Synthesis and Reactivity of Four-Membered Azapalladacycles Derived from N,N-Dialkyl-2-iodoanilines: Insertion Reactions of Carbenes into the Carbon-Palladium Bond

Article abstract of DOI:10.1021/om034270c

Three new four-membered azapalladacycles derived from N,N-dialkyl-2-iodoanilines have been synthesized: [Pd(κ ²2-C₆H₄NMe₂-2)I(PPh₃)] (4a), [Pd{κ²-C₆H₄N(Me)CH ₂Ph-2}I(PPh₃)] (4b), and [Pd{κ²-C ₆H₄N(Me)Pr-2}I(PPh₃)] (4c). On heating in solution azapalladacycles 4a and 4c undergo aryl-aryl interchange between the palladium atom and the phosphine ligand to give the phosphanyl-amine palladium complexes [PdPhI(PNMe₂)] (7a) and [PdPhI{PN-(Me)Pr}] (7c), respectively. Azapalladacycles 4a-c react with dichlorocarbene to give acyl palladium complexes [Pd{κ²-C(O)C₆H ₄NMe₂-2}I(PPh₃)] (8a), [Pd{κ ²-C(O)C₆H₄N(Me)CH₂Ph-2}I(PPh ₃)] (8b), and [Pd{κ²-C(O)C₆H ₄N(Me)Pr-2}I(PPh₃)] (8c), respectively. Smooth insertion of N₂CHCO₂Et into the carbon-palladium bond of azapalladacycles 4a-c results in the formation of the single-insertion products [Pd{κ²-CH(CO₂Et)C₆H₄NMe ₂-2}I(PPh₃)] (9a), [Pd-{κ²-CH(CO ₂Et)C₆H₄N(Me)CH₂Ph-2}I(PPh ₃)] (9b), and [Pd{κ²-CH(CO₂Et)C ₆H₄N(Me)Pr-2}-I(PPh₃)] (9c), respectively. On the other hand, complexes 4a and 4c react with N₂CHTMS to give mainly the single-insertion products [Pd{κ²-CH(SiMe ₃)C₆H₄NMe₂-2}I(PPh₃)] (10a) and [Pd{κ²-CH(SiMe₃)C₆H ₄N(Me)Pr-2}I(PPh₃)] (10c), respectively, while under similar reaction conditions 4b affords N-benzyl-N-methyl-2-[(Z)-2-(trimethylsilyl)vinyl]aniline (11b) as a consequence of a double-insertion process. Solid state structures of palladium complexes 4b, 8b·EtOAc, 9a, 9b, and 9c·Et₂O have been determined by X-ray analysis.

Full text of DOI:10.1021/om034270c

1438
Organometallics 2004, 23, 1438-1447
Syn th esis a n d Rea ctivity of F ou r -Mem ber ed
Aza p a lla d a cycles Der ived fr om
N,N-Dia lk yl-2-iod oa n ilin es: In ser tion Rea ction s of
Ca r ben es in to th e Ca r bon -P a lla d iu m Bon d
Daniel Sole´,*,† Llu´ıs Vallverdu´,† Xavier Solans,‡ Merce` Font-Bardia,‡ and
J osep Bonjoch†
Laboratori de Qu´ımica Orga`nica, Facultat de Farma`cia, Universitat de Barcelona,
Avinguda J oan XXIII s/ n, 08028-Barcelona, Spain, and Departament de Cristal.lografia,
Mineralogia i Dipo`sits Minerals, Universitat de Barcelona, Mart´ı i Franque`s s/ n,
08028-Barcelona, Spain
Received October 30, 2003
Three new four-membered azapalladacycles derived from N,N-dialkyl-2-iodoanilines have
been synthesized: [Pd(κ2-C6H4NMe2-2)I(PPh3)] (4a ), [Pd{κ2-C6H4N(Me)CH2Ph-2}I(PPh3)] (4b),
and [Pd{κ2-C6H4N(Me)Pr-2}I(PPh3)] (4c). On heating in solution azapalladacycles 4a and
4c undergo aryl-aryl interchange between the palladium atom and the phosphine ligand
to give the phosphanyl-amine palladium complexes [PdPhI(PNMe2)] (7a ) and [PdPhI{PN-
(Me)Pr}] (7c), respectively. Azapalladacycles 4a -c react with dichlorocarbene to give acyl
palladium complexes [Pd{κ2-C(O)C6H4NMe2-2}I(PPh3)] (8a ), [Pd{κ2-C(O)C6H4N(Me)CH2Ph-
2}I(PPh3)] (8b), and [Pd{κ2-C(O)C6H4N(Me)Pr-2}I(PPh3)] (8c), respectively. Smooth insertion
of N2CHCO2Et into the carbon-palladium bond of azapalladacycles 4a -c results in the
formation of the single-insertion products [Pd{κ2-CH(CO2Et)C6H4NMe2-2}I(PPh3)] (9a ), [Pd-
{κ2-CH(CO2Et)C6H4N(Me)CH2Ph-2}I(PPh3)] (9b), and [Pd{κ2-CH(CO2Et)C6H4N(Me)Pr-2}-
I(PPh3)] (9c), respectively. On the other hand, complexes 4a and 4c react with N2CHTMS
to give mainly the single-insertion products [Pd{κ2-CH(SiMe3)C6H4NMe2-2}I(PPh3)] (10a )
and [Pd{κ2-CH(SiMe3)C6H4N(Me)Pr-2}I(PPh3)] (10c), respectively, while under similar
reaction conditions 4b affords N-benzyl-N-methyl-2-[(Z)-2-(trimethylsilyl)vinyl]aniline (11b)
as a consequence of a double-insertion process. Solid state structures of palladium complexes
4b, 8b‚EtOAc, 9a , 9b, and 9c‚Et2O have been determined by X-ray analysis.
In tr od u ction
trast, the insertion of carbenes into palladium(II) com-
plexes has been completely ignored,7,8 although it is
becoming increasingly important to understand the
reactivity of these species, due to the growing use of
carbene ligands in palladium chemistry9 as well as the
frequency with which palladium carbenes are proposed
as intermediates in some Pd-catalyzed reactions.10
In the context of our studies on the Pd(0)-catalyzed
intramolecular coupling of aryl halides and ketones,11
we have recently reported the synthesis and X-ray
characterization of azapalladacycles 1 and 2,12 which
constitute the first examples of the family of four-
Insertion reactions into the carbon-metal bond con-
stitute one of the fundamental processes of organome-
tallic chemistry.1 Cyclopalladated complexes, especially
those with nitrogen as the donor atom,2 exhibit high
reactivity to undergo insertion of a variety of substrates.
Emphasis has been placed on insertion reactions of
alkynes,3 carbon monoxide,4 and isocyanides.5,6 In con-
* Corresponding author. E-mail: dsole@ub.edu.
† Laboratori de Qu´ımica Orga`nica, Facultat de Farma`cia.
‡ Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals.
(1) (a) Tsuji, J . Transition Metal Reagents and Catalysts-Innovations
in Organic Synthesis; Wiley: Chichester, 2000. (b) Negishi, E., Ed.
Handbook of Organopalladium Chemistry for Organic Synthesis;
Wiley: New York, 2002; Vols. I and II.
(4) Heck, R. F. Palladium Reagents in Organic Synthesis; Academic
Press: New York, 1985; pp 341-400.
(5) Yamamoto, Y.; Yamazaki, H. Synthesis 1976, 750.
(2) Dupont, J .; Pfeffer, M.; Spencer, J . Eur. J . Inorg. Chem. 2001,
1917.
(6) For the insertion of isocyanides into the metal-carbon bond of
(2-aminoaryl)palladium(II) complexes, see: Vicente, J .; Abad, J .-A.;
Frankland, A. D.; Lo´pez-Serrano, J .; Ram´ırez de Arellano, M. C.; J ones,
P. G. Organometallics 2002, 21, 272.
(7) The migratory insertion in aryl palladium carbene complexes
has recently been described: Albe´niz, A. C.; Espinet, P.; Manrique,
R.; Pe´rez-Mateo, A. Angew. Chem., Int. Ed. 2002, 41, 2363.
(8) For the concerted alkyl-carbene reductive elimination from Pd-
(II) complexes, see: (a) McGuinness, D. S.; Saendig, N.; Yates, B. F.;
Cavell, K. J . J . Am. Chem. Soc. 2001, 123, 4029. For the concerted
aryl-carbene reductive elimination from Pd(II) complexes, see: (b)
Marshall, W. J .; Grushin, V. V. Organometallics 2003, 22, 1591.
(9) For a review, see: Herrmann, W. A. Angew. Chem., Int. Ed. 2002,
41, 1290.
(3) (a) Maassarani, F.; Pfeffer, M.; Le Borgne, G.; Wehman, E.; van
Koten G. J . Am. Chem. Soc. 1984, 106, 8002. (b) Maassarani, F.;
Pfeffer, M.; Le Borgne, G. Organometallics 1987, 6, 2029. (c) Maas-
sarani, F.; Pfeffer, M.; van Koten, G. Organometallics 1989, 8, 871.
(d) Ryabov, A. D.; van Eldik, R.; Le Borgne, G.; Pfeffer, M. Organo-
metallics 1993, 12, 1386. (e) Vicente, J .; Saura-Llamas, I.; Ram´ırez de
Arellano, M. C. J . Chem. Soc., Dalton Trans. 1995, 2529. (f) Vicente,
J .; Saura-Llamas, I.; Palin, M. G.; J ones, P. G. J . Chem. Soc., Dalton
Trans. 1995, 2534. (g) Vicente, J .; Abad, J .-A.; Gil-Rubio, J .; J ones, P.
G. Organometallics 1995, 14, 2677. (h) Vicente, J .; Abad, J .-A.;
Mart´ınez-Viviente, E.; Ram´ırez de Arellano, M. C. Organometallics
2000, 19, 752. (i) Gu¨l, N.; Nelson, J . H.; Willis, A. C.; Rae, A. D.
Organometallics 2002, 21, 2041.
10.1021/om034270c CCC: $27.50 © 2004 American Chemical Society
Publication on Web 02/14/2004

Four-Membered Azapalladacycles
Organometallics, Vol. 23, No. 6, 2004 1439
Ch a r t 1. F ou r -Mem ber ed Aza p a lla d a cycles
Sch em e 1. Syn th esis of F ou r -Mem ber ed
Aza p a lla d a cycles 4a -c
membered azapalladacycles in which the metallacycle
is fused with an aromatic ring.13 We hypothesized that
this kind of palladium complex might be of interest in
the study of insertion reactions not only for their high
reactivity but also because after the insertion the
coordination ability of the amino group would give rise
to the formation of stable five-membered chelates.
