Palladium-assisted formation of carbon-carbon bonds. 9. Synthesis of (2-alkenylaryl)- and indenylpalladium complexes

Article abstract of DOI:10.1021/om000370w

(o-Formylaryl)palladium complexes [Pd{C₆H(CHO)-6-R₃-2,3,4}X(N-N)] [R = OMe; X = Cl; N-N = bpy (2,2′-bipyridine) (1a), tmeda (N,N,N′,N′-tetramethylethylenediamine) (1b). R = H; X = Br; N-N = bpy (2a), tmeda (2b)] react with ylides PhCHqqPPh₃, pyCHqqPPh₃ (py = 2-pyridyl), or ClCHqqPPh₃ to give the (o-alkenylaryl)palladium derivatives [Pd{C₆-HCHqqCHPh-6-(OMe)₃-2,3,4}Cl(N-N)] [N-N = bpy (3a), N-N = tmeda (3b)], [Pd{C₆HCHqqCHpy-6-(OMe)₃-2,3,4}Cl(N-N)] [N-N = bpy (4)], [Pd{C₆H(E-CHqqCHCl)-6-(OMe)₃-2,3,4}-Cl(tmeda)] (5), or [Pd(C₆H₄CHqqCHPh-2)Br(N-N)] [N-N = bpy (6a), N-N = tmeda (6b)]. The compounds 3a, 4, and 6a,b are obtained as mixtures of E and Z isomers, whereas the formation of 3b and 5 is stereoselective (E isomer). The reaction of the (o-acetylaryl)palladium complexes [Pd{C₆HC(O)Me-6-(OMe)₃-2,3,4}Cl(tmeda)] (7) and [Pd{C₆H₄(C(O)Me)-2}Br(bpy)] (8) with bases results in the formation of the 3-palladaindan-1-ones [Pd(κ²-{C₆HC(O)CH₂-6-(OMe)₃-2, 3,4})(tmeda)] (9) and [Pd(κ²-{C₆H₄C(O)CH₂-2}(bpy)] (10). Complexes 3b and 6a,b react with alkynes RCqqCR′ to give indenylpalladium complexes [Pd{η-C₉HBn-1-R-2-R′-3-(OMe)₃-5, 6,7}(tmeda)]TfO [Bn = benzyl, TfO = CF₃SO₃, R = R′ = Me (11); R = C(O)Me, R′ = H (12)] and [Pd{η-C₉H₄Bn-1-R-2-R′-3}(N-N)]TfO [R = R′ = H, N-N = bpy (13a), tmeda (13b); R = R′ = Me, N-N = bpy (14a), tmeda (14b); R = R′ = Et, N-N = bpy (15a), tmeda (15b); R = R′ = Ph, N-N = bpy (16a), tmeda (16b); R = Ph, R′ = H and R = H, R′ = Ph, N-N = bpy (17a); R = H, R′ = Ph, N-N = tmeda (17b); R = Ph, R′ = Me, N-N = bpy (18a), N-N = tmeda (18b)]. Complex 3b reacts with Me₂CqqCqqCH₂, CS₂, or MeNqqCqqS to give [Pd(η³-CMe₂C{C₆H(E-CHqqCHPh)- 6-(OMe)₃-2,3,4}CH₂)(tmeda)]TfO (19), [Pd(S₂C{C₆H-(E-CHqqCHPh)-6-(OMe)₃-2,3,4}) (tmeda)]TfO (20), or [Pd(SC(NMe){C₆H(E-CHqqCHPh)-6-(OMe)₃-2,3,4}) (tmeda)]TfO (21). The crystal structures of 12, 17b, and 18a have been determined; the hapticities of the indenyl five-membered rings are intermediate between η³ and η⁵.

Full text of DOI:10.1021/om000370w

Organometallics 2000, 19, 5597-5607
5597
P a lla d iu m -Assisted F or m a tion of Ca r bon -Ca r bon Bon d s.
9.† Syn th esis of (2-Alk en yla r yl)- a n d In d en ylp a lla d iu m
Com p lexes
J ose´ Vicente,*,‡ J ose´-Antonio Abad,*,§ Ralph Bergs,
M. Carmen Ramirez de Arellano, and Elo´ısa Mart´ınez-Viviente
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Aptdo. 4021, E-30071 Murcia, Spain
Peter G. J ones*,|
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Received May 1, 2000
(o-Formylaryl)palladium complexes [Pd{C6H(CHO)-6-R3-2,3,4}X(N-N)] [R ) OMe; X )
Cl; N-N ) bpy (2,2′-bipyridine) (1a), tmeda (N,N,N′,N′-tetramethylethylenediamine) (1b).
R ) H; X ) Br; N-N ) bpy (2a ), tmeda (2b)] react with ylides PhCHdPPh3, pyCHdPPh3
(py ) 2-pyridyl), or ClCHdPPh3 to give the (o-alkenylaryl)palladium derivatives [Pd{C6-
HCHdCHPh-6-(OMe)3-2,3,4}Cl(N-N)] [N-N ) bpy (3a ), N-N ) tmeda (3b)], [Pd{C6HCHd
CHpy-6-(OMe)3-2,3,4}Cl(N-N)] [N-N ) bpy (4)], [Pd{C6H(E-CHdCHCl)-6-(OMe)3-2,3,4}-
Cl(tmeda)] (5), or [Pd(C6H4CHdCHPh-2)Br(N-N)] [N-N ) bpy (6a ), N-N ) tmeda (6b)].
The compounds 3a , 4, and 6a ,b are obtained as mixtures of E and Z isomers, whereas the
formation of 3b and 5 is stereoselective (E isomer). The reaction of the (o-acetylaryl)palladium
complexes [Pd{C6HC(O)Me-6-(OMe)3-2,3,4}Cl(tmeda)] (7) and [Pd{C6H4(C(O)Me)-2}Br(bpy)]
(8) with bases results in the formation of the 3-palladaindan-1-ones [Pd(κ2-{C6HC(O)CH2-
6-(OMe)3-2,3,4})(tmeda)] (9) and [Pd(κ2-{C6H4C(O)CH2-2}(bpy)] (10). Complexes 3b and 6a ,b
react with alkynes RCtCR′ to give indenylpalladium complexes [Pd{η-C9HBn-1-R-2-R′-3-
(OMe)3-5,6,7}(tmeda)]TfO [Bn ) benzyl, TfO ) CF3SO3, R ) R′ ) Me (11); R ) C(O)Me, R′
) H (12)] and [Pd{η-C9H4Bn-1-R-2-R′-3}(N-N)]TfO [R ) R′ ) H, N-N ) bpy (13a ), tmeda
(13b); R ) R′ ) Me, N-N ) bpy (14a ), tmeda (14b); R ) R′ ) Et, N-N ) bpy (15a ), tmeda
(15b); R ) R′ ) Ph, N-N ) bpy (16a ), tmeda (16b); R ) Ph, R′ ) H and R ) H, R′ ) Ph,
N-N ) bpy (17a ); R ) H, R′ ) Ph, N-N ) tmeda (17b); R ) Ph, R′ ) Me, N-N ) bpy
(18a ), N-N ) tmeda (18b)]. Complex 3b reacts with Me2CdCdCH2, CS2, or MeNdCdS to
give [Pd(η3-CMe2C{C6H(E-CHdCHPh)-6-(OMe)3-2,3,4}CH2)(tmeda)]Tf O (19), [Pd(S2C{C6H-
(E-CHdCHPh)-6-(OMe)3-2,3,4})(tmeda)]TfO (20), or [Pd(SC(NMe){C6H(E-CHdCHPh)-6-
(OMe)3-2,3,4})(tmeda)]TfO (21). The crystal structures of 12, 17b, and 18a have been
determined; the hapticities of the indenyl five-membered rings are intermediate betwen η3
and η5.
In tr od u ction
phorus ylides (i.e., via a Wittig reaction); (ii) oxidative
addition reactions. While the Wittig reaction is a very
well-known synthetic method to prepare organic alkenes
from carbonyl compounds,5 only a few examples are
known of its application on a coordinated ligand.3,4 We
report here the first syntheses of alkenylaryl complexes
through Wittig reactions and discuss their stereoselec-
tivity. When (o-acetylaryl)palladium complexes were
reacted with a phosphorus ylide, not the expected (o-
alkenylaryl)palladium complexes but the products of
cyclopalladation were obtained. As far as we are aware,
these are the only examples of isolated and character-
ized 3-palladaindan-1-ones.6 Some of these results have
been previously communicated.7
Very few (o-alkenylaryl)palladium complexes have
been reported.1,2 They could be of interest in the fields
of nonlinear optics3 or organometallic polymers.4 In this
paper we report the synthesis of (o-alkenylaryl)palla-
dium complexes through two different ways: (i) reac-
tions of (o-formylaryl)palladium complexes with phos-
† Part 8: See ref 17.
‡ E-mail: jvs@fcu.um.es. WWW: http://www.scc.um.es/gi/gqo/.
§ E-mail: jaab@fcu.um.es.
| E-mail: jones@xray36.anchem.nat.tu-bs.de.
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tions in Organic Synthesis; Wiley-VCH: Weinheim, Germany, 1999.
10.1021/om000370w CCC: $19.00 © 2000 American Chemical Society
Publication on Web 11/18/2000

5598 Organometallics, Vol. 19, No. 26, 2000
Vicente et al.
Sch em e 1
di- and triinserted derivatives most of which are of types
A-C, shown in Scheme 1.8-18 After depalladation, some
of these complexes lead to interesting organic com-
pounds.9,13,14,19-38 However, despite the great number
of studies devoted to this topic, the results we report
here have only the precedent of our recent work in
which we showed that (2,3,4-trimethoxy-6-alkenylaryl)-
palladium complexes reacted with different alkynes to
give four indenylpalladium complexes (D in Scheme 1).39
In this paper, we show this type of reaction to be more
general as it applies to other arylpalladium complexes-
with or without the three methoxy groups-and using
the same or other alkynes. Therefore, this represents a
new method for the synthesis of indenylpalladium
complexes (some highly functionalized) of which very
few examples are known.40-43 In addition, while in most
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previous studies only symmetrical alkynes were used,
we now present the results of using some unsymmetrical
ones, which allows us to propose a new empirical scale
to predict the regioselectivity of the insertion reactions.
Finally, we also report reactions of an (o-alkenylaryl)-
palladium complex with cumulenes XdCdY leading to
π-allyl (X ) CH2, Y ) CMe2), dithiobenzoato (X ) Y )
S), or N-methylthiobenzamidinato (X ) S, Y ) NMe)
complexes. While the insertion of allenes into the Pd-C
bond is a well-established method to prepare π-allyl
complexes, we are only aware of one example of inser-
tion of CS2 into a Pd-C bond-that starting from [PdI-
(Me)(PMe3)2] giving a dithioacetate complex44,45 and
none for MeNdCdS.
