Depalladation reactions of iminoacyl- and 2-acetylarylpalladium(II) complexes

Article abstract of DOI:10.1021/om030045j

Reaction with Tl(TfO) (TfO = triflate, CF₃SO₃), in some cases in the presence of CO or EtOH, causes the depalladation of complexes trans-[Pd{C(=NR)C₆H₄{C(O)Me}-2}Br(CNR)₂] [R = 2,6-dimethylphenyl (Xy) (1a), R = ^tBu (1a′)], trans-[Pd{C(=NXy)C₆H(OMe)₃-2,3,4- {C(O)Me}-6}Br(CNXy)₂] (1b), trans-[Pd{C(=NR)C₆H₄(CH=CH₂)-2} Br(CNR)₂] [R = Xy (2), ^tBu(2′)], trans-[Pd{C(=NXy)C(NHXy)=CC₆H₄{C(O)NXy}-2} Br(CNXy)₂] (3), trans-[Pd{C₆H₄{C(O)Me}-2} Br(PPh₃)₂] (4), and [Pd{C₆H₄ {C(O)Me}-2}Br(bpy)] (bpy = 2,2′- bipyridine)(5) to give organic compounds. Complexes 1a, 1a′, and 1b react with Tl(TfO) in Me₂CO or CH₂Cl₂ to give the isoindolinones 2-(2,6-dimethylphenyl)- 3-methylene-2,3-dihydroisoindol-1-one (6a), 2-tert-butyl-3-methylene- 2,3-dihydroisoindol-1-one (6a′), and 2-(2,6-dimethylphenyl)- 5,6,7-trimethoxy-3-methylene-2,3-dihydroisoindol-1-one (6b), respectively. When the reaction with 1a′ is carried out in the presence of a small amount of EtOH, in addition to 6a′, the isoindolinone 2-tert-butyl-3-ethoxy-3- methyl-2,3-dihydroisoindol-1-one (7) and 2-acetyl-N-tert-butylbenzamide (8) are obtained. Complex 2 reacts with Tl(TfO) in the presence of CO to give N-(2,6-dimethylphenyl)-2-vinylbenzamide (9); however, the analogous compound 2′ reacts with Tl(TfO) to give a mixture containing ortho-cyanostyrene (10). Complex 3 reacts with Tl(TfO) to give a separable mixture of N-(2,6-dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-dimethylphenyl)- 3-oxo-2,3-dihydroisoindol-1- ylidene]acetamide (11) and N-(2,6-dimethylphenyl)- 2-(2,6-dimethylphenylamino)-2-[2,6-dimethylphenyl)-3-oxo-2,3-dihydroisoindol-1- ylidene]acetamidic acid (12). When this reaction is carried out in the presence of a small amount of EtOH, 11, 12, and its ethyl ester 13 are obtained. Complex 4 or 5 reacts with CO and Tl(TfO) in Me₂CO to give 3-methylenephthalide (14) or a complex mixture, respectively. Complexes 4 and 5 react with Tl(TfO) in CH₂Cl₂ in the presence of a small amount of EtOH, affording 3-ethoxy-3-methyl-3H-isobenzofuran-1-one (15). The crystal and molecular structures of 6a, 6b, 8·0.11H₂O, 9, 11·0.5Et₂O, 13, and 14 have been determined by X-ray diffraction studies.

Full text of DOI:10.1021/om030045j

Organometallics 2003, 22, 1967-1978
1967
Dep a lla d a tion Rea ction s of Im in oa cyl- a n d
2-Acetyla r ylp a lla d iu m (II) Com p lexes
J ose´ Vicente,*,† J ose´-Antonio Abad,*,‡ and Elo´ısa Mart´ınez-Viviente
Grupo de Quı´mica Organometa´lica, Departamento de Quı´mica 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
Received J anuary 22, 2003
Reaction with Tl(TfO) (TfO ) triflate, CF3SO3), in some cases in the presence of CO or
EtOH, causes the depalladation of complexes trans-[Pd{C(dNR)C6H4{C(O)Me}-2}Br(CNR)2]
t
[R ) 2,6-dimethylphenyl (Xy) (1a ), R ) Bu (1a ′)], trans-[Pd{C(dNXy)C6H(OMe)3-2,3,4-
{C(O)Me}-6}Br(CNXy)2] (1b), trans-[Pd{C(dNR)C6H4(CHdCH2)-2}Br(CNR)2] [R ) Xy (2),
tBu (2′)], trans-[Pd{C(dNXy)C(NHXy)dCC6H4{C(O)NXy}-2}Br(CNXy)2] (3), trans-[Pd{C6H4-
{C(O)Me}-2}Br(PPh3)2] (4), and [Pd{C6H4{C(O)Me}-2}Br(bpy)] (bpy ) 2,2′-bipyridine) (5)
to give organic compounds. Complexes 1a , 1a ′, and 1b react with Tl(TfO) in Me2CO or CH2Cl2
to give the isoindolinones 2-(2,6-dimethylphenyl)-3-methylene-2,3-dihydroisoindol-1-one (6a ),
2-tert-butyl-3-methylene-2,3-dihydroisoindol-1-one (6a ′), and 2-(2,6-dimethylphenyl)-5,6,7-
trimethoxy-3-methylene-2,3-dihydroisoindol-1-one (6b), respectively. When the reaction with
1a ′ is carried out in the presence of a small amount of EtOH, in addition to 6a ′, the
isoindolinone 2-tert-butyl-3-ethoxy-3-methyl-2,3-dihydroisoindol-1-one (7) and 2-acetyl-N-
tert-butylbenzamide (8) are obtained. Complex 2 reacts with Tl(TfO) in the presence of CO
to give N-(2,6-dimethylphenyl)-2-vinylbenzamide (9); however, the analogous compound 2′
reacts with Tl(TfO) to give a mixture containing ortho-cyanostyrene (10). Complex 3 reacts
with Tl(TfO) to give a separable mixture of N-(2,6-dimethylphenyl)-2-(2,6-dimethylphenyl-
amino)-2-[2-(2,6-dimethylphenyl)-3-oxo-2,3-dihydroisoindol-1-ylidene]acetamide (11) and
N-(2,6-dimethylphenyl)-2-(2,6-dimethylphenylamino)-2-[2-(2,6-dimethylphenyl)-3-oxo-2,3-di-
hydroisoindol-1-ylidene]acetamidic acid (12). When this reaction is carried out in the presence
of a small amount of EtOH, 11, 12, and its ethyl ester 13 are obtained. Complex 4 or 5
reacts with CO and Tl(TfO) in Me2CO to give 3-methylenephthalide (14) or a complex
mixture, respectively. Complexes 4 and 5 react with Tl(TfO) in CH2Cl2 in the presence of a
small amount of EtOH, affording 3-ethoxy-3-methyl-3H-isobenzofuran-1-one (15). The crystal
and molecular structures of 6a , 6b, 8‚0.11H2O, 9, 11‚0.5Et2O, 13, and 14 have been
determined by X-ray diffraction studies.
t
In tr od u ction
(R ) Ph, Xy, Bu) salts.8,9 It has been reported that the
reactions of aryliminoacylpalladium complexes with
Grignard reagents, followed by hydrolysis, produce aryl
ketones.10 Very recently, palladium-catalyzed syntheses
of amidines from aryl halides, isocyanides, and organo-
tin compounds11 as well as mappicines, camptothecins,
and homocamptothecins have been described.12 Finally,
the polymerization of isonitriles catalyzed by organo-
palladium complexes has also been reported.13-15
The insertion of unsaturated molecules into carbon-
palladium bonds constitutes a key step in many pal-
ladium-mediated organic reactions.1,2 However, very few
such reactions involving isocyanides have been reported.
Thus, some organopalladium complexes react with
isocyanides, forming, after depalladation, indazolines,3
indazoles,4 ketenimines,5-7 or 2-R-aminoisoindolinium
† E-mail: jvs@um.es http://www.scc.um.es/gi/gqo/.
‡ E-mail: jaab@um.es.
(7) Vicente, J .; Abad, J . A.; Shaw, K. F.; Gil-Rubio, J .; Ram´ırez de
Arellano, M. C.; J ones, P. G. Organometallics 1997, 16, 4557.
(8) Vicente, J .; Saura-Llamas, I.; Gru¨nwald, C.; Alcaraz, C.; J ones,
P. G.; Bautista, D. Organometallics 2002, 21, 3587.
(9) O’Sullivan, R. D.; Parkins, A. W. J . Chem. Soc., Chem. Commun.
1984, 1165.
§ E-mail: p.jones@tu-bs.de.
(1) Heck, R. F. Palladium Reagents in Organic Synthesis; Academic
Press: New York, 1985.
(2) Tsuji, J . Palladium Reagents and Catalysts; J ohn Wiley: Chi-
chester, U.K., 1995.
(3) Yamamoto, Y.; Yamazaki, H. Synthesis 1976, 750.
(4) Gehrig, K.; Klaus, A. J .; Rys, P. Helv. Chim. Acta 1983, 66, 2603.
(5) Albinati, A.; Pregosin, P. S.; Ru¨edi, R. Helv. Chim. Acta 1985,
68, 2046.
(6) Tanase, T.; Fukushima, T.; Nomura, T.; Yamamoto, Y.; Koba-
yashi, K. Inorg. Chem. 1994, 33, 32.
(10) Yamamoto, Y.; Yamazaki, H. Inorg. Chim. Acta 1980, 41, 229.
(11) Saluste, C. G.; Whitby, R. J .; Furber, M. Angew. Chem., Int.
Ed. 2000, 39, 4156.
(12) Curran, D. P.; Du, W. Org. Lett. 2002, 4, 3215.
(13) Takei, F.; Yanai, K.; Onitsuka, K.; Takahashi, S. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 1554.
10.1021/om030045j CCC: $25.00 © 2003 American Chemical Society
Publication on Web 04/03/2003

