A. N. Tavtorkin et al. / Tetrahedron Letters 52 (2011) 824–825
825
Route I
R1 Hal
20-25 ºC
-
78 ºC
Cl2P
PCl2
H2P
PH2
Cl
PCl2
R1
M
R1 PCl2
5
7
a
4a
5a'
75%
3%
R1 P(NAlk2)2
R2 PH2
Route II
R2 Hal
Scheme 3. Chlorination of diphosphine 4a.
R2 PO(OEt)2
R2 PCl2
0
bond cleavage 5a following a decrease in temperature is attribut-
R1 = Ar, Alk; R2 = Alk; M = Li, Mg, Zn, Cd, Hg
Scheme 1. Key routes to dichlorophosphines.
able to the fact that a temperature rise usually favours cleavage
(
elimination) processes. Chlorination of diphosphine 4a was rather
fast and complete conversion was only obtained in 1,2-dimethoxy-
ethane. Monofunctional phosphines are chlorinated with equal
success both in ether and in dichloromethane, whereas diphos-
phines 4b and 4c react markedly better in ether, and for diphos-
phine 4a the more polar solvent, 1,2-dimethoxyethane, was
required. This confirms the assumption that the intermediate com-
pounds are salts.
3
ited signals for PCl (220 ppm) and dichlorophosphines (at about
1
60–190 ppm) in mostly 2:1 ratio. Interestingly, the formed phos-
phorus trichloride is also able to transform a P–H bond into a P–Cl
bond to a considerable extent. Therefore, in several experiments in
5
which less PCl was used (80–90% of the stoichiometric amount),
In summary, we have described a convenient and efficient
method for the synthesis of alkyl/aryldichlorophosphines, which
quantitative yields of dichlorophosphines were obtained according
to NMR data. The process in question can occur in various solvents,
the highest yields of 3a–d being attained in ether or dichlorometh-
ane. The method was also used to prepare bis-dichlorophosphines
12
is also applicable to the preparation of bis-dichlorophosphines.
Acknowledgements
5
a–c (Scheme 2).
As in the case of monofunctional phosphines, the synthesis of
This work was supported by the Russian Foundation for Basic
Research (Project No. 08-03-00586) and by the Federal Target Pro-
gram ‘Scientific and Scientific Pedagogical Personnel of Innovative
Russia’ (contract 02.740.11.0266).
bis-dichlorophosphines 5b and 5c occurred smoothly to afford
quantitative yields according to 31P NMR data. In this case also, yel-
low precipitates due to the intermediates were formed; with
diphosphines, they were poorly soluble and, therefore, the trans-
formation of 4b,c into 5b,c occurs readily in relatively polar ether
and proceeds much more slowly in dichloromethane.
Supplementary data
It is noteworthy that diphosphine 4a reacted differently under
ambient conditions to diphosphines 4b and 4c (Scheme 3).
Low-temperature (ꢀ78 °C) chlorination resulted in the normal
Supplementary data (experimental procedures and characteri-
0
reaction product 5a. At 0 °C, a mixture of 5a and 5a in ꢁ1:1 ratio
was formed (after distillation, the yields were 33% and 44%, respec-
tively). The decrease in the fraction of the product of C–P oxidative
References and notes
1.
(a) Kosolapoff, G. M.; Maier, L., 2nd ed. In Organic Phosphorus Compounds;
Wiley-Interscience: New York, 1972; vol. 1,; (b) van der Boom, M E.; Milstein,
D. Chem. Rev. 2003, 103, 175; (c) Espinet, P.; Soulantica, K. Coord. Chem. Rev.
1999, 193–195, 499.
Table 1
Synthesis of dichlorophosphines
2. (a) Makarova, L. G.; Nesmeyanov, A. N. Methods in Organoelement Chemistry.
Mercury; Nauka: Moscow, 1965. pp 290–291; (b) Fields, R.; Haszeldine, R. N.;
Wood, N. F. J. Chem. Soc. C 1970, 1370; (c) Samstag, W.; Engels, J. W. Angew.