We here report the synthesis of new members of this
family of four-membered azapalladacycles and study
their thermal behavior and their reactions with car-
benes.
Sch em e 2. Rea ction of Iod oa n ilin es 3a a n d 3b
w ith P d (P P h 3)4
Resu lts a n d Discu ssion
tively (Scheme 2). These quite stable palladium com-
plexes could now be characterized and were partially
transformed to the corresponding azapalladacycles.
Thus, when 5a was submitted to flash chromatography
(SiO2, hexane-EtOAc), azapalladacycle 4a (44%) was
obtained, and part of the starting material (25%) was
recovered. Under similar treatment, 5b afforded aza-
palladacycle 4b (65%) and hydroxopalladium compound
6 (13%), together with some of the starting material
(15%). Finally, on treatment with Pd(PPh3)4, 2-iodo-
aniline 3c afforded a reaction mixture in which the main
product was azapalladacycle 4c, the corresponding bis-
(triphenylphosphane)palladium complex not being iso-
lated in this case.
Syn th esis of F ou r -Mem ber ed Aza p a lla d a cycles.
We have previously reported the synthesis of the four-
membered azapalladacycles 1 and 2 by reacting the
corresponding N,N-dialkyl-2-iodoanilines either with
Pd2(dba)3 in the presence of PPh3 or with Pd(PPh3)4.14
The inferior results of the latter process were attributed
to the intermediacy of the corresponding trans-bis-
(triphenylphosphane)palladium(II) complexes, although
these intermediates could not be isolated and character-
ized.12 To establish the best methodology for the syn-
thesis of the four-membered azapalladacycles, we have
studied both procedures starting from iodoanilines
3a -c.
Thus, we can conclude that the reaction of 2-iodo-
anilines with Pd2(dba)3 and PPh3 is a good methodology
for the preparation of the four-membered azapallada-
cycles. Additionally, the results obtained in the reactions
of N,N-dialkyl-2-iodoanilines with Pd(PPh3)4 confirm the
hypotheses12 we made in our previous work: (i) in these
reactions the trans-bis(triphenylphosphane)palladium
complexes are the intermediates in the formation of the
four-membered azapalladacycles; (ii) the steric bulk of
the substituents on the nitrogen atom is the main
reason for the formation of the four-membered palla-
dacycles. When starting from N,N-dialkyl-2-haloani-
lines, the bis(triphenylphosphane)palladium complexes
could be obtained only when substituents at the nitro-
gen were small, otherwise the steric hindrance would
force those substituents out of the plane, directing the
nonbonding electron pair toward the palladium atom
to afford the azapalladacycle, and (iii) the hydroxopal-
ladium species are exclusively formed from the bis-
(triphenylphosphane)palladium complexes.15
The reaction of 2-iodoanilines 3a -c with Pd2(dba)3
and PPh3 (0.55:1 molar ratio) in benzene at room
temperature afforded azapalladacycles 4a -c in good
yields (Scheme 1). These four-membered azapallada-
cycles are robust compounds that can be purified by
flash chromatography without decomposition.
On the other hand, 2-iodoanilines 3a and 3b reacted
with Pd(PPh3)4 (1 equiv) to give the trans-bis(triphen-
ylphosphane)palladium complexes 5a and 5b, respec-
(10) For the mechanism of the palladium-catalyzed cyclopropanation
of alkenes by CH2N2, see: (a) Rodr´ıguez-Garc´ıa, C.; Oliva, A.; Ortun˜o,
R.-M.; Branchadell, V. J . Am. Chem. Soc. 2001, 123, 6157. (b) Straub,
B. F. J . Am. Chem. Soc. 2002, 124, 14195. For the Pd-catalyzed
dimerization of carbene ligands in group 6 metal-carbene complexes,
see: (c) Sierra, M. A.; Manchen˜o, M. J .; Sa´ez, E.; del Amo, J . C. J .
Am. Chem. Soc. 1998, 120, 6812. (d) Sierra, M. A.; del Amo, J . C.;
Manchen˜o, M. J .; Go´mez-Gallego, M. J . Am. Chem. Soc. 2001, 123,
851.
(11) (a) Sole´, D.; Vallverdu´, L.; Bonjoch, J . Adv. Synth. Catal. 2001,
343, 439. (b) Sole´, D.; Vallverdu´, L.; Peidro´, E.; Bonjoch, J . Chem.
Commun. 2001, 1888.
(12) Sole´, D.; Vallverdu´, L.; Solans, X.; Font-Bard´ıa, M.; Bonjoch,
J . J . Am. Chem. Soc. 2003, 125, 1587.
Th er m a l Beh a vior of F ou r -Mem ber ed Aza p a lla -
d a cycles. The thermal stability of azapalladacycles
4a -c was then studied. It was found that on heating
at 110 °C, azapalladacycle 4a underwent aryl-aryl
interchange between the palladium and the phosphine
ligand to give the palladium complex 7a (Scheme 3),
(13) For other types of four-membered Pd-N-C-C palladacycles,
see: (a) Arnek, R.; Zetterberg, K. Organometallics 1987, 6, 1230. (b)
Falvello, L. R.; Fornie´s, J .; Navarro, R.; Sicilia, V.; Toma´s, M. J . Chem.
Soc., Dalton Trans. 1994, 3143. (c) Agnus, Y.; Gross, M.; Labarelle,
M.; Louis, R.; Metz, B. J . Chem. Soc., Chem. Commun. 1994, 939. (d)
Henderson, W.; Oliver, A. G.; Rickard, C. E. F.; Baker, L. J . Inorg.
Chim. Acta 1999, 292, 260.
(14) The oxidative addition of 2-iodoaniline to Pd(0) complexes has
been described, see: (a) Vicente, J .; Abad, J .-A.; Frankland, A. D.;
Ram´ırez de Arellano, M.-C. Chem. Commun. 1997, 959. (b) Vicente,
J .; Abad, J .-A.; Frankland, A. D.; Ram´ırez de Arellano, M. C. Chem.
Eur. J . 1999, 5, 3066.
(15) In fact, the hydroxopalladium complexes were not obtained
during the purification by flash chromatography of either azapalla-
dacycles 4a -c or 1 and 2.12

1440 Organometallics, Vol. 23, No. 6, 2004
Sole´ et al.
prepared by reaction of 4a with CO.22,23 Similarly,
complexes 4b and 4c reacted with dichlorocarbene to
give 8b and 8c, respectively.
Sch em e 3. Th er m a l Ar yl-Ar yl In ter ch a n ge fr om
4a a n d 4c
The formation of acyl palladium complexes 8a -c can
be interpreted assuming that dichlorocarbene, gener-
ated from chloroform and KOt-Bu, undergoes coordina-
tion with the palladium atom of the four-membered
azapalladacycle to give a dichlorocarbene complex.24
Migratory insertion in the latter will afford the corre-
sponding dichloromethylene intermediate, which then
hydrolyzes to the acyl palladium complex.25 The alter-
native pathway involving the hydrolysis of the dichlo-
rocarbene complex to give the carbonyl complex, fol-
lowed by the migratory insertion in the latter to the acyl
palladium compound, seems to be less likely since,
although the carbon-chloride bond in coordinated
dichlorocarbene ligands is reactive toward nucleophiles,
the hydrolysis is a slow reaction24 and the insertion
processes in the four-membered azapalladacycles are
very favorable (vide infra).26,27
Sch em e 4. In ser tion of Dich lor oca r ben e in to th e
C-P d Bon d of 4a -c
In ser tion of Dia zoa lk a n es. Once we had proved the
readiness of four-membered azapalladacycles 4a -c to
undergo insertion reactions, we decided to explore the
reactivity of these palladium complexes with diazoal-
kanes.28,29 The palladium-catalyzed cyclopropanation of
olefins with diazoalkanes is a widely used synthetic
methodology.30 The formation of transient palladium-
carbene complex intermediates from the diazoalkane
and the palladium catalyst seems to be the rate-
determining step of these reactions.10a,b
Initially, we focused on the reaction of 4a -c with
diazomethane. However, when treated with an excess
of diazomethane, palladium complexes 4a -c gave com-
plex reaction mixtures from which no compound could
be isolated and characterized.
which was obtained as a 10:1 mixture of the transP,I
and cisP,I isomers. The identity of 7a was fully con-
firmed by comparison with an authentic sample pre-
pared by oxidative addition of iodobenzene to Pd2(dba)3
in the presence of the PNMe2 ligand.16,17
The thermal aryl-aryl interchange between the pal-
ladium and the phosphine ligand was also observed
starting from azapalladacycle 4c, which under similar
treatment afforded 7c as a 4:1 mixture of the transP,I
and cisP,I isomers. In contrast, under the same reaction
conditions, palladacycle 4b gave a complex reaction
mixture from which no compound could be isolated and
characterized.
The interchange between phosphorus-bound aryl
moieties and palladium-bound aryl groups in RPdL2X
complexes (L ) triarylphosphine, R ) aryl) is a known
process18 that has been recently applied in the synthesis
of different substituted phosphines.19
In ser tion of Dich lor oca r ben e. The synthesis of
carboxylic acids by palladium-catalyzed carbonylation
of aryl halides with chloroform and aqueous alkali has
been described.20 This catalytic reaction uses dichloro-
carbene as a carbon monoxide equivalent and is believed
to proceed through palladium carbene complexes. With
this precedent in mind, we decided to begin our inves-
tigation into the insertion reaction of carbenes by
studying the reaction of azapalladacycles 4a -c with
dichlorocarbene.
On the contrary, we were gratified to find that 4a
smoothly reacted with ethyl diazoacetate to give the
insertion compound 9a , which was obtained in 56% yield
after “flash” chromatography (Scheme 5). Under es-
sentially the same reaction conditions, azapalladacycle
(22) For the insertion of carbon monoxide into the carbon-palladium
bond of 2-aminophenylpalladium(II) complexes, see refs 14a,b.
(23) The chloro analogue of 8a had been prepared previously by
reaction of 2-(dimethylamino)benzaldehyde with Li2PdCl4, followed by
addition of PPh3, see: Anklin, C. G.; Pregosin, P. S. J . Organomet.
Chem. 1983, 243, 101.
(24) The existence of dichlorocarbene complexes of different transi-
tion metals has been unambiguously demonstrated, see for example:
(a) Mansuy, D.; Lange, M.; Chottard, J . C.; Bartoli, J . F.; Chevrier, B.;
Weiss, R. Angew. Chem., Int. Ed. Engl. 1978, 17, 781. (b) Clark, G. R.;
Marsden, K.; Roper, W. R.; Wright, L. J . J . Am. Chem. Soc. 1980, 102,
1206.
