Palladium-assisted formation of carbon-carbon bonds. 7.1 reactions of (2,3,4-trimethoxy-6-X-phenyl)palladium complexes with alkynes (X = C(O)NHBut) and isocyanides (X = C(O)NHBut, C(O)Me, CHO): Crystal and molecular structures of [Pd{C6H{C(O)NHBut}-6-(OMe) 3-2,3,4}(bpy)](CF3SO3)

Article abstract of DOI:10.1021/om970426v

The mercuriation of 3,4,5-trimethoxy(N-tert-butylcarbamoyl)benzene with mercury(II) acetate and subsequent reaction with KCl leads to the formation of [Hg{C₆H{C(O)NHBu^t}- 6-(OMe)₃-2,3,4}Cl] (1), which is symmetrized with [NMe₄]Cl to give [Hg{C₆H{C(O)NHBu^t)- 6-(OMe)₃-2,3,4}₂] (2). The reaction of 2 with [PdCl₂(MeCN)₂] and 2,2′-bipyridine (bpy) affords [Pd(C₆H{C(O)NHBu^t}-6-(OMe)₃-2,3,4)Cl(bpy)] (3), which reacts with Tl(CF₃SO₃) giving [Pd-{C₆H{C(O)NHBu^t}}(bPy)](CF₃SO₃) (4). Complex 2 reacts with [PdCl₂(MeCN)₂] and acetylenes RC≡CR to give metallic palladium and the spirocyclic compound 10-(N-tert-butylcarbamoyl)- 6,7-dimethoxy-1,2,3,4-tetraphenylspiro[4.5]-1,3,6,9-decatetraen-8-one (5) when R = Ph or the monoinserted palladium complex [Pd{C(CO₂Me)=C(CO₂Me)C₆H{C(O)NHBu ^t)-6-(OMe)₃- 2,3,4}(u-Cl)]₂ (6) when R = CO₂Me. By reaction of 6 with L (1:2) or PPh₃ and Tl(CF₃SO₃) (1:4:2), the complexes [Pd{C(CO₂Me)=C(CO₂Me)C₆H{C(O)NHBu ^t}-6-(OMe)₃-2,3,4}Cl(L)] (L = PPh₃ (7), CNXy (8) (Xy = 2,6-dimethylphenyl)) or [Pd{C(CO₂Me)=C(CO₂Me)C₆H{C(O)- NHBu^t}-6-(OMe)₃-2,3,4}(PPh₃) ₂](CF₃SO₃) (9) are obtained respectively. The reactions of 4 and of the related complexes [Pd{C₆H{C(O)Me}-6-(OMe)₃-2,3,4}(bpy)](CF ₃SO₃) (10) or [Pd- {C₆H{C(O)H}-6-(OMe)₃-2,3,4}(NCMe)(bpy)](CF ₃SO₃) (11) with CNXy have also been studied, the following compounds being isolated: [Pd{C(=NXy)C₆H{C(O)NHBu^t}-6-(OMe)₃-2,3,4}- (bpy)](CF₃SO₃) (12) [Pd{C₆H{C(O)Me}-6-(OMe)₃-2,3,4}(CNXy)(bpy)](CF ₃SO₃) (13), [Pd- {C₆H{C(O)H}-6-(OMe)₃-2,3,4}(CNXy)(bpy)](CF ₃SO₃) (14), and the ketenimine 2-(2,6- dimethylphenyl)-1-(((2,6-dimethylphenyl)imino)methylene)-5,6,7-trimethoxy-3- oxoiso- indoline (15). The structures of 4, 7, 12, and 15 have been determined by X-ray crystallography.

Full text of DOI:10.1021/om970426v

Organometallics 1997, 16, 4557-4566
4557
P a lla d iu m -Assisted F or m a tion of Ca r bon -Ca r bon Bon d s.
7.1 Rea ction s of (2,3,4-Tr im eth oxy-6-X-p h en yl)p a lla d iu m
Com p lexes w ith Alk yn es (X ) C(O)NHBu t) a n d
Isocya n id es (X ) C(O)NHBu t, C(O)Me, CHO): Cr ysta l
a n d Molecu la r Str u ctu r es of
[P d {C6H{C(O)NHBu t}-6-(OMe)3-2,3,4}(bp y)](CF 3SO3),
[P d {C(CO2Me)dC(CO2Me)C6H{C(O)NHBu t}-6-(OMe)3-2,3,4)}-
Cl(P P h 3)], [P d {C(dNXy)C6H{C(O)NHBu t}-6-(OMe)3-2,3,4}-
(bp y)](CF 3SO3), a n d th e Keten im in e
2-(2,6-Dim eth ylp h en yl)-1-(((2,6-d im eth ylp h en yl)im in o)-
m eth ylen e)-5,6,7-tr im eth oxy-3-oxoisoin d olin e
J ose´ Vicente,*,† J ose´-Antonio Abad,*,‡ Kenneth F. Shaw, J uan Gil-Rubio, and
M. Carmen Ram´ırez de Arellano
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica,
Universidad de Murcia, Aptdo. 4021, Murcia, 30071 Spain
Peter G. J ones*,|
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Received May 23, 1997X
The mercuriation of 3,4,5-trimethoxy(N-tert-butylcarbamoyl)benzene with mercury(II)
acetate and subsequent reaction with KCl leads to the formation of [Hg{C6H{C(O)NHBut}-
6-(OMe)3-2,3,4}Cl] (1), which is symmetrized with [NMe4]Cl to give [Hg{C6H{C(O)NHBut}-
6-(OMe)3-2,3,4}2] (2). The reaction of 2 with [PdCl2(MeCN)2] and 2,2′-bipyridine (bpy) affords
[Pd(C6H{C(O)NHBut}-6-(OMe)3-2,3,4)Cl(bpy)] (3), which reacts with Tl(CF3SO3) giving [Pd-
{C6H{C(O)NHBut}}(bpy)](CF3SO3) (4). Complex 2 reacts with [PdCl2(MeCN)2] and acetylenes
RCtCR to give metallic palladium and the spirocyclic compound 10-(N-tert-butylcarbamoyl)-
6,7-dimethoxy-1,2,3,4-tetraphenylspiro[4.5]-1,3,6,9-decatetraen-8-one (5) when R ) Ph or
the monoinserted palladium complex [Pd{C(CO2Me)dC(CO2Me)C6H{C(O)NHBut}-6-(OMe)3-
2,3,4}(µ-Cl)]2 (6) when R ) CO2Me. By reaction of 6 with L (1:2) or PPh3 and Tl(CF3SO3)
(1:4:2), the complexes [Pd{C(CO2Me)dC(CO2Me)C6H{C(O)NHBut}-6-(OMe)3-2,3,4}Cl(L)] (L
) PPh3 (7), CNXy (8) (Xy ) 2,6-dimethylphenyl)) or [Pd{C(CO2Me)dC(CO2Me)C6H{C(O)-
NHBut}-6-(OMe)3-2,3,4}(PPh3)2](CF3SO3) (9) are obtained respectively. The reactions of 4
and of the related complexes [Pd{C6H{C(O)Me}-6-(OMe)3-2,3,4}(bpy)](CF3SO3) (10) or [Pd-
{C6H{C(O)H}-6-(OMe)3-2,3,4}(NCMe)(bpy)](CF3SO3) (11) with CNXy have also been studied,
the following compounds being isolated: [Pd{C(dNXy)C6H{C(O)NHBut}-6-(OMe)3-2,3,4}-
(bpy)](CF3SO3) (12) [Pd{C6H{C(O)Me}-6-(OMe)3-2,3,4}(CNXy)(bpy)](CF3SO3) (13), [Pd-
{C6H{C(O)H}-6-(OMe)3-2,3,4}(CNXy)(bpy)](CF3SO3) (14), and the ketenimine 2-(2,6-
dimethylphenyl)-1-(((2,6-dimethylphenyl)imino)methylene)-5,6,7-trimethoxy-3-oxoiso-
indoline (15). The structures of 4, 7, 12, and 15 have been determined by X-ray
crystallography.
In tr od u ction
and alkynes have proved to be useful for the synthesis
of various types of organic compounds.3-9 In this paper,
we report a new example of this type of reaction that
gives a highly functionalized spirocyclic compound.
