Palladium-assisted formation of carbon-carbon bonds. Part 10. Insertion reactions of isocyanides into the Pd-C bond of orthopalladated primary amines. Synthesis of 2-R-aminoisoindolinium salts (R = tBu, 2,6-xylyl)

Article abstract of DOI:10.1021/om020365n

Palladium assisted formation of carbon-carbon bonds was discussed. Insertion reactions of isocyanides into the Pd-C bond of orthopalladated primary amines and synthesis of 2-R-aminoisoindolinium salts were performed. Results showed that formation of this complex requires coordination of a second molecule of isocyanide per palladium through a bridge splitting process.

Full text of DOI:10.1021/om020365n

Organometallics 2002, 21, 3587-3595
3587
P a lla d iu m -Assisted F or m a tion of Ca r bon -Ca r bon Bon d s.
P a r t 10.1 In ser tion Rea ction s of Isocya n id es in to th e
P d -C Bon d of Or th op a lla d a ted P r im a r y Am in es.
t
Syn th esis of 2-R-Am in oisoin d olin iu m Sa lts (R ) Bu ,
2,6-Xylyl)
J ose´ Vicente,*,† Isabel Saura-Llamas, Claus Gru¨nwald, and Carmen Alcaraz
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain
Peter G. J ones‡
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Delia Bautista§
SACE Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain
Received May 6, 2002
The palladated primary amines [Pd{C6H3CH2NH2-2-X-5}(µ-Br)]2 [X ) H (1a ), OMe (1b),
NO2 (1c), F (1d )] react with isocyanides (Pd:RNC ) 1:1) to give [Pd{C6H3CH2NH2-2-X-5}-
Br(RNC)] [R ) Xy ) C6H3Me2-2,6, X ) H (2a ), OMe (2b), NO2 (2c), F (2d ), R ) tBu, X ) H
(3a ), OMe (3b), NO2 (3c), F (3d )]. When XyNC reacts with 1a (Pd:RNC ) 1:2) or with 2a
(Pd:RNC ) 1:1), the complex [Pd{(CdNXy)C6H4CH2NH2-2}(XyNC)Br] (4a ) is obtained. The
reactions of complexes 1 with isocyanides in the ratio Pd:RNC ) 1:3 lead to Pd(I) complexes
[Pd2Br2L4] [L ) XyNC (5); L ) tBu (6)]. On the basis of NMR data we propose the following
reaction pathway for this reduction process: (1) formation of the corresponding monomer 2
or 3, (2) insertion of one molecule of the isocyanide into the Pd-C bond of 2 or 3 to give
[Pd{(CdNR)C6H3CH2NH2-2-X-5}(RNC)Br], (3) cleavage of the N-Pd bond and coordination
of a new isocyanide molecule to give complexes [Pd{(CdNR)C6H3CH2NH2-2-X-5}(RNC)2Br]
[detected in solution for R ) Xy, X ) H (7a ) and isolated as an acetylated derivative of this
complex [Pd{(CdNXy)C6H4CH2NHC(O)Me-2}(XyNC)2Br] (8a )], and (4) decomposition of these
complexes to give 5 or 6. The organic product of these reactions was not identified. By
refluxing mixtures of complexes 1 with RNC and TlOTf (Pd:RNC:TfO ) 1:1:1) the
corresponding isoindolinium triflates 9‚OTf [R ) Xy, X ) H (9a ‚OTf), OMe (9b‚OTf), F
(9d ‚OTf)] or 10‚OTf [R ) tBu, X ) H (10a ‚OTf), OMe (10b‚OTf), F (10d ‚OTf)] were isolated
and characterized. A mechanism of formation of these isoindolinium triflates is proposed.
When the reaction between 1a and XyNC (Pd:RNC ) 1:1) was carried out in refluxing toluene
in the absence of TlOTf, or when 2a was refluxed in toluene, an insertion of the isocyanide
occurs in both cases to give [Pd{(CdNXy)C6H4CH2NH2-2}Br]2 (11). If 1a or 2a is reacted
with XyNC (Pd:RNC ) 1:1.25 or 1:0.25, respectively), the complex [PdBr2{2-(XyNH)-
isoindole}2] (12) is formed. A proposal for the reaction pathway of this process is discussed.
The crystal structures of 3d , 9a ‚OTf, and 12 have been determined.
In tr od u ction
are well known. Since depalladation of the resulting
complexes can afford interesting organic compounds,
Insertion reactions of orthopalladated amines with
unsaturated reagents such as alkenes2-7 or alkynes8-26
(4) Ryabov, A. D.; Sakodinskaya, I. K.; Dvoryantsev, S. N.; Eliseev,
A. V.; Yatsimirsky, A. K. Tetrahedron Lett. 1986, 27, 2169.
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253, 391.
(8) Dupont, J .; Pfeffer, M.; Theurel, L.; Rotteveel, M. A. New J .
Chem. 1991, 15, 551.
(9) Pfeffer, M. Recl. Trav. Chim. Pays-Bas 1990, 109, 567.
(10) Park, S. S.; Choi, J . K.; Yum, E. K.; Ha, D. C. Tetrahedron Lett.
1998, 39, 627.
† E-mail: jvs@um.es. Web: http://www.scc.um.es/gi/gqo/.
‡ Corresponding author regarding the X-ray diffraction study of
9a ‚OTf. E-mail: jones@xray36.anchem.nat.tu-bs.de.
§ Corresponding author regarding the X-ray diffraction study of 3d
and 12. E-mail: dbc@um.es.
(1) Part 9: Vicente, J .; Abad, J . A.; Bergs, R.; Ram´ırez de Arellano,
M. C.; Mart´ınez-Viviente, E.; J ones, P. G. Organometallics 2000, 19,
5597.
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Organomet. Chem. 1991, 406, 309.
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40, 657.
10.1021/om020365n CCC: $22.00 © 2002 American Chemical Society
Publication on Web 07/23/2002

3588 Organometallics, Vol. 21, No. 17, 2002
Vicente et al.
Sch em e 1
they have attracted great interest in organic synthe-
sis.2-15,27-39 Most of these insertion reactions involve
cyclopalladated tertiary benzylamines, while only a few
are devoted to primary amines,23,24,27 because general
syntheses of such cyclopalladated complexes have been
only recently reported.24,40-42 However, the number of
studies on the reactivity of orthopalladated amines with
isocyanides or carbon monoxide is very limited.27,28,43-45
We have reported sequential insertion reactions of
alkynes and CO or isocyanides into cyclopalladated
secondary benzylamines,25 whereas here we report the
reactivity of cyclopalladated primary benzylamines
toward isocyanides. A preliminary communication by
Parkins et al. described the only previously reported
reactions of a cyclopalladated primary amine with
isocyanides.27 In this paper, we study the reactions
between various palladated primary amines and iso-
cyanides at room temperature and in refluxing toluene
under different molar ratios of complex to isocyanide.
(12) Beydoun, N.; Pfeffer, M. Synthesis 1990, 729.
(13) Dupont, J .; Pfeffer, M.; Rotteveel, M. A.; De Cian, A.; Fischer,
J . Organometallics 1989, 8, 1116.
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1989, 8, 871.
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Organometallics 1993, 12, 1386.
Some intermediates have been isolated, allowing the
proposal of reasonable reaction pathways for these
reactions that lead to the formation of 2-aminoisoin-
doles, isolated as their triflate salts or coordinated to
palladium(II).
(21) Maassarani, F.; Pfeffer, M.; Borgne, G. L. Organometallics 1987,
6, 2029.
(22) Maassarani, F.; Pfeffer, M.; Borgne, G. L. Organometallics 1987,
6, 2043.
Resu lts a n d Discu ssion
(23) Vicente, J .; Saura-Llamas, I.; Ram´ırez de Arellano, M. C. J .
Chem. Soc., Dalton Trans. 1995, 2529.
(24) Vicente, J .; Saura-Llamas, I.; Palin, M. G.; J ones, P. G. J . Chem.
Soc., Dalton Trans. 1995, 2535.
(25) Vicente, J .; Saura-Llamas, I.; Turp´ın, J .; Ram´ırez de Arellano,
M. C.; J ones, P. G. Organometallics 1999, 18, 2683.
(26) Arlen, C.; Pfeffer, M.; Bars, O.; Grandjean, D. J . Chem. Soc.,
Dalton Trans. 1983, 1535.
(27) O’Sullivan, R. D.; Parkins, A. W. J . Chem. Soc., Chem. Commun.
1984, 1165.
(28) Yamamoto, Y.; Yamazaki, H. Inorg. Chim. Acta 1980, 41, 229.
(29) Pfeffer, M. Pure Appl. Chem. 1992, 64, 335.
(30) Pfeffer, M.; Sutter, J . P.; De Cian, A.; Fischer, J . Organome-
tallics 1993, 12, 1167.