Dichlorocarbene, generated in situ from chloroform
and KOt-Bu,21 smoothly reacted at room temperature
with azapalladacycle 4a to directly give the acyl pal-
ladium complex 8a (Scheme 4). The identity of 8a was
confirmed by comparison with an authentic sample
(25) As the reaction mixtures were worked up in air, adventitious
water could account for the hydrolysis process.
(26) However, if the hydrolysis had taken place, the migratory
insertion from the resulting CO complex would be very favorable, from
either a pentacoordinated CO complex or a square-planar CO complex
with a cis arrangement between the aryl and the CO ligands.
(27) The generation of CO by hydrolysis of CCl2 and the subsequent
carbonylation of the azapalladacycles can be completely rejected,
because CCl2 can be efficiently generated from chloroform and 50%
NaOH. For a review on the generation of dichlorocarbene and its use
in organic synthesis, see: Fedorynski, M. Chem. Rev. 2003, 103, 1099.
(28) For the formation of metallacarbenes from diazoalkanes, see:
Cohen, R.; Rybtchinski, B.; Gandelman, M.; Rozenberg, H.; Martin, J .
M. L.; Milstein, D. J . Am. Chem. Soc. 2003, 125, 6532.
(16) PNMe2 means N,N-dimethyl-2-(diphenylphosphanyl)aniline.
(17) (a) Crociani, L.; Bandoli, G.; Dolmella, A.; Basato, M.; Corain,
B. Eur. J . Inorg. Chem. 1998, 1811. (b) Amatore, C.; Fuxa, A.; J utand,
A. Chem. Eur. J . 2000, 6, 1474.
(18) (a) Kong, K.-C.; Cheng, C.-H. J . Am. Chem. Soc. 1991, 113,
6313. (b) Goddson, F. E.; Wallow, T. I.; Novak, B. M. J . Am. Chem.
Soc. 1997, 119, 12441.
(19) (a) Kwong, F. Y.; Chan, K. S. Chem. Commun. 2000, 1069. (b)
Kwong, F. Y.; Chan, K. S. Organometallics 2001, 20, 2570. (c) Kwong,
F. Y.; Lai, C. W.; Chan, K. S. Tetrahedron Lett. 2002, 43, 3537.
(20) Grushin, V. V.; Alper, H. Organometallics 1993, 12, 3846.
(21) Doering, W. von E.; Hoffmann, A. K. J . Am. Chem. Soc. 1954,
76, 6162.
(29) Recently, a Pd(II) complex of a non-heteroatom-stabilized
carbene ligand has been prepared by reaction of di(p-tolyl)diazo-
methane with Trpy-PdOAc, see: Bro¨ring, M.; Brandt, C. D.; Stellwag,
S. Chem. Commun. 2003, 2344.
(30) See for example: Marko´, I. E.; Kumamoto, T.; Giard, T. Adv.
Synth. Catal. 2002, 344, 1063, and references therein.

Four-Membered Azapalladacycles
Organometallics, Vol. 23, No. 6, 2004 1441
Sch em e 5. In ser tion Rea ction s of Dia zoa lk a n es
On the other hand, when complex 4c was treated with
Me3SiCHN2 (1:3.3 molar ratio), palladium complex 10c
was obtained in 57% yield after flash chromatography,
together with trace amounts of alkene 11c. The relative
configuration of azapalladacycle 10c was established by
means of NOESY experiments, which allowed the syn
relationship between the N-methyl substituent and the
Me3Si group to be determined. The NOESY experiment
on 10c showed an off-diagonal cross-peak connecting the
N-methyl protons (δ 3.35, d, J ) 2.7 Hz) with the Me3-
Si grouping (δ, -0.27, s), thus indicating that these
substituents are syn-related. The NOESY spectrum also
showed off-diagonal cross-peaks connecting the methyl
protons of the N-propyl group (δ 0.84, t, J ) 7.2 Hz)
with the PPh3 protons (δ 7.42, m, and δ 7.79, m) and
one of the methylene protons (δ 2.50, m) with the PPh3
protons (δ 7.79, m), thus indicating the spatial proximity
between the N-propyl substituent and the PPh3 group.
The insertion of carbenes derived from diazoalkanes
into the Pd-C bond of the four-membered azapallada-
cycles constitutes a new strategy to synthesize azapal-
ladacycles with a palladated stereogenic carbon, which
until now had only been obtained by either direct
palladation of a prochiral ligand34 or transmetalation
of lithiated tertiary amines to chloropalladium com-
plexes.32
The stereoselective formation of alkene 11b in the
reaction of 4b with excess Me3SiCHN2 could be ratio-
nalized as outlined in Scheme 6. The insertion of a first
molecule of Me3SiCHN2 into the Pd-C bond of azapal-
ladacycle 4b will afford 10b. Although this palladium
complex has not been fully characterized, it is most
likely that in 10b the bulky Me3Si group and the
N-methyl substituent present a syn relationship, as
occurs in complex 10c (vide supra). In this context, it
should be noted that in the five-membered azapallada-
cycles 9b, 9c, 10b, and 10c the more sterically demand-
ing substituent at the nitrogen atom (Bn or Pr) and the
substituent at the palladated carbon (CO2Et or Me3Si)
are always anti located. The high stereoselectivity in
the formation of these azapalladacycles is probably the
result of the steric control exerted by the more bulky
N-substituent in the insertion of the carbene in the four-
membered azapalladacycles.
in to th e C-P d Bon d of 4a -ca
a
Compounds 9 and 10 are racemic. The scheme depicts only
one of the enantiomers.
4b afforded a reaction mixture from which the insertion
compound 9b could be isolated in 51% yield. The syn
relationship between the CO2Et group and the N-methyl
substituent in 9b was confirmed by the X-ray diffraction
study of a single crystal. A second compound was also
formed in the reaction of 4b with ethyl diazoacetate.
Although this minor compound could not be isolated in
a pure form and fully characterized, the signals in the
1H and 13C NMR spectra suggested that it may be a
double-insertion product (vide infra) rather than a
diastereomer of 9b. On the other hand, azapalladacycle
4c slowly reacted with ethyl diazoacetate to stereose-
lectively afford the insertion product 9c, which also
shows, as confirmed by X-ray analysis, a syn relation-
ship between the CO2Et group and the N-methyl sub-
stituent.
With these results in hand, attention was next
devoted to the reaction of the four-membered azapal-
ladacycles with trimethylsilyldiazomethane.31 When
complexes 4a -c were treated with Me3SiCHN2 in
benzene at room temperature, different reaction behav-
ior was observed (Scheme 5). Thus, 4a reacted with Me3-
SiCHN2 (1:3.3 molar ratio) to afford 10a in nearly
quantitative yield,32 while, under the same conditions,
4b gave alkene 11b instead of the expected insertion
product. The use of equimolecular amounts of azapal-
ladacycle 4b and Me3SiCHN2 resulted in a complex
reaction mixture, the major product again being alkene
11b, which was isolated in 30% yield. On successive
chromatographic purifications, a fraction enriched with
a second compound was obtained. Although this new
compound could not be isolated as a pure substance, it
was assigned as the monomolecular insertion azapal-
ladacycle 10b on the basis of its NMR data.33
The high tendency of 10b to undergo insertion of a
second molecule of carbene is probably a consequence
of its steric hindrance. So, it is reasonable to assume
that the distortion of the square-planar geometry of the
palladium atom in this very congested palladium inter-
mediate takes place in the same direction as in 9b,
forcing the bulky PPh3 ligand and the benzyl group close
together (vide infra). Pd-N bond dissociation in 10b will
relieve the steric crowding and give rise to a coordina-
tively unsaturated intermediate, which could therefore
react with a second molecule of Me3SiCHN2 to give a
palladium carbene complex.35 Migratory insertion in the
latter would afford a six-membered azapalladacycle.36
For steric reasons, the anti relationship between the two
(33) Significant signals: 1H NMR (CDCl3, 200 MHz) δ 5.31 (d, J )
12.8 Hz, 1H), 4.48 (dd, J ) 12.8 and 5.5 Hz, 1H), 3.54 (d, J ) 2.8 Hz,
3H), 2.87 (d, J ) 6.2 Hz, 1H).
(34) See for example: (a) Sokolov, V. I.; Sorokina, T. A.; Troitskaya,
L. L.; Solovieva, L. I.; Reutov, O. A. J . Organomet. Chem. 1972, 36,
389. (b) Yoneda, A.; Hakushi, T.; Newkome, G. R.; Fronczek, F. R.
Organometallics 1994, 13, 4912. (c) Portscheller, J . L.; Malinakova,
H. C. Org. Lett. 2002, 4, 3679, and references therein.
(31) For the use of Me3SiCHN2 in palladium-catalyzed cyclopropa-
nation reactions, see: Aoyama, T.; Iwamoto, Y.; Nishigaki, S.; Shioiri,
T. Chem. Pharm. Bull. 1989, 37, 253.
(32) For an alternative synthesis of palladacycles with the mono-
anionic CH(SiMe3)C6H4NMe2-2, see: (a) Maassarani, F.; Pfeffer, M.;
Le Borgne, G.; J astrzebski, J . T. B. H.; van Koten, G. Organometallics
1987, 6, 1111. (b) See also refs 3a and 3c.

1442 Organometallics, Vol. 23, No. 6, 2004
Sole´ et al.
Sch em e 6. P r op osed Rea ction P a th for th e
F or m a tion of 11b
F igu r e 1. Molecular structure of 4b (ORTEP view). H
atoms are omitted for clarity. Selected interatomic dis-
tances [Å] and angles [deg], [values for the second mol-
ecule]: Pd(1)-C(11) ) 1.961(9), [1.974(9)]; Pd(1)-N(1) )
2.127(7), [2.090(7)]; Pd(1)-P(1) ) 2.162(3), [2.170(2)]; Pd-
(1)-I(1) ) 2.5883(10), [2.5941(9)]; C(11)-Pd(1)-N(1) )
67.8(3), [68.3(3)]; C(11)-Pd(1)-P(1) ) 96.2(3), [97.8(3)];
N(1)-Pd(1)-I(1) ) 96.2(2), [95.01(19)]; P(1)-Pd(1)-I(1) )
99.65(7), [98.88(7)]; C(16)-N(1)-Pd(1) ) 85.5(5), [87.7(5)];
C(11)-C(16)-N(1) ) 109.3(8), [107.9(8)]; C(16)-C(11)-Pd-
(1) ) 97.3(7), [96.0(7)].
Me3Si groups will be the most accessible one in this
insertion process. Finally, Pd-N bond dissociation and
â syn-elimination of Me3SiI and Pd(0)37 would give
alkene 11b with high stereoselectivity.
