Intramolecular C-N bond formation in the reductive elimination of ortho-palladated arylhydrazones of acetophenone

Article abstract of DOI:10.1016/S0022-328X(02)01466-3

Carbonylation in dichloromethane at room temperature of the dimeric ortho-palladated complex [Pd{C₆H₄C(CH₃)=N- NHC₆H₅} (μ-Cl)]₂ yields in a first step the monocarbonyl isoindolin-1-one. Addition of the stoichiometric amount of NaOMe to the monocarbonyl complex [Pd{C₆H ₄C(CH₃)=N- NHC₆H₅}Cl(CO)] in solution leads instantaneously to reductive elimination and affords the indazole derivative, 3-methyl-l- phenyl-indazole, in high yield. Carbonylation of the related complex [Pd{C₆H₄C(CH₃)=N-NHC₆ H₄-p-NO₂}(μ-Cl)]₂ yields in solution the monocarbonyl [Pd{C₆H₄C(CH₃)=N-NHC₆H ₄p-NO₂}Cl(CO)] which in minutes affords high yield of the isoindolinone derivative, 2-(4-nitroanilino)-3-methylene-isoindolin-1-one. Such different behaviour sheds light on the mechanistic grounds that govern the intramolecular C-N bond formation and the cyclization of ortho-palladated acetophenonearylhydrazones, and shows that the acidity of the N-H bond controls the rate of the reactions. The requirement of the formation of a palladium-nitrogen amido bond cis to a palladium-carbon bond is supported for these results. We suggest that a tautomeric equilibrium of the hydrazonato ligand accounts for the two alternate pathways.

Full text of DOI:10.1016/S0022-328X(02)01466-3

Journal of Organometallic Chemistry 658 (2002) 15ꢀ20
/
www.elsevier.com/locate/jorganchem
Intramolecular CÃ
/
N bond formation in the reductive elimination of
ortho-palladated arylhydrazones of acetophenone
Ara´nzazu Carbayo, Jose´ V. Cuevas, Gabriel Garc´ıa-Herbosa *
Departamento de Qu´ımica, Facultad de Ciencias, Universidad de Burgos, 09001 Burgos, Spain
Received 13 February 2002; received in revised form 21 March 2002; accepted 12 April 2002
Abstract
Carbonylation in dichloromethane at room temperature of the dimeric ortho-palladated complex [Pd{C6H4C(CH3)Ä
NHC6H5}(m-Cl)]2 yields in a first step the monocarbonyl [Pd{C6H4C(CH3)ÄNÃNHC6H5}Cl(CO)] which very slowly (days)
undergoes in solution reductive elimination of palladium to give high yield of the isoindolinone derivative, 2-anilino-3-methylene-
isoindolin-1-one. Addition of the stoichiometric amount of NaOMe to the monocarbonyl complex [Pd{C6H4C(CH3)ÄNÃ
NHC6H5}Cl(CO)] in solution leads instantaneously to reductive elimination and affords the indazole derivative, 3-methyl-1-
phenyl-indazole, in high yield. Carbonylation of the related complex [Pd{C6H4C(CH3)ÄNÃNHC6H4-p-NO2}(m-Cl)]2 yields in
solution the monocarbonyl [Pd{C6H4C(CH3)ÄNÃNHC6H4-p-NO2}Cl(CO)] which in minutes affords high yield of the
isoindolinone derivative, 2-(4-nitroanilino)-3-methylene-isoindolin-1-one. Such different behaviour sheds light on the mechanistic
grounds that govern the intramolecular CÃN bond formation and the cyclization of ortho-palladated acetophenonearylhydrazones,
and shows that the acidity of the NÃH bond controls the rate of the reactions. The requirement of the formation of a palladiumꢀ
nitrogen amido bond cis to a palladiumꢀcarbon bond is supported for these results. We suggest that a tautomeric equilibrium of the
/
NÃ
/
/
/
/
/
/
/
/
/
/
/
/
/
hydrazonato ligand accounts for the two alternate pathways. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Metallacycles; Palladium(II); Carbonylation; Cyclization; Hydrazones
1. Introduction
have also NÃ
occur simultaneously. In such cases, the presence of MÃ
C(aryl) and MÃN(amido) bonds on the same metal
could lead to reductive elimination reactions and CÃ
bond formation. This is the case of acetophenonear-
ylhydrazone ligands PhC(CH3)ÄNNHAr which have
been used to prepare stable complexes containing both
N(amido) bonds [4,5]. The trans-
/
H bonds, CÃ
/
H and NÃ
/
H activations can
/
Organometallic complexes of palladium are a group
of chemicals of great interest as deduced from the huge
number of references and books devoted to this subject.