(31) Wu, G.; Rheingold, A. L.; Geib, S. J .; Heck, R. F. Organome-
tallics 1987, 6, 1941.
(32) Fagnola, M. C.; Candiani, I.; Visentin, G.; Cabri, W.; Zarini,
F.; Mongelli, N.; Bedeschi, A. Tetrahedron Lett. 1997, 38, 2307.
(33) Pfeffer, M.; Sutter, J . P.; Rotteveel, M. A.; De Cian, A.; Fischer,
J . Tetrahedron 1992, 48, 2427.
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Lett. 1997, 38, 2439.
(35) Tao, W.; Silverberg, L. J .; Rheingold, A. L.; Heck, R. F.
Organometallics 1989, 8, 2550.
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S.; Cohen, L. A. Tetrahedron Lett. 1993, 34, 2823.
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Chem. 1995, 60, 3270.
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(39) Ryabov, A. D. Synthesis 1985, 233.
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de Arellano, M. C. Organometallics 1997, 16, 826.
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Trans. 1993, 3619.
Room -Tem p er a tu r e Rea ctivity of Cyclop a lla -
d a ted P r im a r y Ben zyla m in es tow a r d Isocya n id es.
By reacting at room temperature the dimeric complexes
[Pd{C6H3CH2NH2-2-X-5}(µ-Br)]2 [X ) H (1a ), OMe (1b),
NO2 (1c), F (1d )] with isocyanides in the ratio Pd:RNC
) 1:1, the halogen bridges are cleaved and the mono-
meric compounds [Pd{C6H3CH2NH2-2-X-5}Br(RNC)] (2,
3) [R ) Xy ) C6H3Me2-2,6, X ) H (2a ), OMe (2b), NO2
t
(2c), F (2d ); R ) Bu, X ) H (3a ), OMe (3b), NO2 (3c),
F (3d )] are obtained (Scheme 1). The IR spectra of
complexes 2 and 3 show the ν(CtN) stretching frequen-
cies [2180 and 2200 cm-1, respectively] close to those
of related complexes.28,44,46 Furthermore we have de-
termined the structure of 3d by X-ray diffraction (see
below).
By reacting 1a or 2a with XyNC (Pd:XyNC ) 1:2 or
1:1, respectively) the complex resulting from monoin-
sertion of the isocyanide into the Pd-C bond [Pd-
{(CdNXy)C6H4CH2NH2-2}(XyNC)Br] (4a ) was isolated.
1
The H, 13C NMR and IR data of 4a agree with those
found in similar insertion products.44,47 Our proposal for
its structure is based on the X-ray crystal structure of
n
[Pd{C(dNR)(C6H4)(CH2NMe2)2}Br(RNC)] (R ) Bu).44
(42) Fuchita, Y.; Yoshinaga, K.; Hanaki, T.; Kawano, H.; Kinoshita-
Nagaoka, J . J . Organomet. Chem. 1999, 580, 273.
(43) Thompson, J . M.; Heck, R. F. J . Org. Chem. 1975, 40, 2667.
(44) Zografidis, A.; Polborn, K.; Beck, W.; Markies, B. A.; van Koten,
G. Z. Naturforsch., B 1994, 49, 1494.
(45) Tollari, S.; Palmisano, G.; Demartin, F.; Grassi, M.; Magnaghi,
S.; Cenini, S. J . Organomet. Chem. 1995, 488, 79.
(46) Dupont, J .; Pfeffer, M. J . Chem. Soc., Dalton Trans. 1990, 3193.
(47) (a) Alias, F. M.; Belderrain, T. R.; Paneque, M.; Poveda, M. L.;
Carmona, E.; Valerga, P. Organometallics 1998, 17, 5620. (b) Yama-
moto, A. J . Chem. Soc., Dalton Trans. 1999, 1027. (c) Wouters, J . M.
A.; Klein, R. A.; Elsevier, C. J .; Zoutberg, M. C.; Stam, C. H.
Organometallics 1993, 12, 3864. (d) Crociani, B.; Sala, M.; Polo, A.;
Bombieri, G. Organometallics 1986, 5, 1369.

Pd-Assisted Formation of Carbon-Carbon Bonds
Organometallics, Vol. 21, No. 17, 2002 3589
Sch em e 2
Complex 4a reacts with 1 equiv of XyNC to give the
dinuclear palladium(I) complex [Pd2Br2(CNXy)4] (5).
Similar decomposition reactions occurred when com-
pounds 1 were reacted at room temperature with a
larger amount of the isocyanide (Pd:XyNC ) 1:3), giving
complexes [Pd2Br2L4] [L ) XyNC (5), tBuNC (6)]. Com-
plexes 5 and 6 were isolated from 1c or 1a , respectively,
at room temperature. These reactions are similar to that
of [PdI(CH2Ph)(tBuNC)2] with further tBuNC to give
[Pd2I2(tBuNC)4].48 The IR and 1H NMR data of com-
pound 6 agree with those previously reported.48 The
characteristic spectroscopic data of 5, which has been
mentioned recently by Mingos,49 are the signals at δ
2.53 ppm in the 1H NMR spectrum and the intense band
at 2156 cm-1 in the IR spectrum corresponding to
ν(CtN). We have also prepared 5 by reacting [Pd(dba)2]
(dba ) dibenzylidenacetone), XyNC, and ortho-bro-
mobenzaldehyde (2:8:3 molar ratio) in refluxing toluene
and determined its crystal structure.50
occurs through a cationic intermediate that results after
substitution of the chloro ligand by the isocyanide.51
Mech a n ism of F or m a tion of P a lla d iu m (I) Com -
p lexes [P d 2Br 2(CNR)4]. It is reasonable to assume
that formation of 5 or 6 from 1 occurs via complex 2 or
3, respectively, and [Pd{(CdNR)C6H3CH2NH2-2-X-5}-
1
We have also studied by H NMR spectroscopy the
1
reaction of 2a with 2 equiv of XyNC in CDCl3. The H
NMR spectrum measured immediately after the mix-
ture of reagents showed resonances due to 2a and 7a .
After 10 min, complex 2a had disappeared and signals
appeared corresponding to 7a and 5. Two new reso-
nances at 2.26 and 4.80 ppm and that corresponding to
5 grew with time, while the intensity of the signals
corresponding to 7a decreased. After 2.5 days, the
signals corresponding to 7a had disappeared, while
those corresponding to 5 and those at 2.26 and 4.80 ppm
remained. These two resonances could be due to Me and
CH2 protons of some 2-aminoisoindolinium salt or
2-aminoisoindoline or some related derivative.
Rea ction s of Com p lexes 1 tow a r d Isocya n id es
in Reflu xin g Tolu en e in th e Ra tio P d :RNC ) 1:1.
Syn th esis of Isoin d olin iu m Sa lts. A preliminary
communication by Parkins et al. in 1984 described the
reactions of [Pd{C6H4CH2NH2-2}(RNC)I] and RNC (R
t
(RNC)Br] [R ) Xy, X ) H (4a ), OMe, NO2, F; R ) Bu,
X ) H, OMe, NO2, F]. The formation of 5 by treatment
of 4a in dichloromethane with 1 equiv of XyNC for 12 h
further supports the intermediacy of 4a in the synthesis
of 5 from 2a . To find out more details about the
1
mechanism of the formation of 5, we monitored by H
NMR spectroscopy the reaction of 4a with 1 equiv of
XyNC in CDCl3. After 10 min, 4a had disappeared and
two 2:1 singlets at 2.29 and 2.14 ppm corresponding to
the Me groups of XyNC suggest the formation of a com-
plex such as [Pd{(CdNXy)C6H4CH2NH2-2}(XyNC)2Br]
(7a ), resulting from cleavage of the N-Pd bond and
coordination of a new isocyanide molecule. A triplet at
3.89 ppm and a broad signal at 3.70 ppm could be
assigned to the CH2 and NH2 groups, respectively. A
broad resonance at 2.38 ppm revealed the presence of
5. After 20 min, the spectrum does not change signifi-
cantly. Unfortunately, our attempts to isolate the
proposed intermediate 7a failed. Thus, if the solvent is
removed from the reaction mixture after 10 min, the
only isolated complex is 4a , suggesting that it is in
equilibrium with 7a and that such equilibrium reverts
to the left when trying to isolate 7a . If the reaction time
is 4 h, mixtures consisting of 4a and 5 were obtained.