X-r a y Cr ysta l Str u ctu r es. The molecular structures
of complexes 4b, 8b‚EtOAc, 9a , 9b, and 9c‚Et2O have
been determined by X-ray diffraction studies and are
shown in Figures 1-5, respectively.
Although in the five palladium complexes the Pd is
linked to the same atoms (I, P, C, and N), there are
significant differences between the structure of the four-
membered azapalladacycle 4b and those of the five-
membered azapalladacycles 8b, 9a , 9b, and 9c. The
four-membered metallacycle of 4b is planar, and both
the I and P atoms are deviated to the same side from
the mean plane 0.156(1) Å [0.110(1) Å in the second
molecule] and 0.098(2) Å [0.074(2) Å in the second
molecule], respectively. This deviation causes the pal-
ladium atom to be outside of the plane defined by the
four ligands. The planarity of the four-membered ring
causes the length of the Pd-ligand bonds to be shorter
in 4b than in the five-membered azapalladacycles 8b,
9a , 9b, and 9c.
F igu r e 2. Molecular structure of 8b‚0.5CH3CO2CH2CH3
(ORTEP view). H atoms and solvent are omitted for clarity.
Selected interatomic distances [Å] and angles [deg]: Pd-
C(7) ) 1.976(2), Pd-N ) 2.1752(19), Pd-P ) 2.2503(6),
Pd-I ) 2.7509(3), C(7)-Pd-N ) 82.72(8), C(7)-Pd-P )
91.80(7), N-Pd-I ) 94.67(5), P-Pd-I ) 91.444(17), C(1)-
N-Pd ) 106.32(13), C(6)-C(1)-N ) 117.3(2), C(1)-C(6)-
C(7) ) 118.2(2), C(6)-C(7)-Pd ) 110.45(16).
of-plane atom. In similar five-membered azapallada-
cycles both the planar6,14b and envelope form on
nitrogen32a and palladium14a have been described, the
latter being observed when bulky ligands are bonded
to the palladium atom. All the five-membered azapal-
ladacycles show somewhat tetragonally distorted square-
planar coordination around the palladium atom, the
largest deviation to the mean plane being in the C atom
[deviation of 0.166(3) Å in 8b, 0.193(6) Å in 9a , 0.318-
(3) Å in 9b, and 0.326(10) Å in 9c].
The five-membered metallacycles in 8b, 9a , 9b, and
9c have an envelope form with the Pd being the out-
(35) Additionally, the higher nucleophilicity of TMSCHN2 than of
ethyl diazoacetate (Bug, T.; Hartnagel, M.; Schlierf, C.; Mayr, H. Chem.
Eur. J . 2003, 9, 4068) agrees with the experimental fact that the former
has a higher tendency to give the double-insertion product than the
latter, as can be seen when comparing the reactions of 4b with
TMSCHN2 and N2CHCOOEt.
In complexes 9a -c the I and PPh3 ligands are in
equatorial positions, the bulky CO2Et group and the syn-
related N-methyl substituent are in axial positions,38
(36) As the reaction is carried out in the presence of an excess of
diazoalkane, the formation of disubstituted alkenes that could be
inserted into the Pd-C bond of the four-membered palladacycle to give
the six-membered palladacycle cannot be definitively ruled out.
(37) Karabelas, K.; Hallberg, A. J . Org. Chem. 1989, 54, 1773.
(38) The axial position for bulky groups in related complexes has
been previously described. Maassarani, F.; Pfeffer, M.; Spek, A. L.;
Schreurs, A. M. M.; van Koten, G. J . Am. Chem. Soc. 1986, 108, 4222.
See also ref 32a.

Four-Membered Azapalladacycles
Organometallics, Vol. 23, No. 6, 2004 1443
F igu r e 5. Molecular structure of 9c‚Et2O (ORTEP view).
H atoms and solvent are omitted for clarity. Selected
interatomic distances [Å] and angles [deg]: Pd-C(4) )
2.046(10), Pd-N ) 2.180(8), Pd-P ) 2.225(3), Pd-I )
2.6682(11), C(4)-Pd-N ) 84.6(4), C(4)-Pd-P ) 94.3(3),
N-Pd-I ) 92.8(2), P-Pd-I ) 91.86(7), C(5)-C(4)-Pd )
105.3(8), C(10)-C(5)-C(4) ) 124.0(11), C(5)-C(10)-N )
114.4(10), C(10)-N-Pd ) 107.2(6).
F igu r e 3. Molecular structure of 9a (ORTEP view). H
atoms are omitted for clarity. Selected interatomic dis-
tances [Å] and angles [deg]: Pd-C(4) ) 2.058(6), Pd-N )
2.150(5), Pd-P ) 2.2491(16), Pd-I ) 2.6910(7), C(4)-
Pd-N ) 83.8(2), C(4)-Pd-P ) 91.93(17), N-Pd-I )
92.98(14), P-Pd-I ) 92.33(5), C(10)-N-Pd ) 106.3(3),
C(5)-C(4)-Pd ) 106.9(4), C(10)-C(5)-C(4) ) 121.2(6),
C(5)-C(10)-N ) 117.7(5).
azapalladacycles derived from N,N-dialkyl-2-iodoani-
lines. The insertion of dichlorocarbene afforded acyl
palladium complexes, while the insertion of diazoal-
kanes gave rise to a new synthetic entry to five-
membered azapalladacycles with a palladated stereo-
genic carbon. Further investigation will be conducted
both to gain deeper insight into the reaction of carbenes
with the azapalladacycles and to study the insertion of
other substrates into the carbon-palladium bond of
these complexes.
Exp er im en ta l Section
Gen er a l In for m a tion . All reactions were performed under
an argon atmosphere using dry solvents. THF was distilled
under nitrogen from sodium benzophenone ketyl. Benzene,
toluene, dichloromethane, and acetonitrile were dried over
CaH2 and distilled under nitrogen. Other solvents were used
as received. Chemicals were used as received from Acros
(NaBH(OAc)3, Pd(PPh3)4), Aldrich (benzyl bromide, 2-iodoani-
line, propionaldehyde, Pd2(dba)3, N2CHCO2Et, N2CHTMS),
and Fluka (iodomethane, PPh3, KOt-Bu). 2-Iodo-N-methylani-
line39 and 2-iodo-N,N-dimethylaniline40 were prepared accord-
ing to literature procedures. Nuclear magnetic resonance
spectra were recorded in CDCl3. Chemical shifts are given in
parts per million (ppm) relative to Me4Si for 1H and 13C NMR
and relative to 85% H3PO4 for 31P NMR. Only noteworthy IR
absorptions are listed. Melting points were determined in a
capillary tube and are uncorrected. Chromatography refers to
flash chromatography and was carried out on SiO2 (silica gel
60, 230-400 mesh ASTM).
N-Ben zyl-2-iod o-N-m eth yla n ilin e (3b). To a solution of
2-iodo-N-methylaniline (0.7 g, 3.0 mmol) in acetonitrile (50 mL)
were added benzyl bromide (1.43 mL, 12.0 mmol), K2CO3
(3.32 g, 24.0 mmol), and LiI (150 mg), and the mixture was
heated at reflux for 24 h. The solvent was evaporated, and
the residue was partitioned between CH2Cl2 and water. The
organic extracts were dried and concentrated, and the residue
was purified by chromatography (SiO2, from hexane to 1:1
hexane-EtOAc) to give aniline 3b as an oil. Yield: 865 mg,
F igu r e 4. Molecular structure of 9b (ORTEP view). H
atoms are omitted for clarity. Selected interatomic dis-
tances [Å] and angles [deg]: Pd-C(15) ) 2.075(3), Pd-N
) 2.178(2), Pd-P ) 2.2601(8), Pd-I ) 2.6765(3), C(15)-
Pd-N ) 82.83(10), C(15)-Pd-P ) 94.55(8), N-Pd-I )
93.59(7), P-Pd-I ) 92.32(2), C(9)-N-Pd ) 107.73(18),
C(14)-C(9)-N ) 117.0(3), C(9)-C(14)-C(15) ) 120.8(3),
C(14)-C(15)-Pd ) 107.86(19).
and the remaining N-alkyl substituent (CH3 in 9a , CH2-
Ph in 9b, and Pr in 9c) is in the bisector site of the
envelope.
As can be deduced from the pronounced tetragonal
distortion of the square-planar geometry, azapallada-
cycles 9b and 9c are highly stressed structures. In fact,
in compound 9b a short intramolecular distance is
observed between the COOCH2CH3 group and one of
the phenyl groups of PPh3 [C(18)-H(18B)‚‚‚C(19)‚‚‚
C(24) ring, distance of H(18B) to the aromatic centroid
) 2.596 Å]. The distance between the same groups is
markedly longer (3.135 Å) in the less stressed azapal-
ladacycle 9a . Additionally, a short distance is also
observed in compound 9b between another phenyl group
of the PPh3 ligand and the N-Bn group [C(30)-H(30)‚‚‚
C(1)‚‚‚C(6) ring, distance of H(30) to the aromatic
centroid ) 2.735 Å].
(39) Larock, R. C.; Yum, E. K.; Refvik, M. D. J . Org. Chem. 1998,
63, 7652.
(40) Bunnett, J . F.; Mitchel, E.; Galli, C. Tetrahedron 1985, 41,
4119-4132.
In summary, we have studied the insertion reactions
into the carbon-palladium bond in the four-membered

1444 Organometallics, Vol. 23, No. 6, 2004
89%. IR (film) 1580, 1470, 1452 cm-1 1H NMR (CDCl3, 300
MHz): δ 2.61 (s, 3H), 4.11 (s, 2H), 6.79 (ddd, J ) 7.8, 7.5, and
1.8 Hz, 1H), 7.08 (dd, J ) 7.8 and 1.5 Hz, 1H), 7.20-7.35 (m,
4H), 7.45 (m, 2H), 7.87 (dd, J ) 7.8 and 1.8 Hz, 1H). 13C NMR
(CDCl3, 75.5 MHz): δ 41.6 (CH3), 61.1 (CH2), 98.5 (C), 122.2
(CH), 125.4 (CH), 127.0 (CH), 128.1 (CH), 128.6 (CH), 128.9
Sole´ et al.
.
Hz, CH PPh3), 128.4 (d, J (13C-31P) ) 8.2 Hz, CH), 130.6 (s,
CH), 131.6 (d, J (13C-31P) ) 52.2 Hz, C PPh3), 132.6 (s, CH),
134.8 (d, J (13C-31P) ) 12.1 Hz, CH PPh3), 135.3 (s, C), 160.9
(d, J (13C-31P) ) 2 Hz, C). 31P NMR (CDCl3, 121.5 MHz): δ
39.3. Anal. Calcd for C32H29INPPd: C, 55.55; H, 4.22; N, 2.02.
Found: C, 55.63; H, 4.32; N, 2.01.