Particular attention is centred in their applications to
organic synthesis [1]. Palladation reactions have been
widely studied, and N-donor ligands capable of produ-
cing metallacycles have been thoroughly explored with
regard to their synthesis, reactivity, structural and
mechanistic aspects [2]. Most of the N-donor ligands,
like tertiary amines, imines and azobenzenes only
/
/N
/
PdÃ
/
C(aryl) and PdÃ
/
arrangement of such bonds could account for the
stability towards reductive elimination. In fact, cis
arrangement for PdÃ
/
C and PdÃ/N(amido) bonds is
uncommon. Those complexes containing such arrange-
ment normally undergo reductive elimination and are
contain CÃ/H bonds to activate and, in these cases, the
models as intermediates in catalyzed CÃ/N bond forma-
products of their palladation reaction can be quite
precisely anticipated [3]. However, when the ligands
tion reactions and useful in organic synthesis [6].
In this paper we report the spontaneous intramole-
cular CÃ
and the ortho-palladated acetophenonephenylhydra-
zone complexes, [Pd{C6H4C(CH3)ÄNÃNHC6H4-p-
R}(m-Cl)]2 (RꢁH, A1; RꢁNO2, A2) leading to 2-
anilino-3-methylene-isoindolin-1-one 1 and 2-(4-nitroa-
/
N bond formation between carbon monoxide
* Corresponding author. Present address: Quimica Inorganica, Pza.
Misael Banuelos s/n, 09001 Burgos, Spain. Tel.: ꢂ
/
34-947-258-822; fax:
˜
34-947-258-831
/
/
ꢂ/
/
/
E-mail addresses: acarbayo@ubu.es (A. Carbayo), jvcv@ubu.es
(J.V. Cuevas), gherbosa@ubu.es (G. Garc´ıa-Herbosa).
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 4 6 6 - 3

16
A. Carbayo et al. / Journal of Organometallic Chemistry 658 (2002) 15ꢀ20
/
nilino)-3-methylene-isoindolin-1-one 2, two isoindoli-
none derivatives which, to our knowledge, have not
been reported before [7,8]. These type of compounds is
of current pharmacological interest [9,10]. The intramo-
The unstable solution shows a strong n˜/CO band in the IR
spectrum at 2130 cmꢃ1 that is assigned to
[Pd{C6H4C(CH3)Ä
/
NÃ/NHC6H4-p-NO2}Cl(CO)]
B2.
From stirred solutions of B2 under CO, the compound
2-(4-nitroanilino)-3-methylene-isoindolin-1-one 2 can be
recovered in high yield along with the palladium metal.
The almost identical nCO value for the CO bands in both
monocarbonyls B1 and B2 indicates that the coordina-
tion sphere of the metal complex must be both electro-
nically and sterically equivalent in both complexes,
showing independence with the substituents on the
anilino group. Thus, the different reaction rates can be
lecular CÃ
acetophenonephenylhydrazone complex, [Pd{C6H4C-
(CH3)ÄNÃNHC6H5}(m-Cl)]2, in the presence of CO
/N bond formation of the ortho-palladated
/
/
and sodium methoxide, leading to 3-methyl-1-phenyl-
indazole 3 is also described. This can be a convenient
way to prepare 3, an apparently elusive molecule whose
substitued derivatives are also of pharmacological
interest [11ꢀ14]. These different results, depending on
/
the reaction conditions, supply some clue about the
mechanism of the reductive elimination in carbonylated
complexes of ortho-palladated acetophenonearylhydra-
zones while opening a convenient way to synthesizing
molecules of interest.
assigned to the acidity of the pendant NÃ
/
H bond
induced by the different substituents R in the para-
position of the phenyl group. As shown in Scheme 2
pathway 1, the higher acidity of B2 could supply higher
concentrations of C2, and then the formation of 2 at
room temperature takes less than 1 h whereas the
formation of 1 under the same conditions takes 3 days.