However, although reactions of isocyanides with
alkyl-,10-13 alkynyl-,14-16 aryl-,5,17-22 and other23,24 or-
ganopalladium derivatives are known to give insertion
The use of organopalladium complexes in organic
syntheses constitutes a topic of current interest;2 in
particular, reactions involving arylpalladium complexes
† E-mail: jvs@fcu.um.es.
‡ E-mail: jaab@fcu.um.es.
§ WWW: http://www.scc.um.es/gi/gqo/.
| E-mail: jones@xray36.anchem.nat.tu-bs.de.
X Abstract published in Advance ACS Abstracts, September 1, 1997.
(1) Part 6: Vicente, J .; Abad, J . A.; Gil-Rubio, J . Organometallics
1996, 15, 3509.
S0276-7333(97)00426-3 CCC: $14.00 © 1997 American Chemical Society

4558 Organometallics, Vol. 16, No. 21, 1997
Vicente et al.
products, only a few such reactions lead directly11,12,19-21
or after reaction with other reagents13,18 to organic
products. Some heterocyclic compounds are among the
more interesting of these organic products (see Scheme
1).19-21 We report in this paper a member of a new
family of ketenimines that is formed by a new type of
head-to-head coupling of two isocyanide molecules (see
Scheme 1). Ketenimines are useful as dehydrating
agents for peptide syntheses, as coreagents in oxida-
tions, and as building blocks in the synthesis of carbo-
and N-heterocyclic rings.25,26 They are usually prepared
Sch em e 1
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Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 16, No. 21, 1997 4559
Ch a r t 1
have been synthesized by a route, widely exploited by
us, using the corresponding diarylmercurials as trans-
metalating agents.45 Starting from these arylpalladium
compounds, we have recently prepared indenones,
indenols,1,44 benzofulvenes,39 and spirocyclic com-
pounds.1,38-40 Most of these compounds bear a tri-
methoxyaryl moiety, which is also present in many
organic molecules of pharmaceutical interest.46 In this
paper, we report on the synthesis of 2,3,4-trimethoxy-
6-(N-tert-butylcarbamoyl)phenylpalladium complexes and
their reactivity with alkynes and the reactions of (2,3,4-
trimethoxyaryl)palladium complexes, bearing the groups
-C(O)NHBut, -C(O)Me, and CHO at the ortho position,
with 2,6-dimethylphenyl isocyanide. We also report the
first palladium complexes containing a carbamoylaryl
group.47
Exp er im en ta l Section
C, H, and N analyses, melting point determinations, con-
ductance measurements, and NMR spectra were performed
as described elsewhere.39 Infrared spectra were recorded in
the range 4000-200 cm-1 on a FT-IR Perkin-Elmer U-2000
spectrophotometer using Nujol mulls between polyethylene
sheets or KBr pellets. Mass spectra were carried out on a
Hewlett-Packard 5993 spectrometer. The exact molecular
weight of 15 was determined on a Fisons VG-AutoSpec 8000
instrument. Special group symbols: the groups C6H{C(O)-
NHBut}-6-(OMe)3-2,3,4, C(CO2Me)d(CO2Me)[C6H{C(O)NHBut}-
6-(OMe)3-2,3,4], C6H{C(O)Me}-6-(OMe)3-2,3,4 and C6H(CHO)-
6-(OMe)3-2,3,4 are represented as RN, CCRN, RMe, and RH,
respectively (when these groups are bonded to palladium
through carbon and the carbonyl oxygen we use the notations
κ2-RN, κ2-CCRN, κ2-RMe, and κ2-RH, see Chart 1); bpy is the
ligand 2,2′-bipyridine, and Xy is the group 2,6-dimethylphenyl.
The palladium compounds 10, 11, and 16 were prepared
following previously described procedures.41,42 All reactions
were carried out without exclusion of atmospheric air or
moisture and at ambient temperature, unless otherwise
indicated. Chromatographic separations were carried out by
TLC on silica gel (70-230 mesh).
Syn th esis of [Hg(RN)Cl] (1). RNH (8.63 g, 32.3 mmol),
Hg(OAc)2 (10.3 g, 32.3 mmol), and HOAc (8 cm3) were dissolved
in EtOH (180 cm3) and refluxed for 5 h. After the mixture
was cooled, it was stirred overnight and then poured into a
solution of KCl (9.64 g, 130 mmol) in water (250 cm3) to afford
a copious white precipitate. After the reaction mixture was
stirred for 10 min, the precipitate was isolated by filtration,
washed with water, and dried in the oven at 70 °C to yield 1
as a white powder in quantitative yield. Mp: 162 °C. IR
(cm-1): ν(NH) 3428, ν(CO) 1630, ν(HgCl) 338. 1H NMR
(CDCl3): 6.89 (s, 1H, C6H), 6.08 (br s, 1H, NH), 3.93, 3.88,
3.87 (all s, 3H, MeO), 1.46 (s, 9H, C(Me)3). 13C{1H} NMR
(acetone-d6): 168.73 (CdO), 156.28, 154.63, 145.78, 136.67,
134.82 (quaternary C in C6H), 108.66 (CH in C6H), 61.21,
60.77, 56.76 (3MeO), 52.43 (CMe3), 28.71 (C(Me)3). Anal.
Calcd for C14H20ClHgNO4: C, 33.5; H, 4.0; N, 2.8. Found: C,
33.5; H, 4.1; N, 2.8.
(37) Vicente, J .; Abad, J . A.; Bergs, R.; J ones, P. G.; Ram´ırez de
Arellano, M. C. Organometallics 1996, 15, 1422. Vicente, J .; Abad, J .
A.; Bergs, R.; J ones, P. G.; Bautista, D. J . Chem. Soc., Dalton Trans.
1995, 3093.
Syn th esis of [Hg(RN)2] (2). 1 (0.61 g, 1.22 mmol) and
(Me4N)Cl (0.14 g, 1.32 mmol) were stirred in acetone (55 cm3)
for 24 h and then filtered through MgSO4 to give a gray deposit
and a colorless solution. After the solid was washed with
acetone (4 × 5 cm3), the combined filtrate and washings were
evaporated to dryness in vacuo to yield a dry solid foam, 2, in
essentially quantitative yield. At this stage, the purity was
(38) Vicente, J .; Abad, J . A.; Ferna´ndez de Bobadilla, R.; J ones, P.
G.; Ram´ırez de Arellano, M. C. Organometallics 1996, 15, 24.
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1988, 345, 233. (f) Bonnardel, P. A.; Parish, R. V. J . Organomet. Chem.
1996, 515, 221. (g) Bonnardel, P. A.; Parish, R. V.; Pritchard, R. G. J .
Chem. Soc., Dalton Trans. 1996, 3185.
(46) Ziegler, F. E.; Chliwner, I.; Fowler, K. W.; Kanfer, S. J .; Kuo,
S. J .; Sinha, N. D. J . Am. Chem. Soc. 1980, 102, 790. Tomioka, K.;
Ishiguro, T.; Mizuguchi, H.; Komeshima, N.; Koga, K.; Tsukogoshi, G.;
Tsuruo, T.; Tashiro, T.; Tanida, S.; Kishi, T. J . Med. Chem. 1991, 34,
54. Gupta, S. P. Chem. Rev. 1994, 94, 1507. Chan, J . H.; Roth, B. J .
Med. Chem. 1991, 34, 550. Ringel, I.; J affe, D.; Alerhand, S.; Boye, O.;
Muzafar, A.; Brossi, A. J . Med. Chem. 1991, 34, 3334. Hitotsuyanagi,
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Chem. Commun. 1995, 49.
1
generally checked by H NMR and found to be >95%, which
was considered pure enough for synthetic use. If desired, the
crude product could be further purified by several recrystal-
lizations from Et2O/hexane. Mp: 102 °C. IR (cm-1): ν(NH)
3324, ν(CO) 1632. 1H NMR (CDCl3, ppm): 7.01 (s, 1H, C6H),
6.03 (br s, 1H, NH), 3.91 (br s, 6H, 2OMe), 3.90 (s, 3H, OMe),
1.41 (s, 9H, CMe3). 13C{1H} NMR: 170.36 (CdO), 157.98,
152.84, 152.12, 144.94, 138.30 (quaternary C in C6H), 107.53
(CH in C6H), 61.00, 60.73, 56.52 (3MeO), 51.67 (CMe3), 28.74
(C(Me)3). Anal. Calcd for C28H40HgN2O8: C, 45.9; H, 5.5; N,
3.8. Found: C, 45.7; H, 5.4; N, 3.6.
Syn th esis of [P d (RN)Cl(bp y)] (3). The diarylmercurial
2 (306 mg, 0.42 mmol) and [PdCl2(MeCN)2] (103 mg, 0.40
mmol) were stirred in acetone (12 cm3) at 0 °C for 1 h, during
which time the orange suspension changed to an olive brown
solution, which we assume to contain the intermediate [Pd-
(κ2-RN)(µ-Cl)]2 (A). Then bpy (60 mg, 0.40 mmol) was added,
whereby the solution instantly became paler in color. The
mixture was allowed to warm to room temperature and then
filtered and washed (2 × 5 cm3 washings) through MgSO4 to
give a yellow filtrate. The filtrate was evaporated to dryness
(47) Omae, I. Organometallic Intramolecular-Coordination Com-
pounds; Elsevier: Amsterdam, The Netherlands, 1986.

4560 Organometallics, Vol. 16, No. 21, 1997
Vicente et al.
in vacuo, the resultant yellow solid was redissolved in CH2Cl2
(5 cm3) and filtered though Celite, the solution was concen-
trated (1 cm3), and excess diethyl ether was added, which
precipitated a pale yellow solid. At this stage, we could not
obtain analytically pure samples of 3, probably because of the
presence of water (by NMR). For further purification, the solid
was redissolved in acetone (20 cm3), anhydrous MgSO4 and
Na2CO3 were added, and the mixture was stirred for 1 day.
The solution was then filtered to give a yellow filtrate, which
was evaporated to dryness in vacuo, redissolved in the
minimum volume of CH2Cl2, and excess ether added to
precipitate 3, which was isolated as a pale yellow powder.
Yield: 110 mg, 49%. Mp: 259 °C dec. ΛM: 0. IR (cm-1): ν-
(NH) 3332, ν(CO) 1646. 1H NMR (CDCl3, ppm): 9.30 (m, 1H,
bpy), 8.47 (br s, 1H, NH), 8.07 (m, 2H, bpy), 8.05 (m, 1H, bpy),
7.97 (m, 1H, bpy), 7.65 (m, 2H, bpy), 7.64 (m, 1H, bpy), 7.20
(s, 1H, C6H), 4.01, 3.93, 3.89 (all s, 3H, MeO), 1.31 (s, 9H,
CMe3). 13C{1H} NMR: 169.62 (CO), 155.75, 154.00, 153.69,
151.73, 151.23, 149.08, 143.43, 139.44, 138.87, 136.54, 129.25,
127.12, 126.58, 122.26, 121.62, 109.04 (CH of C6H), 60.74,
60.59, 55.99 (all MeO), 51.60 (CMe3), 28.91 (CMe3). Anal.
Calcd for C24H28ClN3O4Pd: C, 51.1; H, 5.0; N, 7.45. Found:
C, 50.5; H, 4.8; N, 7.4.
Syn th esis of [P d (K2-RN)(bp y)](CF 3SO3) (4). Complex 3
(72 mg, 0.12 mmol) and Tl(CF3SO3)(43 mg, 0.12 mmol) were
stirred together in acetone (15 cm3) for 30 min, the mixture
was filtered through Celite to give a bright green-yellow
filtrate, which was evaporated to dryness, and the resultant
yellow powder was recrystallized from CH2Cl2/Et2O to produce
4 as diffraction-quality green-yellow crystals. Yield: 68 mg,
82%. Mp: 254 °C. ΛM: 107 Ω-1 cm2 mol-1. IR (cm-1): ν(NH)
3252, ν(CO) 1575. 1H NMR (CDCl3, ppm): 9.41-7.37 (several
m, 9H, bpy + C6H), 3.97, 3.95, 3.73 (all s, 3H, MeO), 1.54 (s,
9H, CMe3). 13C{1H} NMR: 179.44 (CO), 157.67, 156.94, 156.43,
154.15, 151.89, 148.08, 145.45, 141.12, 140.39, 137.36, 135.66,
126.99, 126.48, 123.76, 123.40, 120.79 (q, 1J CF ) 320 Hz, CF3),
107.87 (CH of C6H), 63.16, 61.36, 56.96 (all MeO), 54.13
(CMe3), 28.88 (CMe3). Anal. Calcd for C25H28F3N3O7PdS: C,
44.3; H, 4.15; N, 6.2; S, 4.7. Found: C, 44.5; H, 3.75; N, 6.2;
S, 5.2.
Syn th esis of 10-(N-ter t-Bu tylcar bam oyl)-6,7-dim eth oxy-
1,2,3,4-tetr aph en ylspir o[4.5]-1,3,6,9-decatetr aen -8-on e (5).
A solution of the intermediate [Pd(κ2-RN)(µ-Cl)]2 (A) was
prepared from 2 (336 mg, 0.46 mmol) and [PdCl2(MeCN)2] (114
mg, 0.44 mmol) as described for 3. Then PhC2Ph (235 mg,
1.32 mmol) in acetone (4 cm3) was added, and the mixture was
allowed to warm to room temperature, a darkening from red
to black was observed. The mixture continued to stir a further
72 h, then the mixture was filtered and washed through
MgSO4 to give a black residue and a green filtrate. The filtrate
was evaporated to dryness, redissolved in chloroform, and
chromatographed. A bright yellow band (Rf ) 0.9, Et2O:
hexane 4:1) was collected, isolated, and dried to give 5 as a
yellow powder. Crystals were grown by the slow diffusion of
water into a methanol solution of 5. Yield: 229 mg, 86%. Mp:
176 °C. IR: ν(NH) 3352, ν(CO) 1649 (br). 1H NMR (CDCl3,
ppm): 7.11 (br, 16H, Ph), 6.95 (br, 2H, Ph), 6.94 (br, 2H, Ph),
6.64 (s, 1H, C6H), 5.28 (br s, 1H, NH), 3.99 (s, 3H, MeO), 3.40
(s, 3H, MeO), 1.23 (s, 9H, CMe3). 13C{1H} NMR: 183.91,
163.45, 160.23, 148.58, 148.07, 141.85, 140.64, 134.70, 133.67,
131.20, 129.76, 129.02, 127.99, 127.62, 127.44, 127.21, 68.47
(spiro C), 61.16 (MeO), 60.33 (MeO), 51.51 (CMe3), 28.38
(CMe3). MS (m/e): 608 (M+, 6.6), 105 (PhCO+, 100), 57 (C4H9,
71.1). Anal. Calcd for C41H37NO4: C, 81.2; H, 6.0; N, 2.3.
Found: C, 81.2; H, 6.2; N, 2.3.
mixture was filtered under gravity to give a yellow residue
and a pale orange solution. The residue was washed with
acetone (5 × 5 cm3) and then removed from the sinter by
slurrying with MeCN. The MeCN slurry was then heated to
boiling, with further additions of solvent until the solid
completely dissolved, giving a yellow solution. This solution
was then filtered hot, cooled, evaporated to dryness, and
removed mechanically under Et2O to yield a dry yellow
powder, 6, soluble in DMSO and hot MeCN. Yield: 333 mg,
67%. Mp: 254-262 °C dec. IR (cm-1): ν(NH) 3296, ν(CO2)
1710, ν(CO) 1582 or 1556. 1H NMR (DMSO-d6, ppm): 9.53
(br s, 1H, NH), 6.86 (s, 1H, C6H), 3.90, 3.82, 3.75, 3.66, 3.55
(each s, 3H, MeO), 1.28 (s, 9H, CMe3). 13C{1H} NMR:
decomposition over the time scale of the experiment. Anal.
Calcd for C20H26ClNO8Pd: C, 43.6; H, 4.8; N, 2.55. Found:
C, 43.6; H, 4.9; N, 2.6.
Syn th esis of [P d (K2-CCRN)Cl(P P h 3)] (7). PPh3 (39 mg,
0.15 mmol) in acetone (4 cm3) was added to a suspension of 6
(82 mg, 0.15 mmol) in acetone (8 cm3); rapid dissolution of the
solid was observed. After 5 min, the solution was filtered
through MgSO4 and the residue washed with acetone (2 × 5
cm3). The yellow filtrate was evaporated to dryness and
redissolved in a minimum quantity of CH2Cl2, and hexane
added to precipitate 7 as a creamy yellow solid. Yield: 93 mg,
77%. Diffraction quality crystals were grown by slow diffusion
of hexane into a CH2Cl2 solution of 7 at -20 °C. Mp: 218 °C
dec. ΛM (acetone): 3 Ω-1 cm2 mol-1. IR (cm-1): ν(NH) 3386,
ν(CO2) 1730, 1708, ν(CO) 1602 or 1582. 1H NMR (CDCl3,
ppm): 7.57-7.24 (m, 15H, PPh3), 6.87 (s, 1H, C6H), 6.28 (br s,
1H, NH), 4.02, 5.67, 3.58, 3.57, 3.34 (each s, 3H, MeO), 1.42
(s, 9H, CMe3). 13C{1H} NMR: 172.82, 169.07, 166.62, 164.48,
153.36, 151.70, 143.23, 133.12, 131.31, 134.72, 134.59, 130.56,
130.43, 127.89, 127.18, 125.23, 105.07 (CH of RCC), 60.55,
60.23, 56.54, 54.08, 52.68, 51.45 (3MeO, 2CO2Me, and CMe3),
28.46 (CMe3). 31P NMR: 33.3 (s). Anal. Calcd for C38H41
-
ClNO8PPd: C, 56.2; H, 5.1; N, 1.7. Found: C, 56.1; H, 5.2; N,
1.7.
Syn th esis of [P d (K2-CCRN)Cl(CNXy)] (8). Complex 6
(101 mg, 0.18 mmol) was suspended in acetone (6 cm3), and a
solution of CNXy (24 mg, 0.18 mmol) in acetone (4 cm3) was
added. The suspension rapidly became paler in color. The
mixture was stirred for 40 min and then filtered through Celite
to give a pale yellow filtrate. The filtrate was evaporated to
dryness to yield a yellow glassy solid. This was then redis-
solved in a minimum volume of CH2Cl2 and hexane added to
precipitate 8 as a voluminous cream solid. Yield: 99 mg, 79%.
Mp: 148 °C, dec. ΛM (acetone): 2 Ω-1 cm2 mol-1. IR (cm-1):
ν(NH) 3338, ν(CtN) 2200, ν(CO2) 1716, ν(CO) 1584 or 1560.
1H NMR (CDCl3, ppm): 7.3-7.0 (m, 3H, C6H3), 6.77 (s, 1H,
C6H), 6.50 (br s, 1H, NH), 3.94, 3.90, 3.83, 3.74, 3.67 (each s,
3H, MeO), 2.41 (s, 6H, C6H3Me2), 1.44 (s, 9H, CMe3). 13C{1H}
NMR: decomposition over the time scale of the experiment.
Anal. Calcd for C29H35ClN2O8Pd: C, 51.1; H, 5.2; N, 4.1.
Found: C, 51.1; H, 5.5; N, 4.1.
Syn th esis of [P d (K2-CCRN)(P P h 3)2](CF 3SO3) (9). Com-
plex 6 (82 mg, 0.15 mmol), TlCF3SO3 (53 mg, 0.15 mmol) and
PPh3 (157 mg, 0.60 mmol) were reacted in CH2Cl2 (14 cm3)
for 10 min, giving almost instantaneously a yellow solution
and a flocculent white precipitate. The mixture was filtered
through Celite to give an orange filtrate, which was evaporated
to dryness to give an orange oil. The mixture was stirred with
hexane (20 cm3), yielding a bright orange solid, 9, which was
isolated by filtration and repeated washings with hexane.
Yield: 134 mg, 76%. 9 could also be synthesized by the
addition of TlCF3SO3 and PPh3 to 7, but the overall yield was
Syn th esis of [P d 2(K2-CCRN)2(µ-Cl)2] (6). The intermedi-
ate A was prepared in an acetone (11 cm3) solution from 2
(366 mg, 0.50 mmol) and [PdCl2(MeCN)2] (123 mg, 0.47 mmol)
as described for 3. MeO2CCtCCO2Me (202 mg, 1.42 mmol)
in acetone (4 cm3) was then added, and the ice bath was
removed. Within 1 min a yellow precipitate appeared. The
mixture continued to stir for a further 15 min, then the
lower. Mp: 116 °C. ΛM (acetone): 129 Ω-1 cm2 mol-1
. IR
(cm-1): ν(NH) 3246, ν(CO2) 1712, ν(CO) 1580 or 1556. 1H
NMR (CDCl3, ppm): 7.71 (br s, 1H, NH), 7.4-7.0 (m, 30H,
2PPh3), 6.92 (s, 1H, C6H), 4.23, 3.85, 3.69, 3.59, 3.54 (all s,
3H, 3MeO and 3CO2Me), 0.98 (s, 9H, CMe3). 13C{1H} NMR:
172.98, 169.04, 153.95, 151.52, 143.22, 134.25, 134.10, 133.93,
133.77, 132.28, 131.36, 131.33, 131.06, 131.03, 129.17, 128.43,

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 16, No. 21, 1997 4561
128.72, 128.68, 128.43, 128.28, 106.61 (CH of C6H), 60.73,
60.29, 57.31, 54.15, 51.74, 51.63 (3MeO, 2CO2Me, CMe3), 27.54
(CMe3). 31P NMR: 32.91 (d, 2J PP ) 32 Hz), 16.41 (d, 2J PP ) 32
Hz). Anal. Calcd for C57H56F3NO11P2PdS: C, 57.6; H, 4.75;
N, 1.2; S 2.7. Found: C, 57.7; H, 5.05; N, 1.3; S, 2.1.
gave [Pd2Cl2(CNXy)4] (70 mg, 25%). The ether solution was
chromatographed (silica gel, Et2O/hexane 1:1) to get a first
fraction (Rf ) 0.3) containing a mixture of bpy and a colorless
organic compound (25 mg). From the second fraction (Rf )
0.1) the ketenimine 15 could be isolated as a yellow solid.
Single crystals were obtained by vapor diffusion of n-hexane
into 1,2-dichloroethane solutions of 15. Yield: 61 mg, 39%.
Mp: 173 °C. IR (cm-1): ν(CdCdN) 2028, ν(CdO) 1682. 1H
NMR (CDCl3, ppm): 7.35 (s, 1H, ArH), 7.21-6.96 (m, 6H, ArH
from Xy groups), 3.970, 3.966, 3.955 (3s, 9H, MeO), 2.21 (s,
6H, Me of Xy group), 2.08 (s, 6H, Me of Xy group). 13C{1H}
NMR: 184.5 (CdCdN), 161.7 (CdO), 154.3, 146.6, 144.8, 137.4,
136.8, 133.6, 132.0 (quaternary carbons), 129.0, 128.52, 128.48,
127.2 (Ar CH of Xy groups), 123.1, 121.6 (quaternary carbons),
102.4 (CH), 86.0 (CdCdN), 61.3 (MeO), 61.2 (MeO), 56.5
(MeO), 18.4 (2Me of Xy group), 18.1 (2Me of Xy group). MS
m/z: 456 (M+, 8), 220 (3), 196 (10), 168 (20), 132 (18), 131 (13),
130 (22), 117 (11), 116 (15), 106 (15), 105 (84), 104 (17), 103
(69), 93 (10), 91 (16), 79 (76), 78 (33), 77 (100). Mol wt calcd
for C28H28N2O4: 456.204908. Found: 456.206322.
Cr ysta l Str u ctu r e An a lyses. Crystal data are presented
in Table 1. Data collection and reduction: Monochromated
Mo KR radiation (λ ) 0.710 73 Å); cell constants refined from
(4, 7) (ω values of ca. 50 reflections to 2θmax) 23°, (12, 15)
ca. 60 reflections to 2θmax ) 23°; (7, 12) absorption correction
by ψ-scans. Structure solution: Heavy-atom (4, 7) or direct
(12, 15) methods. Structure refinement: Full-matrix least-
squares on F2 (program SHELXL-93, G. M. Sheldrick, Uni-
versity of Go¨ttingen) (exception, for 12 the refinement was
blocked); H atoms as rigid methyls or with riding model
(exception, for 12 not all solvent H were located, and for 7 no
solvent H). Ideally staggered H positions for 15.
Syn th esis of [P d {K2-C(dNXy)R N}(bp y)](CF 3SO3) (12).
Tl(CF3SO3) (63 mg, 0.18 mmol) was added to a solution of
complex 3 (100 mg, 0.18 mmol) in acetone (10 mL). The
mixture was stirred for 30 min and filtered through Celite,
and CNXy (24 mg, 0.18 mmol) was added. The solution was
stirred for 30 min and evaporated to dryness. CH2Cl2 was
added to the residue, and it was filtered through Celite. The
yellow-orange solution was evaporated to ca. 3 mL. Addition
of diethyl ether (20 cm3) gave 12 as a yellow-orange solid.
Diffraction quality crystals were grown by slow diffusion of
n-hexane into a CH2Cl2 solution of 12. Yield: 120 mg, 82%.
Mp: 140 °C. IR (cm-1): ν(NH) 3262, ν(CdN) 1634, ν(CO) 1598,
1574, or 1546. 1H NMR (CDCl3, ppm): 8.50-7.97 (m, bpy +
3
3
NH, 7H), 7.59 (t, bpy, 1H, J HH ) 6 Hz), 7.36 (t, 1H, bpy, J HH
) 6 Hz), 7.29 (s, 1H, H6 of RN group), 6.91-6.72 (m, 3H, ArH
of Xy group), 4.07, 3.93, 3.90 (3 s, 9H, 3MeO), 2.48 (s, 6H, 2Me),
1.60 (s, 9H, CMe3). 13C{1H} NMR: 170.9 (CdO), 155.0 (qua-
ternary carbon), 153.2 (CH), 153.0, 152.7 (quaternary carbons),
147.6 (CH), 146.7, 146.5, 146.2 (quaternary carbons), 140.6,
140.1 (CH), 128.5 (CH br), 127.2 (quaternary carbon), 126.9,
125.9, 123.8, 123.5, 123.0 (CH), 122.8 (quaternary carbon),
108.4 (C5 of RN group), 65.9 (Me3C), 62.0, 61.0, 56.9 (3MeO),
54.9 (2Me), 29.0 (Me3C). Anal. Calcd for C34H37F3N4O7PdS:
C, 50.5; H, 4.6; N, 6.9; S, 3.95. Found: C, 50.3; H, 4.65; N,
6.95; S, 3.75.
Syn th esis of [P d(RMe)(CNXy)(bpy)](CF3SO3) (13). CNXy
(32 mg, 0.24 mmol) was added to a suspension of [Pd(η2-
RMe)(bpy)]CF3SO3 (10) (150 mg, 0.24 mmol) in CH2Cl2 (10 cm3),
and the resultant mixture was stirred for 40 min. The yellow-
orange solution was filtered through Celite and evaporated
up to ca. 2 mL. Addition of diethyl ether (25 cm3) gave 13 as
a beige solid. Yield: 164 mg, 91%. Mp: 126 °C. IR (cm-1):
ν(CtN) 2188, ν(CO) 1652. 1H NMR (CDCl3, ppm): 8.70 (d,
2H, bpy), 8.42-8.22 (m, 2H, br, bpy), 7.55-7.34 (very broad
m, 4H, bpy), 7.40 (s, H5 of RMe group, 1H), 7.31-7.11 (2m,
3H, ArH of CNXy), 3.99 (s, 3H, MeO), 3.98 (s, 3H, MeO), 3.86
(s, 3H, MeO), 2.65 (s, 3H, MeCO), 2.26 (s, 6H, 2Me of Xy group).
13C{1H} NMR: 199.4 (CdO), 155.2, 152.0, 150.4 (br), 146.5
(quaternary carbons), 141.7 (CH), 137.0, 135.6, 133.0 (quater-
nary carbons), 130.7 (CH), 128.5 (CH), 128.3 (quaternary
carbon), 127.7 (CH), 124.6 (CH), 112.3 (CH), 61.0 (MeO), 60.5
(MeO), 56.5 (MeO), 28.2 (MeCO), 18.5 (2Me of Xy group). Anal.
Calcd for C31H30F3N3O7PdS: C, 49.5; H, 4.0; N, 5.6; S, 4.25.
Found: C, 49.7; H, 4.0; N, 5.6; S, 4.2.
Syn th esis of [P d (RH)(CNXy)(bp y)](CF 3SO3) (14). CNXy
(12 mg, 0.093 mmol) was added to a solution of [Pd-
(RH)(bpy)(NCMe)]CF3SO3 (11) (60 mg, 0.093 mmol) in CH2Cl2
(8 cm3), and the resultant mixture was stirred for 20 min. The
yellow-orange solution was filtered through Celite and evapo-
rated up to ca. 4 mL. Addition of diethyl ether (10 cm3) gave
14 as a yellow-orange solid. Yield: 52 mg, 76%. Mp: 140 °C.
IR (cm-1): ν(CtN) 2194, ν(CO) 1674. 1H NMR (CDCl3, ppm):
10.36 (s, 1H, CHO), 8.80-8.73 (m, 2H, bpy), 8.42-8.23 (m, 2H,
bpy), 7.87-7.80 (m, 1H, bpy), 7.55-7.41 (m, 2H, bpy), 7.35 (s,
1H, H5 of RH group), 7.29-7.11 (m, 4H, ArH of Xy-NC and a
proton of bpy). 13C{1H} NMR: decomposition over the time
scale of the experiment. Anal. Calcd for C30H28F3N3O7PdS:
C, 48.8; H, 3.8; N, 5.7; S, 4.35. Found: C, 48.2; H, 3.8; N,
5.95; S, 4.4.
Resu lts a n d Discu ssion
Syn th esis of Ar ylm er cu r ia ls a n d Ar ylp a lla d iu m -
(II) Com p lexes. The arene 3,4,5-trimethoxy(N-tert-
butylcarbamoyl)benzene is mercuriated by Hg(OAc)2 in
boiling ethanol giving a solution which, after pouring
into aqueous KCl, affords [Hg(RN)Cl] (1). 2-Chloromer-
cury benzamide and mono- and diethylbenzamides have
been reported.45f Compound 1 can be symmetrized with
[NMe4]Cl to give [Hg(RN)2] (2) (Scheme 2).
The reaction of 2 with [PdCl2(MeCN)2] gives an olive-
brown solution which must contain the complex [Pd(κ2-
RN)(µ-Cl)]2 (A); this seems to be reasonably stable in
solution but decomposes on attempts to isolate it.
However, after addition of bpy (2,2′-bipyridine), the
solution color changes to light yellow and it is possible
to isolate the stable compound [Pd(RN)Cl(bpy)] (3). The
byproduct 1 is easily removed since it is quite soluble
in Et2O, in contrast to 3. This reaction constitutes
another example of the utility of the organomercury
derivatives as transmetalating agents for the synthesis
of new organometallic compounds containing highly
functionalized aryl ligands not easily accessible by the
normal routes, viz. organolithium or magnesium re-
agents.45
Complex 3 reacts with Tl(CF3SO3) forming insoluble
TlCl and the cyclopalladated compound [Pd(κ2-RN)(bpy)]-
(CF3SO3) (4) in which the aryl group is also coordinated
to the palladium atom by the oxygen of the tert-
butylcarbamoyl substituent (Scheme 2), as shown by IR
and confirmed by X-ray studies.
We have previously reported similar cyclometalated
complexes containing the 3,4,5-trimethoxy-6-formyl-
phenyl and 3,4,5-trimethoxy-6-acetylphenyl ligands.41,42
When the ortho group was formylaryl, a rearrangement
took place in which the formyl substituent and the
Syn th esis of 2-(2,6-Dim eth ylp h en yl)-1-(((2,6-d im eth -
ylp h en yl)im in o)m eth ylen e)-5,6,7-tr im eth oxy-3-oxoisoin -
d olin e (15). CNXy (134 mg, 1.02 mmol) was added to a
solution of [Pd(RH)Cl(bpy)] (16) (168 mg, 0.34 mmol) in CH2-
Cl2 (10 cm3), and the resultant mixture was stirred for 25 h.
The brown suspension was filtered to yield a beige solid
identified as [Pd(bpy)Cl2] (27 mg, 24%). The resultant solution
was evaporated to ca. 1 mL. Addition of diethyl ether (25 cm3)

4562 Organometallics, Vol. 16, No. 21, 1997
Ta ble 1. Cr ysta l Da ta for Com p ou n d s 4, 7, 12, a n d 15
Vicente et al.
compound
mol formula
mol wt
4
C
7‚H2O
C38H43ClNO9PPd
830.55
12‚1/3C3H6O
C35H39F3N4O7.3PdS
828.50
15
25H28F3N3O7PdS
C28H28N2O4
456.52
677.96
description
tablet
prism
tablet
tablet
color
cryst size, mm
cryst syst
space group
a, Å
b, Å
c, Å
yellow
pale yellow
0.75 × 0.25 × 0.15
triclinic
P1h
9.345(3)
11.619(3)
19.076(5)
78.47(2)
79.19(2)
66.47(2)
1847.2(9)
2
orange
yellow
0.35 × 0.35 × 0.15
triclinic
P1h
0.60 × 0.35 × 0.35
triclinic
P1h
0.60 × 0.44 × 0.14
triclinic
P1h
10.359(3)
11.293(3)
12.924(3)
107.29(2)
103.18(2)
102.08(2)
1341.6(6)
2
13.241(2)
18.728(2)
23.258(3)
72.406(8)
89.433(8)
88.567(10)
5495.8(12)
6
8.003(2)
11.451(2)
13.796(2)
98.69(2)
103.360(10)
95.77(2)
1203.8(4)
2
R, deg
â, deg
γ, deg
V, Å3
Z
temperature, K
143(2)
0.840
143(2)
0.674
0.78-0.87
Stoe STADI-4
ω/θ
6.1-55.1
9851
8519
467/389
0.0475
173(2)
0.632
0.76-0.90
Siemens P4
ω
6.0-50.0
20560
19075
1407/1320
0.0464
298(2)
0.085
µ, mm-1
trans. %
diffractometer
scan method
2θ range, min-max, deg
no. of reflns measd
no. of independent reflns
parameters/restraints
Rint
Stoe STADI-4
ω/θ
6.0-55.1
5642
5382
367/93
0.017
0.0350
0.0792
1.08
Siemens P4
ω
6.2-50.0
10456
4240
308/4238
0.0429
0.0429
0.1206
1.008
R1a
0.0475
0.1187
1.19
0.0940
0.0940
0.81
wR2b
S(F2)
∆F, e/Å
0.83
1.10
1.16
0.17
a
b
2
R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σI. wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2 +
bP, where P ) (2Fc + Fo2)/3 and a and b are constants set by the program.
2
with the above explanation since the NHBut group is
Sch em e 2
more electron-releasing than Me or H.
Rea ction s w ith Alk yn es. When acetone solutions
containing the intermediate [Pd(κ2-RN)(µ-Cl)]2 (A) are
reacted with diphenylacetylene at room temperature,
a slow precipitation of metallic palladium is observed.
From the resulting solution, the spirocycle 10-(N-tert-
butylcarbamoyl)-6,7-dimethoxy-1,2,3,4-tetraphenylspiro-
[4.5]-1,3,6,9-decatetraen-8-one (5, see Scheme 3) was
isolated in excellent yield. Reaction of A with PhCt
CCO2Me gave a mixture whose 1H and 13C NMR spectra
indicate the presence of two isomeric spiro compounds
(head-to-tail and one of the two other isomers, head-to-
head or tail-to-tail) in a ca. 1:1 molar ratio. We were
not able to obtain a pure isomer from this mixture.
These results are similar to those observed in the
reactions of [Pd(κ2-RMe)(µ-Cl)]2, the 6-acetylaryl complex
analogous to A, with several arylalkynes.39 These
reactions are rare examples of a stoichiometric, pal-
ladium-assisted formation of spirocyclic compounds. The
pathway to 5 must be similar to that proposed previ-
ously, with the participation of a π-allyl intermediate.39
When A is reacted with MeO2CCtCCO2Me, no de-
composition to metallic palladium is observed and the
complex [Pd(κ2-CCRN)(µ-Cl)]2 (6) (Scheme 3), resulting
from the insertion of an alkyne molecule into the
carbon-palladium bond, is isolated. Monoinserted cy-
clopalladated compounds of this type are well docu-
mented,4,7-9 although very few examples are known
with oxygen as the heteroatom bonded to palladium.38,48
Complex 6 is isolated even when an excess of alkyne is
palladium moiety exchanged positions; however, in the
case of the acetylaryl complex, no such rearrangement
used. This is the normal behavior with alkynes sub-
was observed. We proposed that the greater electron-
stituted with electron-withdrawing substituents such as
releasing capacity of the Me group in the acetyl sub-
CF3 or CO2R. With other alkynes, the insertion of the
stituent (compared to the H atom of the formyl group)
first alkyne molecule is usually the rate-determining
was responsible for this different behavior. In the
present example, no isomerization of the aryl ligand is
(48) Ossor, H.; Pfeffer, M.; J astrzebski, J . T. B. H.; Stam, C. H. Inorg.
observed (X-ray crystal structure, see below), consistent
Chem. 1987, 26, 1169.

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 16, No. 21, 1997 4563
Sch em e 3
Sch em e 4
step and, therefore, in most cases, only the di-inserted
compound is obtained.49
It is possible to prepare derivatives of 6 by reacting
it with PPh3 or XyNC (Xy ) C6H3Me2-2,6) to give [Pd-
(κ2-CCRN)Cl(PPh3)] (7) or [Pd(κ2-CCRN)Cl(CNXy)] (8),
resulting from rupture of the chloro bridge. The reac-
tion of 6 or 7 with 2 or 1 equiv of PPh3, respectively, in
the presence of Tl(CF3SO3) yields the cationic compound
[Pd(κ2-CCRN)(PPh3)2](CF3SO3) (9) (Scheme 3). The
coordination of the carbamoyl substituent in complexes
6-9 is based on the IR data. Thus, complexes 6-9 show
bands at 1550-90 cm-1, strongly suggesting coordina-
tion through the O atom (see above). This has also been
confirmed by X-ray diffraction for 7 (see below).
Rea ction s w ith CNXy. Complex 4, formed in situ,
reacts with CNXy to give [Pd{κ2-C(dNXy)RN}(bpy)](CF3-
SO3) (12), the result of the insertion of an isocyanide
molecule into the carbon-palladium bond (Scheme 4).
As shown by an X-ray crystallographic study (see below),
the -C(O)NHBut substituent is O-coordinated to the
palladium atom forming a six-membered chelate ring.
In order to establish comparisons, we have studied
similar reactions of related trimethoxyarylpalladium
complexes previously prepared by us. Thus, the reac-
tion of [Pd(κ2-RMe)(bpy)](CF3SO3) (10) or [Pd(RH)(NCMe)-
(bpy)](CF3SO3) (11) with CNXy affords [Pd(RMe)(CNXy)-
(bpy)](CF3SO3) (13) or [Pd(RH)(CNXy)(bpy)] (CF3SO3)
(14), respectively, instead of an inserted complex. The
greater electron releasing ability of the NHBut group
than that of Me must induce a stronger Pd-O bond in
4 than in 10. This could explain the different behavior
of these complexes when reacted with XyNC. Concern-
ing the strength of the Pd-O bond in 4, see the
discussion of its crystal structure below.
Complexes such as 13 or 14 are considered to be
intermediates in the formation of inserted compounds
such as 12.14,18,21,22,24 When 12 or 13 is reacted with
another equivalent of the isocyanide, mixtures were
obtained that we were not able to separate. However,
from the complex mixture obtained by reacting 14 with
another CNXy, the highly functionalized, stable keten-
imine 15 (see Scheme 3) could be isolated. It is also
possible to obtain 15 by reaction of [Pd(RH)Cl(bpy)] (16)
with 3 equiv of CNXy; in this case, we have identified
some of the other components of the mixture as
[PdCl2(bpy)2] (24%), the palladium(I) complex [Pd2Cl2-
(CNXy)4] (25%),50 bpy, and an unknown organic product.
15 was isolated in 39% yield. The IR spectrum of this
compound exhibits a characteristic cumulene absorption
at 2028 cm-1 typical of ketenimines;25 however, due to
the complexity of 15, determination of its structure by
X-ray diffraction methods was necessary (see below). 15
(50) Rettig, M. F.; Kirk, E. A.; Maitlis, P. M. J . Organomet. Chem.
1976, 111, 113. Rutherford, N. M.; Olmstead, M. M.; Balch, A. L. Inorg.
Chem. 1984, 23, 2833.
(49) Ryabov, A. D.; Vaneldik, R.; Leborgne, G.; Pfeffer, M. Organo-
metallics 1993, 12, 1386.

4564 Organometallics, Vol. 16, No. 21, 1997
Vicente et al.
Sch em e 5
F igu r e 1. ORTEP plot of 4 with the labeling scheme (50%
probability ellipsoids).
common feature in most depalladation reactions,1,2 and
in particular, it occurs in the depalladation of some of
the products of the insertion of isocyanides into the
Pd-C bond.11,20 As far as we are aware, there is no
precedent for the synthesis of heterocyclic ketenimines
resulting from the insertion of two isonitrile molecules
into a carbon-metal bond (see Scheme 1).
Cr yst a l St r u ct u r e of Com p lexes 4, 7‚H 2O, a n d
12‚0.33Me2CO. The structures are shown in Figures
1-3 with selected bond lengths and angles in Tables
2-4. Compound 12 crystallizes with three independent
molecules, for which reason average values are gener-
ally used in the discussion.
The structure determinations confirm in all cases
coordination of the carbamoyl substituent through the
oxygen atom and furthermore the monoinsertion of the
alkyne in 7 and of the isocyanide in 12. The coordina-
tion at the palladium atoms is planar as expected; for
7, the mean deviation of the central five atoms is 0.10
Å and for 12 0.05, 0.05, 0.03 Å in the three molecules.
However, the deviation from an ideal geometry in 4 is
much greater; the four atoms Pd, C1, O4, and N3 are
coplanar to within 0.04 Å, but N2 lies 0.56 Å out of the
plane so defined, presumably to minimize steric pres-
sure between C26-H26 and O1 (the C‚‚‚O and H‚‚‚O
distances are only 2.96, 2.31Å). Associated with this
effect, the interplanar angle of the bpy ligand in 4 is
19°.
F igu r e 2. ORTEP plot of 7 with the labeling scheme (50%
probability ellipsoids).
is the first member of a new family of ketenimine
compounds.
We propose in Scheme 5 a reasonable pathway to
explain the formation of 15. The first product I is a
result of the coordination of the isocyanide. When the
starting product is 11, this intermediate is the isolated
complex 14. The intermediate II is the unstable product
we mentioned above. The di-insertion of isocyanides
into the Pd-C bond to give III is a known process.14,16,22
Formation of the enolato complex IV is electronically
favored (III), and similar compounds have been isolated6
or postulated51,52 in alkyne insertions into the Pd-C
bond of complexes related to 16. The nucleophilic
character of the nitrogen atom of the first inserted
isocyanide (IV), its attack at the carbonyl carbon atom,
and a â-hydrogen elimination causes the formation of
the ketenimine 15. The â-hydrogen elimination is a
(51) Blackburn, T. F.; Schwartz, J . J . Chem. Soc., Chem. Commun.
1977, 157.
(52) Tamaru, Y.; Yamada, Y.; Inoue, K.; Yamamoto, Y.; Yoshida, Z.
J . Org. Chem. 1983, 48, 1286.
The Pd-C bond distances (2.001(3) (4), 1.983(3) (7),
average 1.975 (12) Å) are within the observed range in

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 16, No. 21, 1997 4565
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p lex 4
Bond Lengths
Pd-O(4)
2.009(2)
2.033(3)
1.481(4)
1.315(4)
Pd-C(1)
2.001(3)
2.081(3)
1.276(4)
1.492(4)
Pd-N(2)
Pd-N(3)
C(6)-C(10)
C(10)-N(1)
C(10)-O(4)
C(11)-N(1)
Bond Angles
O(4)-Pd-C(1)
O(4)-Pd-N(3)
C(6)-C(1)-Pd
O(4)-C(10)-N(1)
N(1)-C(10)-C(6)
81.41(11) C(1)-Pd-N(2)
105.55(11)
79.68(10)
94.60(10) N(2)-Pd-N(3)
111.9(2)
120.2(3)
123.0(3)
C(1)-C(6)-C(10) 113.0(3)
O(4)-C(10)-C(6) 116.8(3)
C(10)-O(4)-Pd
C(22)-N(2)-Pd
113.1(2)
114.6(2)
C(10)-N(1)-C(11) 126.3(3)
C(32)-N(3)-Pd 113.6(2)
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p lex 7
Bond Lengths
Pd-C(16)
Pd-P
N-C(10)
O(1)-C(10)
C(1)-C(10)
1.983(3)
2.2239(11)
1.325(4)
1.245(4)
1.499(5)
Pd-O(1)
2.097(3)
2.3768(12)
1.482(5)
1.389(5)
1.339(4)
Pd-Cl
N-C(11)
C(1)-C(2)
C(15)-C(16)
Bond Angles
84.20(12) C(16)-Pd-P
F igu r e 3. ORTEP plot of 12 with the labeling scheme
(50% probability ellipsoids).
C(16)-Pd-O(1)
O(1)-Pd-Cl
C(10)-N-C(11)
O(1)-C(10)-N
N-C(10)-C(1)
95.26(10)
90.85(4)
126.8(2)
122.6(3)
90.32(8)
124.6(3)
121.3(3)
116.0(3)
P-Pd-Cl
C(10)-O(1)-Pd
O(1)-C(10)-C(1)
related complexes (2.027(5)-1.986(3) Å).38,41-43 From
the Pd-N bond lengths trans to carbon (2.081(3) (4),
average 2.130 (12) Å) and those trans to oxygen (2.033-
(3) (4), average 2.034 (12) Å), it can be established that
the order of the trans influence is imine carbon > aryl
>> carbamoyl oxygen. The increase in the Pd-O bond
distance from complex 4 (2.009(2) Å) to 12 (average
2.053 Å) could be attributed to the increase in the size
of the O-Pd-Cn ring from five to six. The longer Pd-O
bond in 7 (2.097(3) Å) can be attributed to the greater
trans influence of PPh3 than bpy, although the increase
in the size of the O-Pd-Cn ring to seven in complex 7
may also be important. The order 7 > 12 > 4 in the
Pd-O bond lengths is reversed for the C-O bond
distance (4 (1.276(4) Å) > 12 (average 1.264 Å) > 7
(1.245(4) Å)), whereas the carbamoyl C-N bond dis-
tances are not significantly different (7 (1.325(4) Å) >
12 (average 1.317 Å) > 4 (1.315(4) Å)). All of these C-O
and C-N distances in the carbamoyl substituent are
longer and shorter, respectively (marginally in the case
of 7), than those usually observed in acyclic amides,
1.231 and 1.334 Å.53 This implies, as expected, a greater
importance of the resonance form ButHN+d(aryl)C-O-
than ButHN-(Aryl)CdO in these complexes [4 > 12 >>
7] than in amides. The stronger Pd-O bond in 4 than
that in 10 could explain why 4 reacts with XyNC to give
the insertion product 12 while 10 gives the adduct 13.
Compounds 4 and 12 exhibit N-H‚‚‚O hydrogen
bonding. In 4, N1-H1‚‚‚O7, with N‚‚‚O of 3.009 Å and
N-H‚‚‚O of 158°, connects the molecules in pairs across
inversion centers. In 12, there are three such H
bonds: N12-H12‚‚‚O3 (2.924 Å, 161°) and N22-H22‚‚‚
O9 (2.981 Å, 164°) involve triflate anions and N32-
H32‚‚‚O99 (2.940 Å, 159°) involves the acetone of
solvation.
C(16)-C(15)-C(2) 123.2(3)
C(15)-C(16)-Pd 122.0(2)
F igu r e 4. ORTEP plot of 15 with the labeling scheme
(50% probability ellipsoids).
and angles. The most interesting feature of the crystal
structure of 15 is that it adopts a self-assembled
supramolecular structure. Dimers are formed through
intermolecular hydrogen bonding between a methyl
hydrogen at C12 and the keto oxygen (see Figures 4 and
5). After a long controversy concerning the validity of
hydrogen bonds of the type C-H‚‚‚O, the phenomenon
is now well-established and is becoming increasingly
important for the understanding of molecular packing
in crystals.30-32,34,36,54 In 15, the C‚‚‚O (3.362(3) Å) and
H‚‚‚O (2.50 Å) distances and the C-H‚‚‚O angle (150°)
Cr ysta l Str u ctu r e of th e Keten im in e 15. The
molecule of 15 is shown in Figure 4 with a packing
diagram in Figure 5; Table 5 gives selected bond lengths
(54) Cardullo, F.; Giuffrida, D.; Kohnke, F. H.; Raymo, F. M.;
Stoddart, J . F.; Williams, D. J . Angew. Chem., Int. Ed. Engl. 1996, 35,
339.
(53) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 1 1987, S1.

4566 Organometallics, Vol. 16, No. 21, 1997
Vicente et al.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p lex 12
Bond Lengths
Pd(1)-C(11)
Pd(1)-O(12)
O(12)-C(12)
N(11)-C(11)
Pd(2)-C(21)
Pd(2)-O(22)
O(22)-C(22)
N(21)-C(21)
Pd(3)-C(31)
Pd(3)-O(32)
O(32)-C(32)
N(31)-C(31)
1.973(5)
2.058(3)
1.269(5)
1.263(6)
1.984(5)
2.046(3)
1.261(5)
1.266(6)
1.967(5)
2.055(3)
1.262(5)
1.267(6)
Pd(1)-N(13)
Pd(1)-N(14)
N(12)-C(12)
N(12)-C(13)
Pd(2)-N(23)
Pd(2)-N(24)
N(22)-C(22)
N(22)-C(23)
Pd(3)-N(33)
Pd(3)-N(34)
N(32)-C(32)
N(32)-C(33)
2.029(4)
2.136(4)
1.312(5)
1.484(6)
2.040(4)
2.127(4)
1.320(6)
1.487(6)
2.033(4)
2.128(4)
1.318(6)
1.484(6)
Bond Angles
C(11)-Pd(1)-N(13)
N(13)-Pd(1)-N(14)
97.7(2)
78.8(2)
C(11)-Pd(1)-O(12)
86.8(2)
96.8(2)
O(12)-Pd(1)-N(14)
C(12)-O(12)-Pd(1) 123.8(3)
C(12)-N(12)-C(13) 126.5(4)
C(121)-C(11)-N(11) 119.4(4)
O(12)-C(12)-N(12) 120.5(4)
N(12)-C(12)-C(122) 118.5(4)
C(11)-N(11)-C(111) 126.9(4)
C(121)-C(11)-Pd(1) 107.5(3)
Pd(1)-C(11)-N(11) 133.0(4)
O(12)-C(12)-C(122) 120.9(4)
C(21)-Pd(2)-N(23) 100.8(2)
C(21)-Pd(2)-O(22)
O(22)-Pd(2)-N(24)
86.4(2)
N(23)-Pd(2)-N(24)
79.2(2)
93.71(14) C(22)-O(22)-Pd(2) 122.2(3)
C(21)-N(21)-C(211) 124.5(4)
C(221)-C(21)-Pd(2) 108.0(3)
Pd(2)-C(21)-N(21) 132.7(4)
O(22)-C(22)-C(222) 121.9(4)
C(22)-N(22)-C(23) 126.4(4)
C(221)-C(21)-N(21) 119.2(4)
O(22)-C(22)-N(22) 122.0(5)
N(22)-C(22)-C(222) 116.1(4)
F igu r e 5. (a) Packing diagram along the a axis of
compound 15 in the solid state. (b) Another perspective
showing the hydrogen bond interactions and interplanar
distances; A ) 1.23 Å, B ) 3.92 Å.
C(31)-Pd(3)-N(33)
N(33)-Pd(3)-N(34)
99.7(2)
78.8(2)
C(31)-Pd(3)-O(32)
O(32)-Pd(3)-N(34)
85.6(2)
95.9(2)
C(32)-O(32)-Pd(3) 122.9(3)
C(32)-N(32)-C(33) 127.1(4)
C(321)-C(31)-N(31) 119.5(5)
O(32)-C(32)-N(32) 120.2(5)
N(32)-C(32)-C(322) 117.7(4)
C(31)-N(31)-C(311) 125.2(5)
C(321)-C(31)-Pd(3) 108.7(3)
Pd(3)-C(31)-N(31) 131.5(4)
O(32)-C(32)-C(322) 122.1(4)
Ta ble 5. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p lex 15
Bond Lengths
O(1)-C(7)
N(1)-C(8)
N(2)-C(21)
1.223(2)
1.423(2)
1.443(2)
N(1)-C(7)
N(2)-C(9)
C(8)-C(9)
1.387(2)
1.218(2)
1.315(2)
are values considered normal for C-H‚‚‚O hydrogen
bonds. The dimers stack along the a axis forming a
tubular cavity in the space between the hydrogen
bonding interactions (Figure 5a). The mean distance
between dimers is approximately 5.15 Å (Figure 5b).
Sp ectr oscop ic Da ta of Com p ou n d s. The IR spec-
tra of compounds containing the NHBut group show a
band at 3428-3246 cm-1 corresponding to the ν(NH)
mode. The arene, RNH, the spirocyclic compound 5, and
complexes 1, 2, 3, 13, and 14 exhibit a band assignable
to the ν(CO) mode at 1674-1630 cm-1, while in 4 the
only band appearing in this region is observed at 1575
cm-1, which can be assigned to a ν(CO) mode of a
coordinated carbonyl group.41,42 In complexes 6-9, one
or two bands corresponding to the νa(CO2) mode appear
at 1730-1708 cm-1 while two bands in the 1602-1556
cm-1 region make it difficult to assign the ν(CO) mode.
Complex 12 exhibits the band assignable to the ν(CdN)
mode at 1634 cm-1, while three bands are observed in
the region expected for the band assignable to the ν(CO)
mode. The ν(CtN) mode in 8, 13, and 14 appears at
2200-2188 cm-1. The ketenimine 15 exhibits bands
assignable to the ν(CdCdN) and ν(CO) modes at 2028
and 1682 cm-1, respectively. A band assignable to
Bond Angles
C(2)-O(2)-C(10) 116.3(2)
C(7)-N(1)-C(8)
111.44(13)
C(7)-N(1)-C(31) 124.58(14) C(8)-N(1)-C(31) 123.98(13)
C(9)-N(2)-C(21) 129.5(2)
O(1)-C(7)-N(1)
N(1)-C(7)-C(6)
C(9)-C(8)-C(1)
125.0(2)
105.64(14)
129.2(2)
168.9(2)
O(1)-C(7)-C(6)
C(9)-C(8)-N(1)
N(1)-C(8)-C(1)
129.3(2)
124.8(2)
105.91(13) N(2)-C(9)-C(8)
compared with other species without such coordination
(e.g., 1-3 170.36-168.73 ppm).
Ack n ow led gm en t. We thank Direccio´n General de
Investigacio´n Cient´ıfica y Te´cnica (Grant No. PB92-
0982-C) and the Fonds der Chemischen Industrie for
financial support. K.F.S. is grateful to the Human
Capital and Mobility Research Program of the Commis-
sion of the European Communities for a research
training fellowship (Contract No. ERBCHBGCT920143).
J .G.-R. and M.C.R.A. are grateful to the Ministerio de
Educacio´n y Ciencia (Spain) for a grant and a contract,
respectively.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement, atomic coordinates, bond
lengths and angles, anisotropic displacement parameters, and
hydrogen coordinates for 4, 7, 12 and 15 (30 pages). Ordering
information is given on any current masthead page.
ν(HgCl) is observed in 1 at 338 cm-1
.
The O-coordination of the carbonyl group in 4 or 12
causes, in their 13C NMR spectra, a deshielding of the
carbonyl carbon atom (δ 179.44 and 170.9 ppm) when
OM970426V