Exp er im en ta l Section
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All reactions involving air- and/or water-sensitive com-
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pounds “Pd(dba)2” ([Pd2(dba)3].dba),46,47 [Pd{C6H(CHO)-6-
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(40) Samuel, E.; Bigorgne, M. J . J . Organomet. Chem. 1969, 19, 9.

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 19, No. 26, 2000 5599
3
(OMe)3-2,3,4}Cl(bpy)] (1a ),48 [Pd(κ2-{C6H(C(O)Me)-6-(OMe)3-
2,3,4})(µ-Cl)]2,49 [Pd{C6H4(CHO)-2}Br(bpy)] (2a ), [Pd{C6H4-
(CHO)-2}Br(tmeda)] (2b), and [Pd{C6H4(C(O)Me)-2}Br(bpy)]
(8)2 were prepared as reported in the literature. Because the
hapticity of the indenyl ligand in complexes 11-18 is inter-
mediate between η3 and η5, we have formulated this ligand as
η-indenyl. (BnPPh3)Cl (Bn ) benzyl) and 2-bromobenzaldehyde
were purchased from Fluka.
(s, 1 H, aryl-H), 6.94 (d, 1 H, CHdCH, J ) 16 Hz), 4.11, 3.93
and 3.91 (s, 3 H, MeO), 1.64 (s, H2O, 2 H). 13C NMR (68 MHz,
CDCl3, ppm): 156.20, 154.51, 153.63, 151.69, 151.19, 149.37,
141.68, 139.08, 138.46, 136.87, 134.07, 128.39, 126.66, 126.60,
126.43, 125.44, 122.16, and 121.42 (aromatic CH and C),
104.73 (Aryl-CH), 61.06, 61.01, and 56.22 (MeO). Anal. Calcd
for C27H25ClN2O3Pd‚H2O: C, 55.40; H, 4.65; N, 4.79. Found:
C, 55.66; H, 4.42; N, 4.80.
Syn th esis of 2-Br om ostilben e (E a n d Z Isom er ic Mix-
tu r e). A commercial 1.6 M diethyl ether solution of MeLi (7.9
cm3, 12.65 mmol) was added to a suspension of (BnPPh3)Cl
(4.92 g, 12.65 mmol) in freshly distilled tetrahydrofuran (45
cm3) under nitrogen. The mixture was stirred for 10 min. Then
2-bromobenzaldehyde (1.3 cm3, 11 mmol) was added and the
resulting mixture stirred for 20 h under nitrogen. Solvents
were evaporated in vacuo, and water (15 cm3) and pentane
(40 cm3) were added. The organic layer was stirred for 1 h with
a large excess of NaBr and then dried over anhydrous MgSO4,
filtered, and evaporated to dryness leaving an oil. 1H NMR
(300 MHz, CDCl3, ppm): 7.7-7.0 (several m, aromatics and
olefinic protons of the E isomer), 6.65 (q, Z-CHdCH-).
Syn th esis of [P d {C6H(CHO)-6-(OMe)3-2,3,4}Cl(tm ed a )]
(1b). PdCl2 (304 mg, 1.71 mmol) and KCl (300 mg, 4.02 mmol)
were dissolved in water (30 mL). [{C6H(CHO)-6-(OMe)3-
2,3,4}2Hg] (1012 mg, 1.71 mmol) and acetone (90 cm3) were
added to the aqueous solution, and the resulting mixture was
stirred at room temperature for 2 h. The acetone was evapo-
rated, and further water (80 cm3) added. The mercurial [Hg-
{C6H(CHO)-6-(OMe)3-2,3,4}Cl] precipitated quantitatively and
was filtered off. The resulting yellow solution was treated with
a solution of N,N,N′,N′-tetramethylethylenediamine (200 mg,
1.71 mmol) in dichloromethane (60 cm3). The organic layer was
decanted, and the aqueous solution was extracted with dichlo-
romethane (40 cm3). The combined extracts were dried with
anhydrous MgSO4 and filtered. The solution was concentrated
(4 cm3) and diethyl ether added to precipitate 1b. Yield: 683
mg, 88%. Mp: 185-186 °C (dec). ΛM (acetone): 0 Ω-1 cm2
mol-1. IR (cm-1): ν(CO), 1670. 1H NMR (270 MHz, CDCl3,
ppm): 11.15 (s, 1 H, CHO), 7.19 (s, 1 H, aryl-H), 4.22, 3.95
and 3.83 (s 3 H, MeO), 2.55-2.80 (m, 4 H, CH2CH2), 2.73, 2.68,
2.54, and 2.29 (s, 3 H, MeN). 13C NMR (68 MHz, CDCl3,
ppm): 195.89 (CHO), 155.53, 151.15, 146.49, 143.32, and
136.36 (C-aryl), 106.52 (CH-aryl), 63.15, 61.02, 60.90, 58.74,
and 55.90 (MeO and CH2CH2), 52.10, 51.07, 48.32, and 47.96
(MeN). Anal. Calcd for C16H27ClN2O4Pd: C, 42.40; H, 6.00; N,
6.18. Found: C, 42.17; H, 5.99; N, 6.18.
Syn th esis of [P d {C6H(E-CHdCHP h )-6-(OMe)3-2,3,4}Cl-
(tm ed a )] (3b). Benzyltriphenylphosphonium chloride (643 mg,
1.66 mmol), potassium tert-butoxide (186 mg, 1.66 mmol), and
1b (500 mg, 1.10 mmol) were reacted for 20 h in dry dichlo-
romethane. The mixture was evaporated to dryness and the
residue stirred in diethyl ether for 1 h. The suspension was
filtered, and the solid was washed with diethyl ether (4 × 10
cm3), benzene/diethyl ether (1:1, 2 × 5 cm3), diethyl ether
(2 × 10 cm3), and water (3 × 10 cm3) and then dissolved in
dichloromethane and stirred with anhydrous MgSO4. The
suspension was filtered over anhydrous MgSO4 and the clear
solution concentrated to 1 cm3. Diethyl ether was added to
precipitate yellow 3b. Yield: 450 mg, 77%. Mp: 196-197 °C
(dec). ΛM (acetone): 0 Ω-1 cm2 mol-1
.
1H NMR (200 MHz,
3
CDCl3, ppm): 8.50 (d, 1 H, CH)CH, J ) 16 Hz), 7.55-7.65,
3
7.10-7.40 (m, 5 H, C6H5), 7.04 (d, 1 H, CHdCH, J ) 16 Hz),
6.84 (s, 1 H, aryl-H), 4.27, 3.89, and 3.86 (s, 3 H, MeO), 2.50-
2.75 (m, 4 H, CH2CH2), 2.72 (s, 6 H, 2 × MeN), 2.52 and 2.25
(s, 3 H, MeN). 13C NMR (68 MHz, CDCl3, ppm): 154.73, 150.50,
141.04, 138.53, 136.79, and 131.73 (aromatic C), 128.52 and
126.00 (o,m-C6H5), 134.12, 126.52, and 125.18 (HC)CH and
p-CHC6H5), 104.69 (CH aryl), 62.80 (CH2), 60.94 and 60.85
(MeO), 58.34 (CH2), 55.95 (MeO), 51.59, 50.63, 47.95, and 47.57
(MeN). Anal. Calcd for C23H33ClN2O3Pd: C, 52.38; H, 6.31; N,
5.31. Found: C, 52.29; H, 6.61; N, 5.40. Single crystals of 3b
were obtained by liquid diffusion of diethyl ether into a solution
of 3b in chloroform.
Syn th esis of [P d {C6H(CHdCHp y)-6-(OMe)3-2,3,4}Cl-
(bp y)] (4). Yellow 4 was prepared analogously to 3a from ((2-
pyridyl)methyl)triphenylphosphonium chloride (237 mg, 0.61
mmol), a 1.6 M solution of nBuLi in hexane (0.38 cm3, 0.61
mmol), and 1a (200 mg, 0.41 mmol) to form a Z/ E mixture
(1:4). Yield: 183 mg, 79%. The pure E-compound can be
isolated by crystallization from dichloromethane/diethyl ether.
Yield: 46 mg, 19%. Mp: 167-169 °C (dec). ΛM (acetone): 11
1
Ω-1 cm2 mol-1. H NMR (300 MHz, CDCl3, ppm): 9.27-9.31
3
(m, 1 H, bpy), 8.67 (d, 1 H, CH)CH, J ) 16 Hz), 8.40-8.46,
7.46-8.15, 6.95-7.28 (m, 11 H, bpy and py), 7.13 (d, 1 H, CHd
Syn th esis of [P d {C6H(CHdCHP h )-6-(OMe)3-2,3,4}Cl-
(bp y)] (3a ). A 1.6 M solution of nBuLi in hexane (0.38 cm3,
0.61 mmol) was added to a suspension of benzyltriphenylphos-
phonium chloride (237 mg, 0.61 mmol) in diethyl ether (8 cm3)
and stirred for 30 min under nitrogen. 1a (200 mg, 0.41 mmol)
was added to give a yellow suspension, which was stirred for
20 h. The mixture was filtered, and the solid residue was
washed with diethyl ether (4 × 10 cm3), benzene/diethyl ether
(1:1, 2 × 5 cm3), diethyl ether (2 × 10 cm3), and water (3 × 10
cm3) and then dissolved in dichloromethane and stirred with
anhydrous MgSO4. The suspension was filtered over anhy-
drous MgSO4 and the clear solution concentrated to 1 cm3.
Diethyl ether was added to precipitate yellow 3a as a Z/ E
mixture (1:3). Yield: 191 mg, 83%. The pure E-compound can
be isolated by crystallization from chloroform/diethyl ether.
Yield: 32 mg, 14%. Mp: 188-190 °C (dec). ΛM (acetone): 0
3
CH, J ) 16 Hz), 7.06 (s, 1 H, aryl-H), 5.30 (s, 1 H, CH2Cl2),
4.10, 3.95, and 3.91 (s, 3 H, MeO). 13C NMR (75 MHz, CDCl3,
ppm): 157.16, 156.24, 154.55, 153.71, 151.74, 151.29, 149.39,
149.23, 142.20, 139.19, 138.58, 138.00, 136.26, 136.17, 126.77,
126.47, 125.85, 122.32, 121.50, 121.15, and 120.95 (aromatic
CH and C), 105.16 (ArylCH), 61.17, 61.08, and 56.04 (MeO),
53.8 (CH2Cl2). Anal. Calcd for C26H24ClN3O3Pd‚0.5 CH2Cl2: C,
52.11; H, 4.13; N, 6.88. Found: C, 52.05; H, 4.31; N, 6.65.
