Ligand exchange and catalysis in phenylation reactions mediated by lead tetracarboxylates

Article abstract of DOI:10.1016/S0022-328X(98)00379-9

An investigation of catalysis and ligand exchange in the arylation of nucleophiles with phenylboronic acid and mixed ligand lead(IV) complexes is described. Although this reaction is known to be catalyzed by mercury(II) acetate, other heavy metals have be

Full text of DOI:10.1016/S0022-328X(98)00379-9

Journal of Organometallic Chemistry 560 (1998) 77–88
Ligand exchange and catalysis in phenylation reactions mediated by
lead tetracarboxylates
Mark G. Moloney a,*, Diana R. Paul a, Russell M. Thompson b, Emma Wright a
a The Department of Chemistry, Dyson Perrins Laboratory, Uni6ersity of Oxford, South Parks Rd, Oxford, OX1 3QY, UK
b Associated Octel Company, Ellesmere Port, South Wirral, L65 4HF, UK
Received 25 October 1997
Abstract
An investigation of catalysis and ligand exchange in the arylation of nucleophiles with phenylboronic acid and mixed ligand
lead(IV) complexes is described. Although this reaction is known to be catalyzed by mercury(II) acetate, other heavy metals have
been shown to have a similar effect, albeit less efficiently. The effect of pyridine has been investigated with a range of chelating
ligands containing a pyridine sub-unit. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Lead(IV); Ligand modification; Phenylation; Catalysis; Mercury(II)
1. Introduction
the expected product 2 could be obtained, although in
the case of chiral ligands, only low enantioselectivity in
the reaction was observed (Scheme 1(a)) [3–5]. Since we
have recently shown that rapid ligand exchange occurs
in a mixture of lead(IV) tetraacetate/tetrabenzoate [6,7],
it seemed likely that similar equilibration in lead(IV)
complexes such as 1 would scramble the ligands
(Scheme 1(b)), thereby providing several different coor-
dinated species with varying reactivity. This would be
similar to the equilibrium which exists in some ligand-
modified transition metal mediated reactions, in which
The arylation of nucleophiles with phenylboronic
acid and lead tetraacetate with mercuric acetate cataly-
sis has been extensively developed, and provides an
important source of phenyl cation synthetic equivalents
[1]; it is also well documented that pyridine is important
in these reactions [2]. In previous work, we described
the use of novel chiral and achiral lead(IV) complexes
such as 1 in place of lead tetraacetate (LTA) for Pinhey
arylation, and demonstrated that comparable yields of
Scheme 1.
* Corresponding author. E-mail: mark.moloney@chem.ox.ac.uk
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00379-9

78
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
Examination of the 207Pb-NMR of mixtures of
lead(IV) tetrabenzoate (LTB) and mercuric(II) salts in-
dicated that ligand exchange depended on the nature of
the counter anion; thus, when 0.1 equivalents of mer-
curic acetate was added to LTB in solution, species in
the LTA/LTB equilibrium system were observed (Fig.
1(a)). However, the addition of mercuric chloride to
LTB gave no change in lPb, consistent with the absence
of ligand exchange (Fig. 1(b)).
it is now well established that there a number of
reactive entities in solution which often possess differ-
ing reactivity patterns [8]. Furthermore, the need to use
both heavy metal cation (Hg(II)) catalysis and pyridine
in the Pinhey arylation procedure [2] introduces addi-
tional ligands, which can further complicate the
lead(IV) coordination chemistry. We therefore exam-
ined both the need for, and nature of, suitable catalysts
and additives in arylation reactions; of particular inter-
est was their effect upon rate and enantioselectivity.
Pyridine has long been known to be useful for the
lead(IV)-mediated arylation reaction, giving cleaner re-
actions and better yields of product [2]. It has been
suggested that pyridine is either a |-donor for lead(IV),
since spectroscopic evidence for the formation of an
adduct with LTA has been reported, [12,13] or alterna-
tively, a base which catalyses the keto-enol tautomer-
ization of the substrate. In order to exploit the benefits
of pyridine, complexes in which the pyridine unit is
tethered to a carboxylic acid ligand were prepared; the
synthesis of the required ligands 6–8 has been reported
[11]. Complexes derived from these ligands, along with
acetic, benzoic, cyclohexanecarboxylic, and cinnamic
acids, were prepared using standard methodology
(Table 2, Schemes 2 and 3) [5,14]. The latter three acids
were chosen on the basis of their known electron-do-
nating properties [7] to observe the possible effects on
the stability, solubility and reactivity of the derived
complexes; benzoic acid is more electron-donating than
acetate, while cyclohexanecarboxylic acid and cinnamic
acid are both less electron-donating. The derived com-
plexes were orange or yellow non-crystalline materials
which were readily soluble in chloroform, and pos-
sessed greater hydrolytic stability than LTA.
Characterization of the lead(IV) complexes showed
in general that the acid carbonyl stretching frequencies
had disappeared from the infra-red spectrum, and only
the ester carbonyl functions (C10) of the chiral ligands
were observed as sharp peaks in the 13C-NMR spec-
trum. No large changes were observed in 1H-NMR
spectra of the complexes when compared to the free
ligand, although small changes did occur in the pattern
of signals corresponding to the side-chain methylene
groups in most complexes. Thus, in the case of ligand 6
2. Synthesis and reactivity of lead(IV) complexes
One particularly valuable approach to the arylation
reaction involves initial in situ formation of the inter-
mediate phenyllead species by boron/lead exchange in
the presence of a suitable catalyst, followed by treat-
ment with a i-dicarbonyl (e.g. 3 or 4) and pyridine
(Scheme 2) [9]. In the first step, mercury(II) acetate
catalysis (0.1 equiv.) has been found to be necessary.
Using these conditions, the products 2 or 5 were ob-
tained in 70 and 71% yield respectively (Scheme 2 and
Table 1, entries 2 and 3), but in the absence of mercury
acetate none of the desired product was obtained (entry
1). Mercury chloride and lead(II) acetate, however,
were also found to be effective catalysts, giving product
5 in good yield, although lower than that obtained with
mercury(II) acetate (entries 4–6). The poorer yield for
the lead(II) catalyst is possibly due to its lower solubil-
ity in chloroform. Despite a recent report which indi-
cated that fluoride was an effective catalyst for
palladium-mediated coupling reactions of boronic acids
with aryl bromides, [10] neither caesium nor potassium
fluoride were useful in these lead(IV)-mediated reac-
tions (entries 7 and 8).
It was also shown that the mercuric chloride cata-
lyzed arylation of i-dicarbonyl 3 could be achieved
using lead complexes other than LTA. Thus, the
lead(IV) complexes prepared from ligands L1 and L2
(n=1, 2) (ligands derived from tartrate and camphoric
acid, respectively) [11] were satisfactorily used in this
procedure (entries 9–14), giving yields almost as high
as LTA in some cases (entries 9, 10).
Scheme 2.

M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
79
Table 1
Reaction of Nucleophiles 3 or 4 with Phenylboronic acid and lead complexes and catalysts according to Scheme 2
Entry
Lead(IV) Complex
Catalyst
Nucleophile
Product
Yield(%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
Pb(OAc)4
None
3
3
4
3
3
4
3
3
3
3
3
3
3
3
—
2
5
2
2
5
2
2
2
2
2
2
2
2
0
70
71
58
53
39
5
Hg(OAc)2 (0.1 eq)
Hg(OAc)2 (0.1 eq)
HgCl2 (0.1 eq)
HgCl2 (1 eq)
Pb(OAc)2 (0.1 eq)
CsF
KF
0
PbL1(O2CPh)2
PbL1(O2CPh)2
PbL1(O2CAr)a2
PbL1(O2CAr)a2
PbL2(O2CPh)b2
PbL2(O2CPh2)c
Hg(OAc)2 (0.1 eq)
HgCl2 (1 eq)
Hg(OAc)2 (0.1 eq)
HgCl2 (1 eq)
HgCl2 (0.1 eq)
HgCl2 (0.1 eq)
71
65
58
54
16
57
a Ar=p-MeC6H4–;
b n=1;
c n=2.
(n=1), the C(11)H2 methylene signal appeared as a
close double doublet when bound to lead(IV), in com-
parison with a singlet for the free ligand, and in the
case of ligand 7 (n=2), the C(12)H2 methylene signal
became a very much more complicated multiplet on
coordination to lead(IV); this could be due to restricted
rotation in their derived complexes, resulting from N–
Pb co-ordination, causing the benzylic protons to ex-
hibit substantial chemical shift differences. 207Pb-NMR
spectroscopy provided some evidence for the solution
structure of these complexes, and multipeak patterns of
the simple mixed ligand systems which have previously
been observed, [6,7] and indicative of slow ligand equili-
bration (on the NMR timescale), were not generally
seen. Indeed, only complex 18 gave four resonances,
consistent with complete ligand exchange. Five com-
plexes (11, 12, 15, 19 and 20) gave broad single reso-
nances, and three (9, 13 and 16) gave two broad
resonances. [6,7] However, more detailed examination
The potential of these 12 novel complexes to mediate
Pinhey’s arylation reaction was initially tested using the
phenylation of methyl Meldrum’s acid 4 (Scheme 2).
Pyridine was used in the second step of all of these
reactions since an initial study in which pyridine was
replaced with complex 8 failed to yield any product.
Thus, the lead(IV) complex, phenylboric acid and a
HgCl2 catalyst were dissolved in dry CHCl3 and stirred
at 40°C for 2 h; the substrate 4 in pyridine was then
added, and the mixture stirred at 40°C for 2 h then
overnight at room temperature. Only four complexes
showed any phenylated product (Table 2). All three
tris(cyclohexanecarboxylate) complexes 11, 15 and 19
were reactive, as was the triacetate complex 17. The
lack of reactivity in the cases of the three tricinnamate
complexes 12, 16 and 20, was probably due to the
insolubility of these complexes in the reaction medium.
The lead(IV) complexes 10, 11, 13, 14 and 18 were
unreactive to phenylation, possibly due to electronic
stabilization or steric protection by the ligands, and it
would seem that electron deficient PbIV centres, particu-
larly those with acetate ligands, are the more reactive;
this is in keeping with earlier results [4,5]. However, by
carrying out the second step of the phenylation reaction
1
of complexes 14 and 18 by H n.O.e. spectroscopy did
not allow the determination of the detailed solution
structure. Moreover, none of the above data allowed
the conformational assignment for the cyclopentyl ring;
this could be either diequatorial or diaxial.
Scheme 3.

80
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
Fig. 1. 207Pb-NMR spectrum of LTB with 0.1 equiv. of (a) HgOAc2; and (b) HgCl2.
under refluxing conditions, six of the complexes showed
reactivity (Table 2), giving much higher yields of the
phenylated product.
Quite unusually, the tribenzoate complex 18 which did
show rapid ligand exchange by 207Pb-NMR spec-
troscopy, gave no product in an attempted phenylation
reaction under either set of reaction conditions. This
would thus confirm that rapid ligand exchange is not a
sole requirement for the observation of reactivity.
An attempt was made to isolate the presumed phenyl-
lead(IV) intermediate in these arylation reactions. [9]
Complex 9, phenylboric acid and HgCl2 were dissolved
in dry chloroform and stirred at 40°C for 2 h. The
reaction mixture was then filtered through Celite® and,
after work-up, the majority of solvent was removed to
give a concentrated solution to which petroleum ether
was then added (1:10 ratio of CHCl3:Petrol 40–60). A
pale yellow precipitate formed on overnight storage at
0°C, which after filtration, was shown spectroscopically
to be 21. Reaction with methyl Meldrum’s acid 4 and
pyridine in dry chloroform gave the phenylated product
5 in 46% yield.
3. Asymmetric reactivity
Those complexes which displayed good reactivity
under the more vigorous refluxing conditions were tested
for asymmetric induction in phenylation reaction on
substrate 3 (Scheme 2). Thus, a lead(IV) complex,
phenylboric acid and HgCl2 were dissolved in dry CHCl3
and stirred at 40°C for 2 h. Methyl 2-oxocyclopentane-
carboxylate 3 in pyridine was added to the cloudy

M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
81
Table 2
deceleration of the ligand-coupling reaction. Further-
more, the complexes 27–32, prepared from the corre-
sponding pyridine N-oxide ligands, were also found to
be completely inert to phenylation reactions.
Preparation of Complexes (Scheme 3) and their Reaction with 4
(Scheme 2)
Complex
n
R
Yield (%) of 5
This variable reactivity of the lead(IV) complexes is
not dissimilar to the reported reactivity of a variety of
chiral hypervalent iodine compounds [15], in which
variable and at best moderate stereoselectivity was ob-
served [16–18].
Thus, we have shown that a number of mercury(II)
and lead(II) salts are useful catalysts for phenyl boron/
lead exchange and subsequent arylation reactions, and
that such catalysis can be achieved without the compli-
cation of existing ligand equilibria. We believe that such
systems, in which ligand exchange is minimized, will be
important in improving the yield in these arylation
reactions, and will prove to be instrumental in permit-
ting the formation of non-racemic products.
9
1
1
1
1
2
2
2
2
3
3
3
3
CH3–
C6H5–
C6H11
C6H5CHꢀCH–
CH3–
C6H5–
C6H11
C6H5CHