242
Russian Chemical Bulletin, Vol. 45, No. 1, January, 1996
80 Hz) and a narrow triplet at - 1 0 . 7 0 ppm (JH-P =
19.2 Hz), which were assigned to the protons o f
B--H...Ir and R u - - H - - I r fragments, respectively. The
signals of the H and C atoms of the coordinated diene
ligand are exhibited in the ~H N M R spectrum (in C6D6)
and 13C{IH} N M R spectrum (in CD2CI2) at 8 4.88
(br.s, 4 H, C H = C H ) , 2.06 (m, 4 H, CH2), 1.54 (br.q,
4 H, CH2) and at 6 67.3 (s, C H = C H ) , 32.0 (s, CH2);
the signals corresponding to the carborane ligand are
observed as separate broadened singlets at 8 2.84 and
41.2, respectively. The signals of the phenyl groups of
the phosphine ligands are observed in their normal
regions: at 8 6.90--7.90 (m, 30 H) in the IH N M R
spectra and at 8 127.6--137.3 (C o, Cm, Cp, and Ckey) in
the 13C N M R spectra. The IR spectrum of cluster 1
(pellets with KBr) exhibits a characteristic v ( B - - H )
band at 2580 cm -1 and v ( C - - H ) band at 3070 c m - l ; no
absorption band corresponding to the bridged hydride
was found in the spectrum. The magnetic equivalence of
the carbon and hydrogen nuclei in the 1,5-cyclooctadiene
and carborane ligands as well as the two equivalent
phosphine ligands at the Ru atom [31p{IH} N M R spectrum (C6D6) , ~3:50.42 (s)] indicate the presence of
symmetry in cluster 1 and suggests that the B(8) atom of
the pentagonal open plane of the carborane cage participates in the B--H...Ir aghostic interaction. The typical
low-field signal at +6.45 ppm (JB--H = 90 Hz) in the
liB N M R spectrum of the cluster in CH2CI 2 evidences
the existence of this interaction; the signals of the other
boron atoms of the carborane ligand are observed in a
substantially higher field, namely, in the region from
- 8 . 0 to - 2 5 . 0 ppm.
The work was carried out with financial support of
the International Science F o u n d a t i o n ( G r a n t No.
M4P 000) and the Russian Foundation for Basic Research (Project No. 93-03-18654).
References
1. F. G. A. Stone, Adv. Organomet. Chem., 1990, 31, 53.
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5.1. T. Chizhevsky, I. A. Lobanova, 1. V. Pisareva, T. V.
Zinevich, V. I. Bregadze, A. 1. Yanovsky, YtL T. Stmchkov,
C. B. Knobler, and M. F. Hawthorne, in Current Topics in
the Chemistry of Boron, Ed. G. W. Kabalka, Roy. Soc.
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6. J. E. Goldberg, J. A. K. Howard, H. Muller, M. U. Pilotti,
and F. G. A. Stone, J. Chem. Soc., Dalton Trans., 1990,
3055.
7. J. E. Goldberg, D. E. Mullica, E. L. Sappenfield, and F. G.
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8. I. T. Chizhevsky, I. A. Lobanova, V. I. Bregadze, P. V.
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Received May 23, 1995
1,3-Dipolar tris-cycloaddition of tert-butylphosphaacetylene to
2,4,6- triazido- 3- chloro- 5- cyanopyridine
S. V. Chapyshev, a* U. Bergstrasser, ~ and M. Regitz b
alnstitute of Chemical Physics in Chernogolovka, Russian Academy of Sciences,
142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: + 7 (096) 515 3588
bKaiserslautern University,
Emvin-Schrodinger Strasse, D-67663 Germany
It has been shown recently that 1,3-cycloaddition
even of such a reactive dipolarophile as norbornene to
2,4,6-triazido-3-chloro-5-cyanopyridine (1) occurs regioselectively to the azido group at position 4 of the
pyridine cycle. !,2 It has been established that consider-
able weakening of the properties of the a - a z i d o groups
in compound 1 as 1,3-dipoles is caused by their strong
conjugation with the electron-acceptor pyridine system. 3 In this connection, study of the reaction o f I with
tert-butylphosphaacetylene (2) as the dipolarophile with
Translated from lzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 252--253, January, 1996.
1066-5285/96/4501-0242 $15.00 © 1996 Plenum Publishing Corporation
1,3-Dipolar tris-cycloaddition
Russ.Chem.Bull., Vol. 45, No. 1, January, 1996
243
an exclusively high cycloaddition potential is of considerable interest. 4
The addition of an equimolar amount of c o m p o u n d
2 to a solution of compound 1 in ether at 0 °C in an
argon atmosphere results in the formation of monoadduct
3 and trisadduct 4 in a ratio of 3 : 1 (according to the
IH N M R spectra). The same ratio of products 3 and 4
was observed in the reaction of c o m p o u n d 1 with
0.5 equiv, of phosphaalkyne 2. However, trisadduct 4 as
the sole reaction product was obtained upon the action
of an excess of 2 on 1.
