MIRONOV et al.
1802
5
double bond in XV. Phosphonic acid XV can readily
be converted back into cyclic ester XIV by dehydra-
tion on heating in benzene with removal of water as
azeotrope. Taking into account the low volatility of
compound XIV and the possibility for secondary proc-
esses due to the presence of a hydroxy group, its mass
spectra were recorded in the temperature range from
100 to 400°C. Up to 300°C, the molecular ion peak
(m/z 310) was the most abundant in the region of large
a.m.u. values, though its absolute intensity was small.
The presence of a chlorine atom gives rise to ion
peak with m/z 312; the intensity ratio of the peaks with
m/z 310 and 312 (3:1) coincides with the theoretical
occurrence of 35Cl and 37Cl isotopes. The exact mass
number is 309.996 (calculated value 309.9961).
Further heating of compound XIV results in elimina-
tion of one more water molecule and formation of
dimeric structure XVI having a P(O)–O–P(O) frag-
ment. Bis-phosphonate XVI showed in the mass spec-
trum the molecular ion cluster with m/z 602/604/606
(intensity ratio 9:6:1), in keeping with the presence of
two chlorine atoms in the molecule.
Thus the reaction of phenylacetylene with 2,2,2-tri-
chloro-4-fluoro-1,3,2λ5-benzodioxaphosphole, as well
as with unsubstituted 2,2,2-trichloro-1,3,2λ5-benzodi-
oxaphosphole, leads to formation of 1,2λ5-benzoxa-
phosphinine 2-oxide derivative in which the fluorine
atom appears in the ortho position with respect to the
endocyclic oxygen atom. The process is accompanied
by regioselective chlorination of the benzo fragment at
the meta position with respect to the fluorine atom and
oxygen atom in the oxaphosphinine ring.
2,2,2-Trichloro-4-fluoro-1,3,2λ -benzodioxaphos-
phole (I). A mixture of 5 g (0.039 mol) of 3-fluoro-
1,2-benzenediol and 5 ml (0.057 mol) of phosphorus
trichloride was stirred for 1 h at 80°C. Excess phos-
phorus trichloride was removed under reduced pres-
sure (12), and the residue was distilled to isolate 4.1 g
(55%) of benzodioxaphosphole II as a colorless
mobile liquid, bp 28–30°C (0.2 mm). 31P NMR spec-
trum (CDCl3): δP 177.7 ppm. Compound II, 4.1 g
(0.021 mol), was dissolved in 30 ml of methylene
chloride, the solution was cooled to –20°C, and a solu-
tion of 1.7 g (0.023 mol) of chlorine in 20 ml of
methylene chloride, cooled to –10°C, was added under
stirring in a stream of argon. The mixture was kept
under reduced pressure (12 mm) to remove excess
chlorine, and the residue was brought into further
syntheses without additional purification. According
to the NMR data, the yield of I was quantitative.
31P NMR spectrum (CH2Cl2): δP –23.7 ppm.
Reaction of phosphorane (I) with phenylacety-
lene. Phenylacetylene, 4.7 ml, was added dropwise to
a solution of 5.6 g (0.021 mol) of phosphorane I in
50 ml of methylene chloride while continuously bub-
bling argon through the mixture (10°C). The mixture
was stirred for 3 h, the solvent was distilled off, and
excess phenylacetylene and chlorostyrenes were re-
moved under reduced pressure (0.1 mm, 150–170°C).
The residue was 6.5 g (93%) of 2,7-dichloro-5-fluoro-
4-phenyl-2H-1,2λ5-benzoxaphosphinine 2-oxide (III)
1
as a vitreous material. H NMR spectrum (250 MHz,
CDCl3), δ, ppm: 7.32–7.44 m (C6H5), 7.21 d.d (8-H,
4JHH = 2.2, 5JPH = 1.9 Hz), 6.99 d.d.d (6-H, 3JFH = 10.7,
4JHH = 2.2 Hz), 6.34 d (3-H, 2JPH = 25.1 Hz). 31P NMR
spectrum (CDCl3): δP 17.5 ppm, d (2JPH = 24.2 Hz).
EXPERIMENTAL
Hydrolysis of 2,7-dichloro-5-fluoro-4-phenyl-2H-
1,2λ -benzoxaphosphinine 2-oxide (III). Compound
The NMR spectra were obtained on Bruker MSL-
5
1
400 (400 MHz for H, 100.6 MHz for 13C and
13C–{1H}, and 162.0 MHz for 31P and 31P–{1H}) and
III, 6.5 g, was dissolved in 15 ml of diethyl ether, and
0.4 ml of water was added. After 24 h, the precipitate
was filtered off. Yield of 7-chloro-5-fluoro-2-hydroxy-
4-phenyl-2H-1,2λ5-benzoxaphosphinine 2-oxide (XIV)
2.9 g (44%), mp >360°C. IR spectrum, ν, cm–1: 3628,
3375–3500 v.br, s (POH), 3094, 3025 (C–Harom), 1975,
1957, 1890, 1637, 1611, 1594, 1573, 1545 (C=C,
C=Carom), 1490, 1462, 1445, 1415, 1334 (δC–H),
1297, 1226, 1202, 1141, 1085, 1048, 999, 969, 938,
921, 903, 857, 838, 813, 779, 760, 749, 701, 681,
1
Bruker WM-250 (250 MHz, H) spectrometers. The
chemical shifts were measured relative to HMDS
(1H, 13C) as internal reference and H3PO4 (31P) as
external reference. The NMR spectra of solutions in
DMSO-d6 were recorded at 40°C, and in the other
solvents, at 20°C. The IR spectra were recorded on
a Bruker Vector-22 Fourier spectrometer from samples
prepared as KBr pellets (compound IV) or dispersed
in mineral oil (V). The mass spectra were run on
a Finnigan MAT-202 high-resolution mass spectrom-
eter (60 eV, emission current 0.5 mA; direct sample
admission into the ion source; continuous recording);
The relative error in the determination of m/z values
did not exceed 5×10–5 a.m.u.
1
631, 573, 504, 453. H NMR spectrum (400 MHz,
DMSO-d6), δ, ppm: 7.33–7.34 m (3H, 11-H, 12-H),
7.23 m (2H, 10-H, 3JHH = 7.7 Hz), 6.95 d.d.d (1H, 8-H,
5
4
4JHH = 1.6, JFH = 1.3, JPH = 0.8 Hz), 6.88 d.d.d (1H,
3
4
6
6-H, JFH = 11.2, JHH = 1.6, JPH = 0.7 Hz), 6.14 d
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 12 2004
Mironov