[P d {K2-C6H4N(Me)P r -2}I(P P h 3)] (4c). Operating as in the
preparation of 4a , starting from 3c (154 mg, 0.56 mmol), Pd2-
(dba)3 (280 mg, 0.30 mmol), and PPh3 (145 mg, 0.55 mmol),
azapalladacycle 4c was obtained after chromatography (SiO2,
from hexane to CH2Cl2). Yield: 342 mg, 95%. Mp: 169-170
°C dec. 1H NMR (CDCl3, 300 MHz): δ 0.92 (t, J ) 7.2 Hz, 3H),
1.49 (m, 1H), 2.54 (m, 1H), 2.91 (ddd, J ) 11.4, 9.9, and 4.2
Hz, 1H), 3.16 (d, J (1H-31P) ) 3 Hz, 3H), 3.30 (td, J ) 11.7
and 4.5 Hz, 1H), 5.87 (dd, J ) 7.5 and 0.9 Hz, 1H), 6.62 (t,
J ) 7.5 Hz, 1H), 6.83 (dd, J ) 7.5 and 0.9 Hz, 1H), 7.02 (td,
J ) 7.5 and 1.2 Hz, 1H), 7.33-7.49 (m, 9H), 7.65-7.76 (m,
6H). 13C NMR (CDCl3, 75.5 MHz): δ 11.5 (s, CH3), 22.5 (s,
CH2), 51.1 (s, CH3), 62.1 (s, CH2), 118.7 (s, CH), 125.0 (s, CH),
125.2 (s, CH), 126.0 (d, J (13C-31P) ) 10.4 Hz, C), 128.0 (d,
J (13C-31P) ) 10.9 Hz, CH PPh3), 128.5 (d, J (13C-31P) ) 8.2
Hz, CH), 130.7 (d, J (13C-31P) ) 2.2 Hz, CH PPh3), 131.7 (d,
J (13C-31P) ) 52.2 Hz, C PPh3), 134.9 (d, J (13C-31P) ) 12.2
Hz, CH PPh3), 162.3 (d, J (13C-31P) ) 4.4 Hz, C). 31P NMR
(CDCl3, 121.5 MHz): δ 38.6. HRMS (FAB): m/z 516.1072
([M - I]+, 516.1064 calcd for C28H29NPPd). Anal. Calcd for
(CH), 138.1 (C), 140.0 (CH), 153.9 (C). HRMS: calcd for C14
14IN 323.0171, found 323.0171.
2-Iod o-N-m eth yl-N-p r op yla n ilin e (3c). To a solution of
-
H
2-iodoaniline (760 mg, 3.46 mmol) and propionaldehyde (0.3
mL, 4.17 mmol) in CH2Cl2 (50 mL) were added acetic acid (0.6
mL, 10.48 mmol) and NaBH(OAc)3 (1.75 g, 8.26 mmol). After
stirring at room temperature for 12 h, the mixture was poured
into saturated aqueous NaHCO3 and extracted with CH2Cl2.
The organic extracts were dried and concentrated. Chroma-
tography (SiO2, from hexane to 95:5 hexane-EtOAc) of the
residue afforded 2-iodo-N-propylaniline (768 mg, 85%). To a
solution of 2-iodo-N-propylaniline (768 mg, 2.94 mmol) in
acetonitrile (40 mL) were added K2CO3 (1.22 g, 8.82 mmol)
and iodomethane (3.66 mL, 58.8 mmol). After stirring at
50 °C for 24 h, the solvent was evaporated and the residue
was partitioned between CH2Cl2 and water. The organic
extracts were washed with water, dried, and concentrated.
Chromatography (SiO2, from hexane to 9:1 hexane-EtOAc)
of the residue afforded 2-iodo-N-methyl-N-propylaniline (3c)
1
as an oil. Yield: 685 mg, 85%. H NMR (CDCl3, 300 MHz): δ
C
28H29INPPd (643.84): C, 52.23; H, 4.54; N, 2.18. Found: C,
0.91 (t, J ) 7.2 Hz, 3H), 1.55 (tq, J ) 7.5 and 7.2 Hz, 2H),
2.89 (t, J ) 7.5 Hz, 2H), 2.69 (s, 3H), 6.77 (ddd, J ) 7.8, 7.2,
and 1.5 Hz, 1H), 7.08 (dd, J ) 8.1 and 1.5 Hz, 1H), 7.29 (ddd,
J ) 8.1, 7.2, and 1.5 Hz, 1H), 7.84 (dd, J ) 7.8 and 1.5 Hz,
1H). 13C NMR (CDCl3, 75.5 MHz): δ 11.7 (CH3), 20.7 (CH2),
42.5 (CH3), 58.5 (CH2), 99.1 (C), 121.9 (CH), 125.1 (CH), 128.8
(CH), 139.9 (CH), 154.4 (C).
52.48; H, 4.52; N, 1.66.
tr a n s-[P d (C6H4NMe2-2)I(P P h 3)2] (5a ). To a solution of
N,N-dimethyl-2-iodoaniline (3a , 100 mg, 0.40 mmol) in ben-
zene (10 mL) was added Pd(PPh3)4 (470 mg, 0.40 mmol). After
stirring at room temperature for 24 h, the solvent was
evaporated and the palladium complex 5a was precipitated
from Et2O as a yellow solid. Yield: 300 mg, 85%. 1H NMR
(CDCl3, 300 MHz, -10 °C): δ 2.58 (s, 6H), 5.91 (d, J ) 7.8 Hz,
1H), 6.05 (t, J ) 7.5 Hz, 1H), 6.51 (t, J ) 7.5 Hz, 1H), 6.91 (m,
1H), 7.20-7.60 (m, 30H). 13C NMR (CDCl3, 75.5 MHz): δ 44.8
(s, CH3), 118.3 (s, CH), 119.8 (s, CH), 123.6 (s, CH), 127.5 (s,
CH PPh3), 129.5 (s, CH PPh3), 130.1 (s, CH), 132.5 (t, J (13C-
31P) ) 20 Hz, C PPh3), 134.8 (s, CH PPh3), 150.0 (s, C), 155.1
(s, C). 31P NMR (CDCl3, 121.5 MHz): δ 19.5.
tr a n s-[P d {C6H4N(Me)CH2P h -2}I(P P h 3)2] (5b). Operating
as in the preparation of 5a , starting from 3b (100 mg, 0.31
mmol) and Pd(PPh3)4 (355 mg, 0.31 mmol), palladium complex
5b was obtained. Yield: 297 mg, quantitative. 1H NMR (CDCl3,
300 MHz): δ 2.36 (s, 3H), 4.15 (s, 2H), 6.10 (m, 2H), 6.59 (t,
J ) 7.5 Hz, 1H), 6.99 (m, 1H), 7.20-7.80 (m, 35H). 13C NMR
(CDCl3, 75.5 MHz): δ 39.2 (s, CH3), 60.5 (s, CH2), 119.1 (s,
CH), 119.7 (s, CH), 123.5 (s, CH), 126.2 (s, CH), 127.2 (br, CH
PPh3), 127.6 (s, CH), 127.9 (s, CH), 129.3 (s, CH PPh3), 131.6
(s, CH), 131.9 (t, J (13C-31P) ) 22.6 Hz, C PPh3), 134.6 (br,
CH PPh3), 137.1 (s, C), 147.3 (s, C), 154.9 (s, C). 31P NMR
(CDCl3, 121.5 MHz): δ 18.1.
[P d (K2-C6H4NMe2-2)I(P P h 3)] (4a ). To a solution of N,N-
dimethyl-2-iodoaniline (3a , 0.3 g, 1.21 mmol) in benzene (10
mL) were added Pd2(dba)3 (0.66 g, 0.72 mmol) and PPh3 (0.32
g, 1.22 mmol). The reddish reaction mixture was stirred at
room temperature for 3 days. The solvent was evaporated, and
the solid residue was purified by “flash” chromatography
(SiO2). Elution with hexane-EtOAc (3:2) afforded pure aza-
palladacycle 4a as an orange solid which was crystallized from
1
dichloromethane. Yield: 558 mg, 75%. Mp: 94-95 °C dec. H
NMR (CDCl3, 300 MHz): δ 3.11 (d, J (1H-31P) ) 3.3 Hz, 6H),
5.86 (dd, J ) 7.5 and 1 Hz, 1H), 6.65 (dd, J ) 7.8 and 7.5 Hz,
1H), 6.87 (dd, J ) 7.8 and 0.9 Hz, 1H), 7.03 (td, J ) 7.8 and
1.5 Hz, 1H), 7.35-7.50 (m, 9H), 7.68-7.77 (m, 6H). 13C NMR
(CDCl3, 75.5 MHz): δ 50.8 (s, CH3), 118.3 (s, CH), 124.6 (d,
J (13C-31P) ) 9.1 Hz, C), 125.1 (s, CH), 125.2 (d, J (13C-31P) )
3 Hz, CH), 128.0 (d, J (13C-31P) ) 11.1 Hz, CH PPh3), 128.7
(d, J (13C-31P) ) 7.1 Hz, CH), 130.7 (s, CH PPh3), 131.5 (d,
J (13C-31P) ) 52.2 Hz, C PPh3), 134.8 (d, J (13C-31P) ) 12.2
Hz, CH PPh3), 165.4 (s, C). 31P NMR (CDCl3, 121.5 MHz): δ
39.3. HRMS (FAB): m/z 488.0759 ([M - I]+, 488.0780 calcd
for C26H25NPPd). Anal. Calcd for C26H25INPPd (615.78)‚CH2-
Cl2: C, 46.28; H, 3.88; N, 2.00. Found: C, 46.28; H, 3.70; N,
1.97.
“F la sh ” Ch r om a togr a p h y of P a lla d iu m Com p lex 5a .
The palladium complex 5a (150 mg, 0.17 mmol) was submitted
to “flash” chromatography (SiO2, from hexane to 1:1 hexane-
EtOAc) to give 5a (38 mg, 25%) and azapalladacycle 4a (46
mg, 44%).
[P d {K2-C6H4N(Me)CH2P h -2}I(P P h 3)] (4b). Operating as
in the preparation of 4a , starting from 3b (150 mg, 0.46 mmol),
Pd2(dba)3 (240 mg, 0.26 mmol), and PPh3 (125 mg, 0.47 mmol),
azapalladacycle 4b was obtained after chromatography (SiO2,
from hexane to CH2Cl2). Yield: 290 mg, 91%. Azapalladacycle
4b was crystallized from hexane-EtOAc. Mp: 108-109 °C dec.