The proposal of the deprotonation of the NÃ
/
H bond
2. Results and discussion
as a necessary first step in the reductive elimination
reaction to give 1 or 2, is also supported by previous
results exhibited by the related ligand 2-acetylpyridine-
As shown in Scheme 1, bubbling carbon monoxide
through a suspension of the ortho-metallated dimer
phenylhydrazone which, possessing deprotonable NÃ
bond, undergoes ortho-palladation reaction while 2-
acetylpyridine-N-methyl-phenylhydrazone, with no NÃ
H bonds, does not reacts under the same conditions [16].
Under such grounds, addition of the stoichiometric
amount of NaOMe in MeOH to complete deprotona-
tion of B1 was carried out trying to accelerate the
reaction but this led to a very different result. The
/H
[Pd{C6H4C(CH3)Ä
/
NÃNHC6H5}(m-Cl)]2 A1 [4] affords
/
a yellow solution characterized by a strong n˜/CO band in
the IR spectrum at 2127 cmꢃ1 that is assigned to
/
[Pd{C6H4C(CH3)Ä
/
NÃ/NHC6H5}Cl(CO)] B1. Similar
but stable monocarbonyls have been reported for
ortho-palladated complexes of oximes [15]. However,
monocarbonyl B1 is only relatively stable in solution
and concentration to vacuum or evaporation under CO
atmosphere yields the starting dimer A1 in a reversible
indazole derivative 3-methyl-1-phenyl-indazole
3
(Scheme 2, pathway 2), the product of the intramole-
cular reductive elimination of ortho-palladated aceto-
phenonephenylhydrazone, was formed in high yield
while palladium metal was recovered from the reaction.
In order to check if B2 could lead to the nitro derivative
of 3, carbonylation of A2 in dichloromethane was
carried out in the presence of HCl gas. In these
conditions B2 appears to be stable while keeping the
HCl atmosphere, as monitored by infrared spectro-
scopy. Addition of NaOMe in MeOH to this solution
led to decomposition as the recovered product was
mainly acetophenone-p-nitrophenylhydrazone. The re-
action of A1 with base in absence of CO leading to the
carbonylationꢀdecarbonylation reaction. Solutions of
/
complex B1 in dichloromethane are unstable and they
decompose, after several hours at room temperature,
affording palladium metal and 2-anilino-3-methylene-
isoindolin-1-one 1, the product of the intramolecular
reductive elimination between the ortho-palladated
hydrazone and the carbon monoxide. Bubbling carbon
monoxide through a suspension of the related ortho-
metallated dimer [Pd{C6H4C(CH3)Ä
/
NÃ/NHC6H4-p-
NO2}(m-Cl)]2 [4] A2 in dichloromethane at room tem-
perature affords an unstable yellow solution that in a
few minutes turns black due to palladium metal formed.
binuclear
NHPh}{m-N(Ph)Ä
been recently reported [17].
The results here presented supply some information
about the mechanisms that control the CÃN bond
complex
[Bu4N][Pd{C6H4C(CH3)Ä
/
NÃ
/
/
NÃ
/
C(CH3)C6H4}(m-Cl)PdCl]
has
/
formation in reductive elimination reactions of ortho-
palladated acetophenonearylhydrazone complexes. Sup-
port of the proposed intermediates C comes from the X-
ray structurally characterized binuclear compounds
of formula [Pd{C6H4C(CH3)Ä
/
NÃ
/
NC6H4-p-R}{P-
Scheme 1.
(OMe)3}]2, where, RꢁH, NO2, that were prepared by
/

A. Carbayo et al. / Journal of Organometallic Chemistry 658 (2002) 15ꢀ
/20
17
Scheme 2. Lꢁany ligand available in the reaction.
/
treatment
of
[Pd{C6H4C(CH3)Ä
/
NÃ
/
NHC6H4-p-
between C and D are shifted to D in the absence of base
and to C in the presence of base.
Carbonylation reactions of ortho-palladated Schiff
base complexes are well known and a putative mechan-
ism was proposed in the past to explain the products of
the reactions [18].
In light of the results reported here we propose in
Scheme 3 an alternate mechanism for the carbonylation
of ortho-palladated Schiff base complexes by accepting
R}Cl{P(OMe)3}] (complexes analogous to B where
CO has been substituted for trimethylphosphite) with
sodium methoxide [4,5]. These complexes contain the
hydrazonate anion proposed for C.