However, we could isolate the acetylated derivative
[Pd{C(dNXy)C6H4CH2NHC(O)Me-2}Br(XyNC)2] (8a ) by
reacting a mixture of 4a and XyNC with acetic anhy-
dride. The instability of 8a caused it to be contaminated
with traces of 5. This prevented correct elemental
analyses and a 13C NMR spectrum. However, the 1H
NMR resonances not due to the traces of 5 are in
accordance with the structure proposed for 8a . A dif-
ferent reaction pathway has been found in the reaction
between [PdCl(Me)(L2)] (L2 ) 2,2′-bipyridine, 1,10-
t
) Bu, Ph) (1:1 molar ratio) in refluxing toluene. The
corresponding isoindolinium iodides and their free bases
were characterized by IR and NMR spectroscopies.27
The present availability of cyclopalladated primary
amines prompted us to extend this work, starting from
our bromo complexes 1a -d . Thus, by refluxing a toluene
solution of 1a with tBuNC (Pd:tBuNC ) 1:1), an
intractable mixture of 2-aminoisoindolinium bromide
1
10a ‚Br (characterized by comparing its H NMR spec-
trum with that of 10a ‚OTf; see below and Scheme 2)
and colloidal Pd(0) was obtained. Under the same
thermal conditions, complex 1a reacts differently with
XyNC (Pd:XyNC ) 1:1) to give the dimer [Pd{(CdNXy)-
C6H4CH2NH2-2}Br]2 (11) (Scheme 3). By refluxing a
toluene suspension of 2a complex 11 was also obtained.
Similar insertion reactions have been observed on
heating other (isocyanide)(aryl)palladium complexes.28,52
Due to the insolubility of 11 in common organic solvents,
no NMR data are available. However, the structure
proposed for 11 is based on its reaction with XyNC to
give 4a and on those determined by X-ray crystal-
lography of related complexes.52-55
t
phenanthroline) and BuNC or XyNC in acetonitrile.
The insertion of the isocyanide into the Pd-Me bond
(48) Otsuka, S.; Tatsuno, Y.; Ataka, K. J . Am. Chem. Soc. 1971, 93,
6705.
(49) Vilar, R.; Mingos, D. M. P.; Cardin, C. J . J . Chem. Soc., Dalton
Trans. 1996, 4313.
(50) Vicente, J .; Abad, J . A.; Mart´ınez-Viviente, E.; J ones, P. G. To
be published.
(51) Delis, J . G. P.; Aubel, P. G.; Vrieze, K.; van Leeuwen, P.;
Veldman, N.; Spek, A. L.; van Neer, F. J . R. Organometallics 1997,
16, 2948.

3590 Organometallics, Vol. 21, No. 17, 2002
Vicente et al.
Sch em e 3
Sch em e 4
presence of thallium triflate would explain the formation
of salts 9 and 10.
Rea ction of Com p lex 1a w ith XyNC in Reflu xin g
Tolu en e in th e Ra tio P d :RNC ) 1:1.25. Syn th esis
a n d Mech a n ism of F or m a tion of [P d Br 2{2-(XyNH)-
isoin d ole}2] (12). If reaction of 1a with XyNC in
refluxing toluene is carried out in the ratio Pd:RNC )
1:1.25, a completely different result is obtained; pal-
ladium metal and complex [PdBr2{2-(XyNH)-isoindole}2]
(12) were formed (Scheme 3). The same result is
obtained if 2a is refluxed in toluene with XyNC in the
ratio Pd:RNC ) 1:0.25.
As 12 is also formed when 11 is refluxed in toluene
with XyNC (1:0.2 molar ratio), it is reasonable to
conclude (i) that 11 is an intermediate in the synthesis
of 12 from 1a (or 2a ) and XyNC and (ii) that XyNC is
required to decompose 11 into palladium metal and 12,
despite not being stoichiometrically necessary. The
following experiment could explain this requirement.
The room-temperature reaction between 11 and XyNC
in an 1:2 molar ratio affords 4a , previously prepared
by reacting 1a or 2a with XyNC at room temperature
(see above). Complex 4a decomposes in refluxing tolu-
ene, giving palladium metal and 12. Therefore, it is
reasonable to assume that formation of 12 requires the
generation and decomposition in refluxing toluene of 4a .
Because such decomposition releases the isocyanide
required to transform 11 into 12, the complex 4a and
the excess of isocyanide play the role of a catalyst in
the synthesis of 12 from 1a , 2a , or 11.
The isoindole ligand in 12 is the result of a C-N
coupling process that requires a reduction of the metal
center. In fact, we observed the formation of Pd metal
in the thermal decomposition of 4a to give 12. Therefore,
we describe here a rare example of a reaction in which
the organic compound resulting from a reductive elimi-
nation appears in the final product coordinated to Pd-
(II). It is reasonable to assume that the required
oxidation of Pd(0) to Pd(II) to give 12 occurred through
an oxidative addition reaction of the isoindolinium salt
9a ‚Br to Pd(0) (Scheme 4), both formed in the decom-
position of 4a , to give A, a hydrido(isoindole)palladium-
(II) complex. One iminium salt has been found to react
We were successful in isolating the triflate salts
9a ‚OTf (OTf ) O3SCF3) and 10a ‚OTf, as well as the
substituted derivatives 9b‚OTf, 9d ‚OTf, 10b‚OTf, and
10d ‚OTf, by refluxing in toluene for 1 h mixtures
containing the corresponding complex 1, RNC, and
TlOTf (Pd:RNC:TfO ) 1:1:1) (Scheme 2). To remove the
colloidal Pd(0) formed, it was surprisingly helpful to
reflux the reaction mixture with NaBr for one more
hour. The organic compounds 9 and 10 were fully
characterized and, additionally, the X-ray crystal struc-
ture of 9a ‚OTf was determined (see below). All reactions
starting from 1c gave complex mixtures.
Mech a n ism of F or m a tion of 2-Am in oisoin d o-
lin iu m Sa lts 9 a n d 10. In agreement with the above
results, it is reasonable to assume that complexes 1
react with isocyanides in refluxing toluene to give the
adducts 2 or 3. Under these conditions the coordinated
isocyanide would insert into the C-Pd bond to give
inserted species such as 11. In the case of the reaction
t
of 1a with BuNC the inserted complex [Pd{(CdNtBu)-
C6H4CH2NH2-2}Br]2 would be unstable, decomposing to
give 10a ‚Br and palladium metal. Contrarily, the reac-
tion of 1a with XyNC would give the stable complex 11.
The iodo complex used by Parkins would give less stable
inserted complexes than our bromo complexes and
would give directly 2-aminoisoindolinium salts and
palladium metal.27 Similarly, the instability of the
triflato derivatives of the inserted complexes obtained
when complexes 1 were reacted with isocyanides in the
(52) Uso´n, R.; Fornie´s, J .; Espinet, P.; Lalinde, E.; J ones, P. G.;
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(55) Uso´n, R.; Fornie´s, J .; Espinet, P.; Garc´ıa, A.; Tomas, M.; Foces-
Foces, C.; Cano, F. H. J . Organomet. Chem. 1985, 282, C35.

Pd-Assisted Formation of Carbon-Carbon Bonds
Organometallics, Vol. 21, No. 17, 2002 3591
F igu r e 2. Thermal ellipsoid plot (50% probability level)
of 9a ‚OTf. Selected bond lengths (Å) and angles (deg):
N(1)-C(1) 1.3237(18); N(1)-C(9) 1.4494(17); N(2)-C(1)
1.3226(18); N(2)-C(2) 1.4646(19); C(1)-C(8) 1.4602(19);
C(2)-C(3) 1.503(2); C(3)-C(8) 1.3955(19); C(1)-N(1)-C(9)
123.64(12); C(1)-N(2)-C(2) 112.64(12); N(2)-C(1)-N(1)
124.90(13); N(2)-C(1)-C(8) 109.02(12); N(1)-C(1)-C(8)
126.06(13); N(2)-C(2)-C(3) 101.98(11).
F igu r e 1. Thermal ellipsoid plot (50% probability level)
of 3d . Selected bond lengths (Å) and angles (deg): Pd-
C(2) 1.927(3); Pd-C(11) 1.990(3); Pd-N(1) 2.053(3); Pd-
Br 2.5127(4); N(1)-C(1) 1.482(4); N(2)-C(2) 1.153(4);
N(2)-C(3) 1.460(3); C(2)-Pd-C(11) 94.24(12); C(11)-Pd-
N(1) 82.02(11); C(2)-Pd-Br 91.88(8); N(1)-Pd-Br 91.93-
(8); C(1)-N(1)-Pd 112.26(19); N(1)-C(1)-C(12) 108.0(2);
C(2)-N(2)-C(3) 175.3(3); N(2)-C(2)-Pd 178.4(3).
with a Ni(0) complex to give a hydrido(imino)nickel(II)
complex.56 In addition, the isolation of hydrido com-
plexes [PdCl(H)L2] (L ) PPh3, PCy3) by reacting PdLn
with HCl at low temperature has been reported.57,58 The
reaction of the hydrido complex A with 9a ‚Br could lead
to 12 and H2 (Scheme 4). The reactions of [M(PPh3)4]
(M ) Ni, Pd) with HX acids have been reported to give
[PdCl2(PPh3)2] and H2 through the same hydrido com-
plexes isolated at low temperature.59 The stoichiometry
of this reaction requires, as observed, half the Pd(0) to
remain unreacted. To support our proposal of a mech-
anism for the synthesis of 12, we reacted 9a ‚OTf with
the Pd(0) complex [Pd(dba)2] and an excess of Bu4NBr
in refluxing toluene and isolated complex 12.
