Substituted Phosphonates and Diphosphonates: The Synthesis Strategy

Full text of DOI:10.1023/A:1013931500566

Russian Journal of General Chemistry, Vol. 71, No. 11, 2001, pp. 1821 1822. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 11, 2001,
pp. 1926 1927.
Original Russian Text Copyright
2001 by Tverdomed, Dogadina, Ionin.
LETTERS
TO THE EDITOR
Substituted Phosphonates and Diphosphonates:
The Synthesis Strategy
S. N. Tverdomed, A. V. Dogadina, and B. I. Ionin
St. Petersburg State Institute of Technology, St. Petersburg, Russia
Received April 24, 2001
R2
R1
ortho-Substituted benzenephosphonates and di-
phosphonates are valuable molecular blocks for the
construction of polydentate ligands. Some simplest
representatives of this class of compounds were pre-
pared in [1 5]. Here we propose a new general route
to benzenephosphonates and diphosphonates and re-
lated acyl halides in which the o-arrangement of
substituents in the benzene ring is provided by the
use of the Diels Alder reaction for construction of
the six-membered ring. Reaction of acetylenephos-
phonates with donor 1,3-alkadienes is known to pro-
ceed smoothly and yield the corresponding carbocy-
clic compounds [6, 7]. We showed that these prod-
ucts can be readily dehydrogenated to aromatic com-
pounds with a KMnO4/Al2O3 mixture.
Cl2(O)P
PCl5/POCl3
PCl5/POCl3
IIa IIc
Ia Ic
yield 60 85%
yield 35 40%
X
IIIa IIIc
R1 = R2 = CH3, X = P(O)Cl2 (a); R1 = R2 = CH3, X = Cl
(b); R1 = CH3, R2 = H, X = P(O)Cl2 (c).
Compounds IIIa IIIc can also be prepared directly
from carbocyclic compounds Ia Ic under the action
of phosphorus pentachloride taken in 50% excess, but,
on the whole, this method is less convenient. Acyl
chlorides IIIa IIIc are low-melting white crystalline
compounds with unpleasant odor; they are readily
hydrolyzed with atmospheric moisture.
Our synthesis strategy (cyclohexa-1,4-dienephos-
P(O)(OMe)2
R2
(MeO)2(O)P
X
R2
phonate
benzenephosphonate
benzenephosphonic
+
R1
R1
dichloride) allows preparation of polysubstituted o-ben-
zenediphosphonic and o-chlorobenzenephosphonic
chlorides, previously inaccessible molecular blocks
for synthesis of polydentate ligands.
X
Ia Ic
R2
(MeO)2(O)P
X
KMnO4/Al2O3
Tetramethyl 4,5-dimethylbenzene-1,2-diphos-
phonate (IIa). a. To a suspension of 0.07 mol of
KMnO4/Al2O3 (1 : 1) in 100 ml of anhydrous acetone,
we added dropwise with cooling and vigorous stirring
a solution of 0.05 mol of tetramethyl 4,5-dimethyl-1,4-
cyclohexadiene-1,2-diphosphonate in 80 ml of acetone.
The reaction mixture was then refluxed for 4 h. After
cooling, the suspension was filtered and the filtrate
was evaporated. The residue was distilled in a vac-
uum. Phosphonate IIa was obtained, bp 170 174 C
(1 mm Hg). Yield 70%.
R1
IIa IIc
R1 = R2 = CH3, X = P(O)(OMe)2 (a); R1 = R2 = CH3,
X = Cl (b); R1 = CH3, R2 = H, X = P(O)(OMe)2 (c).
Compounds II are formed in a high yield (50
70%) and are not contaminated with by-products. Use
of KMnO4 without Al2O3 results in slightly lower
yield (44 50%) and higher KMnO4 consumption.
o-Benzenediphosphonates and o-chlorobenzene-
phosphonates IIa IIc react with phosphorus penta-
chloride to form, respectively, o-benzenediphosphonic
and o-chlorobenzenephosphonic chlorides IIIa IIIc,
the precursors of difficultly available primary phos-
phines [8, 9]. This reaction proceeds readily, affording
the products in high yield (60 85%).
b. A solution of 0.08 mol of tetramethyl 4,5-dimeth-
yl-1,4-cyclohexadiene-1,2-diphosphonate in 100 ml of
anhydrous acetone was slowly added to a solution of
0.17 mol of KMnO4 in 150 ml of acetone with cool-
ing and vigorous stirring. The reaction mixture was
then refluxed for 6 h. The reaction product was isolated
1070-3632/01/7111-1821$25.00 2001 MAIK Nauka/Interperiodica