As shown in Scheme 2, pathway 1, C1 or C2 lead to
the isoindolinones 1 or 2, which are the products of the
reductive elimination reactions of E1 and E2, respec-
tively. Intermediates E, not detected, contain a PdÃ
bond cis to a PdÃN(amido) bond as it is required for CÃ
N bond formation [6], are the result of carbon monoxide
insertion in the palladiumꢀphenyl bonds of D. Although
intermediates D also contain a PdÃC bond cis to a Pdꢀ
/C
/
/
/
/
/
N amido bond, the product of the reductive elimination
at this point was not observed as the four-member ring
expected must be highly strained. The steps C to D
involve a proton migration from CÃ
migration from the less to the more electronegative atom
is similar to that observed in the well-known ketoꢀ
enolic or enꢀaminoꢀimino tautomers. When deproto-
/
H to NÃ
/
H. Such
/
/
/
nation is forced with NaOMe, complex C1 follows a
different pathway 2, leading to the N-phenylindazole
derivative 3, which is the product of the intramolecular
reductive elimination of F, a six membered palladacycle
showing, as in the case of intermediates E, PdÃ
PdÃN(amido) bonds in cis arrangement. The step C1 to
F is an E to Z isomerization around the CÄN double
bond. In pathway 1, the CO insertion into the PdÃ
/
C and
/
/
/C
bond seems to be preferred over the E/Z isomerization
that must occur in the pathway 2. The CO insertion on
intermediate F should lead to a seven-membered palla-
dacycle whose product of reductive elimination has not
been observed. We suggest that the tautomeric equilibria
Scheme 3. Proposed mechanism for the carbonylation of ortho-
palladated imines. NuH: nucleophile, RE: reductive elimination.

18
A. Carbayo et al. / Journal of Organometallic Chemistry 658 (2002) 15ꢀ20
/
the importance of PdÃ
/
N (amido) bonds [6]. First, CO
Arꢁ
[22,23]. In this case the activated group is the Ar group.
Compound 3 appears reported with a yield of B5%
among a group of related derivatives, which were
obtained with 39ꢀ90% yields, in which RꢁMe and
the position of Ar is occupied by alkyl substituents [24].
The synthesis of 1-phenyl-1H-indazole (i.e. RꢁH,
ArꢁPh) has been recently reported via the palladium-
/
2,4,6-C6H2Cl3 and Rꢁ
/
Me has also been reported
coordinates to palladium in position cis to the PdÃ
/
C(aryl) bond following the ‘transphobia’ arguments
according to which soft ligands coordinate cis and
hard ligands trans to PdÃ
influence of the coordinated CO on the trans-nitrogen
atom induces the iminocomplex to change to the
amidocomplex which undergoes CO insertion into the
/
/C bonds [19,20]. Then, the
/
/
/
/
PdÃ
/
C bond. Three pathways are now possible to explain
catalyzed cyclization of [N-aryl-N?-(o-bromophenyl)hy-
drazinato-N?]-triphenylphosphonium bromide [25]. In
short, the synthetic procedures for arylindazoles seem to
be strongly dependent on the nature of substituents R
and Ar on the generic formula shown in Scheme 4. Here
we report a convenient high yield synthesis at room
temperature of compound 3. Although obtained in high
yield, compound 3 is unstable and must be kept cold and
under nitrogen to avoid fast decomposition. It likely
undergoes oxidation via radicals that polymerize giving
insoluble material.
the products of the carbonylations: (1) reductive elim-
ination to I, (2) nucleophilic attack and reductive
elimination affording II, and (3) g-proton elimination
followed by reductive elimination affording III.
In summary, formation of CÃ
/
N bonds seems to be
associated to the ability of the strong p-acceptor ligand
CO to modify the electronic properties of the nitrogen
donor atom of the ligand in trans-position. Such
nitrogen can participate in reductive elimination reac-
tions when it behaves as amidocomplex but no as
iminocomplex. In both pathways the final step is the
reductive elimination of a six-member palladacycle
3. Conclusions
containing a PdÃ
/
C bond cis to a PdÃ/N(amido) bond.
The synthesis of isoindolinones analogous to 1 and 2,
containing the anilino groups 2,4-dinitroanilino, 4-
nitroanilino or 2-nitroanilino was reported many years
ago [7,8]. The procedures are based in multistep synth-
esis and the use of high temperatures. To our knowl-
edge, compound 1, that contains an unsubstituted
anilino group, has not been described yet. Taking into
account the recent interest [9,10] in such kind of
molecules we consider that the procedure reported
here can be a more convenient way to synthesize
isoindolinone derivatives in some cases. Although the
synthesis of N-aryl-indazoles has been carried out from
different approaches, we have not found in the literature
any efficient synthetic procedure for compound 3.