Syn th esis of [P d {C6H(E-CHdCHCl)-6-(OMe)3-2,3,4}Cl-
(tm ed a )] (5). Pale yellow 5 was prepared analogously to 3b
from (chloromethyl)triphenylphosphonium chloride (527 mg,
1.52 mmol), potassium tert-butoxide (170 mg, 1.52 mmol), and
1b (500 mg, 1.10 mmol). Yield: 433 mg, 81%. Mp: >350 °C.
ΛM (acetone): 0 Ω-1 cm2 mol-1
.
1H NMR (300 MHz, CDCl3,
3
ppm): 7.91 (d, 1 H, CH)CH, J ) 13.5 Hz), 6.84 (d 1 H, CHd
1
Ω-1 cm2 mol-1. H NMR (200 MHz, CDCl3, ppm): 9.30-9.33
3
CH, J ) 13.5 Hz), 6.53 (s, 1 H, aryl-H), 4.20, 3.87, and 3.79
3
(m, 1 H, bpy), 8.36 (d, 1 H, CH)CH, J ) 16 Hz), 7.83-8.05,
(s, 3 H, MeO), 2.55-2.75 (m, 4 H, CH2CH2), 2.69 (s, 6 H, 2 ×
MeN), 2.51 and 2.32 (s, 6 H, MeN). 13C NMR (50 MHz, CDCl3,
ppm): 154.82, 150.40, and 141.33 (C-aryl), 137.55 (HC)CH),
134.39 and 130.62 (C-aryl), 115.17 (HC)CH), 105.39 (aryl-CH),
62.83 (CH2), 60.70 (2 × MeO), 58.36 (CH2), 55.93 (MeO), 51.40,
50.76, 47.79 and 47.73 (MeN). Anal. Calcd for C17H28Cl2N2O3-
Pd: C, 42.04; H, 5.81; N, 5.77. Found: C, 42.32; H, 5.86; N,
5.57.
7.70-7.72, 7.45-7.60, 7.05-7.27 (m, 12 H, bpy and C6H5), 6.96
(47) Yatsimirsky, A. K.; Kazankov, G. M.; Ryabov, A. D. J . Chem.
Soc., Perkin Trans. 2 1992, 1295.
(48) Vicente, J .; Abad, J . A.; J ones, P. G. Organometallics 1992, 11,
3512.
(49) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G.; Bembenek,
E. Organometallics 1993, 12, 4151.

5600 Organometallics, Vol. 19, No. 26, 2000
Vicente et al.
Syn t h esis of [P d {C6H 4(CHdCH P h )-2}Br (b p y)] (6a ).
Meth od A. A 1.6 M solution of nBuLi in hexane (0.32 cm3,
0.51 mmol) was added to a suspension of benzyltriphenylphos-
phonium chloride (198 mg, 0.51 mmol) in tetrahydrofuran (15
cm3) under nitrogen, and the resulting mixture was stirred
for 10 min. Complex 2a (200 mg, 0.44 mmol) was added and
the mixture stirred for a further 20 h. The solvent was removed
in vacuo and the residue washed with diethyl ether (4 × 5
cm3) and water (2 × 15 cm3) and then redissolved in dichlo-
romethane; an excess of NaBr was added to the solution, which
was stirred for 1 h. The resulting suspension was treated with
anhydrous magnesium sulfate and filtered. From the filtrate,
evaporation of the solvent and addition of diethyl ether
precipitated yellow 6a as an E/ Z mixture (2.6:1). Yield: 124
mg, 54%.
3.94, 3.88, and 3.82 (s, 3 H, MeO), 2.55-2.80 (m, 4 H, CH2-
CH2), 2.74 (s, 6 H, NMe2), 2.67 [s, 2 H, C(O)CH2], 2.59 (s, 6 H,
NMe2). 13C NMR (75 MHz, CDCl3, ppm): 203.97 [C(O)CH2],
158.57, 150.50, 144.47, 142.26, and 138.98 (C-aryl), 103.31
(CH-aryl), 61.51 (CH2), 61.23 (OMe), 60.58 (OMe), 59.96 (CH2),
55.66 (MeO), 49.32 and 49.19 (Me2N), 41.98 [C(O)CH2]. Anal.
Calcd for C17H28N2O4Pd: C, 47.39; H, 6.55; N, 6.50. Found:
C, 47.30; H, 6.75; N, 6.38. Single crystals of 9 were obtained
by liquid diffusion of diethyl ether or hexane into a solution
of 9 in dichloromethane.
Syn th esis of [P d(K2-{C6H4(C(O)CH2)-2})(bpy)] (10). Com-
plex 8 (80 mg, 0.18 mmol) in methanol (5 cm3) was treated
with a solution of NaOMe in methanol (0.3 cm3, 0.26 mmol)
for 20 h. The solvent was removed in vacuo and the residue
redissolved in dichloromethane (15 cm3). Anhydrous magne-
sium sulfate was added and the mixture stirred for 15 min.
The suspension was filtered, the resulting solution evaporated,
and diethyl ether added to precipitate 10 as a yellow solid.
Yield: 53 mg, 79%. Mp: 155 °C (dec). IR (cm-1): ν(CO), 1644.
1H NMR (300 MHz, CDCl3, ppm): 8.85-8.87 (m, 1 H, bpy),
8.53-8.55 (m, 1 H, bpy), 8.12-8.16 (m, 2 H, bpy), 7.93-8.02
Method B. 2-Bromostilbene (E and Z mixture) (543 mg, 2.1
mmol) was added to “Pd(dba)2” (400 mg, 0.68 mmol) and bpy
(110 mg, 0.68 mmol), and the resulting suspension was slowly
heated to 100 °C, until the mixture became brown (1 h). The
solvent was removed in vacuo, the residue was extracted with
dichloromethane (4 × 10 cm3), and the extracts were filtered
over anhydrous magnesium sulfate. The resulting solution was
evaporated to dryness and the residue triturated with diethyl
ether to give complex 6a as an E/ Z mixture (1:1.7). Yield: 249
mg, 68%. 1H NMR (200 MHz, CDCl3, ppm): 9.39-9.46 (m,
3
(m, 2 H, bpy), 7.73 (b d, 1 H, H3 or H6, J HH ) 7 Hz), 7.55-
7.58 (m, 1 H, H6 or H3), 7.47-7.52 (m, 1 H, bpy), 7.41-7.46
(m, 1 H, bpy), 7.13-7.24 (m, 2 H, H4 and H5), 3.17 (s, 2 H,
CH2). 13C NMR (50 MHz, CDCl3, ppm): 207.83 (CO), 155.84,
154.78, 150.77, and 149.89 (CH), 148.70, 138.44, 132.75,
128.68, 126.07, 125.87, 124.02, 123.86, 122.55, and 122.26
(CH), 44.39 (CH2). Anal. Calcd for C18H14N2OPd: C, 56.79; H,
3.71; N, 7.36. Found: C, 56.49; H, 3.68; N, 7.48.
3
bpy), 8.22 (d, -CH)CHPh E, J HH ) 16 Hz), 7.37 (d,
-CH)CHPh Z, 3J HH ) 12 Hz), 6.74-8.04 (several m, aromatic
3
H’s) 6.40 (d, -CHdCHPh Z, J HH ) 12 Hz). Anal. Calcd for
C24H19BrN2Pd: C, 55.29; H, 3.67; N, 5.37. Found: C, 55.48;
H, 3.55; N, 5.10.
Syn t h esis of [P d {η -C9H Bn -1-Me2-2,3-(OMe)3-5,6,7}-
(tm ed a )]TfO (11). 2-Butyne (30 mg, 0.56 mmol) was added
to a suspension of 3b (100 mg, 0.19 mmol) and Tl(TfO) (67
mg, 0.19 mmol; TfO ) CF3SO3) in CH2Cl2 (5 cm3). The mixture
was stirred for 20 h and filtered over anhydrous MgSO4. The
solution was concentrated to 1 cm3, and diethyl ether was
added to precipitate 11 as a red-violet solid. Yield: 101 mg,
Syn th esis of [P d {C6H4(CHdCHP h )-2}Br (tm ed a )] (6b).
Yellow complex 6b was similarly prepared (method A) from
nBuLi (0.34 cm3, 0.55 mmol), benzyltriphenylphosphonium
chloride (214 mg, 0.55 mmol), and 2b (200 mg, 0.48 mmol) as
1
a 9:1 E/ Z mixture. Yield: 203 mg, 87%. H NMR (300 MHz,
3
CDCl3, ppm): 8.38 (d, -CH)CHPh E, J HH ) 16 Hz), 6.64-
3
1
77%. Mp: 137-139 °C. ΛM (acetone): 118 Ω-1 cm2 mol-1. H
7.65 (several m, aromatic H’s), 7.28 (d, -CHdCHPh E, J HH
3
) 16 Hz), 6.52 (d, -CHdCHPh Z, J HH ) 12 Hz), 2.39-2.81
NMR (200 MHz, CDCl3, ppm): 7.15-7.40 (m, C6H5, 5 H), 6.28
(m, CH2), 2.81 (s, Me, Z), 2.72 (s, Me, E), 2.68 (s, Me, E), 2.65
(s, Me, Z), 2.58 (s, Me, Z), 2.47 (s, Me, E), 2.39 (s, Me, Z), 2.15
(s, Me, E). Anal. Calcd for C20H27BrN2Pd: C, 49.86; H, 5.65;
N, 5.81. Found: C, 49.87; H, 5.45; N, 5.98.
(s, 1 H, Aryl CH), 3.88, 3.80, and 3.77 (s, 3 H, MeO), 3.40 and
2
3.26 (AB system, 2 H, CH2Ph, J HH ) 15 Hz), 2.60-2.95 (m, 4
H, CH2CH2), 2.75, 2.68, 2.67 and 2.63 (s, 3 H, MeN), 2.31, 1.58
(s, indenyl-CH3, 3 H). 13C NMR (50 MHz, CDCl3, ppm): 153.55,
145.33, 141.45, 135.18, and 133.46 (C-aryl), 128.68 and 128.02
(o, m-C6H5), 126.75 (p-C6H5), 124.32 (indenyl-C), 122.32 (C-
aryl), 96.16 (Aryl-CH), 88.47 and 88.01 (indenyl-C), 61.16
(CH2CH2), 60.91 (2 × MeO), 56.41 (MeO), 51.40, 51.26, 51.17,
and 50.94 (MeN), 30.76 (PhCH2), 12.17 (indenyl-CH3). Anal.