We have unsuccessfully attempted to prepare 9a ‚OTf
by reacting (IC6H4CH2NH3-2)OTf with XyNC and Et3N
(1:1:1 molar ratio) in refluxing toluene using as catalyst
the product of the reaction of 2a with TlOTf in acetone
(molar ratio of reagents to catalyst ) 10:1). The salt
(IC6H4CH2NH3-2)OTf was used instead of IC6H4CH2-
NH2-2 because this product is of low stability. We report
the details of the synthesis of both iodo derivatives
starting from commercial IC6H4CH2CO2H-2 (see Sup-
porting Information).
Cr ysta l Str u ctu r es. The crystal structures of 3d
(Figure 1), 9a ‚OTf (Figure 2), and 12 (Figure 3) have
been determined. Complex 3d shows a distorted square-
planar coordination around the palladium atom. The
mean deviation from the plane Pd, N(1), C(11), C(2), and
Br is 0.034 Å. The isocyanide is in cis position with
respect to the aryl ligand. This geometry is in agreement
with the greater transphobia between two carbon donor
F igu r e 3. Thermal ellipsoid plot (50% probability level)
of 12. Selected bond lengths (Å) and angles (deg): Pd-N(1)
2.011(2); Pd-Br 2.4226(3); N(1)-C(8) 1.306(3); N(1)-C(1)
1.466(3); N(2)-C(8) 1.339(3); N(2)-C(11) 1.435(3); C(1)-
C(2) 1.498(3); C(2)-C(3) 1.395(4); C(3)-C(8) 1.478(3);
N(1)-Pd-Br 90.75(6); N(1)-Pd-Br#1 89.24(6); C(8)-N(1)-
C(1) 110.1(2); C(8)-N(1)-Pd 127.5(2); C(1)-N(1)-Pd 122.1-
(2); C(8)-N(2)-C(11) 124.9(2); N(1)-C(8)-N(2) 122.8(2);
N(1)-C(8)-C(3) 111.4(2); N(2)-C(8)-C(3) 125.8(2).
ligands than between a C and an N donor ligand.60 In
the asymmetric unit, molecules of 3d associate through
intermolecular N-H‚‚‚Br hydrogen bonds (see Table 1),
forming ribbons parallel to the x axis (Figure 4). In the
salt 9a ‚OTf the interplanar angle between the two ring
systems is 68°. The classical H bonds NH‚‚‚O connect
the ions in spiral chains parallel to the y axis. The three
nonclassical CH‚‚‚O bonds link these chains to form a
three-dimensional network (Table 1). Figure 5 shows
all the H bonds formed by one cation. In complex 12
the ligands are in a square-planar coordination around
(56) Aresta, M.; Quaranta, E.; Dibenedetto, A.; Giannoccaro, P.;
Tommasi, I.; Lanfranchi, M.; Tiripicchio, A. Organometallics 1997, 16,
834.
(57) van der Linde, R.; De J ongh, R. O. J . Chem. Soc., Chem.
Commun. 1971, 563.
(58) Kudo, K.; Hidai, M.; Murayama, T.; Uchida, Y. J . Chem. Soc.,
Chem. Commun. 1970, 1701.
(59) Cariati, R.; Ugo, R.; Bonati, F. Inorg. Chem. 1966, 5, 1128.

3592 Organometallics, Vol. 21, No. 17, 2002
Vicente et al.
Ta ble 1. Hyd r ogen Bon d s [Å a n d d eg] for 3d a a n d
9a ‚OTfb
D-H‚‚‚A
d(D-H) d(H‚‚‚A) d(D‚‚‚A)
(DHA)
3d
N(1)-H(1)‚‚‚Br#1
N(1)-H(2)‚‚‚Br#2
9a ‚OTf
0.83(3)
0.82(2)
2.65(3)
2.77(3)
3.433(3)
3.458(3)
158(4)
144(3)
N(2)-H(02)‚‚‚O(1)
0.877(19) 1.95(2)
2.8115(17) 166.1(17)
N(1)-H(01)‚‚‚O(2)#1 0.895(17) 1.976(17) 2.8561(16) 167.3(15)
C(2)-H(2B)‚‚‚O(1)#2 0.99
0.95
2.47
2.59
2.51
3.3578(19) 149.1
3.4288(19) 146.7
3.4442(18) 169.5
C(7)-H(7)‚‚‚O(3)#1
C(11)-H(11)‚‚‚O(3)#3 0.95
a
Symmetry transformations used to generate equivalent at-
oms: #1 -x + 1, -y + 1, -z + 2; #2 -x + 2, -y + 1, -z + 2.
b
Symmetry transformations used to generate equivalent atoms:
#1 -x + 1/2, y + 1/2, -z + 1/2; #2 -x + 1, -y + 1, -z; #3 -x + 3/2,
y + 1/2, -z + 1/2.
F igu r e 5. View of the hydrogen bond environment of the
cation in 9a ‚OTf.
suggest that a delocalization of electron density occurs
between the atoms N(1), C(8), and N(2). The same
occurs in the group N(1)-C(1)-N(2) of the salt 9a ‚OTf.
Additionally, the angles C(8)-N(2)-C(11) [124.9(2)°] in
12 and C(9)-N(1)-C(1) [123.64(12)°] in 9a ‚OTf are far
away from the expected sp3 hybridization for N(2) and
N(1), respectively, if a lone pair were assumed on these
atoms. The N(1) in 12 is only slightly out of the plane
Pd-C(1)-C(8) [the C(1)-N(1)-C(8) plane forms angles
of 5.8° and 5.4° with Pd-N(1)-C(8) and Pd-N(1)-C(1)
planes, respectively], indicating that the lone pair is
marginally located on N(1). Probably, the two pairs of
electrons (the lone and the π pairs) are delocalized over
Pd-N(1)-C(8)-N(2) bonds. The atoms C(1), N(1), C(8),
N(2), and C(3) are coplanar (mean deviation from the
plane 0.01 Å).
F igu r e 4. View of the hydrogen bond interactions in 3d .
the palladium atom (Figure 3). The Pd-Br bond length
[2.4226(3) Å] is normal [mean value of 59 trans-
dibromopalladium complexes from CCDC: 2.430(3) Å].
The lower trans influence of a bromo than an aryl group
explains the shorter Pd-Br bond length in 12 than in
3d [2.5128(4) Å]. The Pd-N [2.011(2) Å] is also normal
[mean value of 57 compounds containing the group Pd-
N(C)dC-N from CCDC, 2.035(6) Å]. The similar N-C
bond distances in the group N(1)-C(8)-N(2) [N(1)-C(8)
1.306(3), C(8)-N(2) 1.339(3) Å] and the significantly
longer distances of N(1) and N(2) with their other
neighbors [N(1)-C(1) 1.466(3), N(2)-C(11), 1.435(3) Å]
Con clu sion s
The room-temperature reactions of cyclopalladated
primary amines 1 with excess of isocyanides proceed
through the following steps: (1) coordination of the
isocyanide after bridge-splitting of the dimer, (2) inser-
tion of a molecule of the isocyanide into the Pd-C bond
of the resulting monomer, (3) coordination of a third
isocyanide by cleavage of the Pd-NH2 bond, and (4) a
decomposition process that gives the Pd(I) complex [Pd2-
Br2(RNC)4] and some 2-aminoisoindole derivative that
could not be isolated.
The reactions in refluxing toluene of 1 with RNC and
TlOTf (Pd:RNC:TfO ) 1:1:1) lead to the corresponding
2-R-aminoisoindolinium triflates 9 and 10. Similarly, 1a
reacts with tBuNC (Pd:tBuNC ) 1:1) in refluxing
toluene to give 2-tBu-aminoisoindolinium bromide,
10a ‚Br , which could not be fully separated from pal-
ladium(0). However, the reaction of 1a with XyNC (1:2
molar ratio) in refluxing toluene gives the monoinserted
complex 11. The C-N coupling leading to isoindoles
requires the use of an excess of XyNC, and the product
finally obtained is complex 12, in which two molecules
of 2-aminoisoindole are coordinated to PdBr2. We give
experimental data that strongly suggest that the forma-
tion of this complex requires (1) coordination of a second
molecule of isocyanide per palladium through a bridge-
splitting process from complex 11, (2) decomposition of
(60) (a) Vicente, J .; Arcas, A.; Bautista, D.; Tiripicchio, A.; Tiripic-
chio-Camellini, M. New J . Chem. 1996, 20, 345. (b) Vicente, J .; Arcas,
A.; Bautista, D.; J ones, P. G. Organometallics 1997, 16, 2127. (c)
Vicente, J .; Abad, J . A.; Frankland, A. D.; Ram´ırez de Arellano, M. C.
Chem. Commun. 1997, 959. (d) Vicente, J .; Arcas, A.; Blasco, M. A.;
Lozano, J .; Ram´ırez de Arellano, M. C. Organometallics 1998, 17, 5374.
(e) Vicente, J .; Abad, J . A.; Frankland, A. D.; Ram´ırez de Arellano, M.
C. Chem. Eur. J . 1999, 5, 3066. (f) Vicente, J .; Chicote, M. T.; Rubio,
C.; Ram´ırez de Arellano, M. C.; J ones, P. G. Organometallics 1999,
18, 2750. (g) Lohner, P.; Pfeffer, M.; Fischer, J . J . Organomet. Chem.
2000, 607, 12. (h) Larraz, C.; Navarro, R.; Urriolabeitia, E. P. New J .
Chem. 2000, 24, 623. (i) Albert, J .; Cadena, J . M.; Delgado, S.; Granell,
J . J . Organomet. Chem. 2000, 603, 235. (j) Albert, J .; Cadena, J . M.;
Granell, J . R.; Solans, X.; Fontbardia, M. Tetrahedron Asymm. 2000,
11, 1943. (k) Fernandez, S.; Navarro, R.; Urriolabeitia, E. P. J .
Organomet. Chem. 2000, 602, 151. (l) Albert, J .; Bosque, R.; Cadena,
J . M.; Granell, J . R.; Muller, G.; Ordinas, J . I. Tetrahedron Asymm.
2000, 11, 3335. (m) Albert, J .; Bosque, R.; Cadena, J . M.; Delgado, S.;
Granell, J . J . Organomet. Chem. 2001, 634, 83. (n) Vicente, J .; Arcas,
A.; Ferna´ndez-Herna´ndez, J .; Bautista, D. Organometallics 2001, 20,
2767. (o) J alil, M. A.; Fujinami, S.; Nishikawa, H. J . Chem. Soc., Dalton
Trans. 2001, 1091. (p) Fernandez-Rivas, C.; Cardenas, D. J .; Martin-
Matute, B.; Monge, A.; Gutierrez-Puebla, E.; Echavarren, A. M.
Organometallics 2001, 20, 2998. (q) Carbayo, A.; Cuevas, J . Y.; Garcia-
Herbosa, G.; Garcia-Granda, S.; Miguel, D. Eur. J . Inorg. Chem. 2001,
2361. (r) Fernandez-Rivas, C.; Cardenas, D. J .; Martin-Matute, B.;
Monge, A.; Gutierrez-Puebla, E.; Echavarren, A. M. Organometallics
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2002, 21, 272.

Pd-Assisted Formation of Carbon-Carbon Bonds
Organometallics, Vol. 21, No. 17, 2002 3593
CH2), 5.44 (br s, 2 H, NH2), 6.83-7.37 (m, 6 H, C6H3). Anal.
Calcd for C16H16BrFN2Pd: C, 43.52; H, 3.65; N, 6.34. Found:
C, 43.67; H, 3.53; N, 6.19.
the resulting complex 4a to give 2-Xy-aminoisoindo-
linium bromide (9a ‚Br ) and Pd(0), (3) an oxidative
addition reaction between these two products to give a
hydrido(bromo)(isoindole)palladium(II) complex, and (4)
the reaction of this hydrido complex with 9a ‚Br to give
complex 12.
Syn th esis of [P d {C6H4CH2NH2-2}Br (tBu NC)] (3a ). 3a
was obtained starting from 1a (192 mg, 0.328 mmol) and
tBuNC (74 µL, 0.655 mmol) in CH2Cl2 (20 mL). Yield: 205 mg,
83%. Dec pt: 130 °C. IR (Nujol, cm-1): ν 2202 (CtN). 1H NMR
(200 MHz, CDCl3): δ 1.54 (s, 9 H, Me), 3.92 (br s, 2 H, NH2),
4.20 (t, 2 H, CH2, 3J (H,H) ) 5.6 Hz), 6.91-7.16 (m, 4 H, C6H4).
Anal. Calcd for C12H17BrN2Pd: C, 38.38; H, 4.56; N, 7.46.
Found: C, 38.18; H, 4.47; N, 7.25.
Exp er im en ta l Section
Gen er a l P r oced u r es. Infrared spectra were recorded on
Perkin-Elmer 1430 and 16F-PC-FT spectrometers. NMR spec-
tra were carried out with a Varian Unity 300 or a Bruker 200.
Chemical shifts are referenced to TMS [1H and 13C{1H}]. The
starting materials [Pd{C6H3CH2NH2-2-X-5}(µ-Br2)]2 (X ) F,
NO2, OMe) were prepared as reported.40 The preparation of
IC6H4CH2NH2-2 and (IC6H4CH2NH3-2)OTf is reported in the
Supporting Information.
Syn t h esis of [P d {C6H 3CH 2NH 2-2-OMe-5}Br {t Bu NC)]
(3b). 3b was obtained starting from 1b (74 mg, 0.115 mmol)
t
and BuNC (30 µL, 0.266 mmol) in CH2Cl2 (20 mL). Yield: 80
1
mg, 86%. Dec pt: 147 °C. IR (Nujol, cm-1): ν 2200 (CtN). H
NMR (200 MHz, CDCl3): δ 1.58 (s, 9 H, Me), 3.76 (s, 3 H,
OMe), 4.18 (t, 2 H, CH2, 3J (H,H) ) 5.9 Hz), 6.61 (dd, 1 H,
H4, 3J (H,H) ) 8.4 Hz, 4J (H,H) ) 2.4 Hz), 6.73 (d, 1 H, H6,
4J (H,H) ) 2.4 Hz), 6.97 (d, 1 H, H3, 3J (H,H) ) 8.4 Hz). The
signal for NH2 was overlapped by that of OMe. Anal. Calcd
for C13H19BrN2OPd: C, 38.49; H, 4.72; N, 6.91. Found: C,
38.17; H, 4.84; N, 6.96.
Syn th esis of [P d {C6H4CH2NH2-2}(µ-Br )]2 (1a ). Benzyl-
amine (488 µL, 4.46 mmol) was added to a suspension of [Pd-
(OAc)2]3 (1.00 g, 1.49 mmol) in 50 mL of acetone. The resulting
solution was refluxed for 8 h. The reaction mixture was
filtered, and NaBr (1.00 g) was added to the orange filtrate.
The resulting suspension was stirred at room temperature
overnight and evaporated to dryness. The residue was stirred
with CH2Cl2 (30 mL) and filtered and the solid washed with
water until the filtrates were colorless. After washing with
Et2O, the solid was dried in vacuo to give 1a as a yellow solid.
Yield: 558 mg, 43%. Dec pt: 187 °C. 1H NMR [300 MHz,
Syn th esis of [P d{C6H3CH2NH2-2-NO2-5}Br (tBu NC)] (3c).
3c was obtained starting from 1c (79 mg, 0.116 mmol) and
tBuNC (30 µL, 0.266 mmol) in CH2Cl2 (20 mL). Yield: 55 mg,
56%. Dec pt: 201 °C. IR (Nujol, cm-1): ν 2210 (CtN). 1H NMR
(200 MHz, CDCl3): δ 1.60 (s, 9 H, Me), 4.19 (br s, 2 H, NH2),
4.36 (t, 2 H, CH2, 3J (H,H) ) 5.8 Hz), 7.18 (d, 1 H, H3, 3J (H,H)
3
4
) 8.3 Hz), 7.92 (dd, 1 H, H4, J (H,H) ) 8.3 Hz, J (H,H) ) 2.3
3
Hz), 7.99 (d, 1 H, H6, 4J (H,H) ) 2.3 Hz). Anal. Calcd for C12H16
-
(CD3)2SO]: δ 3.94 (t, 4 H, CH2, J (H,H) ) 5.3 Hz), 5.51 (br s,
4 H, NH2), 6.66-7.70 (m, 8 H, C6H4). Anal. Calcd for C14H16
-
BrN3O2Pd: C, 34.27; H, 3.83; N, 9.99. Found: C, 34.52; H,
3.78; N, 9.66.
Br2N2Pd2: C, 28.75; H, 2.76; N, 4,79. Found: C, 29.11; H, 2.55;
N, 4.55.
Syn th esis of [P d {C6H3CH2NH2-2-F -5}Br (tBu NC)] (3d ).