1H NMR (CDCl3, 300 MHz): δ 3.33 (d, J (1H-31P) ) 2.7 Hz,
3H), 4.04 (dd, J (1H-1H) ) 11.7 and J (1H-31P) ) 9 Hz, 1H),
4.54 (d, J ) 11.7 Hz, 1H), 5.62 (d, J ) 7.2 Hz, 1H), 6.50 (ddt,
J ) 7.5, 7.2, and 1 Hz, 1H), 6.94 (dd, J ) 7.8 and 1.2 Hz, 1H),
7.01 (ddd, J ) 7.8, 7.2, and 1.2 Hz, 1H), 7.20-7.50 (m, 18H),
7.61 (dd, J ) 7 and 1 Hz, 2H). 13C NMR (CDCl3, 75.5 MHz):
δ 50.4 (s, CH3), 64.1 (s, CH2), 119.7 (s, CH), 124.6 (s, CH), 125.1
(d, J (13C-31P) ) 3 Hz, CH), 126.0 (d, J (13C-31P) ) 11.6 Hz,
C), 127.7 (s, CH), 127.8 (s, CH), 127.9 (d, J (13C-31P) ) 10.9
“F la sh ” Ch r om a togr a p h y of P a lla d iu m Com p lex 5b.
The palladium complex 5b (200 mg, 0.21 mmol) was submitted
to “flash” chromatography (SiO2, from hexane to 1:1 hexane-
EtOAc) to give 5b (30 mg, 15%), azapalladacycle 4b (92 mg,
63%), and hydroxopalladium complex 6 (16 mg, 13%).
[P d {K2-C6H 4N(Me)CH 2P h -2}OH (P P h 3)] (6). 1H NMR
(CDCl3, 300 MHz): δ 3.29 (d, J (1H-31P) ) 3 Hz, 3H), 4.01 (dd,
J (1H-1H) ) 11.4 and J (1H-31P) ) 8.4 Hz, 1H), 4.52 (d, J )
11.4 Hz, 1H), 5.53 (d, J ) 7.8 Hz, 1H), 6.48 (m, 1H), 6.93-
7.04 (m, 2H), 7.20-7.46 (m, 18H), 7.55-7.75 (m, 2H). 13C NMR
(CDCl3, 75.5 MHz): δ 49.0 (s, CH3), 63.2 (s, CH2), 118.9 (s,
CH), 124.5 (s, CH), 125.1 (s, CH), 127.8 (s, CH), 127.9 (s, CH),
128.0 (d, J (13C-31P) ) 11.6 Hz, CH PPh3), 129.5 (d, J (13C-

Four-Membered Azapalladacycles
Organometallics, Vol. 23, No. 6, 2004 1445
31P) ) 7.6 Hz, CH), 130.5 (d, J (13C-31P) ) 51.1 Hz, C PPh3),
130.6 (s, CH), 132.6 (s, CH), 134.8 (d, J (13C-31P) ) 12.6 Hz,
CH PPh3), 135.5 (s, C), 160.5 (s, C), one C not observed. 31P
NMR (CDCl3, 121.5 MHz): δ 35.7.
residue afforded palladacycle 8a . Yield: 37 mg, 72%. Mp: 86-
87 °C. IR (film): 1666, 1479, 1435 cm-1. 1H NMR (CDCl3, 300
MHz): δ 3.58 (d, J (1H-31P) ) 1.8 Hz, 6H), 7.23 (t, J ) 7.5 Hz,
1H), 7.29-7.45 (m, 10H), 7.58 (ddd, J ) 8.1, 7.5, and 1.5 Hz,
1H), 7.65 (d, J ) 7.5 Hz, 1H), 7.70-7.80 (m, 6H). 13C NMR
(CDCl3, 75.5 MHz): δ 54.3 (s, CH3), 120.4 (d, J (13C-31P) ) 2.8
Hz, CH), 125.4 (s, CH), 127.9 (d, J (13C-31P) ) 11 Hz, CH PPh3),
128.5 (s, CH), 130.1 (d, J (13C-31P) ) 2.2 Hz, CH PPh3), 132.5
(d, J (13C-31P) ) 50.1 Hz, C PPh3), 134.1 (s, CH), 134.7
(d, J (13C-31P) ) 12.1 Hz, CH PPh3), 140.8 (d, J (13C-31P) )
9.9 Hz, C), 156.7 (d, J (13C-31P) ) 2.5 Hz, C), 209.8 (d,
J (13C-31P) ) 14.3 Hz, C). 31P NMR (CDCl3, 121.5 MHz): δ
40.0. Anal. Calcd for C27H25INOPPd (643.78): C, 50.37; H, 3.91;
N, 2.18. Found: C, 50.25; H, 4.13; N, 2.03.
[P d {K2-C(O)C6H4N(Me)CH2P h -2}I(P P h 3)] (8b). Operat-
ing as in the preparation of 8a , starting from 4b (27 mg, 0.04
mmol), azapalladacycle 8b was obtained after chromatography
(SiO2, from hexane to 1:1 hexane-EtOAc). Yield: 18 mg, 64%.
Azapalladacycle 8b was crystallized from EtOAc. Mp: 140-
142 °C. 1H NMR (CDCl3, 300 MHz): δ 3.92 (d, J (1H-31P) )
1.8 Hz, 3H), 4.08 (dd, J ) 11.7 Hz and J (1H-31P) ) 6 Hz, 1H),
5.56 (d, J ) 11.7 Hz, 1H), 6.98-7.09 (m, 3H), 7.15-7.22 (m,
2H), 7.28-7.43 (m, 12H), 7.55-7.67 (m, 6H), 7.80 (d, J ) 8.1
Hz, 1H). 13C NMR (CDCl3, 75.5 MHz): δ 53.5 (s, CH3), 67.4 (s,
CH2), 121.5 (d, J (13C-31P) ) 2.5 Hz, CH), 124.9 (s, CH), 127.8
(d, J (13C-31P) ) 10.4 Hz, CH PPh3), 127.9 (s, CH), 128.4 (s,
CH), 128.6 (s, CH), 130.0 (d, J (13C-31P) ) 2.2 Hz, CH PPh3),
131.5 (s, CH), 132.5 (d, J (13C-31P) ) 49.5 Hz, C PPh3), 133.7
(s, CH), 134.5 (s, C), 134.7 (d, J (13C-31P) ) 11.6 Hz, CH PPh3),
142.9 (d, J (13C-31P) ) 9.9 Hz, C), 153.3 (d, J (13C-31P) ) 1.5
Hz, C), 207.6 (d, J (13C-31P) ) 14 Hz, C). 31P NMR (CDCl3,
121.5 MHz): δ 38.6.
[P d P h I(P NMe2)] (7a ).16 A solution of azapalladacycle 4a
(20 mg, 0.032 mmol) in THF (5 mL) was stirred at 110 °C in
a sealed tube for 36 h. The solvent was evaporated, and the
residue was purified by flash chromatography (SiO2, CH2Cl2)
to give palladium complex 7a as an 10:1 mixture of the
transP,I and cisP,I isomers. Yield: 11 mg, 55%. transP,I
isomer: 1H NMR (CDCl3, 400 MHz): δ 3.40 (s, 6H), 6.64-
6.74 (m, 3H), 6.94 (m, 2H), 7.28-7.39 (m, 10H), 7.42-7.48 (m,
2H), 7.59 (tt, J ) 8.4 and 1.2 Hz, 1H), 7.69 (dd, J ) 8.4 and
4.4 Hz, 1H). 13C NMR (CDCl3, 100.6 MHz): δ 53.8 (s, CH3),
122.5 (s, CH), 123.0 (d, J (13C-31P) ) 10 Hz, CH), 126.6 (d,
J (13C-31P) ) 1.5 Hz, CH), 128.4 (d, J (13C-31P) ) 6.1 Hz, CH),
128.7 (d, J (13C-31P) ) 10.7 Hz, CH), 129.1 (d, J (13C-31P) )
53.7 Hz, C), 130.9 (d, J (13C-31P) ) 3.1 Hz, CH), 131.1 (d,
J (13C-31P) ) 46.5 Hz, C), 133.2 (d, J (13C-31P) ) 12.3 Hz, CH),
133.3 (d, J (13C-31P) ) 1.5 Hz, CH), 134.4 (s, CH), 137.7 (d,
J (13C-31P) ) 4.6 Hz, CH), 138.7 (s, C), 159.5 (d, J (13C-31P) )
18.4 Hz, C). 31P NMR (CDCl3, 121.5 MHz): δ 23.7. cisP,I
isomer: 31P NMR (CDCl3, 121.5 MHz): δ 36.5.