It can be seen from the data presented above that the
reaction of substituted pyridine 1 with tert-butylphosphaacetylene occurs regioselectively with the initial addition of 2 to the y-azido group of 1, as in the case of
norbornene. In turn, the monoadduct 3 formed readily
reacts with extremely reactive phosph'aalkyne 2 to give
trisadduct 4. The higher reactivity of the c(-azido groups
of c o m p o u n d 3 compared to that of the c~-azido groups
of the original compound 1 is likely caused by the
influence of the electron-donor triazaphosphole cycle in
the molecule of 3, which favors an increase in the
negative charge on the cc-N atoms of its azido groups.
Thus, no intermediate bisadducts could be detected in
noticeable concentrations, when the reaction of compound 1 with 2 was monitored using 31p N M R spectroscopy, which testifies to the very high reactivity of
c(-azido groups in pyridines with two electron-donor
triazaphosphole substituents. An interesting feature of
the 31p N M R spectrum of trisadduct 4 is the equivalence of the P atoms of the two c~-triazaphosphole
cycles, which is manifested as the signal at 181.2 ppm,
whose intensity is fourfold higher than that of the signal
of the P atom of the y-triazaphosphole cycle (at
177.9 ppm).
0.7 Hz); 1.45 (d, 9 H, 3 Me, 4jp H = 1.4 Hz); 1.43 (d.
9 H, 3 Me, 4Jp, H = 1.4 Hz). 13C NMR (CDCI3), 6:200.6
(d, C=P, IJp,c = 57.6 Hz); 200.1 (d, C=P, IJp,c = 593 Hz);
199.6 (d, C=P, IJp,c -- 57.7 Hz); 153.7 (d, C(2), 2Jp,c =
7.6 Hz); 150.9 (d, C(6), 2Jp, C ----- 9.3 Hz); 149.9 (d, C(4),
2Jp,c = 9.3 Hz); 122.4 (s, C(3)); 110.5 (s, C-~N); 101.5 (s,
C(5)); 35.71 (d, CMe3, 2jp,¢ = 15.3 Hz); 35.65 (d, CMe 3,
2Jpc = 14.4 Hz); 35.56 (d, CMe3, 2Jpc = 11.7 Hz); 31.3 (d,
3 Me, 3 j p , ~ = 7.6 Hz); 31.2 (d, 3 Mel 3Jp,C = 8.5 Hz); 31.1
(d, 3 Me, JP,C = 9.3 Hz).
2,6-Diazido-4-(3H- 1,2,3,4-triazaphospholo)-3-chloro5-cyanopyridine (3). M.p. 181--182 °C. IR (KBr), v/cm-l:
References
2230 (C=N); 2150 (N3). IH NMR (CDCI3), 8:1.47 (d, 9 H,
3 Me, 4Jp,H = 1.4 Hz). 13C NMR (CDCI3), 8:199.6 (d,
C=P, IJpc --- 59.2 Hz); 155.0 (s, C(2)); 154.7 (s, C(6)); 149.8
(d C ( 4 ) ' 2 J p c = 7.9 Hz); 112.6 (s, C(3)); 110.3 (s, C~N);
94.1 (s, C(5)); 35.5 (d, CMe3, 2Jp,C = 15.0 Hz); 31.2 (d, 3
Me, 3Jp,C = 8.2 Hz). 31p NMR (CDCI3), 5." 180.3.
2,4,6-Tris(3H- 1,2,3,4-triazaphospholo)-3-ehloro-5-eyanopyridine (4). M.p. 117--118 °C. 1R (KBr), v/cm-l: 2225
(C-=N). IH NMR (CDCI3), 8:1.47 (d, 9 H, 3 Me, 4Jp,H =
C1
N3"
CN
"N"
1
"N 3
-+:c=-P1 --./..
P'~Nt N
P"N I N
. ~N-~../~I~,,~.~N~,
3
4
1. S. V. Chapyshev and T. Ibata, Heterocycles, 1993, 36, 2185.
2. S. V. Chapyshev, Khim. Geterotsikl. Soedin., 1993, 1650
[Chem. HeterocycL Compd., 1993 (gngl. Transl.)].
3. S. V. Chapyshev and N. V. Chapysheva, Khim. Geterotsikl.
Soedin., 1994, 666 [Chem. HeterocycL Compd., 1994 (Engl.
Transl.)].
4. M. Regitz. J. HeterocycL Chem., 1994, 31, 663.
Received July 11, 1995;
in revised form November 1, 1995
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