3d was obtained starting from 1d (100 mg, 0.161 mmol) and
tBuNC (37 µL, 0.328 mmol) in CH2Cl2 (20 mL). Yield: 112 mg,
89%. Dec pt: 137 °C. IR (Nujol, cm-1): ν 2018 (CtN). 1H NMR
(200 MHz, CDCl3): δ 1.56 (s, 9 H, Me), 3.91 (br s, 2 H, NH2),
4.23 (t, 2 H, CH2, 3J (H,H) ) 5.8 Hz), 6.75 (dt, 1 H, H4, 3J (F,H)
Syn th esis of Com p lexes 2 a n d 3. RNC (R ) Xy, tBu) was
added to a suspension of 1 in CH2Cl2. Within a few minutes a
slightly yellow solution resulted, which was stirred at room
temperature for 15 min. Concentrating the solution to a
volume of ca. 2 mL and subsequent addition of diethyl ether
afforded complexes 2 or 3 as colorless solids.
)
3J (H,H) ) 8.5 Hz, 4J (H,H) ) 2.5 Hz), 6.82 (dd, 1 H, H6,
3J (F,H) ) 9.2 Hz, 4J (H,H) ) 2.5 Hz), 7.01 (dd, 1 H, H3, 3J (H,H)
Syn th esis of [P d {C6H4CH2NH2-2}Br {XyNC}] (2a ). 2a
was obtained starting from 1a (407 mg, 0.696 mmol) and XyNC
(183 mg, 1.395 mmol) in CH2Cl2 (50 mL). Yield: 530 mg, 90%.
Dec pt: 211 °C. IR (Nujol, cm-1): ν 2178 (CtN). 1H NMR (200
MHz, CDCl3): δ 2.50 (s, 6 H, Me), 3.99 (br s, 2 H, NH2), 4.33
4
) 8.2 Hz, J (F,H) ) 5.6 Hz). Anal. Calcd for C12H16BrFN2Pd:
C, 36.62; H, 4.10; N, 7.12. Found: C, 36.62; H, 3.95; N, 6.85.
Syn th esis of [P d {C(dNXy)C6H4CH2NH2-2}Br (XyNC)]‚1/
2CH2Cl2 (4a ). To a suspension of 2a (233 mg, 0.550 mmol) in
CH2Cl2 (50 mL) was added XyNC (80 mg, 0.610 mmol). The
resulting solution was stirred at room temperature during 1.5
h and then was concentrated (ca. 1 mL). Upon addition of Et2O,
a solid crystallized, which is filtrated, washed with ether, and
dried in vacuo to give pale yellow 4a . Yield: 254 mg, 83%.
Dec pt: 175 °C. IR (Nujol, cm-1): ν 1634 (CdN), 2184 (CtN).
1H NMR (200 MHz, CDCl3): δ 2.13, 2.29 (s, 12 H, Me), 3.49
3
(t, 2 H, CH2, J (H,H) ) 6.0 Hz), 6.88-7.40 (m, 7 H, C6H4 and
C6H3). Anal. Calcd for C16H17BrN2Pd: C, 45.26; H, 4.04; N,
6.60. Found: C, 45.22; H, 4.05; N, 6.80.
Syn th esis of [P d{C6H3CH2NH2-2-OMe-5}Br (XyNC)] (2b).
2b was obtained starting from 1b (91 mg, 0.141 mmol) and
XyNC (37 mg, 0.282 mmol) in CH2Cl2 (20 mL). Yield: 99 mg,
77%. Dec pt: 201 °C. IR (Nujol, cm-1): ν 2184 (CtN). 1H NMR
(200 MHz, CDCl3): δ 2.53 (s, 6 H, Me), 3.71 (s, 3 H, OMe),
3.82 (br s, 2 H, NH2), 4.29 (t, 2 H, CH2, 3J (H,H) ) 6.0 Hz),
3
(br s, 2 H, NH2), 3.90 (t, 2 H, CH2, J (H,H) ) 5.9 Hz), 6.77-
7.57 (m, 10 H, C6H4, C6H3). 13C NMR: (50 MHz, CDCl3): δ
18.6, 19.1 (Me), 44.3 (CH2), 123.4, 125.7 (CH), 126.8 (aromatic
C), 127.7, 127.9, 128.5, 128.6, 129.4 (CH), 135.1, 135.4 (aro-
3
4
6.58 (dd, 1 H, H4, J (H,H) ) 8.3 Hz, J (H,H) ) 2.5 Hz), 6.95
(d, 1 H, H6, 4J (H,H) ) 2.5 Hz), 7.00 (d, 1 H, H3, 3J (H,H) ) 8.3
Hz), 7.11-7.23 (m, 3 H, C6H3). Anal. Calcd for C17H19BrN2-
OPd: C, 45.01; H, 4.22; N, 6.17. Found: C, 45.09; H, 3.95; N,
6.13.
matic C), 150.8 (CN), 180.8 (CdN). Anal. Calcd for C25.5H27
-
BrClN3Pd: C, 51.28; H, 4.56; N, 7.04. Found: C, 51.27; H, 4.48;
N, 7.11.
Syn th esis of [P d{C6H3CH2NH2-2-NO2-5}Br (XyNC)] (2c).
2c was obtained starting from 1c (116 mg, 0.171 mmol) and
XyNC (45 mg, 0.343 mmol) in CH2Cl2 (20 mL). Yield: 120 mg,
74%. Dec pt: 209 °C. IR (Nujol, cm-1): ν 2188 cm-1 (CtN).
NMR: the insolubility of 2c in any common organic solvent
prevented us from measuring its NMR spectra. Anal. Calcd
for C16H16BrN3O2Pd: C, 41.01; H, 3.44; N, 8.97. Found: C,
40.86; H, 3.18; N, 8.97.
Syn th esis of [P d {C6H3CH2NH2-2-F -5}Br {XyNC}] (2d ).
2d was obtained starting from 1d (100 mg, 0.161 mmol) and
XyNC (43 mg, 0.328 mmol) in CH2Cl2 (20 mL). Yield: 100 mg,
91%. Dec pt: 168 °C. IR (Nujol, cm-1): ν 2180 (CtN). 1H NMR
[200 MHz, (CD3)2SO]: δ 2.49 (s, 6 H, Me), 4.01 (br s, 2 H,
Syn th esis of [P d 2Br 2(XyNC)4] (5). To a suspension of 1c
(123 mg, 0.199 mmol) in CH2Cl2 (30 mL) was added XyNC (156
mg, 1.19 mmol). The resulting mixture was stirred at room
temperature overnight. The solvent was removed in vacuo, the
solid was washed with Et2O, and the resulting suspension was
filtered. The yellow solid was dried in vacuo to give 5. Yield:
93 mg, 52%. Dec pt: 228 °C. IR (Nujol, cm-1): ν 2156 (CtN).
1H NMR (300 MHz, CDCl3): δ 2.53 (s, 24 H, Me), 7.08-7.27
(m, 12 H, C6H3). 13C NMR (50 MHz, CDCl3): δ 19.2 (Me), 128.1
(m-C’s of C6H3), 130.6 (p-C of C6H3) 135.7 (o-C’s of C6H3), 143.0
(br, i-C of C6H3), the signal for XyNC was not observed. Anal.
Calcd for C36H36Br2N4Pd2: C, 48.19; H, 4.04; N, 6.24. Found:
C, 48.24; H, 4.07; N, 6.34.

3594 Organometallics, Vol. 21, No. 17, 2002
Vicente et al.
Syn th esis of [P d 2Br 2(tBu NC)4] (6). This yellow complex
was obtained as 5 from 1a (107 mg, 0.183 mmol) in CH2Cl2
4.83 (s, 2 H, CH2), 7.28-7.38 (m, 3 H, Xy), 7.75 (td, 1 H, H5,
4
3J (F,H) ) 3J (H,H) ) 8.9 Hz, J (H,H) ) 2.4 Hz), 7.87 (dd, 1 H,
t
(30 mL) and BuNC (125 µL, 1.107 mmol). Yield: 98 mg, 76%.
H6, 3J (H,H) ) 8.6 Hz, 4J (F,H) ) 4.7 Hz), 8.19 (dd, 1 H, H3,
3J (F,H) ) 8.3 Hz, 4J (H,H) ) 2.4 Hz), 10.59 (s, 1 H, NH), 11.56
(s, 1 H, NH). 13C NMR [75 MHz, (CD3)2SO]: δ 17.4 (Me), 51.4
(CH2), 110.2 (d, C(3) or C(5), 2J (C,F) ) 25.6 Hz), 121.5 (d, C(3)
1
IR (Nujol, cm-1): ν 2166 (CtN). H NMR (300 MHz, CDCl3):
δ 1.54 (s, 36 H). 13C NMR (50 MHz, CDCl3): δ 30.3 (Me), 58.2
t
(CMe3), the signal for BuNC was not observed.
