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Nucleophilic Ligand Exchange by Phosphoranes.

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1,2,3,4-tetrahydronaphthalene-2,3-dicarboximides,
e.R.Aryl=
p-tolyl, of which the endo-form has m.p. 136-137OC and in
the IH-NMR spectrum has a 3H singlet at z = 7.7 and 2H
quartets at T = 6.0-6.1 and T = 4.3-4.4, while the exo-form
has m.p. 226-227’C and in the ‘H-NMR spectrum a 3H
singlet at T = 7.8 and 2H singlets at T = 6.8 and 5 = 4.5.
Received: Oct. 27th, 1964, revised Sept. 13th, 1966
[Z 322 IE]
German version: Angew. Chem. 78, 984 (1966)
[l] Part IV of Studies in the Chemistry of Isoindoles. - Part
111: R . Krelter and J. Seubert, Tetrahedron Letters 1966, 3015.
[2] M . P. C a w and K . Muth, J. org. Chemistry 27, 757 (1962).
[2a] F. R . Jensen and W. E. Coleman, J. org. Chemistry 23, 869
(1958).
[3] R . Criegee and M . Krieger, Chem. Ber. 98, 387 (1965).
[4] R . Kreher and J. Seubert, Angew. Chem. 76, 682 (1964);
Angew. Chem. internat. Edit. 3, 639 (1964).
[5] R . Huisgen, F. Bayerlein, and W. Heyclkamp, Chem. Ber. 92,
3223 (1959).
[6] D . F. Veber and W . Lwowski, J. Amer. chem. SOC.85, 646
(1963).
Bis(2,2’-biphenylylene)phosphorane and the
Bis(2,2’-biphenylylene)phosphoranyl Radical
By Dr. D. Hellwinkel
Organisch-Chemisches Institut, Universitat Heidelberg
(Germany)
Whereas earlier attempts t o prepare hydrido derivatives of
quinquevalent phosphorus, arsenic, and antimony were unsuccessful 11-31, we have now succeeded in synthesizing a
stable derivative of the hypothetical phosphorane, PH5.
Bis(2,2’-biphenylylene)phosphonium iodide141 is treated
with a small excess of LiAlH4 in ether under nitrogen in a
double Schlenk tube with ice cooling. After filtration and cooling to -70 “C bis(2,2’-biphenylylene)phosphorane ( I ) crystallizes. Several recrystallizations from ether afford the pure
product in 45 % yield; the compound is stable indefinitely
under nitrogen in the dark and can be kept for some days in
air, but decomposes with discoloration between 95 and
100 ‘C, depending on the rate of heating.
The product ( I ) was identified by elemental analysis (C, H,
P), by its 1H-NMR spectrum ( ~ H - P= 9.33 ppm; JH-P =482 Hz; in benzene, TMS as internal standard), and by its
IR spectrum (+-H = 2097 cm-1). Further evidence of structure is provided by evolution of hydrogen on treatment with
ethanolic HC1 or ethanolic iodine solution, which regenerate
the bis(2,2’-biphenylylene)phosphonium cation in good
yield :
The phosphorane ( I ) reacts with methyl- or butyl-lithium in
ether with evolution of methane or butane, respectively,
giving a dark violet solution which is almost completely
decolorized within an hour. An excess of LiAIH4 reacts with
( I ) only after addition of tetrahydrofuran, H2 being evolved
and a n intensely blue-green solution formed which is also
decolorized within an hour. On ethanolysis, 2-biphenylyl2‘,2”-biphenylylenephosphine ( 3 ) can be isolated from both
these reaction mixtures in about 75% yield. With strong
bases ( I ) evidently forms the corresponding base, the bis(2,2’-biphenylylene)phosphoranyl anion ( 2 ) 151, which is
violet in ether and blue-green in T H F and rearranges with
fission of a P-C bond to a colorless carbanion which is finally protonated to the phosphine ( 3 ) .
968
Organic phosphorus radicals usually are unstable, and
therefore few ESR-spectroscopic studies of them have been
reported (6-91. If a ca. 0.5 M solution of the phosphorane ( I )
in benzene is prepared at 20’C with stringent exclusion of
oxygen and moisture, a pale violet coloration is observed
which becomes very intense in the course of several hours
(even if the solution is exposed only to diffuse daylight).