Syn th esis of [P d {C6H(C(O)Me)-6-(OMe)3-2,3,4}Cl(tm e-
d a )] (7). A solution of N,N,N′,N′-tetramethylethylenediamine
(520 mg, 4.47 mmol) in dichloromethane (20 cm3) was added
to a suspension of [Pd(κ2-{C6H(C(O)Me)-6-(OMe)3-2,3,4})(µ-
Cl)]2 (1440 mg, 2.05 mmol) in dichloromethane (30 cm3). After
30 min of stirring, the resulting solution was passed through
Celite and evaporated to 2 cm3. The yellow compound 7
precipitated by addition of diethyl ether. Yield: 1752 mg, 91%.
Mp: 143-145 °C (dec). ΛM (acetone): 0 Ω-1 cm2 mol-1. IR
Calcd for
C28H39F3N2O6PdS: C, 48.38; H, 5.66; N, 4.03.
Found: C, 48.01; H, 5.88; N, 4.07.
Syn t h esis of [P d {η -C9H 2Bn -1-(Ac)-2-(OMe)3-5,6,7}-
(tm ed a )]TfO (12). Crude 12 was similarly prepared from
3-butyne-2-one (35 mg, 0.51 mmol), 3b (120 mg, 0.23 mmol),
and Tl(TfO) (81 mg, 0.23 mmol). The compound was purified
by chromatography: Elution with chloroform-acetone (1:1)
rendered dark red 12. Yield: 52 mg, 32%. Mp: 236-237 °C.
1
(cm-1): ν(CO), 1650. H NMR (200 MHz, CDCl3, ppm): 7.05
(s, 1 H, aryl-H), 4.23, 3.93, and 3.83 (s, 3 H, MeO), 2.45-3.00
(m, 4 H, CH2CH2), 2.90, 2.75, 2.66, 2.61, and 2.26 [s, 3 H, MeN
and C(O)Me]. 13C NMR (50 MHz, CDCl3, ppm): 201.33 [C(O)-
Me], 154.85, 149.43, 144.55, 139.23, and 135.80 (C-aryl), 110.11
(CH-aryl), 62.70 (CH2), 60.54 (OMe), 60.44 (OMe), 58.56 (CH2),
55.99 (MeO), 51.38, 50.68, 48.47, and 47.79 (MeN), 29.68 [C(O)-
CH3]. Anal. Calcd for C17H29ClN2O4Pd: C, 43.69; H, 6.26; N,
5.99. Found: C, 43.47; H, 6.44; N, 5.94.
1
ΛM (acetone): 118 Ω-1 cm2 mol-1. H NMR (300 MHz, CDCl3,
ppm): 7.20-7.31 (m, 5 H, C6H5), 6.54 (s, 1 H, aryl-H or indenyl-
CH), 6.18 (s, 1 H, indenyl-CH or aryl-H), 4.23 (d, 1 H, CH2Ph,
2J HH ) 14 Hz), 4.03, 3.87, and 3.84 (s, 3 H, MeO), 3.38 (d, 1 H,
CH2Ph, 2J HH ) 14 Hz), 2.50-3.15 (m, 4 H, CH2CH2), 2.96, 2.85,
2.73, and 2.67 (s, 3 H, MeN), 2.48 [s, 3 H, C(O)CH3]. 13C NMR
(50 MHz, CDCl3, ppm): 190.62 (CdO), 156.55, 145.52, 142.92,
135.81, and 133.42 (C-aryl), 128.68 and 128.33 (o,m-C6H5),
126.89 (p-C6H5), 120.43 and 118.08 (C-aryl and indenyl-C),
96.68 (R-CH), 94.23 (indenyl-C), 76.44 (indenyl-CH), 62.00
(CH2CH2), 61.38 and 61.23 (MeO), 61.09 (CH2CH2), 56.54
(MeO), 54.61, 53.04, 51.81, and 51.36 (MeN), 31.04 (PhCH2),
27.79 [C(O)CH3]. Anal. Calcd for C28H37F3N2O7PdS: C, 47.43;
H, 5.26; N, 3.95; S, 4.52. Found: C, 47.64; H, 5.30; N, 4.02; S,
4.49. Single crystals of 12 were obtained by liquid diffusion of
diethyl ether into a solution of 12 in chloroform.
Syn th esis of [P d (K2-{C6H(C(O)CH2)-6-(OMe)3-2,3,4})-
(tm ed a )] (9). NaOMe (1.5 mmol of a freshly titrated solution
in methanol) was added to a solution of 7 (600 mg, 1.29 mmol)
in methanol (5 cm3). The mixture was stirred for 5 min and
evaporated to dryness in vacuo, and the residue was stirred
with dichloromethane (5 cm3) and anhydrous MgSO4. The
suspension was filtered over anhydrous MgSO4 and concen-
trated to 1 cm3, and the yellow complex 9 was precipitated by
addition of diethyl ether. Yield: 472 mg, 87%. Mp: 157-158
°C (dec). ΛM (acetone): 0 Ω-1 cm2 mol-1. IR (cm-1): ν(CO),
1
1642. H NMR (300 MHz, CDCl3, ppm): 6.97 (s, 1 H, aryl-H),

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 19, No. 26, 2000 5601
Syn th esis of [P d (η-C9H6Bn -1)(bp y)]TfO (13a ). A satu-
rated dichloromethane solution of HCtCH (10 cm3) was added
to a suspension of 6a (60 mg, 0.11 mmol) and Tl(TfO) (41 mg,
0.11 mmol) in dichloromethane (10 cm3). The mixture was
stirred at room temperature for 20 h and then filtered over
Celite giving a red solution, which was concentrated to 1 cm3.
Diethyl ether was added to precipitate 13a as a brown solid.
Yield: 56 mg, 83%. Mp: 140 °C. ΛM (acetone): 120 Ω-1 cm2
Syn th esis of [P d (η-C9H4Bn -1-Et2-2,3)(bp y)]TfO (15a ).
The orange brown complex 15a was similarly prepared from
6a (60 mg, 0.11 mmol), Tl(TfO) (41 mg, 0.11 mmol), and EtCt
CEt (0.025 cm3, 0.22 mmol). Yield: 49 mg, 66%. Mp: 127 °C.
1
ΛM (acetone): 103 Ω-1 cm2 mol-1. H NMR (200 MHz, CDCl3,
ppm): 6.95-8.57 (several m, 17 H aromatic H's), 3.92 and 3.42
2
(AB system, 2 H, CH2Ph, J HH ) 15 Hz), 2.19-2.61 (m, 4 H, 2
× CH2CH3), 1.41 and 0.89 (t, 3 H, Me, 3J HH ) 7 Hz). 13C NMR
(50 MHz, CDCl3, ppm): 153.16 (C bpy), 151.94 (CH bpy),
151.65 (C bpy), 141.26 (CH bpy), 136.92, 135.61, 135.10, and
131.52 (C), 128.99, 128.13, 128.01, 127.76, 127.52, 127.36,
127.18, 124.70, 116.27, and 116.20 (CH), 96.58 and 91.60 (C),
31.05 (CH2Ph), 19.36 and 18.92 (CH2Me), 16.42 and 11.58 (Me).
Anal. Calcd for C31H29F3N2O3PdS: C, 55.32; H, 4.34; N, 4.16;
S, 4.76. Found: C, 55.08; H, 4.18; N, 4.19; S, 4.53.
1
mol-1. H NMR (200 MHz, CDCl3, ppm): 8.00-8.94 (several
m, 8 H, bpy), 6.98-7.79 (several m, 9 H aromatic H's), 6.84
3
3
(d, 1 H, H2 or H3, J HH ) 3 Hz), 6.30 (d, 1 H, H3 or H2, J HH
2
) 3 Hz), 3.63 and 3.48 (AB system, 2 H, CH2Ph, J HH ) 15
Hz). 13C NMR (75 MHz, CDCl3, ppm): 156.67 (CH bpy), 153.69
(C bpy), 152.56 (CH bpy), 152.03 (C bpy), 141.27 and 140.77
(CH bpy), 136.97, 136.87, and 135.47 (C), 129.02, 128.51,
128.20, 127.75, 127.42, 127.37, 124.39, 124.12, 118.97, 117.01,
and 112.57 (CH), 96.55 (C), 80.49 (CH), 32.77 (CH2). HR FAB
MS: calcd for C26H21N2Pd, m/e 465.0745 (32.4), 466.0755 (74.4),
467.0739 (100), 469.0744 (80.4), 471.0756 (37.3); found, m/e
465.0733 (30.3), 466.0738 (73.2), 467.0734 (100), 469.0741
(75.8), 471.0753 (37.8).
Syn th esis of [P d (η-C9H4Bn -1-Et2-2,3)(tm ed a )]TfO (15b).
The reddish brown complex was obtained from 6b (60 mg, 0.12
mmol), Tl(TfO) (44 mg, 0.12 mmol), and EtCtCEt (0.027 cm3,
0.24 mmol). It was obtained as a reddish brown oil. Yield: 41
mg, 54%. 1H NMR (200 MHz, CDCl3, ppm): 6.78-7.32 (several
m, 9 H aromatic H’s), 3.51 and 3.32 (AB system, 2 H, CH2Ph,
2J HH ) 15 Hz), 2.5-3.0 (m, 6 H, CH2CH2 + CH2Me), 2.76, 2.67,
2.58, and 2.52 (s, 3 H, MeN), 2.06-2.17 (m, 2 H CH2Me), 1.33
and 1.18 (t, 3 H, Me, 3J HH ) 7 Hz). 13C NMR (75 MHz, CDCl3,
ppm): 136.38, 135.09, 135.07, and 131.94 (C), 128.91, 127.79,
127.34, 127.09, 127.05, 115.26, and 114.90 (CH), 94.12 and
89.43 (C), 61.24 (2 C, CH2CH2), 51.96 and 51.70 (MeN), 51.32
(2 × NMe), 30.85 (CH2Ph), 18.71 (2 × CH2Me), 17.45 and 11.70
(Me). HR FAB MS: calcd for C26H37N2Pd, m/e 481.1997 (32.3),
482.2007 (74.4), 483.1991 (100), 485.1996 (80.3), 487.2008
(37.3); found, m/e 481.2043 (32.5), 482.2063 (78.5), 483.2058
(100), 485.2068 (84.7), 487.2081 (41.0).
Syn th esis of [P d (η-C9H6Bn -1)(tm ed a )]TfO (13b). The
reddish brown complex 13b was similarly prepared from 6b
(60 mg, 0.12 mmol) and Tl(TfO) (44 mg, 0.12 mmol). Yield:
38 mg, 53%. Mp: 130 °C. ΛM (acetone): 141 Ω-1 cm2 mol-1
.
1H NMR (200 MHz, CDCl3, ppm): 6.96-7.32 (several m, 9 H
3
aromatic H's), 6.90 (d, 1 H, H2 or H3, J HH ) 3 Hz), 5.64 (d, 1
3
H, H3 or H2, J HH ) 3 Hz), 3.31 and 3.24 (AB system, 2 H,
2
CH2Ph, J HH ) 15 Hz), 2.59-2.89 (m, 4 H, CH2CH2), 2.89 (s,
3 H, Me), 2.79 (s, 3 H, Me), 2.70 (s, 3 H, Me), 2.59 (s, 3 H, Me).
13C NMR (75 MHz, CDCl3, ppm): 136.66, 136.46 and 135.89
(C), 128.90, 128.18, 127.64, 127.52, 127.12, 117.41, 115.92, and
112.32 (CH), 94.19 (C), 77.59 (CH), 61.78 and 60.86 (NCH2),
53.94, 53.13, 51.87, and 51.73 (Me), 32.91 (CH2Ph). Anal. Calcd
for C23H29F3N2O3PdS: C, 47.88; H, 5.07; N, 4.86; S, 5.56.
Found: C, 47.82; H, 5.26; N, 4.90; S, 5.70.
Syn th esis of [P d (η-C9H4Bn -1-P h 2-2,3)(bp y)]TfO (16a ).
The brown complex 16a was similarly prepared from 6a (60
mg, 0.11 mmol), Tl(TfO) (41 mg, 0.11 mmol), and PhCtCPh
(39 mg, 0.22 mmol). Yield: 46 mg, 54%. Mp: 180 °C. ΛM
(acetone): 109 Ω-1 cm2 mol-1 1H NMR (300 MHz, CDCl3,
.
Syn th esis of [P d (η-C9H4Bn -1-Me2-2,3)(bp y)]TfO (14a ).
The brown complex 14a was similarly prepared from 6a (60
mg, 0.11 mmol), Tl(TfO) (41 mg, 0.11 mmol), and MeCtCMe
(0.017 cm3, 0.22 mmol). Yield: 52 mg, 73%. Mp: 132 °C. ΛM
ppm): 7.81-8.79 (several m, 8 H bpy), 6.99-7.55 (several m,
19H, aromatic H’s), 3.85 and 3.74 (AB system, 2 H, CH2Ph,
2J HH ) 13 Hz). 13C NMR (75 MHz, CD2Cl2): 153.39 (2xC bpy),
152.49, 151.91, 141.40, and 141.06 (CH bpy), 135.15, 134.62,
133.94, and 131.15 (C), 131.05 (CH), 130.49 and 129.85 (C),
129.77, 129.52, 129.16, 129.02, 128.69, 128.61, 128.51, 127.85,
127.75, 127.06, 126.98, 124.42, 123.75, 118.51, and 117.46
(CH), 94.89 and 94.21 (C), 31.05 (CH2Ph). Anal. Calcd for
(acetone): 123 Ω-1 cm2 mol-1 1H NMR (200 MHz, CDCl3,
.
ppm): 6.94-8.52 (several m, 17 H aromatic H's), 3.98 and 3.50
(AB system, 2 H, CH2Ph, 2J HH ) 15 Hz), 2.41 and 1.73 (s, 3 H,
Me). 13C NMR (50 MHz, CDCl3, ppm): 153.01 (C bpy), 152.35
(CH bpy), 151.44 (C bpy), 141.13 (CH bpy), 137.26, 136.58, and
134.73 (C), 128.94, 128.26, 127.95, 127.73, 127.53, and 127.11
(CH), 126.53 (C), 124.42, 116.10, and 115.80 (CH), 91.46 and
91.42 (C), 31.09 (CH2Ph), 12.72 and 10.48 (Me). Anal. Calcd
for C29H25F3N2O3PdS: C, 54.00; H, 3.91; N, 4.34; S, 4.97.
Found: C, 53.29; H, 3.93; N, 4.37; S, 5.05. HR FAB MS: calcd
for C28H25N2Pd, m/e 493.1058 (31.9), 494.1068 (73.9), 495.1052
(100), 497.1057 (79.7), 499.1069 (37.2); found, m/e 493.1073
(35.4), 494.1086 (69.0), 495.1078 (100), 497.1075 (83.6), 499.1082
(35.9)
C
39H29F3N2O3PdS: C, 60.90; H, 3.80; N, 3.64; S, 4.17. Found:
C, 60.90; H, 3.96; N, 3.89; S, 4.05.
Syn th esis of [P d(η-C9H4Bn -1-P h 2-2,3)(tm eda)]TfO (16b).
The reddish brown complex 16b was similarly prepared from
6b (60 mg, 0.12 mmol), Tl(TfO) (44 mg, 0.12 mmol), and PhCt
CPh (44 mg, 0.24 mmol). Yield: 64 mg, 73%. Mp: 160 °C (dec).
1
ΛM (acetone): 135 Ω-1 cm2 mol-1. H NMR (200 MHz, CDCl3,
ppm): 6.85-7.47 (several m, 19 H, aromatic H’s), 3.40 and
3.33 (AB system, 2 H, CH2Ph, 2J HH ) 14 Hz), 2.5-2.9 (m, 4 H,
CH2CH2), 3.05, 2.64, 2.50 and 2.05 (s, 3 H, MeN). 13C NMR
(50 MHz, CDCl3, ppm): 135.40, 134.77, 132.87, 131.47. 130.81
and 130.44 (C), 130.94, 129.09, 128.99, 128.95, 128.75, 128.57,
128.48, 128.41, 127.95, 127.75, 126.81, 117.43, and 116.95
(CH), 91.46 and 93.05 (C), 62.05 and 61.37 (CH2N), 53.41,
52.04, 51.17, and 49.00 (MeN), 30.89 (CH2Ph). Anal. Calcd for
Syn th esis of [P d(η-C9H4Bn -1-Me2-2,3)(tm eda)]TfO (14b).
The reddish-brown complex 14b was similarly prepared from
6b (60 mg, 0.12 mmol), Tl(TfO) (44 mg, 0.12 mmol), and MeCt
CMe (0.018 cm3, 0.24 mmol). Yield: 42 mg, 56%. Mp: 115 °C.
1
ΛM (acetone): 110 Ω-1 cm2 mol-1. H NMR (200 MHz, CDCl3,
ppm): 6.80-7.28 (several m, 9 H aromatic H’s), 3.48 and 3.34
(AB system, 2 H, CH2Ph, 2J HH ) 15 Hz), 2.5-3.0 (m, 4 H, CH2-
CH2), 2.79, 2,69, 2.59, and 2.52 (s, 3 H, MeN), 2.40 and 1.47
(s, 3 H, Me). 13C NMR (50 MHz, CDCl3, ppm): 137.19, 136.35,
and 134.93 (C), 128.85, 128.06, 127.17, 126.99, and 126.90
(CH), 126.36 (C), 114.83 and 114.47 (CH), 88.82 and 88.73 (C),
61.07 (2 C, CH2CH2), 51.82, 51.58, 51.36, and 51.10 (MeN),
31.97 (CH2Ph), 12.40 and 10.21 (Me). HR FAB MS: calcd for
C
35H37F3N2O3PdS: C, 57.65; H, 5.11; N, 3.84; S, 4.40. Found:
C, 57.44; H, 5.23; N, 4.04; S, 4.30.
Syn th eses of [P d (η-C9H5Bn -1-P h -3)(bp y)]TfO (17a ) a n d
[P d (η-C9H5Bn -1-P h -2)(bp y)]TfO (17a ′). The mixture of re-
gioisomers 17a and 17a ′ was similarly prepared from 6a (60
mg, 0.11 mmol), Tl(TfO) (41 mg, 0.11 mmol), and PhCtCPh
(0.024 cm3, 0.22 mmol). Color: brown. Yield: 56 mg, 73%. 17a :
17a ′) 1.5:1. 1H NMR (200 MHz, CDCl3, ppm): 7.0-9.0 (several
m, aromatic H’s), 6.93 (s, H2 indenyl 17a ), 6.43 (s, 1 H, H3
indenyl 17a ′), 3.89 (s, 2 H, CH2Ph 17a ′), 3.74 and 3.57 (AB
C
24H33N2Pd, m/e 453.1684 (32.9), 454.1694 (74.9), 455.1678
(100), 457.1683 (81.1), 459.1695 (37.4); found, m/e 453.1679
(36.0), 454.1694 (69.4), 455.1696 (100), 457.1691 (80.0), 459.1689
(38.6).
2
system, 2 H, CH2Ph 17a , J HH ) 15 Hz). Anal. Calcd for

5602 Organometallics, Vol. 19, No. 26, 2000
Vicente et al.
C33H25F3N2O3PdS: C, 57.19; H, 3.64; N, 4.04; S, 4.63. Found:
C, 57.29; H, 3.71; N, 4.13; S, 4.25.
ppm): 153.57, 149.36, 141.28, 136.57, and 132.84 (C-aryl),
131.12, 128.82, 128.09, 126.28, and 124.61 (CH-aryl and CHd
CH), 126.32 and 120.61 (C-allyl and C-aryl), 104.45 (aryl CH),
84.42 (CMe2), 61.86 (MeO), 61.31 (CH2CH2), 60.83 (MeO), 59.86
(CH2CH2), 57.35 (allyl-CH2), 55.97 (MeO), 52.07, 51.75, 50.31,
and 49.40 (MeN), 23.87 and 23.14 (allyl-CH3). Anal. Calcd for
Syn th esis of [P d (η-C9H5Bn -1-P h -3)(tm ed a )]TfO (17b).
The brown complex 17b was similarly prepared from 6b (60
mg, 0.12 mmol), Tl(TfO) (44 mg, 0.12 mmol), and PhCtCH
(0.027 cm3, 0.24 mmol). Yield: 59 mg, 75%. Mp: 139 °C (dec).
1
ΛM (acetone): 155 Ω-1 cm2 mol-1. H NMR (300 MHz, CDCl3,
C
29H41F3N2O6PdS: C, 49.12; H, 5.83; N, 3.95. Found: C, 49.46;
H, 5.84; N, 3.96.
ppm): 7.05-7.91 (several m, 14 H, aromatic H’s), 7.03 (s, 1
H, H2 indenyl), 3.34 (s, 2 H, CH2Ph), 2.50-2.80 (m, 4 H, CH2-
CH2), 2.76, 2.50, 2.14, and 2.05 (s, 3 H, MeN). 13C NMR (75
MHz, CDCl3, ppm): 137.41, 135.85, 134.09, and 132.72 (C),
129.74, 129.16, 128.91, 128.70, 128.29, 127.61, 127.38, 127.12,
117.80, and 116.36 (CH), 110.38 (CH2 indenyl), 92.97 and
91.81 (C), 61.50 and 61.12 (CH2N), 52.28, 51.41, 51.20, and
49.14 (Me), 32.87 (CH2Ph). HR FAB MS: calcd for C28H33N2-
Pd, m/e 501.1684 (31.9), 502.1694 (73.9), 503.1678 (100),
505.1683 (79.6), 507.1695 (37.2); found, m/e 501.1679 (30.4),
502.1695 (75.2), 503.1692 (100), 505.1686 (74.3), 507.1715
(37.2). Single crystals of 17b were were grown by liquid
diffusion of diethyl ether into a solution of 17b in dichlo-
romethane.