2
3
or C(5), J (C,F) ) 23.2 Hz), 126.2 (d, C(6), J (C,F) ) 9.1 Hz),
Syn th esis of [P d {C(dNXy)C6H4CH2NHC(O)Me-2}Br -
(XyNC)2] (8a ). To a solution of 4a (52 mg, 0.094 mmol) in
CH2Cl2 (40 mL) were added XyNC (20 mg, 0.152 mmol) and
acetic anhydride (30 mL, 0.318 mmol), and the mixture was
stirred at room temperature for 10 min. The solution was
brought to dryness in vacuo, and the remaining oily residue
was dissolved in CH2Cl2 (2 mL). After addition of n-hexane
and filtration, complex 8a was obtained as a pale yellow solid.
Yield: 43 mg, 63%. IR (Nujol, cm-1): ν 1614, 1634 (CdO,
CdN), 2182 (CtN), 3276 (NH). 1H NMR (300 MHz, CDCl3):
δ 1.83 [s, 3 H, C(O)Me], 2.19 [s, 12 H, C6H3(Me)2], 2.22 [s, 6
H, C6H3(Me)2], 4.60 [d, 3J (H,H) ) 6.3 Hz, 2 H, CH2], 6.98-
7.53 (m, H, C6H4 + C6H3), 8.44 [d, br, 1 H, NHC(O)Me]. The
instability of 8a prevented us from recording its 13C NMR
spectrum and obtaining correct elemental analyses (see Dis-
cussion).
3
129.0 (CH of Xy), 129.2 (CH of Xy), 129.3 (d, C(9), J (C,F) )
10.4 Hz), 131.7 (ipso-C of Xy), 135.3 (C of Xy), 140.8 (d, p-C of
4
4
C6H3F, J (C,F) ) 1.8 Hz), 160.4 (d, CNXy, J (C,F) ) 3.6 Hz),
1
161.9 (d, C(4), J (C,F) ) 244.8 Hz). Anal. Calcd for C17H16F4-
N2O3S: C, 50.49; H, 3.99; N, 6.93; S, 7.93. Found: C, 50.45;
H, 4,08; N, 7.04; S, 7.49. FAB+-MS: m/z 255.3 [M+].
Syn th esis of [2-(tBu NH)-isoin d olin iu m ]OTf (10a ‚OTf).
10a ‚OTf was obtained starting from 1a (120 mg, 0.205 mmol),
tBuNC (46 µL, 0.407 mmol), and TlOTf (145 mg, 0.410 mmol).
Yield: 69 mg, 50%. Mp: 201 °C. IR (Nujol, cm-1): ν 1660
(CdN). 1H NMR [200 MHz, (CD3)2CO]: δ 1.64 (s, 9 H, Me),
5.03 (s, 2 H, CH2), 7.59-7.67 (m, 2 H, C6H4), 7.80-7.82 (m, 1
H, C6H4), 8.31-8.35 (m, 1 H, C6H4), 8.85 (s, 1 H, NH), 9.50 (s,
1 H, NH). 13C NMR [50 MHz, (CD3)2CO]: δ 28.0 (Me), 53.2
(CH2), 55.1 (CMe3), 124.1, 124.2, 129.1, 134.2 (CH), 143.8, 160.9
(C of C6H4), 166.2 (CNtBu). Anal. Calcd for C13H17F3N2O3S:
C, 46.15; H, 5.06; N, 8.28; S, 9.48. Found: C, 46.12; H, 5.32;
N, 8.33; S, 9.19. FAB+-MS: m/z 189.3 [M+].
Syn th esis of 9‚OTf a n d 10‚OTf. A stoichiometric amount
of RNC (R ) Xy, tBu) was added to a suspension of 1 in
acetone. Upon addition of TlOTf, immediate precipitation of
TlBr occurred. The solvent was removed in vacuo, and the
remaining residue was suspended in toluene and refluxed for
1 h, upon which Pd(0) precipitated. To the black reaction
mixture was added NaBr (1.00 g) (see Discussion), and the
mixture was refluxed for one more hour. After cooling to room
Syn t h esis of [2-(t Bu NH )-4-OMe-isoin d olin iu m ]OTf
(10b‚OTf). 10b‚OTf was obtained starting from 1b (126 mg,
0.195 mmol), tBuNC (44 µL, 0.390 mmol), and TlOTf (138 mg,
0.390 mmol). Yield: 65 mg, 45%. Mp: 217 °C. IR (Nujol, cm-1):
ν 1656 (CdN). 1H NMR [300 MHz, (CD3)2CO]: δ 1.63 (s, 9
H, Me), 3.87 (s, 3 H, OMe), 4.93 (s, 2 H, CH2), 7.34 (dd, 1 H,
H5, 3J (H,H) ) 8.5 Hz, 4J (H,H) ) 2.3 Hz), 7.68 (d, 1 H, H6,
t
temperature in the case of BuNC, the toluene was removed
in vacuo and the remaining black residue was suspended in
CH2Cl2 and filtered through Celite. In the case of XyNC the
toluene mixture was directly filtered through Celite. The
filtrate was brought to dryness, the oily residue was dissolved
in about 1 mL of CH2Cl2, and addition of Et2O afforded
compounds 10‚OTf and 9‚OTf as colorless solids.
Syn th esis of [2-(XyNH)-isoin d olin iu m ]OTf (9a ‚OTf).
9a ‚OTf was obtained starting from 1a (102 mg, 0.175 mmol),
XyNC (46 mg, 0.351 mmol), and TlOTf (124 mg, 0.351 mmol).
Yield: 55 mg, 41%. Mp: 170 °C. IR (Nujol, cm-1): ν 1660
(CdN). 1H NMR [300 MHz, (CD3)2SO]: δ 2.24 (s, 6 H, Me),
4.84 (s, 2 H, CH2), 6.47-6.55 (m, 3 H, C6H3), 6.99-7.06 (m, 3
H, C6H4), 7.53-7.55 (m, 1 H, C6H4), 9.58 (s, 1 H, NH), 10.72
(s, 1 H, NH). 13C NMR [75 MHz, (CD3)2SO]: δ 17.4 (Me), 61.3
(CH2), 123.5, 124.0 (CH of C6H4), 127.6 (C of C6H4), 128.7, 129.0
(C of Xy), 129.1 (CH of C6H4), 132.0 (ipso-C of Xy), 133.8 (CH
of C6H4), 135.3 (C of Xy), 144.6 (CH of C6H4), 161.1 (s, CN).
Anal. Calcd for C17H17F3N2O3S: C, 52.84; H, 4.43; N, 7.25; S,
8.30. Found: C, 53.04; H, 4.64; N, 7.39; S, 7.86. FAB+-MS:
m/z 237 [M+].
4
3J (H,H) ) 8.5 Hz), 7.91 (d, 1 H, H3, J (H,H) ) 2.3 Hz), 8.80
(s, 1 H, NH), 9.46 (s, 1 H, NH). 13C NMR [75 MHz, (CD3)2CO]:
δ 28.4 (Me), 53.1 (CH2), 55.5 (CMe3), 56.5 (OMe), 107.3, 123.0,
125.4 (CH), 131.3, 136.4 (C of C6H3OMe), 161.3 (CNtBu), 161.4
(COMe). Anal. Calcd for C14H19F3N2O4S: C, 45.65; H, 5.20; N,
7.60; S, 8.70. Found: C, 45.50; H, 5.56; N, 7.74; S, 8.47. FAB+-
MS: m/z 219.3 [M+].
Syn th esis of [2-(tBu NH)-4-F -isoin d olin iu m ]OTf (10d ‚
OTf). 10d ‚OTf was obtained starting from 1d (109 mg, 0.176
mmol), tBuNC (40 µL, 0.354 mmol), and TlOTf (125 mg, 0.354
mmol). Yield: 65 mg, 52%. Mp: 174 °C. IR (Nujol, cm-1): ν
1659 (CdN). 1H NMR [300 MHz, (CD3)2CO]: δ 1.64 (s, 9 H,
Me), 5.02 (s, 2 H, CH2), 7.60 (td, 1 H, H5, 3J (H,H) ) 3J (F,H) )
8,9 Hz, 4J (H,H) ) 2.4 Hz), 7.87 (dd, 1 H, H6, 3J (H,H) ) 8.4
Hz, 4J (F,H) ) 4.7 Hz), 8.19 (dd, 1 H, H3, 3J (F,H) ) 8.6 Hz,
4J (H,H) ) 2.3 Hz), 8.89 (s, 1 H, NH), 9.63 (s, 1 H, NH). 13C
NMR [75 MHz, (CD3)2CO]: δ 28.3 (Me), 53.3 (CH2), 55.7
(CMe3), 111.4 (d, C(3) or C(5), 2J (C,F) ) 25.6 Hz), 122.0 (d,
2
3
C(3) or C(5), J (C,F) ) 23.8 Hz), 126.5 (d, C(6), J (C,F) ) 8.5
Hz), 131.8 (d, C of C6H3F, 3J (C,F) ) 10.4 Hz), 140.0 (C of
C6H3F), 160.6 (CNtBu), 163.5 (d, C(9), 1J (C,F) ) 246.0 Hz).