Chem. 1992, 104, 1367–1369; (d) Malenko, D. M.; Gololobov, Yu. G. J. Gen. Chem.
2
PCl
5
R
PH
2
R
PH
2
x PCl
5
R
PCl
2
(
USSR, Engl. Transl.) 1976, 46, 2291.
-
2PCl3, -2HCl
3.
(a) Langer, F.; Puentener, K.; Stuermer, R.; Knochel, P. Tetrahedron: Asymmetry
1997, 8, 715; (b) Diemert, K.; Kuchen, W.; Kutter, J. Phosphorus, Sulfur Silicon
Relat. Elem. 1983, 15, 155.
1
a-d
2a-d
3a-d
4
.
.
(a) Berven, B. M.; Koutsantonis, G. A. Synthesis 2008, 2626; (b) Dahlenburg, L.;
Kaunert, A. Eur. J. Inorg. Chem. 1998, 885.
(a) Burch, G. M.; Goldwite, H.; Haszeldine, R. N. J. Chem. Soc. 1963, 1083; (b)
Yurchenko, R. I.; Lavrova, E. E.; Voitsekhovskaya, O. M.; Yurchenko, A. G. J. Gen.
Chem. (USSR, Engl. Transl.) 1984, 54, 2366.
Entry
Product
Yield(%)
5
PCl2
1
2
3
3a
3b
3c
80
82
83
PCl2
6. (a) Issleib, K.; Kuemmel, R. Chem. Ber. 1967, 100, 3331; (b) Märkl, G.; Weber,
W.; Weiß, W. Chem. Ber. 1985, 118, 2365; (c) Märkl, G.; Amrhein, J.; Stoiber, T.;
Striebl, U.; Kreitmeier, P. Tetrahedron 2002, 58, 2551.
PCl2
PCl2
7
.
Lindner, E.; Schmid, M.; Wald, J.; Queisser, J. A.; Gepraegs, M.; Wegner, P.;
Nachtigal, C. J. Organomet. Chem. 2000, 602, 173.
(a) Humphreys, A. S.; Filipovska, A.; Berners-Price, S. J.; Koutsantonis, G. A.;
Skelton, B. W.; White, A. H. Dalton Trans. 2007, 43, 4943; (b) Field, L. D.;
Wilkinson, M. P. Tetrahedron Lett. 1997, 38, 2779.
4
3d
52
8
.
9.
Kischkel, H.; Roeschenthaler, G.-V. Chem. Ber. 1985, 118, 4842.
1
0. (a) Deng, R. M. K.; Dillon, K. B. J. Chem. Soc., Dalton Trans. 1984, 1911; (b)
Kormachev, V. V.; Mitrasov, Y. N.; Kukhtin, V. A. J. Gen. Chem. (USSR, Engl.
Transl.) 1981, 51, 2301.
4
PCl
5
n
n
H P
PH2 -4PCl
3
, -4HCl
Cl
2
P
PCl
2
11. Holmes, R. R.; Bertaut, E. F. J. Am. Chem. Soc. 1958, 80, 2980.
12. General method for the preparation of dichlorophosphines (3a–d) and bis-
chlorodiphosphines (5a–c). Phosphine (10 mmol) or diphosphine (5 mmol) in
2
4
a-c
5
a-c
a, 73%
b, 63%
c, 59%
Et
20 mmol) in Et
PCl dissolved to give a voluminous yellow precipitate, which in turn dissolved
2
O (5 ml) was added dropwise to a stirred suspension of PCl
5
(4.16 g,
a: n = 2, b: n = 3, c: n = 4
2
O (10 ml). In the first few minutes after mixing the reactants,
5
on stirring for several hours. When all the yellow precipitate had dissolved, the
solvent was evaporated and the residue purified by distillation.
Scheme 2. Synthesis of bis-dichlorophosphines.