Syn t h esis of [P d {S2C{C6H (E-CH dCH P h )-6-(OMe)3-
2,3,4}}(tm ed a )]TfO (20). Carbon disulfide (47 mg, 0.62 mmol)
was added to a suspension of 3b (120 mg, 0.23 mmol) and Tl-
(TfO) (81 mg, 0.23 mmol) in CH2Cl2 (5 cm3). The intensely
orange-colored mixture was stirred for 20 h and filtered over
anhydrous MgSO4. The solution was concentrated (1 cm3), and
diethyl ether was added to precipitate 20 as an orange solid.
Yield: 147 mg, 90%. Mp: 175-176 °C. ΛM (acetone): 113 Ω-1
cm2 mol-1. 1H NMR (300 MHz, CDCl3, ppm): 7.34-7.54 (m, 6
H, C6H5 and CH)CH), 6.90 (d, 1 H, CHdCH, 3J ) 16 Hz),
6.86 (s, 1 H, aryl-H), 4.04, 4.00, and 3.90 (s, 3 H, MeO), 3.11
(s, 4 H, CH2-CH2), 2.85 (s, 12 H, MeN). 13C NMR (50 MHz,
CDCl3, ppm): 214.26 (v w CS2, tentative), 158.41, 153.04,
141.29, 136.44, and 136.21 (C-aryl), 132.13 (CHdCH or
p-C6H5), 129.36 (C-aryl), 128.85 and 126.89 (o,m-C6H5), 128.56
and 126.32 (CHdCH and/or p-C6H5), 107.36 (aryl-CH), 61.29
(CH2CH2), 61.58, 60.96, and 56.42 (MeO), 50.20 (MeN). Anal.
Calcd for C25H33F3N2O6PdS3: C, 41.87; H, 4.64; N, 3.91; S,
13.41. Found: C, 41.93; H, 4.78; N, 4.00; S, 13.34.
Syn th esis of [P d(η-C9H4Bn -1-P h -2-Me-3)(bpy)]TfO (18a).
The brown complex 18a was similarly prepared from 6a (100
mg, 0.18 mmol), Tl(TfO) (68 mg, 0.18 mmol), and PhCtCMe
(0.045 cm3, 0.36 mmol). Yield: 72 mg, 70%. Mp: 154 °C. ΛM
(acetone): 116 Ω-1 cm2 mol-1 1H NMR (200 MHz, CDCl3,
.
ppm): 8.8-7.5 (several m, 8 H bpy), 7.38 (bs, 5 H, Ph-2
indenyl), 7.2-7.0 (several m, 9H, aromatic H’s), 3.78 and 3.53
Syn th esis of [P d{S(NMe)C{C6H(E-CHdCHP h )-6-(OMe)3-
2,3,4}}(tm ed a )]TfO (21). The yellow complex 21 was simi-
larly prepared from methyl isocyanate (35 mg, 0.48 mmol), 3b
(120 mg, 0.23 mmol), and Tl(TfO) (81 mg, 0.23 mmol). Yield:
102 mg, 63%. Mp: 142-143 °C. ΛM (acetone): 121 Ω-1 cm2
(AB system, 2 H, CH2Ph, 2J HH ) 14 Hz), 1.68 (s, 3 H, Me). 13
C
NMR (50 MHz, CD2Cl2, ppm): 153.23 and 153.20 (C bpy),
152.46, 151.43, 141.17, and 141.08 (CH bpy), 136.77, 135.60,
135.01, 131.31, and 130.75 (C), 130.66, 128.80, 128.72, 128.54,
128.35, 128.16, 127.66, 127.34, 126.92, 124.11, 124.01, 117.13,
and 116.46 (CH), 93.20 and 91.54 (C), 30.99 (CH2Ph), 10.98
(Me). Anal. Calcd for C34H27F3N2O3PdS: C, 57.76; H, 3.85; N,
3.96; S, 4.53. Found: C, 57.52; H, 3.84; N, 3.78; S, 4.48. Single
crystals of 18a were grown by liquid diffusion of diethyl ether
into a solution of 18a in 1,2-dichloroethane.
1
mol-1. H NMR (200 MHz, CDCl3, ppm): 7.30-7.60 (m, 5 H,
C6H5), 7.14 (d, 1 H, CH)CH, 3J ) 16 Hz), 7.03 (d, 1 H,
CH)CH, 3J ) 16 Hz), 6.95 (s, 1 H, aryl-H), 4.00, 3.97, and
3.89 (s, 3 H, MeO), 2.90-3.15 (s, 4 H, CH2-CH2), 2.99, 2.96,
2.82 (s, 3 H, MeN), 2.80 (s, 2 × MeN, 6 H). 13C NMR (50 MHz,
CDCl3, ppm): 194.95 (CdS), 155.47, 149.43, 141.29 and 136.56
(C-aryl), 131.48 (CHdCH or p-C6H5), 130.40 (C-aryl), 128.87
(o,m-C6H5), 128.31 (CHdCH or p-C6H5), 126.75 (o, m-C6H5),
124.13 (C-aryl), 124.05 (CHdCH or p-C6H5), 104.08 (aryl-CH),
61.80 and 61.75 (CH2CH2), 61.69, 61.02, and 56.09 (MeO),
51.73, 51.66, 50.81, and 50.75 (Me2N), 36.82 (MeN). Anal.
Calcd for C26H36F3N3O6PdS2: C, 43.73; H, 5.08; N, 5.88; S, 8.98.
Found: C, 43.61; H, 5.15; N, 6.01; S, 9.34.
Syn t h esis of [P d (η-C9H 4Bn -1-P h -2-Me-3)(t m ed a )]TfO
(18b). The brown complex 18b was similarly prepared from
6b (100 mg, 0.20 mmol), Tl(TfO) (73 mg, 0.20 mmol), and
PhCtCMe (0.050 cm3, 0.40 mmol). Yield: 83 mg, 62%. Mp:
1
162 °C (dec). ΛM (acetone): 139 Ω-1 cm2 mol-1. H NMR (300
MHz, CDCl3, ppm): 7.5-7.4 (several m, 5 H, Ph-2-indenyl),
7.15-6.85 (several m, 9 H aromatic H’s), 3.31 and 3.27 (AB
2
system, 2 H, CH2Ph, J HH ) 15 Hz), 3.1-2.5 (m, 4 H, CH2-
X-r a y Str u ctu r e Deter m in a tion s. Crystal data are given
in Table 1. Crystals were mounted on glass fibers in inert oil
and transferred to the cold gas stream of the diffractometer.
Data were collected in ω-scan mode using Mo KR radiation (λ
) 0.710 73 Å). Structures were solved by direct methods and
refined anisotropically against F2 (program SHELXL-93 for
12, otherwise SHELXL-97, G. M. Sheldrick, University of
Go¨ttingen, Go¨ttingen, Germany). Hydrogen atoms were in-
cluded using a riding model or rigid methyl groups. Special
features of refinement: In 12 and 18a the triflate anions are
disordered over two positions; in 17b the TMEDA ligands
(excluding N atoms) and the ring C21-26 are similarly
disordered. In all cases an extensive system of restraints (to
light atom displacement factors, local ring symmetry, and
similarity of disorder components) was employed to ensure
stability of refinement. Compound 18a crystallizes as a diethyl
ether hemisolvate.
CH2), 2.91, 2.65, 2.63, and 2.54 (s, 3 H, MeN), 1.38 (s, 3H, Me).
13C NMR (75 MHz, CDCl3, ppm): 136.13 (C), 135.17 (2 × C),
132.21 (C), 130.70 (C), 130.46, 129.14, 128.91, 128.55, 128.23,
127.97, 127.49, 126.86, 115.92, and 115.36 (CH), 90.82 and
88.86 (C), 61.40 (2 × C, CH2CH2), 52.01 and 51.80 (MeN), 51.33
(2 × C, MeN), 31.08 (CH2Ph), 10.79 (Me). HR FAB MS: calcd
for C29H35N2Pd, m/e 515.1841 (31.6), 516.1851 (73.6), 517.1835
(100), 519.1839 (79.3), 521.1852 (37.2); found, m/e 515.1849
(35.2), 516.1861 (79.8), 517.1853 (100), 519.1843 (72.7), 521.1858
(43.8).
Syn th esis of [P d{η3-CMe2C{C6H(E-CHdCHP h )-6-(OMe)3-
2,3,4}CH2}(tm ed a )]TfO (19). 3-Methyl-1,2-butadiene (34 mg,
0.50 mmol) was added to a suspension of 3b (120 mg, 0.23
mmol) and Tl(TfO) (81 mg, 0.23 mmol) in CH2Cl2 (5 cm3). The
mixture was stirred for 20 h and filtered over anhydrous
MgSO4. The solution was concentrated to 1 cm3 and chromato-
graphed. Elution with chloroform-acetone (1:1) rendered
colorless 19. Yield: 71 mg, 44%. Mp: 196-198 °C. ΛM
Resu lts a n d Discu ssion
(acetone): 110 Ω-1 cm2 mol-1
.