Anal. Calcd for C13H16F4N2O3S: C, 43.82; H, 4.53; N, 7.86; S,
9.00. Found: C, 44.11; H, 4.66; N, 7.93; S, 8.75. FAB+-MS:
m/z 207.3 [M+].
Syn th esis of [2-(XyNH)-4-OMe-isoin d olin iu m ]OTf (9b‚
OTf). 9b‚OTf was obtained starting from 1b (119 mg, 0.184
mmol), XyNC (49 mg, 0.374 mmol), and TlOTf (0.371 mmol).
Yield: 60 mg, 39%. Mp: 198 °C. IR (Nujol, cm-1): ν 1660
(CdN). 1H NMR [300 MHz, (CD3)2SO]: δ 2.24 (s, 6 H, Me),
3.90 (s, 3 H, OMe), 4.75 (s, 2 H, CH2), 7.29-7.38 (m, 3 H, C6H3),
Syn th esis of [P d {C(dNXy)C6H4CH2NH2-2}Br ]2 (11). A
suspension of 2a (84 mg, 0.198 mmol) in toluene (10 mL) was
refluxed for 6 h. Filtration of the reaction mixture and washing
the solid with CH2Cl2 gave 11 as an olive green solid. Due to
the insolubility in common organic solvents, no NMR data are
available. Yield: 50 mg, 60%. Dec pt: 226 °C. IR (Nujol, cm-1):
ν 1576, 1538 (CdN). Anal. Calcd for C32H34Br2N4Pd2: C,
45.26; H, 4.04; N, 6.60. Found: C, 45.04; H, 3.83; N, 6.43.
Syn th esis of [P d Br 2{2-(XyNH)-isoin d ole}2] (12). XyNC
(48 mg, 0.366 mmol) was added to a suspension of 1a (85 mg,
0.145 mmol) in 10 mL of toluene. On refluxing the reaction
mixture for 3 h, Pd(0) was precipitated. The solution was
removed in vacuo, and the remaining black residue was
extracted with CH2Cl2. The CH2Cl2 extract was filtered
through MgSO4. On concentrating the yellow filtrate to about
4
7.45 (dd, 1 H, H5, 3J (H,H) ) 8.4, J (H,H) ) 2.6 Hz), 7.71 (d, 1
H, H6, 3J (H,H) ) 8.4 Hz), 7.97 (d, 1 H, H3, 4J (H,H) ) 2.6 Hz),
10.39 (s, 1 H, NH), 11.47 (s, 1 H, NH). 13C NMR 75 MHz,
(CD3)2SO]: δ 17.4 (Me), 51.1 (CH2), 55.8 (OMe), 106.9, 121.6,
125.0 (CH of C6H3), 128.7 (C of C6H3), 129.0, 129.1 (C of Xy),
131.8 (ipso-C of Xy), 135.3 (C of Xy), 136.8 (C of C6H3), 159.7
(COMe), 161 (CN). Anal. Calcd for C18H19F3N2O4S: C, 51.92;
H, 4.60; N, 6.73; S, 7.70. Found: C, 52.14; H, 4,94; N, 6.87; S,
7.53. FAB+-MS: m/z 267.3 [M+].
Syn th esis of [2-(XyNH)-4-F-isoin dolin iu m ]OTf (9d‚OTf).
9d ‚OTf was obtained starting from 1d (121 mg, 0.195 mmol),
XyNC (51 mg, 0.389 mmol), and TlOTf (138 mg, 0.390 mmol).
Yield: 40 mg, 25%. Mp: 165 °C. IR (Nujol, cm-1): ν 1658
(CdN). 1H NMR [300 MHz, (CD3)2SO]: δ 2.24 (s, 6 H, Me),

Pd-Assisted Formation of Carbon-Carbon Bonds
Organometallics, Vol. 21, No. 17, 2002 3595
Ta ble 2. Cr ysta l Da ta for Com p lexes 3d , 9a ‚OTf, a n d 12
3d
9a ‚OTf
12
formula
Mr
C
12H16BrFN2Pd
C17H17F3N2O3S
386.39
C32H32Br2N4Pd
738.84
393.58
cryst size (mm)
cryst syst
cell constants
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
0.44 × 0.44 × 0.34
0.40 × 0.25 × 0.18
0.52 × 0.18 × 0.14
triclinic
monoclinic
triclinic
5.3580(3)
10.0813(6)
13.6049(8)
80.825(5)
82.462(4)
76.751(4)
702.73(7)
2
10.5482(12)
11.9641(14)
13.9946(16)
90
100.052(3)
90
7.9207(7)
8.9482(8)
11.1669(8)
95.579(7)
100.911(5)
99.556(7)
759.58(11)
1
1739.0(3)
4
Z
λ (Å)
T (K)
0.71073
173(2)
0.71073
143(2)
0.71073
173(2)
space group
P1h
P21/n
1.476
0.237
P1h
F
calc (Mg/m3)
1.860
1.615
abs coeff (mm-1
transmn
)
4.155
0.914/0.654
384
3.268
0.902/0.762
368
F(000)
800
θ range (deg)
limiting indices
3.05-25.00
-6 e h e 6
-11 e k e 11
-16 e l e 1
2.24-30.03
-14 e h e 14
-16 e k e 8
-19 e l e 18
3.18-27.50
-10 e h e 10
-11 e k e 11
-14 e l e 14
no. of reflns
measd
indep
2626
2473
14 177
5073
6477
3493
Rint
abs corr
0.0088
ψ scans
2473/9/166
0.0213
0.0500
0.415
0.0567
none
5073/0/245
0.0390
0.0967
0.362
0.0147
ψ scans
3493/179/181
0.0266
0.0685
0.562
no. of data/restraints/params
R1a
wR2b
largest diff peak (e Å-3
)
S(F2)c
1.061
0.927
1.161
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2 ) [∑{w(Fo - Fc2)2}/∑{w(Fo2)2}]0.5; w-1 ) σ2(Fo2) + (aP)2 + bP, where P )
2
2
[Fo + 2Fc2]/3 and a and b are constants adjusted by the program. c S(F2) ) [∑{w(Fo - Fc2)2}/(n - p)]0.5, where n is the number of data
and p the number of parameters.
1 mL of volume and adding hexane, a yellow solid precipitated,
which was filtrated off, washed with hexane, and dried in
vacuo. Yield: 24 mg, 45%. Dec pt: 140 °C. IR (Nujol, cm-1):
ν 1620 (CdN). 1H NMR (300 MHz, CDCl3): δ 2.37 (s, 12 H,
Me), 4.88 (s, 4 H, CH2), 6.24-7.47 (m, 7 H, C6H4 and C6H3),
8.05 (br s, 2 H, NH). 13C NMR (75 MHz, CDCl3): δ 19.1 (Me),
60.4 (CH2), 121.2, 122.1, 127.0, 128.2, 128.5, 129.6 (CH of C6H4
and C6H3), 131.6, 135.1, 137.8, 150.1 (C of C6H4, C6H3), 164.1
(CdN). Anal. Calcd for C32H34Br2N4Pd: C, 52.02; H, 4.37; N,
7.58. Found: C, 51.93; H, 4.32; N, 7.38.
X-r a y Str u ctu r e Deter m in a tion s. X-ray intensities of
compound 3d and 12 were measured on a Siemens P4 with a
LT2 low-temperature attachment. Compound 9a ‚OTf was
measured on a Bruker SMART 1000 CCD/LT3. See Table 2.
The structures of the compounds 3d and 9a ‚OTf were solved
by direct methods, compound 12 was solved by the heavy atom
method, and all were refined anisotropically on F2 (compounds
12 and 9a ‚OTf, program SHELX-97; 3d , program SHELX-
93, G. M. Sheldrick, University of Go¨ttingen). The hydrogens
at N were located in the Fourier difference maps and refined
freely. Methyl groups were refined using rigid groups, for the
compounds 3d and 9a ‚OTf; in the latter, the methyl hydrogens
at C(15) are disordered over two positions. Other hydrogens
were refined using a riding method.
Ack n ow led gm en t. We thank Ministerio de Ciencia
y Tecnolog´ıa (BQU2001-0133) and INTAS (97-0166) for
financial support. C.G. and C.A. are grateful to Training
and Mobility of Researchers Program of the Commission
of the European Communities for Grants (No. ERBFM-
BICT983442 and ERBFMBICT972044, respectively).
Su p p or tin g In for m a tion Ava ila ble: Listing of all refined
and calculated atomic coordinates, all anisotropic thermal
parameters, and all bond lengths and angles for complexes 3d ,
9a ‚OTf, and 12. The method of synthesis of IC6H4CH2NH2-2
and (IC6H4CH2NH3-2)OTf. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM020365N