Related derivatives with the formula shown in Scheme
4 have been published. Thus, high yields have been
reported for the synthesis of the compound in which
Ortho-palladated acetophenonephenylhydrazones re-
act with carbon monoxide and, depending on condi-
tions, undergo cyclization giving isoindolinone
derivatives or N-phenylindazole that contain new
carbonꢀ
tion about the reductive elimination mechanisms of
palladacycles containing palladiumꢀcarbon s bonds
arranged cis to palladiumꢀnitrogen amido bonds.
/nitrogen bonds. These results supply informa-
/
/
4. Experimental
4.1. General considerations
1H-NMR spectra were recorded on a Bruker AC 80
instrument and a Varian XL-400 instrument. 13C-NMR
was recorded on a Varian XL-400 instrument. 1H
chemical shifts were measured with TMS as internal
reference at 25 8C. 13C chemical shifts were measured
with reference to the residual solvent resonances. All
chemical shifts are reported in d units, parts per million
(ppm). Solid IR spectra were recorded as KBr disk (in
Arꢁ
Arꢁ
When Rꢁ
/
Ph and Rꢁ
Ph.
/
Ph [21], but not when Rꢁ
/
Me and
/
/
COOC2H5 and Arꢁ
/
Ph a 85% of yield has
been reported [21]. It seems to be clear that the synthesis
(or the stability) of N-aryl-indazoles is affected by the
nature of R, although in that paper the authors did not
mention it. The synthesis of the indazolium hexaclor-
oantimonate where, the substituted indazole is that with
the range 4000ꢀ
instrument. Solution IR spectra were recorded (in the
range 2200ꢀ Elmer 843 spec-
1700 cmꢃ1) on a Perkinꢀ
/
400 cmꢃ1) on a Nicolet Impact 410
/
/
trometer. Mass spectra were obtained with a Hewlett
Packard II mass spectrometer with a Hewlett Packard
5791 A Mass Selective Detector. Microanalyses were
performed by the SCAI (Servicios Centrales de Apoyo a
la Investigacion de la Universidad de Burgos) with
sulfanilamide and acetanilide as patrons.
Complexes [Pd{C6H4C(CH3)Ä
/
NÃNHC6H4p-R}(m-
/
Scheme 4.
Cl)]2 (RꢁH, A1; RꢁNO2, A2) where, prepared
/
/

A. Carbayo et al. / Journal of Organometallic Chemistry 658 (2002) 15ꢀ
/20
19
according to published procedures [4]. All reactions
were carried out using Schlenk techniques. Solvents
were distilled and dried over calcium dihydride (hexane
and methylene chloride) and degassed by standard
methods prior to use.
Cl)]2 (A2) (500 mg, 0.63 mmol) in dichloromethane (100
ml) at r.t. The mixture was filtered and the black solid
formed was removed. The orange solution was partially
pumped and hexane (25 ml) was added to induce
1
precipitation of 2. Yield: 220 mg, 62%. H-NMR (400
MHz, CDCl3): dꢁ
H)ꢁ1.99 Hz), 6.82ꢀ
1H, NH) ppm; 13C{1H}-NMR (400 MHz, CDCl3): dꢁ
/
5.28 (dd, 2H, AB system, 2J(HÃ
/
4.2. Identification in solution of [Pd{C6H4C(CH3)Ä
/
NÃ
/
/
/
8.20 (m, 8H, aromatics), 6.70 (s,
NHC6H5}Cl(CO)] (B1)
/
165.3 (CO), 146.3, 140.4, 134.1, 132.5, 129.6, 129.2,
128.2, 125.4, 123.5, 121.3, 120.3, 113.2, 113.1, 90.5
When carbon monoxide was bubbled through a
suspension of [Pd{C6H4C(CH3)ÄNÃNHC6H5}(m-Cl)]2
/
/
(CH2) ppm; IR: n˜/
ꢁ
/
3264 cmꢃ1(NH), n˜
/
ꢁ
/
1712 cmꢃ1
n˜
(A1) (500 mg, 0.71 mmol) in dichloromethane (100 ml)
at room temperature (r.t.), a yellow solution, that slowly
turned black, was formed. The solution showed a strong
(CÄO), n˜
/
/
ꢁ
/
1600cmꢃ1
(
/
n˜/as NO2), n˜/
ꢁ
/
1328cmꢃ1
(/
/sym
NO2); Anal. Calc. (%) for C15H11N3O3 (281.29): C,
64.04; H, 3.94; N, 14.94. Found: C, 63.91; H, 4.03; N,
15.09%.
n˜
band in the infrared at 2127 cmꢃ1 that was
CO
assigned to B1. Concentration to isolate the solid under
CO atmosphere afforded the starting dimer A1.