Half an hour after preparation of the solution the ESR
spectrum shows a well-formed doublet with a coupling constant of 18 gauss; the intensity of the signal increases during
about 7 hr to a constant value while the doublet is gradually
transformed into a singlet owing to the increasing radical
concentration (in less concentrated solutions the doublet
remains). Simultaneously the IH-NMR spectrum is observed t o lose the original strong doublet (J= 482 Hz) due
t o the hydrogen bound to phosphorus. These results indicate
quantitative conversion of ( I ) into the bis(2,2’-biphenylylene)phosphoranyl radical ( 4 ) .
The radical ( 4 ) , characterized by its ESR doublet, also
arises when bis(2,2’-biphenylylene)phosphonium iodide [41 is
treated with Na,’K alloy in benzene, the solution being
filtered immediately on appearance of a red-violet color in
order to prevent further reaction to the anion.
Received: August 1st an.1 Sept. Znd, 1366
[ Z 317 IE]
German version: Angew. Chem. 78, 985 (1966)
M’irfig and K . Torsell, Acta chem. scand. 7, 1293 (1953).
CViberg and K . Modritzer, Z. Naturforsch. I l b , 747 (1956).
R . Sauers, Chem. and Ind. 1960, 717.
Hellwinkel, Chem. Ber. 98, 576 (1965).
[5] Cf. A . Moertker, Diploma Thesis, Universitgt Heidelberg,
1960: G. Witfig and A. Maercker, unpublished.
[6] E. Muller, H . Eggensperger, and K . Scheffler, Liebigs Ann.
Chem. 658, 103, (1962).
[7] A . H. Cowley and M . H . Hnooslt, J. Amer. chem. SOC.88,
[l] G.
[2] E.
[3] R .
[4] D.
2595 (1966).
[S] A. D. Eritt and E. T. Kaiser, J. org. Chemistry 31, 112 (1966).
[9] U . Schmidt, K . Kabiizke, K. Markau, and A . Miifler, Chem.
Ber. 99, 1491 (1966).
Nucleophilic Ligand Exchange by Phosphoranes [ *1
By Dr. M. Schlosser, T. Kadibelban, and Dr. G . Steinhoff
Ofganisch-Chemisches Institut,
Universitlt Heidelberg (Germany)
The organic groups of phosphorus ylides [I], phosphines 121,
phosphine oxides 131, or phosphine sulfides (41 undergo nucleophilic exchange with organolithium reagents. We have now
observed similar replacements also with pentaorganylphosphorus compounds.
If an ethereal solution (c M 0.01 M) of pentaphenylphosphorus is treated at room temperature with, for instance,
Angew. Clrem. internat. Edit. Vol. 5 (1966)
1 No. I 1
121 H. Gilrnnrt and ti. E. Brown, J. Amer. chem. SOC.67, 824
(1945); T. V. Tolnloeva and K. A . Kocheshkov, Doklady Akad.
Nauk SSSR 77, 621 (1951); A . Moewker; Diploma Thesis, Universitiit Heidelbcrg, 1960.
[3] D. Seyfertli, D. E. Welch, and J . K. Heeren, J. Arner. chem.
SOC.86, 1100 (1964).
[4] D. Seyferlh and D. E. Welch, J. organomet. Chemistry 2, 1
(1964).
[5] W . Toocl~ternzaizr~,
Angew. Chem. 78, 355 (1966); Angew.
Chem. internat. Edit. 5 , 351 (1966); cf. also [7].
[6] K. Dimrotli, G. Polil, and H . Follmann, Chem. Ber. 99, 635
(1966). have recently discussed such an a,a-dimetalated phosphonium sall as a possible intermediate in a Wittig reaction.
[7] D. Hellwinkel, Chem. Ber. 98, 576 (1965).