1968 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
Sch em e 1
ent in position 3 (see 6, 11-13 in Schemes 2 and 4),
have attracted considerable interest because of their
reported pharmacological activity.19-26 Several natural
alkaloids such as neuvamine,19,20 lennoxamine,19,21 pic-
tonamine,27 or molecules having antitumor activity28
contain an isoindolinone moiety. However, there are few
methods reported for the synthesis of this type of
compound.29-33
Imidic acids [RC(dNR′)OH], usually existing in equi-
librium with their tautomers, the amides [RC(dO)NHR′],
are unstable compounds. Both circumstances make
imidic acids very difficult to isolate.34 We report here
the synthesis of a mixture of an amide and its tauto-
meric imidic acid form, their separation, and also the
synthesis of the ethyl ester of this acid.
Exp er im en ta l Section
The IR and NMR spectra, elemental analyses, conductivity
measurements in Me2CO, and melting point determinations
were performed as described previously.8 The long-range 13C-
1H correlations (HMBC) of 7, 14, and 15 were measured in a
200 MHz Bruker Avance spectrometer equipped with a QNP
probe. The syntheses of 1a , 2, 3,18 4, and 516 have been reported
previously. The compound [Pd{C6H(OMe)3-2,3,4-{C(O)Me}-6}-
Br(bpy)] was prepared by the reaction of the analogous
[Pd{C6H(OMe)3-2,3,4-{C(O)Me}-6}Cl(bpy)]35 with NaBr. The
We have recently reported the synthesis of ortho-
substituted arylpalladium complexes [Pd(C6H4X-2)BrL2]
(I, Scheme 1) [L2 ) trans-(PR3)2, R ) Ph, X ) CHdCH2,
CHO, C(O)Me, CN; R ) p-To ) 4-tolyl, X ) CHdCH2;
L2 ) bpy ) 2,2′-bipyridine, X ) CHO, C(O)Me, CN; L2
) tmeda ) N,N,N′,N′-tetramethylethylenediamine, X
) CHO, CN]16 and studied their reactivity toward
alkynes,17 to give indenols (II1) or indenones (II2), and
toward XyNC, to give aryliminopalladium complexes
(III) or some products resulting after a tri-insertion
process (IV1 and IV2).18 Some of the above complexes
were reacted with Tl(TfO) to substitute the bromo
ligand, whereby we expected either (i) coordination of
the ortho groups or the imine-N to give cyclometalated
or polynuclear complexes or (ii) decomposition of the
resulting cationic or triflato complex to give N-hetero-
cyclic compounds; we have already reported those
reactions that lead to new stable complexes.18 In this
paper we describe (i) the synthesis of new complexes of
type III (R ) Xy, tBu); (ii) the reactivity toward Tl(TfO),
sometimes in the presence of CO or EtOH, of these new
complexes, and some of those of types III and IV1
previously reported; and (iii) the reactivity of some
ortho-substituted arylpalladium complexes of type I
toward CO and Tl(TfO), to force the cleavage of the
Pd-C bond giving organic compounds. These reactions
constitute a stoichiometric synthesis of functionalized
arenes from their corresponding bromoarenes and an
incentive for future studies on the catalytic synthesis
of such functionalized arenes.
t
isonitriles XyNC (Xy ) 2,6-dimethylphenyl) and BuNC were
purchased from Fluka. The preparations of the compounds
were carried out at room temperature and without precautions
against light, moisture, and O2, unless otherwise stated. The
preparative thin layer chromatographic separations were
performed using silica gel 60 A.C.C. (70-200 µm). For colorless
substances fluorescent silica gel (GF254) was added (ap-
proximately 5%). Elemental analyses and mass fragment data
of all compounds and the synthesis and spectroscopic proper-
ties of 2′ and 10 have been included in the Supporting
Information.
Syn th esis of tr a n s-[P d {C(dNtBu )C6H4{C(O)Me}-2}Br -
t
(CNtBu )2] (1a ′). BuNC (0.196 cm3, 1.73 mmol) was added to
a solution of [Pd{C6H4{C(O)Me}-2}Br(bpy)] (bpy ) 2,2′-bi-
pyridine) (5) (200 mg, 0.43 mmol) in CH2Cl2 (15 cm3). The
resulting yellow solution was stirred for 30 min, the solvent
(19) Valencia, E.; Shamma, M.; Fajardo, V. Tetrahedron Lett. 1984,
25, 599.
(20) Alonso, R.; Castedo, L.; Dom´ınguez, D. Tetrahedron Lett. 1985,
26, 2925.
(21) Moody, C. J .; Warellow, G. J . Tetrahedron Lett. 1987, 28, 6089.
(22) Csende, F.; Szabo, Z.; Stajer, G. Heterocycles 1993, 36, 1809.
(23) Takahashi, I.; Hirano, E.; Kawakami, T.; Kitajima, H. Hetero-
cycles 1996, 43, 2343.
(24) Epsztajn, J .; Grzelak, R.; J ozwiak, A. Synthesis 1996, 1212.
(25) Allin, S. M.; Northfield, C. J .; Page, M. I.; Slawin, A. M. Z.
Tetrahedron Lett. 1998, 39, 4905, and references therein.
(26) Zhuang, Z.-P.; Kung, M.-P.; Mu, M.; Kung, H.-F. J . Med. Chem.
1998, 41, 157.
(27) Valencia, E.; Fajardo, V.; Firdous, S.; Freyer, A. J .; Shamma,
M. Tetrahedron Lett. 1985, 26, 993.
(28) Taylor, E. C.; J ennings, L. D.; Mao, Z.; Hu, B.; J un, J .-G.; Zhou,
P. J . Org. Chem. 1997, 62, 5392.
(29) Thompson, J . M.; Heck, R. C. J . Org. Chem. 1975, 40, 2667.
(30) Couture, A.; Deniau, E.; Grandclaudon, P. Tetrahedron 1992,
53, 10313.
Among the organic species we have synthesized, the
isoindolinones are especially important. These com-
pounds, particularly those with an alkylidene substitu-
(31) Comins, D. L.; J oseph, S. P.; Zhang, Y.-M. Tetrahedron Lett.
1996, 37, 793.
(32) Guha, S.; Mukherjee, A. K.; Khan, M. W.; Kundu, N. G. Acta
Crystallogr. Sect. C 1999, C55, 818, and references therein.
(33) Kundu, N. G.; Khan, M. W.; Mukhopadhyay, R. Tetrahedron
1999, 55, 12361.
(34) Kantlehner, W.; Mergen, W. W. In Comprehensive Organic
Functional Group Transformations; Katritzky, A. R., Meth-Cohn, O.
C., Rees, W., Eds.; Pergamon Press: Oxford, 1995; Vol. 5, p 685.
(35) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G.; Bembenek,
E. Organometallics 1993, 12, 4151.
(14) Ito, Y.; Miyake, T.; Hatano, S.; Shima, R.; Ohara, T.; Suginome,
M. J . Am. Chem. Soc. 1998, 120, 11880.
(15) Takei, F.; Yanai, K.; Onitsuka, K.; Takahashi, S. Chem. Eur.
J . 2000, 6, 983.
(16) Vicente, J .; Abad, J . A.; Mart´ınez-Viviente, E.; Ram´ırez de
Arellano, M. C. Organometallics 2000, 19, 752.
(17) Vicente, J .; Abad, J . A.; Lopez-Pelaez, B.; Martinez-Viviente,
E. Organometallics 2002, 21, 58.
(18) Vicente, J .; Abad, J . A.; Mart´ınez-Viviente, E.; J ones, P. G.
Organometallics 2002, 21, 4454.