1H NMR (200 MHz, CDCl3,
3
ppm): 7.25-7.48 (m, 5 H, C6H5), 7.05 (d, 1 H, CHdCH, J )
16 Hz), 6.96 (s, 1 H, aryl-H), 6.94 (d,1 H, CHdCH, 3J ) 16
Hz), 4.04, 3.96 and 3.87 (s, 3 H, MeO), 3.68 (d, 1 H, allyl-CH2,
Wittig Rea ction s. The reactions of 2-formylaryl
complex 1 or 2 with ylides Ph3PdCHR [R ) Ph, py (2-
pyridyl), Cl] led to 2-(2′-R-vinyl)aryl complexes 3-5 or
6, respectively (see Scheme 2). The ylides were gener-
ated in situ by reacting the corresponding phosphonium
2J HH ) 1 Hz), 3.45 (d, 1 H, allyl-CH2, J HH ) 1 Hz), 2.80-3.00
2
(m, 4 H, CH2CH2), 3.04, 2.86, 2.82, and 2.61 (s, 3 H, MeN),
1.47 and 1.06 (s, 3 H, allyl-CH3). 13C NMR (50 MHz, CDCl3,

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 19, No. 26, 2000 5603
Ta ble 1. Su m m a r y of X-r a y Da ta for Com p lexes 12, 17b, a n d 18a
compound
12
17b
18a .0.5C4H10
O
formula
Mr
C
28H37F3N2O7PdS
C29H33F3N2O3PdS
653.03
C36H32F3N2O3.5PdS
744.10
709.06
habit
red-brown prism
0.7 × 0.35 × 0.2
monoclinic
P21/n
brown tablet
0.4 × 0.4 × 0.15
monoclinic
P21/n
red cube
cryst size (mm)
cryst system
space group
diffractometer
cell constants
a (Å)
0.09 × 0.09 × 0.07
monoclinic
C2/c
Bruker SMART
Siemens P4
Stoe STADI-4
13.5419(14)
11.2163(14)
21.111(2)
102.819(8)
10.414(2)
21.840(3)
12.379(2)
95.48(2)
22.8471(14)
16.2595(11)
18.5179(12)
111.016(2)
6421.5
b (Å)
c (Å)
â (deg)
V (Å3)
3126.7
2802.6
Z
4
4
8
Dx (Mg m-3
)
1.506
0.72
ψ-scans, 0.74-0.88
1456
100
50
1.548
0.79
ψ-scans, 0.69-0.77
1336
130
50
1.539
0.71
SADABS, 0.81-0.98
3032
130
52.7
µ (mm-1
abs corr, transms
F(000)
)
T (°C)
2θ(max) (deg)
no. of reflcns
measd
6107
5491
0.018
390
5227
4940
0.034
322
20 539
6573
0.051
454
indepdt
Rint
no. of params
no. of restraints
wR2a
453
319
537
0.122
0.044
1.04
1.1
0.114
0.052
1.05
0.6
0.107
0.041
0.94
R1b
S
max ∆F (e Å-3
)
0.8
R1 ) Σ||Fo| - |Fc||/Σ|Fo| for reflections with I > 2σ(I). wR2 ) [Σ[w(Fo2 - Fc2)2]/Σ[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2 +
a
b
bP, where P ) (2Fc + Fo2)/3 and a and b are constants set by the program.
2
Sch em e 2
procedure offers a better yield and it is less laborious.
Unfortunately, is was not possible to prepare 6b using
the same method. Complexes 3a , 4, and 6a , containing
the ligand bpy, were isolated as mixtures of the two
stereoisomers [E:Z ) 3:1 (3a ), 4:1 (4), and 2.6:1 (6a ),
respectively], although it was possible to isolate the most
abundant E-3a and E-4 by recrystallizing the corre-
sponding mixtures. When the same ylides were reacted
with the tmeda complex 1b, complexes 3b and the
analogue to 4 were obtained with complete regioselec-
tivity toward the E isomer-the Z isomer was not
observed in the crude product-independently of the
method used for the formation of the ylide: nBuLi/
(BnPh3P)Cl or NaOMe/(BnPh3P)Cl. However, although
the tmeda complex analogous to 4 could be isolated
spectroscopically pure, good elemental analysis for
carbon could not be obtained. (Anal. Calcd for C22H32
-
ClN3O3Pd: C, 50.01; H, 6.10; N, 7.95. Found: C, 49.19;
H, 6.02; N, 7.54.) If the same reaction is carried out from
the tmeda complex 2b, the complex 6b is obtained as
isomeric mixtures with variable E:Z ratios (range 2:1
to 9:1).
It is known that semistabilized ylides, such as those
used in these reactions, react with organic carbonyl
compounds to give ca. 1:1 E:Z mixtures.50 One of the
mechanistic proposals for the Wittig reaction involves
the formation of oxaphosphetanes (OPA).50 Very recent
calculations suggest that, in the case of semistabilized
ylides, planar transition states (TS’s), which would give
a trans OPA, are 2.1 kcal more stable than a puckered
transition state leading to a cis OPA.51 Moreover, in our
chloride with nBuLi (1:1) (3a , 4, 6) or potassium tert-
butoxide (3b, 5). In addition, complex 6a was prepared
by an oxidative addition reaction of 2-bromostilbene to
“Pd(dba)2” in the presence of bpy (2,2′-bipyridine). This
(50) J ohnson, A. V. Ylides and Imines of Phosphorus; J . Wiley &
Sons: New York, 1993.

5604 Organometallics, Vol. 19, No. 26, 2000
Vicente et al.
Sch em e 3
react with alkynes to give mono-, di- and triinserted
derivatives (see Scheme 1)8-18 or, after depalladation,
organic compounds such as spirocycles,9,19 indenols,
indenones,20 carbocycles,9,21-26 and oxygen,27-29
sulfur,30-32 or nitrogen heterocycles.13,14,24,27,28,33-38 In
some cases, the palladation reaction and the insertion
of the alkyne are part of a catalytic cycle yielding
interesting organic compounds.26,53-64 This explains the
present interest of this topic.
We have recently reported four indenyl complexes
with Y ) OMe (L2 ) tmeda, R ) R′ ) H, Ph; R ) H, R′
) Ph; L2 ) bpy, R ) R′ ) Me) (Scheme 1).39 obtained
from the reactions of (2,3,4-trimethoxy-6-alkenylaryl)-
palladium complexes with alkynes. To explore the limits
of this method we have extended the study to other
alkynes and (o-alkenylaryl)palladium complexes. Thus,
when complex 3b is reacted with excess of alkynes RCt
CR′ [R ) R′ ) Me, Et, R ) H, R′ ) C(O)Me] in the
presence of TlOTf (1:3-2:1 molar ratios), an annulation
process takes place with the formation of the inde-
nylpalladium derivatives 11 and 12, the latter being the
only regioisomer observed in the reaction (see Scheme
4). This method constitutes an easy synthesis of indenyl
palladium complexes, because, in contrast to the tradi-
tional method, it requires neither precautions against
air and moisture nor the synthesis of the family of R,R′-
indenes. Because the above and previous examples
involved Y ) OMe,39 we investigated the reactions of
2-palladastilbenyl complexes 6a,b (Y ) H) with a family
of symmetrical (R ) R′ ) H, Me, Et, Ph) and unsym-
metrical (R ) Ph, R′ ) H, Me) alkynes. Again, these
reactions result in the formation of the indenyl com-
plexes 13-18 (Scheme 4) in yields 53-83%. The reac-
tion of the bpy complex 6a with PhCtCH gives a 1.5:1
mixture of regioisomers 17a and 17a ′, respectively;
however, the tmeda complex 6b gives 17b as the only
regioisomer. Here, as in the case of the Wittig reactions
commented above, replacing bpy by tmeda results in a
greater selectivity. The formation of 17b results from
the insertion of PhCtCH into the C-Pd bond in such a
way that the CPh moiety is attached to the carbon atom
previously coordinated to Pd (CPd); the same regiose-
lectivity was found in the reaction of 3b with PhCt
CH.39 However, in the insertion of PhCtCMe the group
attached to CPd is CMe.
case, the examination of simple models shows a sterical
hindrance between the metallic moiety and the phenyl
substituents of the ylidic group (PPh3 and CHPh) in the
cis OPA’s or TS’s, whereas it decreases markedly in the
trans case. Thus a steric effect could be responsible of
the observed regioselectivity favoring the E geometry.
In these cases, the presence of the methyl substituents
of the tmeda ligand enhances the steric hindrance
between the metallic fragment and the ylidic Ph groups
(PPh3 and CHPh) in the cis OPA's and TS’s, increasing
the energy differences between both possibilities and
favoring even more the E geometry of the alkenyl
group. A further example is the reaction of 1b with
Ph3PdCHCl, which gives also exclusively the E isomer
[Pd{C6H(E-CHdCHCl)-6-(OMe)3-2,3,4}Cl(tmeda)] (5).
The spectroscopic data for complexes 3-6 are in
accordance with the proposed structures. A useful tool
has been the study of the signals corresponding to the
-CHdCH- group. In the case of complexes 3, 4, and 6,
3
these hydrogens appear as two doublets with J HH
)
3
16 Hz for the E isomers and J HH ) 12 Hz for the Z
isomers. Complex 5 shows J HH ) 13.5 Hz, which
3
corresponds to an E disposition since the presence of a
chloro substituent in a CHdCH grouping causes a
lowering of these coupling constants.52
It is reasonable to assume that these reactions occur
through the insertion of the alkyne into the aryl C-Pd
bond forming an alkenylpalladium intermediate A
The o-acetylcomplexes [Pd{C6H(C(O)Me)-6-(OMe)3-
2,3,4}Cl(tmeda)] (7) [prepared by reacting [Pd(κ2-{C6H-
(C(O)Me)-6-(OMe)3-2,3,4})(µ-Cl)]2 with tmeda] and [Pd-
{C6H4(C(O)Me)-2}Br(bpy)] (8)2 reacted differently with
Ph3PdCHPh, since it acts as a base deprotonating the
acetyl methyl groups and forming the 3-palladaindan-
1-ones [Pd(κ2-{C6H(C(O)CH2)-6-(OMe)3-2,3,4})(tmeda)]
(9) and [Pd(κ2-{C6H4(C(O)CH2)-2})(bpy)] (10). These
syntheses are improved by reaction of 7 and 8 with
NaOMe as a base (Scheme 3). The crystal structure of
9 has been previously communicated.7 As far as we are
aware, these are the only examples of isolated and
characterized 3-palladaindan-1-ones.6
(53) Park, S. S.; Choi, J . K.; Yum, E. K.; Ha, D. C. Tetrahedron Lett.
1998, 39, 627.
(54) Trost, B. M.; Sorum, M. T.; Chan, C.; Harms, A. E.; Ruhter, G.
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hedron Lett. 1997, 38, 2311.
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F.; Mongelli, N.; Bedeschi, A. Tetrahedron Lett. 1997, 38, 2307.
(57) Zhang, H. C.; Brumfield, K. K.; Maryanoff, B. E. Tetrahedron
Lett. 1997, 38, 2439.
(58) Wensbo, D.; Eriksson, A.; J eschke, T.; Annby, U.; Gronowitz,
S.; Cohen, L. A. Tetrahedron Lett. 1993, 34, 2823.
(59) Yamada, H.; Aoyagi, S.; Kibayashi, C. Tetrahedron Lett. 1997,
38, 3027.
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60, 3270.
Rea ction s w ith Alk yn es. F or m a tion of In d e-
n ylp a lla d iu m Com p lexes. Arylpalladium complexes
(61) Coperet, C.; Sugihara, T.; Wu, G. Z.; Shimoyama, I.; Negishi,
E. J . Am. Chem. Soc. 1995, 117, 3422.
(51) Yamataka, H.; Nagase, S. J . Am. Chem. Soc. 1998, 120, 7530.