[8] G. Wiiti2 and E. Kocliendiirfer, Chem. Ber. 97, 741 (1964);
C. Wittig and A . Mnercker, Chem. Ber. 97, 747 (1964).
5 equivalents of p-tolyl-lithium, the tetraaryIphosphonium
salt obtained by subsequent action of acids shows the IR
bands of a tolyl group. Phenyl-lithium (7 %) is liberated and
can be converted into bromobenzene by 1,2-dibromoethane.
Whether this exchange occurs by way of a sexicovalent ate
complex ( I ) [51 is being studied by kinetic and N M R methods.
Li ' [ ( C ~ H ? ) ~ P - C ~ H ~ - C H ~ - P I -
1)
When primary or secondary alkyl-lithium compounds in
petroleum ether are allowed to act o n pentaphenylphosphorus,
phosphorus ylides (and resins) are obtained. n-Butyl-lithium
affords triphenyiphosphine n-butylide as the LiCl adduct (2),
which was characterized as n-butyltriphenylphosphonium
bromide (yield 12-24 %), m.p. 233-236 "C, and l-phenylformed by reaction with benzaldehyde).
I-pentene (yield 8
With a n excess of butyl-lithium some of the product (2) is
metalated further, giving (3) (yield up to 14 7; calculated on
pentaphenylphosphorane) [61; ( 3 ) was trapped as ([1,1-D&
buty1)triphenylphosphonium bromide, m.p. 232-234 "C,
with DBr.
x;
Ligand Exchange with Compounds of
Quinquevalent Arsenic [*I
By Dr. D. Hellwinkel and Dr. G. Kilthau
Organisch-Chemisches Institut,
Universitat Heidelberg (Germany)
Aryl- and alkyl-bis-2,2'-biphenylylenearsenic( I ) , which can
be prepared from bi~-2,2'-biphenylylenearsoniumiodide and
lithium aryls (11, alkyls 121, or Grignard compounds [31,
undergo ligand exchange [41 on reaction with suitable organolithium reagcnts in ether (c = 0.05 M) (cf. table).
Only the singly bound ligand R of the phosphoranes ( 4 ) and
( 5 ) could be removed (in ether or tetrahydrofuran) (cf. the
following communication).
EX-
R':R
change
( %)
-
-
1O:l
-
1:l
4:1
1O:l
1O:l
96
92
-
97
2: 1
-
9s
1:l
3: 1
10: 1
3: 1
95
96
80
95
10: I
10: 1
-
-
10: 1
10: 1
10: 1
[a] Molar proportions in each case
-
.-
-
I 1
R:R
5:1
10: I
2:1
-
8:l
10. I
1
Exchange
(
m
.
.
ExR':R
change
5: I
10: I
2: 1
10: 1
96
-
1 I
R':R
Exchange
( %)
10: I
10: I
-
90
90
4. I
90
All the mixtures indicated in the table were stirred for 10 hr
and then hydrolysed. The exchange products were identified
by mixed melting points and by comparison of I R spectra.
+ LiR
The structures of the phosphoranes (4)-(8) were proved by
elemental analysis, N M R and I R spectra, or comparison
with authentic material. Compounds ( 4 ) [71 and (5) [*I were
known; compounds (6). m.p. 185-186'C, (71, m.p. 198.5 to
2OO0C,and (8),m.p. 177.5-178 OC, were synthesized analogously.
Received: July 18th and September 15th, 1966
[Z 329a IE]
German version: Angew. Chem. 78, 1018 (1966)
[*] We are grateful to Prof. G. Wittig for suggestions and discussions, and to the Deiitsche Forschurigsgemeinschaft for
generous support.
[I] G. Wittig and ti. Geifiler, Liebigs Ann. Chem. 580, 44 (1953);
G. Wittig and M . Sclilosser, Chem. Ber. 94, 1377 (1961);
M . Schlosser, Angew. Chem. 74, 291 (1962); Angew. Chem.
inlernat. Edit. I , 266 (1962).
Angew. Chem. internnt. Edit.
1 Vol. 5 (1966) /
No. I 1
The table shows that the strength of bonding of the ligands R
decreases in the order:
Formulation of these exchange reactions via intermediate
hexaarylarsenate(v) complexes (2) is supported by the fact
969
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