Depalladation Reactions
Organometallics, Vol. 22, No. 9, 2003 1969
was evaporated, and addition of Et2O (20 cm3) produced the
precipitation of a yellow solid, which was filtered, washed with
Et2O (2 × 5 cm3), and air-dried, giving yellow 1a ′. Yield: 180
mg, 75%. Mp: 103 °C dec. IR (cm-1): ν(CtN) 2194, ν(CdO)
Syn th esis of 2-(2,6-Dim eth ylp h en yl)-5,6,7-tr im eth oxy-
3-m eth ylen e-2,3-d ih yd r oisoin d ol-1-on e (6b). Complex 1b
(300 mg, 0.38 mmol) and Tl(TfO) (134 mg, 0.38 mmol) were
mixed in CH2Cl2 (15 cm3) and stirred for 16 h. The resulting
black suspension was filtered over Celite, and the filtrate was
evaporated to dryness. The residue was extracted with Et2O
(25 cm3), and the extract was filtered through a layer of
anhydrous MgSO4. The solution was applied to a preparative
TLC plate. Eluant: Et2O. The colorless band at Rf ) 0.75 was
collected and extracted with Me2CO (30 cm3). The extract was
treated with anhydrous MgSO4 for 1 h and filtered. Evapora-
tion to dryness afforded a solid, which was recrystallized from
Et2O/n-hexane to give white 6b. Yield: 88 mg, 68%. Mp: 194
°C. IR (cm-1): ν(CdO) 1698, 1694. 1H NMR (300 MHz,
CDCl3): δ 7.25-7.12 (m, C6H3, 3H), 7.01 (s, C6H, 1H), 5.00 (d,
CH2, 1H, 2J HH ) 2 Hz), 4.26 (d, CH2, 1H, 2J HH ) 2 Hz), 4.15 (s,
MeO, 3H), 3.97 (s, MeO, 3H), 3.91 (s, MeO, 3H), 2.09 (s, 2×Me,
6H). 13C NMR (75 MHz, CDCl3): δ 164.2 (CdO), 157.7
(quaternary C), 151.4 (quaternary C), 143.3 (quaternary C),
141.3 (quaternary C), 137.4 (2xCMe), 133.6 (quaternary C),
132.4 (quaternary C), 128.7 (CH), 128.3 (2×CH-CMe), 114.1
(quaternary C), 98.6 (CH), 88.1 (CH2), 59.4 (MeO), 58.3 (MeO),
53.3 (MeO), 14.6 (2×Me). Single crystals were grown by slow
evaporation of solutions of 6b in Et2O.
1
1682, 1686, ν(CdN) 1606. H NMR (200 MHz, CDCl3): δ 8.24
3
3
(d, 1H, J HH ) 8 Hz), 7.42 (t, 1H, J HH ) 8 Hz), 7.31 (t, 1H,
3J HH ) 7 Hz), 7.13 (d, 1H, J HH ) 7 Hz), 2.44 (s, MeCO, 3H),
3
1.55 (s, tBu, 9H), 1.42 (s, 2× Bu, 18H). 13C{1H} NMR (50 MHz,
t
CDCl3): δ 204.5 (CdO), 164.6 (CdN), 141.8 (quaternary C),
140.6 (quaternary C), 133.1 (CH), 128.5 (CH), 127.9 (CH), 125.3
(CH), 58.0 (quaternary C), 57.5 (quaternary C), 32.3 (MeCO),
t
t
30.5 (3×Me, Bu), 29.7 (6×Me, 2× Bu).
Syn t h esis of tr a n s-[P d {C(dNXy)C6H (OMe)3-2,3,4-
{C(O)Me}-6}Br (CNXy)2] (1b). [Pd{C6H(OMe)3-2,3,4-{C(O)-
Me}-6}Br(bpy)] (200 mg, 0.39 mmol) and XyNC (153 mg, 1.17
mmol) were mixed in CH2Cl2 (15 cm3) under N2 to give a yellow
solution, which was immediately concentrated in vacuo to
dryness. Et2O (20 cm3) was added and then the solvent
partially evaporated, precipitating a solid, which was filtered
and air-dried to give yellow 1b. Yield: 237 mg, 77%. Mp: 118
°C dec. IR (cm-1): ν(CtN) 2186, 2214, ν(CdO) 1702, ν(CdN)
1618. 1H NMR (200 MHz, CDCl3): δ 7.26-7.15 (m, 2H), 7.05-
7.01 (m, 4H), 6.90-6.84 (m, 4H), 4.07 (s, 3H, MeO), 3.92 (s,
3H, MeO), 3.64 (b s, 3H, MeO), 2.64 (s, MeCO, 3H), 2,35 (s,
6H, 2×Me), 2.26 (s, 12H, 4×Me).
Syn t h esis of 2-ter t-Bu t yl-3-et h oxy-3-m et h yl-2,3-d i-
h yd r oisoin d ol-1-on e (7) a n d 2-Acetyl-N-(ter t-bu tyl)ben z-
a m id e (8). Tl(TfO) (701 mg, 1.98 mmol) and EtOH (1 drop)
were added to a solution of 1a ′ in CH2Cl2 (15 cm3). The
resulting black suspension was stirred for 16 h and filtered
over Celite. The filtrate was evaporated to dryness, and the
residue was extracted with Et2O (25 cm3), leaving an oily
mixture (327 mg) that could not be resolved. The yellow
ethereal solution was concentrated and applied to a prepara-
tive TLC plate (eluant: n-hexane/Et2O, 1:2). Three bands were
collected and extracted with Me2CO (30 cm3), the extracts were
treated with anhydrous MgSO4 for 1 h, then filtered, and the
filtrates were evaporated to dryness, affording the correspond-
ing compounds: 6a ′, Rf ) 0.89, yield: 67 mg, 17%. 7, Rf )
0.74, yield: 117 mg, 24%, white oily solid (this fraction must
be separated very carefully from the previous one in order to
obtain pure 7; a 1.5% discrepancy in %C of 7 is due to this
separation difficulty). 8, Rf ) 0.24, yield: 134 mg, 32%, white
solid which was washed with n-hexane and dried in vacuo.
Com p ou n d 7. Mp: 38-42 °C. IR (cm-1): ν(CdO) 1692 (b).
1H NMR (200 MHz, CDCl3): δ 7.72 (apparent dt, H2 C6H4 next
to CdO, 1H, 3J HH ) 7 Hz, 4J HH ) 1 Hz), 7.53 (apparent dt, H4
Syn th esis of 2-(2,6-d im eth ylp h en yl)-3-m eth ylen e-2,3-
d ih yd r oisoin d ol-1-on e (6a ). Complex 1a (300 mg, 0.43
mmol) and Tl(TfO) (152 mg, 0.43 mmol) were mixed in Me2CO
(15 cm3) and stirred for 16 h. The resulting black suspension
was filtered over Celite, and the filtrate was concentrated (ca.
3 cm3) and applied to a preparative TLC plate. Eluant:
n-hexane/Et2O, 1:1. The colorless band at Rf ) 0.7 was collected
and extracted with Me2CO (30 cm3). The resulting solution was
stirred with anhydrous MgSO4 for 1 h and filtered. The
solution was evaporated to dryness and the residue recrystal-
lized from Et2O, affording colorless crystals of 6a . Yield: 70
1
mg, 65%. Mp: 83 °C. IR (cm-1): ν(CdO) 1794. H NMR (300
3
MHz, CDCl3): δ 7.87 (apparent dt, C6H4, 1H, J HH ) 7 Hz,
3
4
4J HH ) 1 Hz), 7.70 (apparent dt, C6H4, 1H, J HH ) 7 Hz, J HH
3
4
) 1 Hz), 7.58 (td, C6H4, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 7.49
(td, C6H4, 1H, 3J HH ) 7 Hz, 4J HH ) 1 Hz), 7.21-7.09 (m, C6H3,
2
2
3 H), 5.07 (d, CH2, 1H, J HH ) 2 Hz), 4.32 (d, CH2, 1H, J HH
)
2 Hz), 2.04 (s, 2×Me, 6 H). 13C NMR (75 MHz, CDCl3): δ 166.2
(CdO), 141.5 (quaternary C), 137.3 (2×CMe), 136.3 (quater-
nary C), 132.1 (CH), 129.6 (CH), 129.5 (quaternary C), 129.0
(CH), 128.4 (2×CH-CMe), 123.6 (CH), 120.2 (CH), 89.7 (CH2),
17.7 (2×Me). Single crystals were grown by cooling solutions
of 6a in n-pentane.
3
4
C6H4, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 7.43 (td, H3 C6H4, 1H,
3J HH ) 7 Hz, 4J HH ) 1 Hz), 7.36 (td, H5 C6H4 next to the ethoxy
group, 2H, 3J HH ) 7 Hz, 4J HH ) 1 Hz), 3.02 (AB system coupled
Syn th esis of 2-ter t-Bu tyl-3-m eth ylen e-2,3-d ih yd r oiso-
in d ol-1-on e (6a ′). Complex 1a ′ (1.100 g, 1.98 mmol) was
reacted with Tl(TfO) (701 mg, 1.98 mmol) in Me2CO for 16 h.
The resulting black suspension was filtered over Celite, the
filtrate was evaporated to dryness, and the residue was
extracted with n-pentane (25 cm3). The extract was filtered
through a layer of anhydrous MgSO4, and the filtrate was
applied to a preparative TLC plate. Eluant: n-hexane/Et2O,
1:2. The colorless band at Rf ) 0.7 was collected and extracted
with Me2CO (30 cm3). The extract was treated with anhydrous
MgSO4 for 1 h and filtered. Evaporation to dryness afforded
6a ′ as a colorless liquid. This product is unstable and it
decomposes completely in 2 days. For this reason it was not
possible to obtain correct elemental analyses. Yield: 179 mg,
approximately 45%. IR (cm-1): ν(CdO) 1716. 1H NMR (300
2
3
with the Me group, ddq, CH2, 2H, J HH ) 9 Hz, J HH ) 7 Hz),
t
3
1.88 (s, Me, 3 H), 1.66 (s, Bu, 9 H), 1.11 (t, CH2Me, 3H, J HH
) 7 Hz). 13C NMR (50 MHz, CDCl3): δ 168.0 (CdO), 146.4
(C6 CCOEt), 132.1 (CCO), 131.8 (CH4), 129.1 (CH3), 122.8
(CH2), 120.9 (CH5), 95.1 (C(OEt)Me), 58.4 (CH2), 55.9 (CMe3),
28.7 (CMe3), 28.1 (Me), 14.9 (CH2Me).
Com p ou n d 8. Mp: 108-110 °C. IR (cm-1): ν(NH) 3306,
ν(CdO) 1682. 1H NMR (200 MHz, CDCl3): δ 7.57-7.53 (m,
1H), 7.46-7.43 (m, 3H) 5,74 (b s, NH, 1H), 2.56 (s, C(O)Me,
t
3H), 1.47 (s, Bu, 9H). 13C NMR (50 MHz, CDCl3): δ 201.8
(CdO), 168.4 (C(O)NH), 139.2 (quaternary C), 137.1 (quater-
nary C), 130.8 (CH), 129.7 (CH), 127.8 (CH), 127.4 (CH), 52.0
(CMe3), 29.4 (C(O)Me), 28.7 (CMe3). Single crystals of 8‚
0.11H2O were grown by slow evaporation of solutions of 8 in
Et2O.
Syn t h esis of 2-Vin yl-N-(2,6-d im et h ylp h en yl)b en z-
a m id e (9). CO was bubbled through a solution of 2 (100 mg,
0.15 mmol) in Me2CO (10 cm3) for 1 min, and then Tl(TfO) (53
mg, 0.15 mmol) was added. CO was bubbled again for 30 min,
the reaction flask was then closed, and the reaction was
continued for 16 h. The resulting suspension containing
metallic palladium was filtered over Celite, and the red filtrate
3
MHz, CDCl3): δ 7.72 (apparent dt, C6H4, 1H, J HH ) 7 Hz,
3
4
4J HH ) 1 Hz), 7.60 (apparent dt, C6H4, 1H, J HH ) 7 Hz, J HH
3
4
) 1 Hz), 7.51 (td, C6H4, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 7.43
3
4
(td, C6H4, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 5.27 and 5.22 (AB
system, CH2, 2H, 2J HH ) 2 Hz), 1.75 (s, tBu, 9H). 13C NMR (75
MHz, CDCl3): δ 168.5 (CdO), 142.1 (quaternary C), 137.4
(quaternary C), 131.5 (CH), 129.7 (CdCH2), 129.0 (CH), 122.6
(CH), 118.8 (CH), 92.5 (CH2), 57.7 (CMe3), 29.9 (CMe3).