[P d P h I{P N(Me)P r }] (7c).41 A solution of azapalladacycle
4c (25 mg, 0.039 mmol) in toluene (10 mL) was stirred at
110 °C in a sealed tube for 24 h. The solvent was evaporated,
and the residue was purified by flash chromatography (SiO2,
from hexane to 1:1 hexane-EtOAc). Elution with hexane-
EtOAc (4:1) afforded azapalladacycle 7c-transP,I. Yield: 8 mg,
32%. Elution with hexane-EtOAc (3:2) afforded azapallada-
cycle 7c-cisP,I. Yield: 2 mg, 8%. transP,I isomer: 1H NMR
(CDCl3, 400 MHz): δ 0.91 (t, J ) 7.2 Hz, 3H), 1.03 (m, 1H),
2.42 (m, 1H), 3.19 (td, J ) 11.6 and 4 Hz, 1H), 3.33 (s, 3H),
4.40 (td, J ) 11.6 and 4.8 Hz, 1H), 6.65-6.74 (m, 3H), 6.94
(m, 2H), 7.07-7.13 (m, 2H), 7.27-7.49 (m, 10H), 7.57-7.68
(m, 2H). 13C NMR (CDCl3, 100.6 MHz): δ 11.2 (s, CH3), 21.7
(s, CH2), 54.1 (s, CH3), 64.9 (s, CH2), 122.4 (s, CH), 122.9 (d,
J (13C-31P) ) 10 Hz, CH), 126.7 (s, CH), 128.4 (d, J (13C-31P)
) 6.1 Hz, CH), 128.5 (d, J (13C-31P) ) 10.8 Hz, CH), 128.8 (d,
J (13C-31P) ) 11.5 Hz, CH), 129.9 (d, J (13C-31P) ) 53 Hz, C),
130.7 (d, J (13C-31P) ) 3 Hz, CH), 131.0 (d, J (13C-31P) ) 3 Hz,
CH), 133.0 (d, J (13C-31P) ) 12.2 Hz, CH), 133.1 (d, J (13C-
31P) ) 50 Hz, C), 133.4 (d, J (13C-31P) ) 1.5 Hz, CH), 133.4
(d, J (13C-31P) ) 12.3 Hz, CH), 134.4 (s, CH), 137.7 (d,
J (13C-31P) ) 4.5 Hz, CH), 139.3 (d, J (13C-31P) ) 2.3 Hz, C),
157.3 (d, J (13C-31P) ) 18.4 Hz, C). 31P NMR (CDCl3, 121.5
MHz): δ 27.3. MS(FAB): m/z 1161 [2M+ + 2 - I], 1084
[2M+ + 2 - I - C6H5], 566 [M+ - C6H5], 516 [M+ - I], 439
[M+ - I - C6H5]. cisP,I isomer: 1H NMR (CDCl3, 400 MHz):
δ 0.87 (t, J ) 7.2 Hz, 3H), 0.98 (m, 1H), 2.45 (m, 1H), 3.31 (td,
J ) 12 and 4.4 Hz, 1H), 3.57 (s, 3H), 4.83 (td, J ) 12 and 4.8
Hz, 1H), 7.31 (m, 1H), 7.38 (m, 1H), 7.41-7.49 (m, 6H), 7.50-
7.57 (m, 3H), 7.61-7.70 (m, 3H), 7.75-7.85 (m, 5H). 13C NMR
(CDCl3, 100.6 MHz): δ 10.8 (s, CH3), 21.9 (s, CH2), 57.1
(s, CH3), 67.8 (s, CH2), 122.2 (d, J (13C-31P) ) 12.3 Hz, CH),
128.7 (d, J (13C-31P) ) 11.6 Hz, CH), 128.8 (d, J (13C-31P) )
12.2 Hz, CH), 129.7 (d, J (13C-31P) ) 5.3 Hz, CH), 130.3 (d,
J (13C-31P) ) 59 Hz, C), 131.8-132.1 (several CH), 134.0-134.5
(several CH), 157.9 (d, J (13C-31P) ) 17.6 Hz, C). 31P NMR
(CDCl3, 121.5 MHz): δ 40.6. MS(FAB): m/z 566 [M+ - C6H5],
439 [M+ - I - C6H5].
[P d {K2-C(O)C6H4N(Me)P r -2}I(P P h 3)] (8c). Operating as
in the preparation of 8a , starting from 4c (32 mg, 0.05 mmol)
and stirring the reaction mixture at room temperature for 41
h, azapalladacycle 8c was obtained after chromatography
(SiO2, from hexane to 1:1 hexane-EtOAc). Yield: 23 mg, 69%.
Azapalladacycle 8b was crystallized from dichloromethane. IR
1
(film): 1665, 1435, 1095 cm-1. H NMR (CDCl3, 300 MHz): δ
0.90 (t, J ) 7.2 Hz, 3H), 1.09 (m, 1H), 2.34 (m, 1H), 3.08 (m,
1H), 3.61 (d, J ) 1.5 Hz, 3H), 4.51 (td, J ) 12 and 4.5 Hz,
1H), 7.23 (m, 1H), 7.31-7.45 (m, 9H), 7.58-7.61 (m, 2H),
7.68-7.77 (m, 6H). 13C NMR (CDCl3, 75.5 MHz): δ 11.1
(s, CH3), 22.2 (s, CH2), 54.2 (s, CH3), 65.6 (s, CH2), 120.6 (d,
J (13C-31P) ) 3 Hz, CH), 125.2 (s, CH), 127.9 (d, J (13C-31P) )
11.1 Hz, CH PPh3), 128.5 (s, CH), 130.1 (d, J (13C-31P) ) 2 Hz,
CH PPh3), 132.7 (d, J (13C-31P) ) 49.7 Hz, C PPh3), 134.3 (s,
CH), 134.7 (d, J (13C-31P) ) 11.6 Hz, CH PPh3), 142.7 (d,
J (13C-31P) ) 9.7 Hz, C), 154.4 (d, J (13C-31P) ) 3 Hz, C), 209.4
(d, J (13C-31P) ) 14.2 Hz, C). 31P NMR (CDCl3, 121.5 MHz): δ
43.2. Anal. Calcd for C29H29INOPPd (671.85)‚3/4CH2Cl2: C,
48.58; H, 4.18; N, 1.90. Found: C, 48.18; H, 4.21; N, 1.77.
[P d {K2-CH(CO2Et)C6H4NMe2-2}I(P P h 3)] (9a ). To a solu-
tion of azapalladacycle 4a (30 mg, 0.05 mmol) in benzene (10
mL) was added ethyl diazoacetate (0.55 mmol, 1.1 mL of 0.5
M solution in benzene). The mixture was stirred at room
temperature for 24 h under argon, and the solvent was
evaporated. Chromatography (SiO2, from hexane to 4:1 hex-
ane-EtOAc) of the residue afforded palladacycle 9a , which was
crystallized from Et2O-EtOAc. Yield: 20 mg, 56%. Mp: 187-
188 °C. IR (film): 1681, 1436, 1146 cm-1 1H NMR (CDCl3,
.
300 MHz): δ 0.87 (t, J ) 7.2 Hz, 3H), 3.42 (d, J (1H-31P) ) 5.7
Hz, 3H), 3.42 (masked, 1H), 3.55 (s, 3H), 3.65 (dq, J ) 10.8
and 7.2 Hz, 1H), 4.01 (dq, J ) 10.8 and 7.2 Hz, 1H), 6.75 (dd,
J ) 7.5 and 1.2 Hz, 1H), 7.05 (td, J ) 7.5 and 1.2 Hz, 1H),
7.21 (ddd, J ) 8.1, 7.5, and 1.2 Hz, 1H), 7.35 (dd, J ) 8.1 and
1.2 Hz, 1H), 7.37-7.50 (m, 9H), 7.77-7.88 (m, 6H). 13C NMR
(CDCl3, 75.5 MHz): δ 13.9 (s, CH3), 51.6 (s, CH), 52.1 (s, CH3),
55.7 (s, CH3), 59.9 (s, CH2), 121.5 (s, CH), 127.4 (s, CH), 127.5
(s, CH), 127.8 (d, J (13C-31P) ) 10.6 Hz, CH PPh3), 129.0 (s,
CH), 130.5 (s, CH), 132.2 (d, J (13C-31P) ) 52.2 Hz, C PPh3),
[P d{K2-C(O)C6H4NMe2-2}I(P P h 3)] (8a). KOt-Bu (1.6 mmol,
1.6 mL of 1 M solution in tert-butyl alcohol) was added to
CHCl3 (10 mL). After 5 min at room temperature, a solution
of palladacycle 4a (49 mg, 0.08 mmol) in CHCl3 (5 mL) was
added dropwise. The mixture was stirred at room temperature
for 5 h under argon, and the solvent was evaporated. Chro-
matography (SiO2, from hexane to 1:1 hexane-EtOAc) of the
(41) PN(Me)Pr means N-methyl-N-propyl-2-(diphenylphosphanyl)-
aniline.

1446 Organometallics, Vol. 23, No. 6, 2004
Sole´ et al.
Ta ble 1. Selected Cr ysta llogr a p h ic Da ta of Com p lexes 4b, 8b‚EtOAc, 9a , 9b, a n d 9c‚Et2O
4b
8b‚0.5EtOAc
9a
9b
9c‚Et2O
formula
fw
C
32H29INPPd
C35H33INO2PPd
763.90
C30H31INO2PPd
701.83
C36H35INO2PPd
777.92
C36H45INO3PPd
804.00
691.85
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
triclinic
P1h
monoclinic
P21/n
9.5280(10)
26.6000(10)
12.8330(10)
90
101.9260(10)
90
3182.3(4)
4
monoclinic
P21/n
11.9350(10)
14.3460(10)
16.9290(10)
90
92.27(2)
90
2896.3(4)
4
monoclinic
P21/c
16.9770(10)
10.1480(10)
21.7403(8)
90
121.688(3)
90
3187.1(4)
4
orthorhombic
Pbca
20.3370(10)
14.7750(10)
23.6080(10)
90
10.4880(10)
13.6220(10)
19.1130(10)
100.81(2)
91.99(2)
97.95(2)
2651.2(3)
4
90
90
7093.7(7)
8
1.506
Z
D
calcd, Mg/m3
1.733
1.594
1.610
1.621
F(000)
1368
1520
1392
1552
3248
cryst size, mm
θ range, deg
0.2 × 0.1 × 0.1
1.09-25.00
7042
6992 (0.0642)
0.0472
0.1 × 0.1 × 0.2
1.79-31.55
27 490
9233 (0.0454)
0.0321
0.1 × 0.1 × 0.2
2.05-28.92
10 477
4698 (0.0429)
0.0645
0.1 × 0.1 × 0.2
1.89-31.59
20 290
8363 (0.0219)
0.0338
0.1 × 0.1 × 0.2
2.42-31.74
24 044
8028 (0.0905)
0.0760
no. of reflns collected
no. of indep reflns (Rint
R1 (I > 2σ(I))
)
wR2 (I > 2σ(I))
0.1121
1.017
0.0790
1.109
0.2142
1.179
0.0917
1.221
0.1550
0.872
goodness of fit on F2
135.3 (d, J (13C-31P) ) 11 Hz, CH PPh3), 141.1 (s, C), 155.6 (s,
C), 174.2 (s, C). 31P NMR (CDCl3, 121.5 MHz): δ 31.2. Anal.
Calcd for C30H31INO2PPd: C, 51.34; H, 4.45; N, 2.00. Found:
C, 51.43; H, 4.42; N, 1.90.
[P d {K2-CH(SiMe3)C6H4NMe2-2}I(P P h 3)] (10a ). To a solu-
tion of azapalladacycle 4a (25 mg, 0.04 mmol) in benzene
(10 mL) was added trimethylsilyl diazomethane (0.13 mmol,
65 µL of 2 M solution in hexane). The mixture was stirred at
room temperature for 24 h under argon, and the solvent was
evaporated. Chromatography (SiO2, from hexane to 1:1 hex-
ane-EtOAc) of the residue afforded palladacycle 10a . Yield:
26 mg, 95%. 1H NMR (CDCl3, 300 MHz): δ -0.22 (s, 9H), 2.72
(d, J (1H-31P) ) 6.6 Hz, 1H), 3.37 (d, J (1H-31P) ) 3.3 Hz, 3H),
3.50 (d, J (1H-31P) ) 1.5 Hz, 3H), 6.65 (dd, J ) 7.5 and 1.2 Hz,
1H), 6.98 (td, J ) 7.5 and 1.2 Hz, 1H), 7.07 (td, J ) 7.5 and
1.2 Hz, 1H), 7.27 (d, J ) 7.5 Hz, 1H), 7.35-7.548 (m, 9H),
7.75-7.84 (m, 6H). 13C NMR (CDCl3, 75.5 MHz): δ 1.52 (s,
CH3), 1.54 (s, CH3), 50.4 (d, J (13C-31P) ) 2.6 Hz, CH3),
51.4 (s, CH), 57.4 (s, CH3), 121.5 (s, CH), 124.7 (s, CH), 127.0
(s, CH), 127.4 (s, CH), 127.9 (d, J (13C-31P) ) 10.6 Hz, CH
PPh3), 130.4 (d, J (13C-31P) ) 2.6 Hz, CH PPh3), 132.4 (d,
J (13C-31P) ) 48.7 Hz, C PPh3), 135.3 (d, J (13C-31P) ) 10.6
Hz, CH PPh3), 148.5 (s, C), 152.3 (s, C).31P NMR (CDCl3, 121.5
MHz): δ 35.2.
