with initial formation of
phosphorylated thiourea XI that, under the action of
the second amine molecule, undergoes cyclization to
compound XII.
To compare the activities of the halomethyl groups
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 8 2004

1170
KIBARDINA et al.
from the elemental analysis. We failed to isolate pure
compounds from the reaction mixture.
chloride and the solvent were removed and the residue
was fractionated to obtain 7 g (60%) of compound X,
bp 136 C (0.08 ppm), n2D0 1.5962. IR spectrum
1
(KBr), , cm : 1975 (NCS). 31P NMR spectrum:
EXPERIMENTAL
P
3 ppm. Found, %: P 10.65. C8H7BrNO2PS. Calculated,
%: P 10.61.
The IR spectra were obtained on a UR-20 spec-
1
trometer in the range 400 3600 cm in thin films.
1
2-(Diethylamino)-4-phenoxy-4,5-dihydro-
The H NMR spectra were measured on Bruker WM-
5
1,3,4 -thiazaphosphole 4-oxide (XII). To a solution
250 and Varian T-60 spectrometers against internal
TMS. The 31P NMR spectra were recorded an MSL-
400 (161.97 MHz) Fourier and KGU-4 (10.2 MHz)
NMR spectrometers against external 85% H3PO4.
of 2 g of isothiocyanate X in 10 ml of benzene, 1 g
of diethylamine was added dropwise with stirring.
After 12 h, diethylamine hydrochloride was filtered
off, the solvent was removed, and the residue was
fractionated to give 0.9 g (47%) of crystalline product
Phenyl (bromomethyl)chlorophosphonate (II).
A mixture of 21 g of phosphonic dichloride I and 9 g
of phenol was heated for 4 h at 175 C. Fractionation
of the reaction mixture gave 19 g (70%) of compound
XII, mp 75 C. 31P NMR spectrum: P 62 ppm [1].
(Bromomethyl)(chloromethyl)phosphinoyl iso-
cyanate (XIV). To a suspension of 3.2 g of sodium
cyanate in 15 ml of acetonitrile, 11.3 g of phosphinic
chloride XIII was added with stirring, and the result-
ing mixture was refluxed for 7 h. The liquid phase
was separated, the solvent was removed, and the
residue was factionated in a vacuum to obtain 3.5 g
(30%) of compound XIV, bp 103 C (0.05 mm Hg),
II, bp 106 C (0.09 mm Hg). 31P NMR spectrum:
P
1
26 ppm. H NMR spectrum (CCl4), , ppm: 3.83 d
3
(2H, CH2P, JHCP 8 Hz). Found, %: P 11.28. C7H7
BrClO2P. Calculated, %: P 11.48.
Phenyl trimethylsilyl (bromomethyl)phos-
phonate (VI). A mixture of 4.05 g of chlorophos-
phonate II and 3.0 g of N,O-bis(trimethylsilyl)acet-
amide (III) was heated for 1 h at 140 C. Fractionation
of the reaction mixture gave 2.8 g (58%) of compound
VI, bp 116 C (0.08 mm Hg), n2D0 1.5040. 31P NMR
n2D0 1.5645. 31P NMR spectrum:
24 ppm. Found,
P
%: P 12.94. C3H4BrClNO2P. Calculated, %: P 13.30.
N-[(Bromomethyl)(chloromethyl)phosphinoyl]-
N ,N -diethylurea (XV). To a solution of 2.3 g of
isocyanate XIV in 20 ml of ether, 0.73 g of diethyl-
amine was added. The precipitate that formed was
filtered off and washed with ether to obtain 1.9 g
(61%) of compound XV, mp 93 C. IR spectrum
spectrum:
7 ppm. Found, %: P 9.60. C10H16BrO3
PSi. CalculPated, %: P 9.91.
Phenyl (bromomethyl)[N-methyl-N(trimethyl-
silyl)amido]phosphonate (VII). A mixture of 10.8 g
of chlorophosphonate II and 7.0 g of heptamethyldi-
silazane was heated for 1 h at 130 C. Fractionation of
the reaction mixture gave 7.7 g (57%) of compound
1
(KBr), , cm : 1216 (P=O), 1639 (C=O), 3123 (NH).
31P NMR spectrum: P 32.3 ppm. Found, %: C 26.78;
H 5.01; N 8.32; P 9.70. C8H7BrNO2PS. Calculated,
%: C 27.45; H 4.90; N 9.15, P 10.13.
VII, bp 131 C (0.09 mm Hg), n2D0 1.5235. 31P NMR
1
spectrum:
24 ppm. H NMR spectrum (CCl4), ,
P
3
ppm: 0.24 s (9H, Me3Si), 2.61 d (3H, CH3N, JHP
13 Hz), 3.53 d (2H, CH2P, JHCP 9 Hz), 7.1 m (5H,
ACKNOWLEDGMENTS
2
C6H5O). Found, %: P 8.96. C11H19BrNO2SiP. Cal-
culated, %: P 9.22.
The work was financially supported by the Russian
Foundation for Basic Research (project no. 03-03-
33064).
5
3-Methyl-1-phenyl-4-phenoxy-1,3,4 -diazaphos-
pholidin-2-one 4-oxide (IX). A mixture of 4 g of
phosphonate III and 1.4 g of phenyl isocyanate was
kept for 1 h at 100 C. The crystals that formed were
repeatedly washed with carbon tetrachloride and ether
to obtain 2.5 g (69%) of compound IX, mp 139 C.
REFERENCES
1. Kamalov, R.M., Khailova, N.A., Gazikasheva, A.A.,
Chertanova, L.F., Pudovik, M.A., and Pudovik, A.N.,
Dokl. Akad. Nauk SSSR, 1991, vol. 316, no. 6, p. 1406.
31P NMR spectrum:
23.4 ppm. Found, %: N 9.50,
P
2. Kamalov, R.M., Stepanov, G.S., Chertanova, L.F.,
Gazikasheva, A.A., Pudovik, M.A., and Pudovik, A.N.,
Heteroatom. Chem., 1992, vol. 3, no. 2, p. 115.
P 10.62. C15H15N2O3P. Calculated,%: N 9.27, P 10.26.
Phenyl (bromomethyl)isothiocyanatophos-
phonate (X). A mixture of 10.8 g of chlorophos-
phonate II and 4 g of potassium thiocyanate in 20 ml
of acetonitrile was kept for 24 h at 20 C. Potassium
3. Pudovik, M.A., Krepysheva, N.E., Al’myanova, R.Kh.,
Kamalov, R.M., and Pudovik, A.N., Zh. Obshch. Khim.,
1996, vol. 88, no. 3, p. 360.
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