1970 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
was concentrated and applied to a preparative TLC plate
(eluant: n-hexane/Et2O, 1:1). A colorless band at Rf ) 0.4 was
extracted with Me2CO (30 cm3). The extract was stirred with
anhydrous MgSO4 and filtered. Evaporation to dryness of the
resulting solution afforded a white solid, which was recrystal-
lized from n-hexane to give 9. Yield: 26 mg, 68%. Mp: 124
Syn th esis of th e Eth yl Ester of th e N-(2,6-Dim eth yl-
p h en yl)-2-(2,6-d im eth ylp h en yla m in o)-2-[2-(2,6-d im eth yl-
p h en yl)-3-oxo-2,3-d ih yd r oisoin d ol-1-ylid en e]a ceta m id ic
Acid (13). Tl(TfO) (374 mg, 1.06 mmol) and EtOH (one drop)
were added to a solution of 3 (1.000 g, 1.06 mmol) in CH2Cl2
(20 cm3). The resulting black suspension was stirred for 20 h
and filtered over Celite, and the yellow filtrate was con-
centrated and applied to a preparative TLC plate (eluant:
n-hexane/Et2O, 1:2), where two main yellow bands separated.
From the band at Rf ) 0.26 a 2:1 mixture of 11 and 12 was
obtained. Yield: 317 mg, 51%. The band at Rf ) 0.61 was
collected and extracted with Me2CO (30 cm3). The extract was
treated with anhydrous MgSO4 for 1 h, filtered, and evaporated
to dryness, affording the yellow ester 13. Yield: 98 mg, 18%.
Mp: 206-208 °C. IR (cm-1): ν(NH) 3384, ν(CdO), ν(CdN)
1
°C. IR (cm-1): ν(NH) 3280, ν(CdO) 1650. H NMR (300 MHz,
3
CDCl3): δ 7.64 (d, C6H4, 2H, J HH ) 7 Hz), 7.47 (t, C6H4, 1H,
3
3J HH ) 7 Hz), 7.36 (t, C6H4, 1H, J HH ) 7 Hz), 7.24 (dd,
3
3
CHdCH2, 1H, J HH ) 17 Hz, J HH ) 11 Hz), 7.14-7.12 (m,
3H, C6H3), 7.06 (bs, NH, 1H), 5.77 (dd, 1H, CHdCH2 H trans
3
2
to H, J HH ) 17 Hz, J HH ) 1 Hz), 5.39 (dd, 1H, CHdCH2
H
cis to H, J HH ) 11 Hz, J HH ) 1 Hz), 2.33 (s, 2×Me, 6H). 13C
NMR (75 MHz, CDCl3): δ 167.6 (CdO), 136.4 (quaternary C),
135.5 (2×CMe), 135.3 (quaternary C), 134.6 (CH), 133.7
(quaternary C), 130.5 (CH), 128.4 (2×CHCMe), 127.8 (CH),
127.6 (CH), 127.4 (CH), 126.5 (CH), 117.1 (CH2), 18.7 (2×Me).
Single crystals were grown by slow evaporation of solutions
of 9 in Et2O.
3
2
1
1698, 1694, 1660. H NMR (300 MHz, CDCl3): δ 7.99 (d, 1H,
3
3J HH ) 8 Hz), 7.59-7.58 (m, 2H), 7.43 (q, 1H, J HH ) 4 Hz),
7.10-7.05 (m, 3H), 6.80-6.69 (m, 6H), 4.79 (s, NH, 1H), 4.39
(q, CH2, 2H, 2J HH ) 7 Hz), 2.22 (s, 2×Me, 6H), 1.48 (bs, 4×Me,
2
1
12H), 1.39 (t, CH2Me, 3H, J HH ) 7 Hz). H NMR (300 MHz,
Syn th esis of N-(2,6-Dim eth ylp h en yl)-2-(2,6-d im eth yl-
p h en yla m in o)-2-[2-(2,6-d im eth ylp h en yl)-3-oxo-2,3-d ih y-
d r oisoin d ol-1-ylid en e]a ceta m id e (11) a n d N-(2,6-Dim eth -
ylph en yl)-2-(2,6-dim eth ylph en ylam in o)-2-[2-(2,6-dim eth yl-
p h en yl)-3-oxo-2,3-d ih yd r oisoin d ol-1-ylid en e]a ceta m id ic
Acid (12). Tl(TfO) (314 mg, 0.89 mmol) was added to a
suspension of 3 (844 mg, 0.89 mmol) in Me2CO (20 cm3). The
resulting red suspension was stirred for 20 h. During this time
decomposition to metallic palladium was observed and a dark
brownish suspension formed. This was filtered over Celite, and
the filtrate was concentrated and applied to a preparative TLC
plate (eluant: n-hexane/Et2O, 1:2). A yellow band at Rf ) 0.21
was collected and extracted with Me2CO (30 cm3). The result-
ing solution was dried with anhydrous MgSO4 for 1 h and
filtered, and the filtrate was evaporated to dryness, giving a
2:3 mixture of both tautomers 11 and 12 Yield: 326 mg, 71%.
A sample of this mixture (200 mg) was dissolved in Et2O (30
cm3), the solution was evaporated to dryness, and the residue
was treated with Et2O (30 cm3), causing the precipitation of a
solid, which was filtered and air-dried to give yellow 12 (83
mg, 41%). The same process was repeated with the mother
liquor, giving 11 (54 mg, 27%).
3
3
CDCl3, -60 °C): δ 8.04 (d, 1H, J HH ) 7 Hz), 7.66 (t, 1H, J HH
) 7 Hz), 7.55-7.45 (m, 2H), 7.14-7.10 (m, 3H), 6.87-6.81 (m,
4H), 6.72-6.64 (m, 2H), 4.81 (s, NH, 1H), 4.40 (m, CH2), 2.35
(s, Me, 3H), 2.30 (s, Me, 3H), 2.16 (s, Me, 3H), 2.01 (s, Me,
3H), 1.43 (t, CH2Me, 3H, J HH ) 7 Hz), 0.89 (s, Me, 3H), 0.63
(s, Me, 3H). Single crystals were grown by slow evaporation
2
of solutions of 13 in Et2O.
Syn th esis of 3-Meth ylen eph th alide (14). CO was bubbled
for 1 min through a solution of 4 (850 mg, 1.02 mmol) in
Me2CO (20 cm3). Tl(TfO) (360 mg, 1.02 mmol) was added and
CO bubbled again for 30 min. The flask was closed, and the
mixture was stirred for 16 h. The resulting dark red suspen-
sion was filtered over Celite, the filtrate was evaporated to
dryness, and the residue was extracted with Et2O (20 cm3).
The extract was concentrated and applied to a preparative TLC
plate (eluant: n-hexane/Et2O, 1:1). A colorless band (Rf ) 0.62)
was collected and extracted with Me2CO (30 cm3), and the
extract was treated with anhydrous MgSO4 for 1 h. The
suspension was filtered and the filtrate was evaporated to
dryness, affording 14 as a white oil. Yield: 48 mg, 32%. 1H
NMR (200 MHz, CDCl3): δ 7.91 (dt, H2 C6H4 next to CdO,
1H, 3J HH ) 8 Hz, 4J HH ) 1 Hz), 7.74-7.71 (m, H4 and H5 C6H4
next to CdCH2, 2H), 7.64-7.54 (m, H3 C6H4, 1H), 5.23 (AB
Com p ou n d 11. Mp: 136-138 °C. IR (cm-1): ν(NH) 3388,
3366, 3262 b, ν(CdO) 1698, 1660. 1H NMR (300 MHz,
2
system, CH2, 2H, J HH ) 3 Hz). 13C NMR (75 MHz, CDCl3): δ
3
3
CDCl3): δ 7.97 (d, 1H, J HH ) 7 Hz), 7.73 (d, 1H, J HH ) 7
3
4
166.8 (CdO), 151.9 (CdCH2), 139.0 (C6 CCdCH2 ), 134.4
(CH4), 130.4 (CH3), 125.3 (CH2), 125.2 (C1 CCO), 120.6 (CH5),
91.2 (CH2). These data are coincident with those described
previously.37 Single crystals were grown by slow evaporation
of solutions of 14 in CDCl3/Et2O.
Hz), 7.43 (td, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 7.37 (td, 1H,
3J HH ) 7 Hz, 4J HH ) 1 Hz), 7.3-7.2 (m, 3H), 7.1-6.95 (m, 6H),
6.86 (s, NH, 1H), 5.07 (s, NH, 1H), 2.36 (s, 2×Me, 6H), 2.20 (s,
2×Me, 6H), 1.66 (s, 2×Me, 6H). 13C NMR (75 MHz, CDCl3): δ
165.8 (CdO), 161.6 (CdO), 137.8 (quaternary C), 137.0 (qua-
ternary C), 135.9 (quaternary C), 135.7 (quaternary C), 135.6
(quaternary C), 134.9 (quaternary C), 132.7 (quaternary C),
132.1 (CH), 129.9 (CH), 129.14 (CH), 129.11 (CH), 128.6 (CH),
127.54 (CH), 127.48 (quaternary C), 127.3 (quaternary C),
127.0 (CH), 126.8 (CH), 124.0 (CH), 122.0 (CH), 112.9 (qua-
ternary C), 18.8 (2×Me), 18.3 (2×Me), 18.1 (2×Me). Single
crystals of 11‚0.5Et2O were grown by slow evaporation of
solutions of 11 in n-hexane/Et2O, 1:1.
Syn th esis of 3-Eth oxy-3-m eth yl-3H-isoben zofu r a n -1-
on e (15). This was prepared from 4 or 5 (1.2 g, 2.60 mmol),
Tl(TfO) (919 mg, 2.60 mmol), and CO following the procedure
used to prepare 14 but adding a drop of EtOH to the solvent
(CH2Cl2, 20 cm3) (Rf ) 0.59 in the preparative TLC). Yield
(preparation from 5): 370 mg, 74% (yellowish liquid). IR
1
(cm-1): n(CdO) 1672. H NMR (200 MHz, CDCl3): δ 7.88 (d,
H2 C6H4 next to CdO, 1H, 3J HH ) 7 Hz), 7.75 (t, H4 C6H4, 1H,
Com p ou n d 12. Mp: 206-208 °C. IR (cm-1): ν(OH), ν(NH)
3
3J HH ) 7 Hz), 7.60 (t, H3 C6H4, 1H, J HH ) 7 Hz), 7.53 (d, H5
3420, 3232 b,ν(CdO), ν(CdN) 1682, 1668. 1H NMR (300 MHz,
3
C6H4 next to the ethoxy group, 1H, J HH ) 7 Hz), 3.18 (ddq,
3
3
2
3
CDCl3): δ 8.15 (d, 1H, J HH ) 7 Hz), 8.04 (d, 1H, J HH ) 7
AB part of an ABM3 system, CH2, 2H, J HH ) 9 Hz, J HH ) 7
3
4
Hz), 1.85 (s, Me, 3H), 1.15 (t, CH2Me, 3H, J HH ) 7 Hz). 13C
3
Hz), 7.63 (td, 1H, J HH ) 7 Hz, J HH ) 1 Hz), 7.56 (b t, 1H,
3J HH ) 7 Hz), 7.05-7.02 (m, 4H), 6.95-6.79 (m, 5H), 5.58 (s,
NH, 1H), 2.39 (s, 2×Me, 6H), 2.24 (s, 2×Me, 6H), 1.54 (s, OH,
1H), 1.48 (s, 2×Me, 6H). 13C NMR (75 MHz, CDCl3): δ 166.5
(CdO), 160.9 (quaternary C), 138.5 (quaternary C), 137.1
(quaternary C), 136.5 (quaternary C), 135.4 (quaternary C),
135.1 (quaternary C), 133.0 (quaternary C), 132.7 (CH), 130.7
(quaternary C), 130.4 (quaternary C), 130.3 (CH), 129.2 (CH),
128.7 (quaternary C), 128.5 (CH), 128.2 (CH), 128.0 (CH), 126.8
(CH), 124.7 (CH), 124.1 (CH), 123.1 (CH), 122.2 (quaternary
C), 18.9 (2×Me), 18.6 (2×Me), 17.7 (2×Me).
NMR (50 MHz, CDCl3): δ 168.0 (CdO), 147.9 (C6 CCOEt),
134.4 (CH4), 130.3 (CH3), 127.1 (C1 CCO), 125.3 (CH2), 122.0
(CH5), 108.5 (COEt), 59.4 (CH2), 25.5 (Me), 14.9 (CH2Me).
X-r a y Str u ctu r e Deter m in a tion s. Data were registered
using Mo KR radiation on a Siemens P4 (6a ,9) or Bruker
(36) Ishizone, T.; Sugiyama, K.; Hirao, A.; Nakahama, S. Macro-
molecules 1993, 26, 3009.
(37) Kundu, N. G.; Pal, M.; Nandi, B. J . Chem. Soc., Perkin Trans.
1 1998, 561.