[P d{K2-CH(CO2Et)C6H4N(Me)CH2P h -2}I(P P h 3)] (9b). Op-
erating as in the preparation of 9a , starting from 4b (36 mg,
0.05 mmol) and stirring the reaction mixture at room temper-
ature for 36 h, azapalladacycle 9b was obtained after chro-
matography (SiO2, from hexane to 4:1 hexane-EtOAc).
Yield: 20 mg, 51%. Azapalladacycle 9b was crystallized from
1
Et2O-EtOAc. H NMR (CDCl3, 400 MHz): δ 0.73 (t, J ) 7.2
Hz, 3H), 3.15 (d, J (1H-31P) ) 6 Hz, 1H), 3.45 (dq, J ) 10.8
and 7.2 Hz, 1H), 3.72 (d, J (1H-31P) ) 2.8 Hz, 3H), 3.83 (dq,
J ) 10.8 and 7.2 Hz, 1H), 4.53 (dd, J (1H-1H) ) 13.2 and J (1H-
31P) ) 7.6 Hz, 1H), 5.45 (d, J ) 13.2 Hz, 1H), 6.70 (dd, J )
7.5 and 1.2 Hz, 1H), 7.07 (td, J ) 7.5 and 1.2 Hz, 1H), 7.14-
7.50 (m, 15H), 7.56-7.64 (m, 5H), 7.83-7.89 (m, 2H). 13C
NMR (CDCl3, 100.6 MHz): δ 13.7 (s, CH3), 51.2 (s, CH),
52.7 (d, J (13C-31P) ) 3.1 Hz, CH3), 59.8 (s, CH2), 67.4 (d,
J (13C-31P) ) 1.5 Hz, CH2), 122.5 (s, CH), 127.6 (s, CH), 127.7
(s, CH), 127.8 (d, J (13C-31P) ) 10.8 Hz, CH PPh3), 127.9 (s,
CH), 129.1 (s, CH), 130.3 (d, J (13C-31P) ) 2.2 Hz, CH PPh3),
130.9 (s, CH), 131.9 (d, J (13C-31P) ) 51.4 Hz, C PPh3), 132.9
(s, CH), 135.1 (d, J (13C-31P) ) 10.7 Hz, CH PPh3), 135.8 (s,
C), 143.4 (s, C), 153.0 (d, J (13C-31P) ) 2.3 Hz, C), 174.7 (s, C).
31P NMR (CDCl3, 121.5 MHz): δ 33.3.
[P d {K2-CH(SiMe3)C6H4N(Me)P r -2}I(P P h 3)] (10c). Oper-
ating as in the preparation of 10a , starting from 4c (25 mg,
0.039 mmol), azapalladacycle 10c was obtained after chroma-
tography (SiO2, from hexane to 1:1 hexane-EtOAc). Yield: 16
mg, 57%. Azapalladacycle 10c was crystallized from Et2O-
1
EtOAc. H NMR (CDCl3, 300 MHz): δ -0.27 (s, 9H), 0.84 (t,
J ) 7.2 Hz, 3H), 0.95 (m, 1H), 2.50 (m, 1H), 2.84 (d, J (1H-
31P) ) 6.3 Hz, 1H), 3.04 (m, 1H), 3.35 (d, J (1H-31P) ) 2.7 Hz,
3H), 4.43 (td, J ) 11.7 and 3.9 Hz, 1H), 6.65 (d, J ) 7.5 Hz,
1H), 6.95 (td, J ) 7.5 and 1.2 Hz, 1H), 7.05 (td, J ) 7.5 and
1.2 Hz, 1H), 7.16 (d, J ) 7.5 Hz, 1H), 7.35-7.49 (m, 9H), 7.73-
7.84 (m, 6H). 13C NMR (CDCl3, 63 MHz): δ 1.62 (s, CH3), 11.3
(s, CH3), 21.1 (s, CH2), 50.2 (s, CH3), 50.7 (s, CH), 68.5 (s, CH2),
121.3 (s, CH), 125.0 (s, CH), 126.8 (s, CH), 126.9 (s, CH), 127.9
(d, J (13C-31P) ) 10.3 Hz, CH PPh3), 130.3 (d, J (13C-31P) )
2.4 Hz, CH PPh3), 132.4 (d, J (13C-31P) ) 47.9 Hz, C PPh3),
135.5 (d, J (13C-31P) ) 10.9 Hz, CH PPh3), 149.5 (s, C), 150.9
(s, C). 31P NMR (CDCl3, 121.5 MHz): δ 33.0. Anal. Calcd for
[P d {K2-CH(CO2Et)C6H4N(Me)P r -2}I(P P h 3)] (9c). Oper-
ating as in the preparation of 9a , starting from 4c (35 mg,
0.05 mmol) and stirring the reaction mixture at room temper-
ature for 72 h, azapalladacycle 9c was obtained after chro-
matography (SiO2, from hexane to 4:1 hexane-EtOAc).
Yield: 13 mg, 33%. Azapalladacycle 9c was crystallized from
1
Et2O-EtOAc. Mp: 156-158 °C. H NMR (CDCl3, 300 MHz):
δ 0.84 (t, J ) 7.2 Hz, 3H), 0.95 (t, J ) 7.2 Hz, 3H), 1.25 (m,
1H), 2.61 (m, 1H), 3.22 (m, 1H), 3.43 (d, J (1H-31P) ) 2.7 Hz,
3H), 3.43 (masked, 1H), 3.60 (dq, J ) 10.8 and 7.2 Hz, 1H),
3.98 (dq, J ) 10.8 and 7.2 Hz, 1H), 4.41 (td, J ) 11.7 and 3.9
Hz, 1H), 6.76 (d, J ) 7.5 Hz, 1H), 7.03 (td, J ) 7.5 and 1.2 Hz,
1H), 7.21 (td, J ) 7.5 and 1.2 Hz, 1H), 7.26 (d, J ) 7.5 Hz,
1H), 7.36-7.50 (m, 9H), 7.77-7.87 (m, 6H). 13C NMR (CDCl3,
100.6 MHz): δ 10.9 (s, CH3), 13.9 (s, CH3), 21.7 (s, CH2), 50.9
(s, CH), 51.8 (d, J (13C-31P) ) 2.3 Hz, CH3), 59.9 (s, CH2), 66.9
(d, J (13C-31P) ) 2.3 Hz, CH2), 121.3 (s, CH), 127.3 (s, CH),
127.7 (s, CH), 127.9 (d, J (13C-31P) ) 10.8 Hz, CH PPh3), 129.0
(s, CH), 130.4 (d, J (13C-31P) ) 2.3 Hz, CH PPh3), 132.3 (d,
J (13C-31P) ) 52.1 Hz, C PPh3), 135.3 (d, J (13C-31P) ) 10.8
Hz, CH PPh3), 142.8 (s, C), 152.9 (d, J (13C-31P) ) 3 Hz, C),
174.5 (s, C). 31P NMR (CDCl3, 121.5 MHz): δ 33.1.
C
32H39INPPdSi (730.04)‚2Et2O: C, 54.70; H, 6.77; N, 1.59.
Found: C, 54.89; H, 6.51; N, 1.75.
N-Ben zyl-N-m eth yl-2-[(Z)-2-(tr im eth ylsilyl)vin yl]a n i-
lin e (11b). Operating as in the preparation of 10a , starting
from 4b (25 mg, 0.036 mmol), 11b was obtained after chro-
matography (SiO2, from hexane to 1:1 hexane-EtOAc).
Yield: 8 mg, 73%. 1H NMR (CDCl3, 300 MHz): δ 0.05 (s, 9H),
2.62 (s, 3H), 4.14 (s, 2H), 5.82 (d, J ) 15 Hz, 1H), 6.98 (d, J )
8.1 Hz, 1H), 7.00 (m, 1H), 7.20-7.40 (m, 7H), 7.60 (d, J ) 15
Hz, 1H). 13C NMR (CDCl3, 75.5 MHz): δ 0.3 (CH3), 40.2 (CH3),

Four-Membered Azapalladacycles
Organometallics, Vol. 23, No. 6, 2004 1447
60.4 (CH2), 118.6 (CH), 121.4 (CH), 126.9 (CH), 128.2 (CH),
128.3 (CH), 128.4 (CH), 130.2 (CH), 130.3 (CH), 134.1 (C),
138.7 (C), 146.0 (CH), 151.2 (CH). HRMS (FAB): m/z 295.1756
(M+, 295.1764 calcd for C19H25NSi).
Cr ystallogr aph y. Intensities were collected with a MAR345
diffractometer with an image plate detector, and cell param-
eters were determined from all measured intensities. The
structures were solved by direct methods, using the SHELXS-
97 computer program, and refined by full-matrix least-squares
method with the SHELXL97 computer program.42 Crystal data
for complexes 4b, 8b‚0.5EtOAc, 9a , 9b, and 9c‚Et2O are listed
in Table 1, and their ORTEP plots are shown in Figures 1-5,
respectively (H atoms and solvents are omitted for clarity).
Other crystallographic data are deposited as Supporting
Information.
Ack n ow led gm en t. This work was supported by
MCYT, Spain (Project BQU2001-3551). Thanks are also
given to the DURSI (Catalonia) for Grant 2001SGR-
00083 and a fellowship to L.V.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data of 4b, 8b‚EtOAc, 9a , 9b, and 9c‚Et2O are given in PDF
and CIF formats. 1H and 13C NMR spectra for compounds 4a -
c, 5a ,b, 6, 7a ,c, 8a -c, 9a -c, and 10a ,c are also provided. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(42) Sheldrick, G. M. SHELXL97, computer program for the deter-
mination of crystal structure; University of Go¨ttingen: Germany, 1997.
OM034270C