(52) Gu¨nther, H. NMR Spectroscopy. An Introduction; J . Wiley &
Sons: Chichester, U.K., 1980; p 110.
(62) Liao, H. Y.; Cheng, C. H. J . Org. Chem. 1995, 60, 3711.
(63) Larock, R. C.; Yum, E. K. J . Am. Chem. Soc. 1991, 113, 6689.
(64) Larock, R. C.; Tian, Q. P. J . Org. Chem. 1998, 63, 2002.

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 19, No. 26, 2000 5605
Sch em e 4
Sch em e 5
(Scheme 5); this behavior is well-documented.8,65,66
Addition of the C-Pd bond to the alkenyl substituent,
a well-known process occurring in palladium-catalyzed
cyclization reactions,67 would give the alkylpalladium
complex B. The successive â-hydride elimination, to give
the hydrido benzofulveno π-complex C, and readdition
through D to give a three-coordinated σ-indenyl complex
E should lead to the more stable η-indenyl complexes
11-18 (Scheme 5).39 According to this pathway, the
observed regioselectivity of the reaction with MeC(O)Ct
CH, PhCtCH, or PhCtCMe (Scheme 4) must be
determined in the alkyne insertion step. We have
previously proposed an empirical scale that gives the
tendency of the CR′ moiety of an alkyne RCtCR′ to be
attached to CPd; this scale was based on data from the
literature relative to catalytic and stoichiometric reac-
tions involving alkynes and arylpalladium species:68
CO2Et ≈ CHO ≈ C(O)Me ≈ SO2C6H4Me-4 g H > Me ≈
Et > aryl > But ≈ SiR3. Because the regioselectivity in
the formation of 17b and 18a ,b, as well as that previ-
ously found in the reaction of PhCtCH with complex
3b,39 did not follow such a scale but instead showed Me
> Ph > H, we have reconsidered this series. We notice
that the position of H in the scale was based only in a
work by Liao and Cheng.62 These authors proposed a
mechanism that does not include an insertion step of
the alkyne into the C-Pd bond. This seems also to
happen in the recently reported palladium-catalyzed
synthesis of indoles,56,69 benzofurans,55 and azaindols.70
Consequently, the above scale must be corrected to be
the following: CO2Et ≈ CHO ≈ C(O)Me ≈ SO2C6H4-
Me-4 > Me ≈ Et > aryl > But ≈ SiR3 > H. If we accept
this new order, only the synthesis of 12 remains an
exception.
The results of our reactions are independent of the E
and/or Z nature of the styryl substituent, as we had
noted previously,39 which agrees with our proposed
pathway.
We have attempted similar reactions with (2-vinyl-
aryl)palladium complexes [Pd{C6H4(CHdCH2)-2}Br-
(PR3)2] (R ) Ph, C6H4Me-4), but no indenylderivatives
are formed and, instead, decomposition gave a mixture
of organic materials.
Rea ction s w ith Cu m u len es. The complex 3b reacts
with CH2dCdCMe2 to give the η3-allyl complex [Pd(η3-
CMe2C{C6H(E-CHdCHPh)-6-(OMe)3-2,3,4}CH2)(tmeda)]-
TfO (19) (Scheme 6). This is an expected result since
(65) 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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Arellano, M. C.; J ones, P. G. Organometallics 1997, 16, 4557.
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15, 3509.
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(70) Ujjainwala, F.; Warner, D. Tetrahedron Lett. 1998, 39, 5355.

5606 Organometallics, Vol. 19, No. 26, 2000
Vicente et al.
Sch em e 6
F igu r e 1. Thermal ellipsoid plot of the cation of complex
12 (30% probability levels) with the labeling scheme.
Selected bond lengths (Å) and angles (deg): Pd-N(1) 2.115-
(3), Pd-N(2) 2.112(4), Pd-C(1) 2.185(4), Pd-C(2) 2.175-
(4), Pd-C(3) 2.220(4), C(41)-O(4) 1.213(5); N(1)-Pd-N(2)
84.64(14).
6-(OMe)3-2,3,4})(tmeda)]TfO (20) and [Pd(SC{C6H(E-
CHdCHPh)-6-(OMe)3-2,3,4}NMe)(tmeda)]TfO (21), re-
spectively (Scheme 6). We are only aware of one example
of insertion of CS2 into a Pd-C bond-that starting from
[PdI(Me)(PMe3)2] and giving a dithioacetate complex44,45
and none for MeNdCdS. The 13C NMR spectrum of 20
shows a weak signal at 214.26 ppm, which may be
assignable to the CS2 grouping of a η2-dithiocarboxylate
ligand.82 Complex 21 exhibits a signal at 194.95 ppm
that should be associated with the quaternary carbon
of the η2-SC(NMe) group.
The reactions of the compounds 6a ,b with these
cumulenes, under the same conditions, result in the
formation of ill-defined mixtures.
similar reactions are known and constitute a simple
route to allylpalladium complexes.71-74 Moreover, inser-
tion of allenes into carbon-palladium bonds to give
allylpalladium species is very probably a key step
in many palladium-catalyzed reactions involving
allenes.75-81
We have also tested with other cumulenes similar
reactions that could result in the formation of hetero-
cycles.82 Thus, we carried out reactions of 3b with CS2
and MeNdCdS in the presence of TlOTf; however, they
result in the formation of [Pd(S2C{C6H(E-CHdCHPh)-
X-r a y Str u ctu r e Deter m in a tion s. The crystal and
molecular structures of the indenyl complexes 12, 17b,
and 18a have been determined by X-ray diffraction
studies (see Figures 1-3 and Table 1). The crystal
structure of 3b was reported in a preliminary com-
munication.7 In complex 12 the distances of Pd to the
“allylic” carbons C(1) [2.185(4) Å], C(2) [2.175(4) Å], and
C(3) [2.220(4) Å] are significantly shorter than those to
the “ene” carbons C(11) [2.567(4) Å] and C(12) [2.547(4)
Å]. However these differences are not enough to support
a η3 formulation for the indenyl ligand since the ∆MC
value (difference beween the average of the metal-
carbon distances to the “allyl” and “ene” carbons)83,84 of
0.36 Å lies between those corresponding to η3 (0.5-0.9
Å) and those expected for η5 coordination (0-0.2 Å).83-89
Similar intermediate values are observed for the fold
(71) Stevens, R. R.; Shier, G. D. J . Organomet. Chem. 1970, 21, 495.
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1817.
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Lett. 1998, 39, 435.
(83) Honan, M. B.; Atwood, J . L.; Bernal, I.; Herrmann, W. A. J .
Organomet. Chem. 1979, 179, 403.
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4, 929.
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anov, V. G.; Struchkov, Y. T.; Andrae, S.; Ustynyuk, Y. A.; Malyugina,
S. G. J . Organomet. Chem. 1978, 159, 189.
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H.; Vrieze, K. Tetrahedron Lett. 1999, 40, 4255.
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J . Am. Chem. Soc. 1986, 108, 2460.

Palladium-Assisted Formation of C-C Bonds
Organometallics, Vol. 19, No. 26, 2000 5607
atom on this ring)83,84,87 of 0.46 Å could correspond to a
η3 situation (>0.3 Å).84 In consequence, and as we have
observed previously in similar indenylpalladium com-
plexes,39 we conclude that the hapticity of the indenyl
ligand is intermediate between η3 and η5. Very recently,
an indenylpalladium complex has been described and
the authors have found a similar ambiguity in estab-
lishing the hapticity of this ligand.43
In the case of the compounds 17b and 18a the data
are also ambiguous but it is possible to observe a
tendency toward a “more η3 character”: ∆MC 0.41 and
0.42 Å, fold angles 17.7 and 14.5°, slip angles 15.0 and
15.8°, and slip distortions 0.52 and 0.55 Å, respectively.
Furthermore, the distances between the palladium atom
and the “ene” carbons are longer for 17b and 18a
(average: 2.603 and 2.630 Å) than for 12 (2.557 Å).
F igu r e 2. The cation of complex 17b with the labeling
scheme. Only one position of the disordered groups is
shown. Selected bond lengths (Å) and angles (deg): Pd-
N(1) 2.143(4), Pd-N(2) 2.143(5), Pd-C(1) 2.204(5), Pd-
C(2) 2.157(6), Pd-C(3) 2.244(5); N(1)-Pd-N(2) 83.42(17).
Con clu sion s
The synthesis of (o-alkenylaryl)palladium complexes,
which could be of interest in the fields of nonlinear
optics or organometallic polymers, is reported using
two different methods, namely, oxidative addition or
Wittig reactions. The latter represents one of the scarce
examples of reaction of a phosphorus ylide with a
carbonyl compound coordinated to a metal. In some
cases, this reaction leads to the first 3-palladaindan-1-
ones. Some of the (o-alkenylaryl)palladium complexes
have been reacted with symmetrical and unsymmetrical
alkynes to give, without precautions against air or
moisture, a familly of highly substituted indenylpalla-
dium complexes. A new scale for the regioselectivity of
the insertion of alkynes into the C-Pd bond of arylpal-
ladium complexes is reported. Finally, an (o-alkenyl-
aryl)palladium complex has been shown to react with
CH2dCdCMe2 to give η3-allyl complex or with CS2 or
MeNdCdS, in the presence of TlOTf, to give the
insertion product.
F igu r e 3. Thermal ellipsoid plot of the cation of complex
18a (30% probability levels) with the labeling scheme.
Selected bond lengths (Å) and angles (deg): Pd-N(1)
2.091(3), Pd-N(2) 2.096(3), Pd-C(1) 2.211(3), Pd-C(2)
2.167(4); N(1)-Pd-N(2) 78.59(12).
Ack n ow led gm en t. We thank the Direccio´n General
de Investigacio´n Cient´ıfica y Te´cnica (Grant PB97-1047)
and the Fonds der Chemischen Industrie for financial
support. R.B. is grateful to the Human Capital and
Mobility Research Program of the Commission of the
European Communities for a research training fellow-
ship (Contract No. ERBCHBGCT920143), and E.M.-V.,
to Fundacio´n Se´neca (Comunidad Auto´noma de la
Regio´n de Murcia. Spain) for a grant.
angle (dihedral angle between the plane defined by the
three “allylic” carbons and that formed by the benzenoid
carbons)89,90 with a value of 11.2° (20-29° for η3, 7-10°
87,89
for η5)
and the slip angle (the angle between the
normal to the plane through the metal atom and the
centroid-metal vector)83,84,87 with 13.2° (20-24° for η3,
2-5° for η5).84,87 However, the slip distortion (distance
between the C5 centroid and the projection of the metal
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
positional parameters, bond lengths and interbond angles,
atomic displacement parameters, and hydrogen atom param-
eters. This material is available free of charge via the Internet
at http://pubs.acs.org.
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