Depalladation Reactions
Organometallics, Vol. 22, No. 9, 2003 1971
Ta ble 1. Su m m a r y of X-r a y Da ta for Com p ou n d 6a , 6b, 8‚0.11H2O, a n d 9
6a
6b
8‚0.11H2O
9
formula
Mr
cryst syst
space group
a (Å)
C
17H15NO
C20H21NO4
339.38
orthorhombic
Pbcn
11.9844(11)
14.5392(14)
19.9966(18)
90
C
13H17.22NO2.11
C
17H17NO
249.30
monoclinic
P21/c
8.5260(8)
10.4956(10)
15.3645(16)
90
94.882(9)
90
1369.9(2)
4
221.26
tetragonal
I41/a
17.8744(14)
17.8744(14)
15.6983(18)
90
251.32
monoclinic
P21/c
12.2829(12)
11.5491(12)
10.1581(11)
90
110.02(2)
90
1353.9(2)
4
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
90
90
90
90
3484.3(6)
8
5015.5(8)
16
T (K)
D
173(2)
1.209
133(2)
1.294
133(2)
1.172
173(2)
1.233
calc (Mg m-3
)
F(000)
528
0.075
2400
2400/0/174
0.944
1440
0.090
4219
4219/0/231
1.025
1906
0.079
2571
2571/0/156
1.007
536
0.076
2377
2377/0/178
0.938
µ (mm-1
)
no. of indep reflns
no. of data/restraints/params
S(F2)
wR2 [all reflns]
R1[I>2σ(I)]
0.0925
0.0352
-0.183
0.0917
0.0359
-0.209
0.0982
0.0369
-0.182
0.0867
0.0352
-0.192
max. ∆F (e Å-3
)
Ta ble 2. Su m m a r y of X-r a y Da ta for Com p ou n d s
Resu lts
11‚0.5Et2O, 13, a n d 14
The aim of this work was to study the conditions
required to demetalate some of the previously reported
aryl and iminoacyl complexes of types I, III, and IV1
(Scheme 1)18 to give organic compounds. Previous at-
tempts starting from complexes of the types I and IV2
were unsuccessful.18 To extend this study, we have
prepared some new complexes of type III (see below).
We have attempted to force the cleavage of the Pd-C
bond by replacing the bromo ligand for TfO. We have
also carried out these reactions in the presence of CO.
Only those leading to positive results are reported here.
No precautions were taken against light, moisture, and
oxygen in these depalladation reactions. The influence
of the presence of EtOH in some reactions was also
studied.
11
13
14
formula
Mr
cryst syst
space group
a (Å)
C
36H38N3O2.5
C
36H37N3O2
C9H6O2
146.14
monoclinic
Cc
7.7327(8)
13.3949(14)
13.5108(14)
90
96.419(3)
90
1390.7(3)
8
552.69
monoclinic
P21/c
10.9302(11)
25.491(2)
21.9214(18)
90
94.002(3)
90
6092.8(10)
8
543.69
monoclinic
P21/n
12.1747(14)
15.6855(18)
15.9240(18)
90
90.116(3)
90
3040.9(6)
4
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
T (K)
133(2)
1.205
133(2)
1.188
133(2)
1.396
D
calc (Mg m-3
)
F(000)
2360
0.076
1160
0.074
6206
608
µ (mm-1
)
0.099
2029
no. of indep reflns 11 357
Syn th esis of New Im in oa cyl P a lla d iu m Com -
p lexes. We have prepared the new compounds trans-
[Pd{C(dNtBu)C6H4[C(O)Me]-2}Br(CNtBu)2] (1a ′), trans-
[Pd{C(dNXy)C6H(OMe)-2,3,4-[C(O)Me]-6}Br(CNXy)2]
(1b ), and trans-[Pd{C(dNtBu)C6H4(CHdCH2)-2}-
Br(CNtBu)2] (2′) in order to expand the reactivity studies
on the analogous 1a and 2. They were synthesized
following the same procedures used for 1a and 2,18 viz.,
reactions of the corresponding isocyanide with [Pd(R)-
BrL2] [L2 ) bpy, R ) C6H4{C(O)Me}-2 (for 1a ′), C6H-
(OMe)3-2,3,4-{C(O)Me}-6 (for 1b); L ) PPh3, R )
C6H4(CHdCH2)-2 (for 2′)] (Scheme 2). However, while
1a ′ was easily isolated and characterized, the reaction
to give 1b had to be carried out under N2 and rapidly,
as otherwise the Pd(I) dimer [Pd2Br2(CNXy)4] is ob-
tained.8,18,38,39 We had previously observed this reduc-
tion in the reaction of [Pd(R)(µ-Br)]2 or [Pd(R)Br(L)] with
R′NC (Pd:R′NC ) 1:3 or 1:2, respectively; R ) C,N-
C6H4CH2NH2-2-X-5, X ) H, MeO, NO2, F; L ) R′NC,
no. of data/
restraints/
params
11357/996/797 6206/110/381 2029/2/199
S(F2)
0.979
1.003
1.077
wR2 [all reflns]
R1[I>2σ(I)]
0.1367
0.0517
-0.328
0.1260
0.0486
-0.371
0.0818
0.0310
-0.179
max. ∆F (e Å-3
)
SMART 1000 CCD diffractometer. Structures were solved by
direct methods and refined anisotropically on F2 (program
SHELXL-97, G. M. Sheldrick, University of Go¨ttingen, Ger-
many). Treatment of hydrogen atoms: NH freely refined,
methyls as rigid groups, other H riding. Crystal data are
presented in Tables 1 and 2. Special features of refinement:
For compound 8, a significant difference peak was refined as
a partially occupied water site, for which the H atoms were
not located. Compound 11 crystallizes with two independent
molecules and an ether molecule in the asymmetric unit; the
latter is disordered over two sites with occupation 0.683,
0.317(6). A small difference peak (0.6 e/Å3) in 13 lies near C9
and may be an alternative position for C10. For compounds
11 and 13, which diffracted weakly, systems of restraints (to
dimensions of the two independent molecules for 11, to
displacement parameters for both structures) were employed
to improve refinement stability. Compound 14 crystallizes with
two independent molecules; Friedel opposite reflections were
merged because the anomalous dispersion was not signi-
ficant. Tables 1 and 2 give details of data collection and
refinement.
t
R′ ) Xy, Bu)8 or that between [Pd(dba)2], 2-BrC6H4-
CHO, and an excess of XyNC.18 It is curious that the
synthesis of 1a did not cause this problem.18 This
difference may be regarded as a consequence of the
(38) Vilar, R.; Mingos, D. M. P.; Cardin, C. J . J . Chem. Soc., Dalton
Trans. 1996, 4313.
(39) Dura`-Vila`, V.; Mingos, D. M. P.; Vilar, R.; White, A. J . P.;
Williams, D. J . J . Organomet. Chem. 2000, 600, 198.

1972 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
Sch em e 2
Sch em e 3
(tert-butyl)benzamide (8), as well as 6a ′. Indeed, when
the reaction of 1a ′ with Tl(TfO) was carried out in 1:15
EtOH/CH2Cl2 or in EtOH as solvent, more complex
mixtures formed; the only component we could identify
was compound 8. Interestingly, the reactivity of 1a and
1b with TlOTf in CH2Cl2 was not affected in this way
by the presence of EtOH. As mentioned in the Introduc-
tion, isoindolinones, particularly those with an alkyl-
idene substituent in position 3, have attracted consider-
able interest because of their reported pharmacological
activity.19-28 However, there are few methods for the
synthesis of 3-alkylidene-isoindolin-1-ones and iso-
nitriles are not employed in any of them.29-33
The reactions of 2 or 2′ with Tl(TfO) in Me2CO
afforded complicated mixtures of compounds. However,
when the reaction with 2 was carried out in the presence
of CO (see below), a depalladation to 2-vinyl-N-(2,6-
dimethylphenyl)benzamide (9) (Scheme 3) took place.
This difference in reactivity due to the presence of CO
was not observed with 2′, which, with or without CO,
afforded a complex mixture from which only ortho-
cyanostyrene (10) (39%) could be isolated and charac-
terized. The spectroscopic data of this unexpected
product are coincident with those previously described
in the literature (see Supporting Information).36 The
major product in this reaction was a solid which could
not be identified (see Supporting Information). This
different and unexpected behavior of 2′ with respect to
2 could be due to the above-mentioned impurities
present in 2′.
Complex 3 reacts with Tl(TfO) in Me2CO to give, after
20 h at room temperature, a precipitate of TlBr plus
metallic palladium and a solution from which the highly
functionalized 3-alkylidene-2,3-dihydroisoindolines 11
and 12 could be isolated (71% total yield, Scheme 4).
These tautomers could not be separated by chromatog-
raphy, but they displayed an exploitable difference in
solubility. Thus, when a solution of both products in
Et2O was evaporated to dryness and Et2O added again,
the major tautomer did not redissolve and could be
isolated by filtration, while the other could be similarly
separated from the mother liquors. In the solid state,
11 and 12 are stable and they do not interconvert.
However, if 12 is dissolved in CH2Cl2 and refluxed for
16 h, it transforms completely into 11. The latter is
stable at room temperature in CDCl3 for several days,
while under the same conditions 12 transforms partially
into 11. The addition of an acid does not accelerate the
interconversion of these products. Several reviews deal-
ing with imidoyl compounds have discussed the question
additional reactivity introduced by the three MeO
groups. The preparation of 2′ must also be carried out
under N2 and rapidly (as with 2).18 However, we have
not been able to isolate it as a pure substance, as it
forms as the major product together with tenacious
minor impurities, of similar solubility in Et2O and
hexane, which significantly affect the carbon analysis
(see Supporting Information).
Rea ction s w ith Tl(TfO). The reaction of 1a , 1a ′, or
1b with Tl(TfO) in CH2Cl2 or Me2CO results, after 16 h
stirring at room temperature, in the precipitation of
TlBr plus metallic palladium and the formation of the
isoindolinone 6a , 6a ′ or 6b, which can be isolated from
the resulting solutions in 65, 45 or 68% yield, respec-
tively (Scheme 2). 6a and 6b are stable white solids
which have been fully characterized, including X-ray
diffraction studies. In contrast, 6a ′ is a liquid that
decomposes completely within 2 days, although it could
be characterized by NMR and mass spectroscopy. Our
attempts to prepare 6a using 1a or [Pd(dba)2] as catalyst
failed (10% of 1a , Tl2CO3, Me2CO at room temperature
or DMF at 90 °C; 10% of [Pd(dba)2], Tl(TfO), DMF, 90
°C).
When Tl(TfO) and a drop of EtOH were added to a
solution of 1a ′ in CH2Cl2, a mixture of products was
obtained, after 16 h stirring at room temperature. The
fraction insoluble in Et2O, an oily mixture, could not
be separated, but its spectroscopic data (IR, NMR, and
EI-MS) suggested it to be a mixture of two compounds,
one of them being probably the triflate salt of the ethyl
ester of the 2-acetyl-N-tert-butyl benzimidic acid (X in
Scheme 2). The fraction soluble in Et2O contained a
mixture of products that could be separated by prepara-
tive TLC. They were identified as 2-tert-butyl-3-ethoxy-
3-methyl-2,3-dihydroisoindol-1-one (7) and 2-acetyl-N-