4.6. Synthesis of 3-methyl-1-phenyl-indazole (3)
4.3. Identification in solution of [Pd{C6H4C(CH3)Ä
/
NÃ
/
Carbon monoxide was bubbled during 1 h through a
NHC6H4pNO2}Cl(CO)]2 (B2)
suspension of 500 mg (0.71 mmol) of [Pd{C6H4C(CH3)Ä
/
NÃNHC6H5}(m-Cl)]2 (A1) in dichloromethane (100 ml)
/
When carbon monoxide was bubbled through a
suspension of [Pd{C6H4C(CH3)ÄNÃNHC6H4pNO2}-
at r.t. The mixture was filtered and 1.78 ml of a 0.8 M
solution of NaOMe in MeOH were added (equivalent to
1.4 mmol of NaOMe). The mixture was stirred for 1 h
and the black solid was removed by filtration. The
/
/
(m-Cl)]2 (A2) (500 mg, 0.63 mmol) in dichloromethane
(100 ml) at r.t., an unstable yellow solution, that slowly
turned black (Section 2), was formed. The solution
showed a strong n˜ CO band in the infrared at 2130 cmꢃ1
that was assigned to B2.
resulting orangeꢀbrown solution was pumped and
/
hexane (25 ml) was added to induce precipitation of 3
1
(250 mg, 1.2 mmol, 85%). H-NMR (80 MHz, CDCl3):
dꢁ
/
2.70 (s, 3H, CH3), 7.11ꢀ8.29 (m, 9H, aromatics)
/
4.4. Synthesis of 2-anilino-3-methylene-isoindolin-1-one
(1)
ppm; MS (70 eV, EI): m/z (%): 208 (100); Anal. Calc.
(%) for C14H12N2 (208.28): C, 80.72; H, 5.81; N, 13.45.
Found: C, 80.57; H, 5.83; N, 13.69%.
Carbon monoxide was bubbled during 72 h through a
suspension
of
complex
[Pd{C6H4C(CH3)Ä
/
NÃ
/
NHC6H5}(m-Cl)]2 (A1) (500 mg, 0.71 mmol) in dichlor-
omethane (100 ml) at r.t. The mixture was filtered and
the black solid formed was removed. The resulting
yellow solution was concentrated under vacuum and
the product 1 was precipitated by the addition of hexane
(25 ml). The product 1 was collected as a pale yellow
solid by filtration to yield 238 mg (1.01 mmol, 71%). 1H-
Acknowledgements
The authors gratefully acknowledge to the Spanish
Direccio´n General de Ensenanza Superior (PB97-0470-
˜
C02) and the Junta de Castilla y Leo´n (BU08/99) for
financial support. We also acknowledge to the Servicios
Centrales de Apoyo a la Investigacio´n (SCAI) de la
Universidad de Burgos for technical support.
NMR (400 MHz, CDCl3): dꢁ
2J(HÃ
H)ꢁ1.90 Hz), 6.54ꢀ7.86 (m, 9H, aromatics), 6.54
(s, 1H, NH) ppm; 13C{1H}-NMR (400 MHz, CDCl3):
dꢁ165.3 (CO), 151.7, 139.6, 134.0, 133.2, 133.0, 130.1,
128.6, 125.8, 125.7, 123.7, 120.7, 112.0, 111.8, 90.9
(CH2) ppm; IR: n˜
3278 cmꢃ1(NH), n˜ 1706 cmꢃ1
(CÄO); Anal. Calc. (%) for C15H12N2O (236.29): C,
/
5.22 (dd, 2H, AB system,
/
/
/
/
References
/
ꢁ
/
/
ꢁ
/
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isoindolin-1-one (2)
Carbon monoxide was bubbled during 1h through a
suspension of [Pd{C6H4C(CH3)Ä
/
NÃNHC6H4pNO2}(m-
/

20
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