1822
TVERDOMED et al.
1
similarly to procedure a. Yield 50%. H NMR spec-
2-Chloro-4,5-dimethylbenzene-1-phosphonic di-
3
4
5
chloride (IIIb) was prepared similarly to IIIa. Yield
trum, , ppm: 7.6 m (2H, JHP 16, JHP 5, JHH 0.6,
1
3JPP 8.0 Hz), 3.37 d (12H, JHP 9.6 Hz), 1.90 s (6H).
3
85%, bp 88 93 C (0.05 mm Hg). H NMR spectrum,
3
4
13C NMR spectrum, C, ppm: 140.06 m (C4, 5, JCP
3
, ppm: 7.76 d (1H, JHP 17.8 Hz), 7.22 d (1H, JHP
8.8 Hz), 2.25 s (3H), 2.19 s (3H). 13C NMR spectrum,
4
2
3
15.2, JCP 10.9 Hz), 136.06 d (C3, 6, JCP 12.8, JCP
C, ppm: 145.83 d (C4, JCP 4.6 Hz), 135.62 d
3
1
2
11.0 Hz), 126.12 d (C1, 2, JCP 191.1, JCP 10.8 Hz),
(C5, JCP 16.0 Hz), 134.34 d (C3, JCP 12.4 Hz),
2
3
51.77 s (CMeO), 18.5 s (C7, 8). 31P NMR spectrum:
P
132.32 d (C6, JCP 12.5 Hz), 132.03 s (C2), 127.87 d
2
18.70 ppm, s.
(C1, JCP 161.5 Hz), 19.45 s (C8), 18.68 s (C7). 31P
1
Dimethyl 2-chloro-4,5-dimethylbenzene-1-phos-
phonate (IIb) was prepared similarly to IIa. Yield
54% (method a), 42% (method b). bp 105 108 C
NMR spectrum:
29.12 ppm, s.
P
4-Methylbenzene-1,2-diphosphonic tetrachloride
1
(IIIc) was prepared similarly to IIIa. Yield 72%,
(1 mm Hg). H NMR spectrum, , ppm: 7.49 d (1H,
1
3JHP 15.0 Hz), 6.98 d (1H, JHP 6.2 Hz), 3.56 d
4
bp 151 155 C (0.05 mm Hg). H NMR spectrum, ,
3
3
ppm: 8.18 m (1H, JHP 29.02, JHH 7.8 Hz), 8.09 m
(6H, JHP 13.0 Hz), 2.04 s (6H). 13C NMR spectrum,
3
(1H, JHP 29.21 Hz), 7.67 d (1H, 3JHH 7.8 Hz), 2.52 s
3
C, ppm: 142.38 d (C4, 2JCP 2.2 Hz), 136.06 d (C6,
3JCP 8.2 Hz), 134.15 d (C5, 3JCP 15.3 Hz), 132.73 d
(3H). 13C NMR spectrum, C, ppm: 145.98 d (C4,
3JCP 11.8 Hz), 134.98 d.d (C6, JCP 13.1, JCP
2
3
4
2
(C2, JCP 3.0 Hz), 130.67 d (C3, JCP 10.5 Hz),
13.3 Hz), 134.79 d (C5, JCP 19.1 Hz), 134.6 d
3
122.35 d (C1, JCP 193.0 Hz), 52.11 d (CMeO, JCP
1
2
(C3, JCP 10.2 Hz), 134.5 d.d (C2, JCP 185.1, 2JCP
2
1
4.1 Hz), 51.5 d (CMeO, JCP 4.1 Hz), 18.69 s (C8),
2
8.3 Hz), 131.6 d.d (C1, JCP 188.4, JCP 7.5 Hz),
20.55 s (C7). 31P NMR spectrum, P, ppm: 31.1 d,
31.4 d (3JPP 16.2 Hz).
1
2
18.04 s (C7). 31P NMR spectrum:
18.14 ppm, s.
P
Tetramethyl 4-methylbenzene-1,2-diphosphonate
(IIc) was prepared similarly to IIa. Yield 62% (meth-
od a), 49% (method b). bp 163 166 C (1 mm Hg).
1
The H, 13C, and 31P NMR spectra were recorded
on a Bruker C-200 instrument with operating fre-
quencies of 200.05 (1H), 50.328 (13C), and
81.014 MHz (31P). Solvents CCl4 and CDCl3. Internal
reference CDCl3 (13C) and TMS (1H), external ref-
erence 85% H3PO4 (31P).
1H NMR spectrum, , ppm: 7.51 d.d (1H, JHP 14.0,
3
2JHH 7.6 Hz), 7.46 d (1H, JHP 20.0 Hz), 6.98 d (1H,
3
3JHH 7.8 Hz), 3.50 d (12H, JHP 7.4 Hz), 2.15 s (3H).
3
13C NMR spectrum, C, ppm: 141.59 d (C4, 3JCP 12.1
Hz), 135.16 d.d (C6, JCP 8.5, JCP 13.6 Hz), 134.51
2
3
d.d (C3, JCP 9.1, JCP 13.3 Hz), 131.36 d.d (C5, 3JCP
2
3
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1
2
13.4 Hz), 128.90 d.d (C2, JCP2 189.0, JCP 10.7 Hz),
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1
2
2
(CMeO, JCP 3.8 Hz), 51.79 d (CMeO, JCP 4.6 Hz),
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1
bp 164 169 C (0.05 mm Hg). H NMR spectrum,
3
, ppm: 8.03 m (2H, JHP 16.01 Hz), 2.44 s (6H). 13C
NMR spectrum, C, ppm: 144.23 m (C4, 5 3JCP
,
2
3
12.3 Hz), 135.42 m (C3, 6, JCP2 16.1, JCP 16.1 Hz),
132.48 d.d (C1, 2, JCP 157.88, JCP 11.2 Hz), 19.87 s
1
(C7, 8). 31P NMR spectrum, , ppm: 31.90 s.
vol. 39, pp. 1706 1711.
P
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001