Depalladation Reactions
Sch em e 4
Organometallics, Vol. 22, No. 9, 2003 1973
Sch em e 6
Sch em e 5
formed without CO, nor if, instead of bubbling CO, N2
or H2 was bubbled or a few drops of distilled water were
added. As mentioned above, the reactivity of complex
2′ with TlOTf was not similarly affected by the presence
of CO. The reaction of 1a , 1a ′, or 1b with Tl(TfO) is not
affected by the presence of CO either, forming again the
isoindolinones 6a , 6a ′, or 6b, respectively.
By bubbling CO through a suspension of complex 4
and Tl(TfO) in Me2CO or CH2Cl2, 3-methylenephthalide
14 (32% yield) was obtained (Scheme 5). The same
reaction with complex 5 afforded an intractable mixture.
Both 4 and 5 reacted with Tl(TfO) and CO in CH2Cl2
with a drop of EtOH, giving 3-ethoxy-3-methyl-3H-
isobenzofuran-1-one (15) (74%).
of whether imidic acids can exist in general.34 They are
unstable compounds that may be in equilibrium with
the stable amide molecule. This is confirmed by theo-
retical investigations, which demonstrate that the amide
form is about 11 kcal/mol more stable than the tauto-
meric imidic acid.40
When the reaction of 3 with Tl(TfO) was carried out
in CH2Cl2 plus a drop of EtOH, 13, the ethyl ester of
12, was obtained in addition to 11 and 12. The yield of
13 varies from 15 to 40%, depending on the added
amount of EtOH.
Rea ction s w ith CO a n d Tl(TfO). The reactions of
complexes of types I and III (Scheme 1) with CO did
not lead to complexes resulting from the insertion of CO
into the C-Pd bond. Usually, the starting material was
recovered or, if TlOTf was added, intractable mixtures
formed. The only exceptions were the results described
in this section.
By bubbling CO through a solution of 2 in Me2CO for
1 min, then adding Tl(TfO), bubbling CO again for 30
min, and stirring the reaction mixture for 16 h at room
temperature, 2-vinyl-N-(2,6-dimethylphenyl)benzamide
(9) was obtained in 68% yield (Scheme 3). 9 was not
Discu ssion
The starting materials for the synthesis of complexes
under study were 2-X-bromoarenes, X being CHdCH2,
CHO, or C(O)Me. The oxidative addition reactions of
these arenes with [Pd(dba)2] ()[Pd2(dba)3]‚dba; dba )
dibenzylideneacetone)16 and the insertion reactions of
isocyanides18 afforded new organic groups attached to
palladium resulting after formation of one or three new
C-C bonds (Scheme 1). In addition, in the case of
compounds of type IV1, the X group (X ) CHO)
participated in a C-H bond cleavage and a C-N bond
formation. Although we did not isolate products of
insertion of CO into the C-Pd bond, the results of
(40) Sygula, A. J . Chem. Res. (S) 1989, 56.

1974 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
Sch em e 7
Sch em e 8
that reactions of this type constitute an important step
in palladium-catalyzed carbonylations,1,2,41 as well as
in the termination step of the palladium-catalyzed
copolymerization of CO and olefins.42-44
When the Ar group was ortho-acetylaryl, the inter-
mediate B evolved to give an X-heterocycle D or E
depending on the nucleophile (Scheme 7 or 8). When
this was H2O (R′′ ) H, Scheme 7), we propose a
nucleophilic attack of X on the C-OH carbon of the enol
tautomer B′ to form an X-C bond. The position of the
three methoxy groups in 6b is in agreement with this
proposal. An alternative route assuming that the nu-
cleophile was the O atom would require a rearrange-
ment from the O-heterocycle to the N-heterocycle to
explain the formation of isoindolinones 6, and this would
require very severe conditions.45 Similarly, when R′′OH
was EtOH, the nucleophilic attack of X at the carbonyl
carbon of the intermediate B and migration of the Et
group to the oxygen atom of the acetyl group would give
7 (X ) NtBu, Scheme 8) or 15 (X ) O). However,
formation of 7 (from 1a ′, Schemes 2 and 8) was ac-
companied with that of the corresponding intermediate
C (compound 8, Schemes 2 and 6), D (compound 6a ′,
Schemes 2 and 7), and probably X ) [HB]TfO (R′′ )
Et, X ) NHtBu, Schemes 2 and 6). This complicated
behavior of 1a ′ in the presence of EtOH contrasts with
that of its homologues 1a and 1b (Scheme 2), whose
reactivity with TlOTf is not affected by the presence or
absence of added nucleophiles (EtOH + H2O; Scheme
2). This difference could be explained by the different
reactions leading to 14 and 15 from 4 and 5, respec-
tively, show that such an insertion took place. Therefore,
the depalladation of these inserted complexes represents
a stoichiometric synthesis of functionalized arenes, N-
or O-heterocyclic compounds from bromoarenes. As
mentioned above, we fruitlessly attempted the synthesis
of some of these organic compounds under catalytic
conditions. However, catalytic applications of these
stoichiometric reactions could still be an objective for
future studies.
We believe that all depalladation reactions reported
here share three common steps: (i) The substitution of
the bromo ligand in the iminoacyl complexes [Pd-
{C(dNR)Ar}BrL2] (1-3) by TfO to give the intermedi-
ates A (Scheme 6), which are formulated as cationic,
assuming that the very labile TfO is substituted by
Me2CO, H2O, or EtOH; when starting from the aryl
complexes [Pd(Ar)BrL2] (4, 5) the corresponding acyl
complexes [Pd{C(dO)Ar}BrL2], resulting after insertion
of CO, were not isolated but the nature of compounds
resulting after the reaction with Tl(TfO), 14 and 15
(Schemes 5 and 7), demonstrate that such insertion took
place. The formation of 9 in the reaction of 2 with
Tl(TfO) requires the presence of CO, although it is not
incorporated into the molecule. In this case, it is possible
that the intermediate A was a cationic carbonyl complex
(S ) CO, Scheme 6). (ii) The nucleophilic attack on the
iminoacyl (X ) NXy, NtBu) or acyl (X ) O) carbon in A
by EtOH or H2O (R′′OH, Scheme 6), the latter coming
from atmospheric or solvent moisture. (iii) The decom-
position of the resulting adduct to give (probably
through an intermediate hydrido palladium complex,
Scheme 6) metallic palladium, the neutral ligand L,
HOTf, and ArC(dX)OR′′, B, an imidic acid (X ) NXy,
R′′ ) H, 12), or an imidic acid ester (NXy, R′′ ) OEt,
13). When R′′ ) H, B may cyclize to give 14 (when X )
O and Ar ) C6H4C(O)Me; see below and Scheme 7) or
may transform into its tautomeric form, the amide C,
ArC(dO)XH [X ) NtBu, Ar ) a (8, Scheme 6); X ) NXy,
Ar ) b (9), c (11)]. As mentioned above, amides C are
more stable than their imidic acid tautomers, B. How-
ever, when X ) NXy, we have been able to isolate both
tautomers 11 and 12 (Scheme 4).
t
nature of the isocyanide (XyNC in 1a and 1b and BuNC
in 1a ′): the more basic character of the NtBu group, with
respect to the NXy group, could favor in B the formation
of C to give 8 or of [HB]TfO ) X (Schemes 2 and 6).
Such processes would thus compete with the cyclization
reactions B f B′ f D (6a ′; Scheme 7) or B f E (7;
Scheme 8), which for 1a and 1b would be the main
reaction pathways. Additionally, as noted above, 6a and
6b are stable, while 6a ′ decomposes within 2 days. This
difference in stability could be due to the additional
conjugation effect of the xylyl group in the isoindol-
inones 6a and 6b, which is not present in 6a ′ containing
t
the Bu group. The instability of 6a ′ could also explain
the formation of other products in the reaction of 1a ′
with Tl(OTf) in the presence of EtOH.
Although the very simple reaction pathways proposed
in Schemes 6-8 allow a systematization of the forma-
tion of such different products as 6-15, some questions
remain unanswered because too many factors can
The stability of the bromo precursors toward nucleo-
philes can be explained as a consequence of the low
electrophilic character of the iminoacyl carbon in the
neutral bromo complexes, and the instability of A should
be due to the enhancement of the electrophilic character
of such carbon due to its cationic nature. It is very likely
(41) Lin, Y. S.; Yamamoto, A. Organometallics 1998, 17, 3466.
(42) Zuideveld, M. A.; Kamer, P. C. J .; van Leeuwen, P.; Klusener,
P. A. A.; Stil, H. A.; Roobeek, C. F. J . Am. Chem. Soc. 1998, 120, 7977.
(43) Mul, W. P.; Drent, E.; J ansens, P. J .; Kramer, A. H.; Sonne-
mans, M. H. W. J . Am. Chem. Soc. 2001, 123, 5350.
(44) Bianchini, C.; Meli, A. Coord. Chem. Rev. 2002, 225, 35.
(45) Curtin, D. Y.; Miller, L. L. J . Am. Chem. Soc. 1967, 89, 637.

Depalladation Reactions
Organometallics, Vol. 22, No. 9, 2003 1975
Ta ble 3. Hyd r ogen Bon d s for Com p ou n d s 6a , 6b, 8‚0.11H2O, 9, 11‚0.5Et2O, 13, a n d 14
symmetry transformations used
to generate equivalent atoms
D-H‚‚‚A
d(D-H) (Å)
d(H‚‚‚A) (Å)
d(D‚‚‚A) (Å)
(DHA) (deg)
6a
6b
C(6)-H(6)‚‚‚O(1)#1
C(2)-H(2B)‚‚‚O(1)#1
C(7)-H(7)‚‚‚O(1)#1
C(15)-H(15)‚‚‚O(2)#2
C(18)-H(18B)‚‚‚O(3)#3
C(9)-H(9B)‚‚‚O(4)#4
N-H(0)‚‚‚O(1)#1
0.95
0.95
0.95
0.95
0.98
0.98
0.887(15)
0.871(15)
0.875(15)
0.867(16)
0.867(16)
0.98
0.98
0.95
0.95
0.95
2.64
2.44
2.47
2.58
2.51
2.57
1.999(16)
2.087(16)
2.094(16)
2.078(18)
2.197(18)
2.47
2.46
2.42
2.41
2.46
3.4839(18)
3.3600(16)
3.3865(16)
3.4515(15)
3.2568(16)
3.5438(16)
2.8839(16)
2.9528(15)
2.969(2)
2.904(3)
3.051(8)
3.393(3)
3.414(3)
148.6
161.7
162.8
152.5
133.2
174.9
175.9(13)
172.3(13)
178.0(19)
159(2)
168(2)
157.6
163.3
163.9
176.2
157.8
#1 -1+x,y,z
#1 -x+1/2,y-1/2,z
#2 -x+1/2,-y+3/2,z+1/2
#3 -x,y,-z+1/2
#4 -x,-y+1,-z
#1 -y+1/4,x-1/4,z-1/4
#1 x,-y+1/2,z+1/2
8
9
11
N-H(0)‚‚‚O#1
N(3′)-H(03′)‚‚‚O(1)
N(3)-H(03)‚‚‚O(99)#1
N(3)-H(03)‚‚‚O(99′)#1
C(27)-H(27A)‚‚‚O(1′)#2
C(27′)-H(27F)‚‚‚O(1)
C(33)-H(33)‚‚‚O(1)#1
C(8)-H(8B)‚‚‚O(1)#1
C(8′)-H(8′2)‚‚‚O(1′)#2
#1 x,-y+3/2,z+1/2
#2 x,1.5-y,-0.5+z
13
14
3.345(2)
3.356(2)
3.360(2)
#1 x+1,y,z
#1 x,-y+1,z+1/2
#2 x+1/2,y-1/2,z
F igu r e 1. Ellipsoid representation of 6a with 50%
probability ellipsoids and the labeling scheme. Selected
bond lengths (Å) and angles (deg): O-C(1) ) 1.2152(16),
C(1)-N ) 1.3853(17), C(1)-C(9) ) 1.4862(18), C(2)-C(3)
) 1.3260(19), C(2)-N ) 1.4173(16), C(2)-C(4) ) 1.4698(19),
N-C(11) ) 1.4355(16); O-C(1)-N ) 125.25(12), O-C(1)-
C(9) ) 129.50(13), N-C(1)-C(9) ) 105.25(11), C(3)-
C(2)-N ) 125.06(12), C(3)-C(2)-C(4) ) 129.61(13),
N-C(2)-C(4) ) 105.33(11), C(1)-N-C(2) ) 112.35(11),
C(1)-N-C(11) ) 124.89(11), C(2)-N-C(11) ) 122.62(10).
F igu r e 2. Ellipsoid representation of 6b with 50% prob-
ability ellipsoids and the labeling scheme. Selected bond
lengths (Å) and angles (deg): O(1)-C(3) ) 1.2214(14),
C(1)-C(2) ) 1.3283(17), C(1)-N(2) ) 1.4171(15), C(1)-
C(7A) ) 1.4713(17), N(2)-C(3) ) 1.3853(15), N(2)-C(11)
) 1.4352(15), C(3)-C(3A) ) 1.4760(16); C(2)-C(1)-N(2)
) 125.51(11), C(2)-C(1)-C(7A) ) 129.36(11), N(2)-C(1)-
C(7A) ) 105.13(10), C(3)-N(2)-C(1) ) 112.26(10), C(3)-
N(2)-C(11) ) 123.35(10), C(1)-N(2)-C(11) ) 124.18(9),
O(1)-C(3)-N(2)
)
124.34(11), O(1)-C(3)-C(3A)
)
130.20(11), N(2)-C(3)-C(3A) ) 105.46(10).
influence the results. Thus, the reaction of 5 with CO
and Tl(TfO) in the absence of EtOH gave an intractable
mixture of products instead of the phthalide 14 obtained
in the reaction starting from 4. Although this is most
likely due to the different nature of the neutral ligands
(PPh3 in 4 and bpy in 5) and/or the geometry of
complexes, it is unclear how these factors influence so
markedly the course of such reactions. Finally, we do
not attempt to explain the formation of ortho-cyano-
styrene in the reaction of 2′ with Tl(TfO), as we cannot
account for the influence of the impurities present in
the starting material. In any case, ortho-cyanostyrene
was not among the impurities of 2′.
X-r a y Diffr a ction Stu d ies of 6a , 6b, 8‚0.11H2O, 9,
11‚0.5Et2O, 13, a n d 14. The structures of 6a (Figure
1) and 6b (Figure 2) consist of an almost planar
arrangement of the atoms in the indoline rings, the O,
and the methylene C atoms. This plane and that of the
carbon atoms of the xylyl ring (both with mean deviation
0.01 Å) subtend an angle of 88°. The distances and bond
angles are similar to those of other 3-alkylideneiso-
indolin-1-ones.32,46,47 In 6a , there is only one contact that
could be a C-H‚‚‚O hydrogen bond, namely, H(6)‚‚‚O
(Table 3 summarizes hydrogen bonds for all structures
presented here), which links the molecules by transla-
tion parallel to the x axis. In 6b, there are five
intermolecular C-H‚‚‚O hydrogen bonds with H‚‚‚O <
2.67 Å; the three shortest, including a bifurcated system
at O(1), combine to form layers parallel to xy at z ) 0.25
and 0.75 (Figure 3).
The amide 8 (Figure 4) shows typical structural
values,48 confirming the presence of an amidic carbon-
oxygen double bond. The structure of 9 (Figure 5) is very
similar to that of 8. In both cases, the molecules are
connected by intermolecular hydrogen bonds N-H‚‚‚O
forming chains parallel to the z axis (Figures 6 and 7).
In 8, the role of the partially occupied water site may
also be to form hydrogen bonds (Owater‚‚‚O(2) 2.65 Å),
and the chains are reinforced by a weak C-H...O(2)
interaction.
(47) Kundu, N. G.; Khan, M. W.; Guha, S.; Mukherjee, A. K. Acta
Crystallogr. 1999, C55, 239.
(46) Khan, M. W.; Guha, S.; Mukherjee, A. K.; Kundu, N. G. Acta
Crystallogr. C 1998, 54, 119.
(48) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1.

1976 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
F igu r e 5. Ellipsoid representation of 9 with 50% prob-
ability ellipsoids and the labeling scheme. Selected bond
lengths (Å) and angles (deg): C(1)-C(7) ) 1.4989(18),
C(7)-O ) 1.2348(15), C(7)-N ) 1.3472(17), C(8)-C(9) )
F igu r e 3. Packing diagram of 6b, showing hydrogen bonds
(dashed lines). Only H atoms involved in H bonds, together
with their geminal neighbors, are included. View direction
parallel to the z axis.
1.319(2), C(11)-N
) 1.4381(17); C(6)-C(1)-C(2) )
120.06(13), C(6)-C(1)-C(7) ) 117.92(12), C(2)-C(1)-C(7)
) 121.84(12), O-C(7)-N ) 122.63(12), O-C(7)-C(1) )
121.73(12), N-C(7)-C(1) ) 115.56(11), C(9)-C(8)-C(2) )
126.23(14), C(16)-C(11)-C(12) ) 122.20(12), C(16)-
C(11)-N ) 119.81(12), C(12)-C(11)-N ) 117.96(12), C(7)-
N-C(11) ) 122.68(11).
F igu r e 4. Ellipsoid representation of 8 with 50% prob-
ability ellipsoids and the labeling scheme. Selected bond
lengths (Å) and angles (deg): C(1)-C(7) ) 1.5033(19),
C(2)-C(12) ) 1.501(2), C(7)-O(1) ) 1.2400(16), C(7)-N )
1.3354(17), C(8)-N ) 1.4804(17), C(12)-O(2) ) 1.2178(18);
C(6)-C(1)-C(2) ) 119.29(13), C(6)-C(1)-C(7) ) 119.82(13),
C(2)-C(1)-C(7) ) 120.58(13), C(3)-C(2)-C(1) ) 118.94(14),
C(3)-C(2)-C(12)
) 117.37(13), C(1)-C(2)-C(12) )
123.69(13), O(1)-C(7)-N ) 124.33(13), O(1)-C(7)-C(1) )
120.11(12), N-C(7)-C(1) ) 115.54(12), O(2)-C(12)-C(2)
) 119.03(14), O(2)-C(12)-C(13) ) 120.47(15), C(2)-C(12)-
C(13) ) 120.35(13), C(7)-N-C(8) ) 124.97(12).
F igu r e 6. Packing diagram of 8, showing helical chains
of molecules (related by the 41 operator) connected by
hydrogen bonds (dashed lines). Only H atoms involved in
H bonds, together with their geminal neighbors, are
included. The partially occupied water site (see text) is
omitted. View direction parallel to the z axis.
The structure of 11‚0.5Et2O (Figure 8) shows two
independent molecules of 11 with slight differences in
the bonding distances and angles. The alkylideneiso-
indolinone fragment is similar to that found in com-
pounds 6. The alkylidene CdC bond [C(8)-C(20) 1.357(3)
Å] is somewhat longer than the CdCH2 bond in 6a
[C(2)-C(3), 1.3260(19) Å] or 6b [1.3283(17) Å]; this may
be due to the conjugation with the alkylidene substit-
uents. The C(20)-N(2) [1.372(3) Å] and C(30)-N(3)
[1.358(3) Å] bond lengths are typical of sp2 carbon atoms
bonded through a single bond to planar NHR groups.48
The carbonyl C(1)-O(1) and C(30)-O(2) bond lengths
[1.234(2) and 1.244(2) Å, respectively] are characteristic
of Csp2dO in amides.48 The delocalization of electron
density over the groups of atoms N(3), C(30), O(2) and
N(2), C(20), C(8) is shown by the coplanarity of the
groups of atoms C(31), N(3), H(3), C(30), O(2), C(20) and
C(21), N(2), H(02), C(20), C(30), C(8), with mean devia-
tions of 0.01 and 0.03 Å, respectively (0.04 and 0.10 Å
in the second molecule). The angle between both planes
is 80° and 83° in molecules 1 and 2, respectively. The
molecules of 11 are connected through N-H‚‚‚O hydro-
gen bonds from N(3)-H(03) to both oxygen positions of
the disordered ether molecule, and from N(3′)-H(03′)
to O(1). The hydrogens at N(2) and N(2′) do not form
hydrogen bonds but lie close to the ring at C(11)/C(11′),
with H(02)‚‚‚C(11) 2.30 Å and H(02′)‚‚‚C(11′) 2.29 Å.
Finally there are two short C-H‚‚‚O interactions from
methyl hydrogens. The net effect is to connect the
molecules in helical chains parallel to the y axis, but
the packing diagram is too congested to be easily
assimilated. The compound 13 (Figure 9) has a very
similar structure to 11, but, in agreement with its
proposed structure (Scheme 4), the C(30)-N(3) distance
[1.265(2) Å] corresponds to a CdN bond, while the
C(30)-O(2) distance [1.352(2) Å] is close to the value
expected for a single bond. Again, there are no hydrogen
bonds involving N(2)-H(02) (cf. H(02)‚‚‚C(11) 2.25 Å),
but one short C-H‚‚‚O contact that connects the mol-
ecules by translation parallel to the x axis.

Depalladation Reactions
Organometallics, Vol. 22, No. 9, 2003 1977
F igu r e 7. Packing diagram of 9, showing chains of
molecules connected by hydrogen bonds (dashed lines).
Only H atoms involved in H bonds, together with their
geminal neighbors, are included. View direction perpen-
dicular to the xy plane.
F igu r e 9. Ellipsoid representation of 13 with 50% prob-
ability ellipsoids and the labeling scheme. Selected bond
lengths (Å) and angles (deg): C(1)-O(1) ) 1.222(2), C(1)-
N(1) ) 1.390(2), C(1)-C(2) ) 1.467(2), C(2)-C(3) ) 1.394(2),
C(7)-C(8) ) 1.476(2), C(8)-C(20) ) 1.358(2), C(8)-N(1)
) 1.440(2), C(9)-O(2) ) 1.452(2), C(11)-N(1) ) 1.442(2),
C(20)-N(2) ) 1.386(2), C(20)-C(30) ) 1.514(2), C(21)-N(2)
) 1.424(2), C(30)-N(3) ) 1.265(2), C(30)-O(2) ) 1.352(2),
C(31)-N(3) ) 1.423(2); O(1)-C(1)-N(1) ) 124.27(16),
O(1)-C(1)-C(2) ) 129.81(16), N(1)-C(1)-C(2) ) 105.89(14),
C(20)-C(8)-N(1)
) 125.42(15), C(20)-C(8)-C(7) )
130.04(15), N(1)-C(8)-C(7) ) 104.53(13), O(2)-C(9)-C(10)
) 107.77(16), C(8)-C(20)-N(2) ) 123.05(15), C(8)-C(20)-
C(30) ) 120.19(15), N(2)-C(20)-C(30) ) 116.63(14), N(3)-
C(30)-O(2) ) 120.28(15), N(3)-C(30)-C(20) ) 129.03(16),
O(2)-C(30)-C(20)
) 110.68(14), C(1)-N(1)-C(8) )
111.84(13), C(1)-N(1)-C(11) ) 119.33(14), C(8)-N(1)-
C(11) ) 128.07(13), C(20)-N(2)-C(21) ) 129.05(15), C(30)-
N(3)-C(31) ) 125.65(15), C(30)-O(2)-C(9) ) 116.18(13).
mined. It shows the presence of two independent
molecules with slight differences in the bonding dis-
tances and angles, but all of them within the expected
ranges.48 The two molecules also pack independently of
each other, forming short hydrogen bonds C(8)-
H(8B)‚‚‚O(1) and C(8′)-H(8′2)‚‚‚O(1′); these connect the
molecules to chains parallel to the z axis or the
diagonals [-110] and [110], respectively.
F igu r e 8. Ellipsoid representation of 11 with 30% prob-
ability ellipsoids and the labeling scheme, excluding the
disordered ether molecule. Selected bond lengths (Å) and
angles (deg) for one of two independent molecules in the
crystal: C(1)-O(1) ) 1.234(2), C(1)-N(1) ) 1.379(3), C(1)-
C(2) ) 1.458(3), C(7)-C(8) ) 1.465(3), C(8)-C(20) )
1.357(3), C(8)-N(1) ) 1.438(2), C(11)-N(1) ) 1.442(3),
C(20)-N(2) ) 1.372(3), C(20)-C(30) ) 1.519(3), C(21)-N(2)
) 1.432(3), C(30)-O(2) ) 1.224(2), C(30)-N(3) ) 1.358(3),
C(31)-N(3) ) 1.445(3); O(1)-C(1)-N(1) ) 124.1(2), O(1)-
C(1)-C(2) ) 129.88(19), N(1)-C(1)-C(2) ) 106.00(17),
C(3)-C(2)-C(7) ) 121.9(2), C(3)-C(2)-C(1) ) 128.7(2),
C(7)-C(2)-C(1) ) 109.34(18), C(6)-C(7)-C(2) ) 118.83(19),
C(6)-C(7)-C(8) ) 133.56(19), C(2)-C(7)-C(8) ) 107.60(18),
Oth er Str u ctu r a l Stu d ies. The spectroscopic data
of 7 and 15 are in accordance with their proposed
structures (Schemes 2 and 5). Thus, the very strong IR
band at 1692 and 1672 cm-1, respectively, and a peak
at 168 ppm in their 13C NMR spectra indicate the
1
presence of the carbonyl group. In the H NMR spec-
trum, the diastereotopic methylene protons of the Et
group appear as characteristic doublets of doublets of
quartets, as expected for the AB part of an ABM3
system. 13C-1H long-range correlations (HMBC) have
allowed the assignment of all the aromatic carbons in
these two compounds. The quaternary aromatic carbons
close to the CMeOEt groups appear at considerably
higher frequencies (146.4 ppm in 7 and 147.9 ppm in
15) than the ones close to the carbonyl groups (132.1
ppm in 7 and 127.1 ppm in 15). The isoindolinones 6a ,
6a ′, and 6b show the 13C carbonyl resonance at 166.2,
168.5, and 164.8 ppm, respectively. In their 1H NMR
C(20)-C(8)-N(1)
) 125.57(19), C(20)-C(8)-C(7) )
129.02(19), N(1)-C(8)-C(7) ) 105.17(17), C(8)-C(20)-
N(2) ) 123.67(19), C(8)-C(20)-C(30) ) 118.38(18), N(2)-
C(20)-C(30) ) 117.83(18), O(2)-C(30)-N(3) ) 123.43(19),
O(2)-C(30)-C(20) ) 119.80(18), N(3)-C(30)-C(20) )
116.73(18), C(1)-N(1)-C(8) ) 111.79(17), C(1)-N(1)-
C(11) ) 120.86(17), C(8)-N(1)-C(11) ) 126.79(16), C(20)-
N(2)-C(21) ) 128.62(19), C(30)-N(3)-C(31) ) 123.47(18).
The compound 14 (Figure 10) has been previously
described,37 but its X-ray structure had not been deter-

1978 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
respectively) than in 6a ′ (0.05 ppm), where they clearly
show second-order character. This difference might be
due to the anisotropic effect of the xylyl group, which
strongly differentiates the two methylidene protons in
6a and 6b. In the 3-methylenephthalide 14, the second-
order character of the methylidene protons is much
stronger, and they appear as an AB system. The
carbonylic carbon resonance is at 166.8 ppm. The
aromatic carbons in 14 have also been assigned through
a
13C-1H long-range correlation (HMBC). Again, the
quaternary aromatic carbon close to the carbonyl group
has a lower chemical shift (127.1 ppm) than the other
one, close to the vinylidene group (139.0 ppm), although
the difference here is lower than in 7 and 15. Finally,
the FAB mass spectra show signals corresponding to
the molecular ion and its protonated species, respec-
tively. In the case of 15 the fragment resulting from the
loss of CO2 was also observed.
F igu r e 10. Ellipsoid representation of 14 with 50%
probability ellipsoids and the labeling scheme. Selected
bond lengths (Å) and angles (deg) for one of the two
independent molecules (unprimed atom names): C(1)-O(1)
) 1.202(2), C(1)-O(2) ) 1.3804(19), C(1)-C(7A) ) 1.472(2),
O(2)-C(3) ) 1.4027(19), C(3)-C(8) ) 1.323(2), C(3)-C(3A)
) 1.463(2); O(1)-C(1)-O(2) ) 121.18(14), O(1)-C(1)-
C(7A) ) 131.40(15), O(2)-C(1)-C(7A) ) 107.41(13), C(1)-
O(2)-C(3) ) 109.98(12), C(8)-C(3)-O(2) ) 121.57(14),
Ack n ow led gm en t. We thank Ministerio de Ciencia
y Tecnolog´ıa, FEDER (BQU2001-0133), and the Fonds
der Chemischen Industrie for financial support and
Fundacio´n Se´neca (Comunidad Auto´noma de la Regio´n
de Murcia, Murcia, Spain) for the award of a Grant to
E.M.-V.
C(8)-C(3)-C(3A)
) 131.00(15), O(2)-C(3)-C(3A) )
107.43(13), C(4)-C(3A)-C(7A) ) 121.26(14), C(4)-C(3A)-
C(3) ) 131.34(15), C(7A)-C(3A)-C(3) ) 107.39(13), C(3A)-
C(7A)-C(7) ) 121.81(14), C(3A)-C(7A)-C(1) ) 107.72(13),
C(7)-C(7A)-C(1) ) 130.45(15).
Su p p or tin g In for m a tion Ava ila ble: Listing of all refined
and calculated atomic coordinates, anisotropic thermal pa-
rameters, and bond lengths and angles for 6a , 6b, 8‚0.11H2O,
9, 11‚0.5Et2O, 13, and 14; synthesis and spectroscopic proper-
ties of 2′ and 10; elemental analyses, mass fragment data;
packing of the two independent molecules in 14. This material
is available free of charge via the Internet at http://pubs.acs.org.
spectra, the two inequivalent protons of the methylidene
2
group appear as characteristic doublets, with J HH ) 2
Hz. The difference in chemical shift between these two
protons is much higher in 6a and 6b (0.75 and 0.74 ppm,
OM030045J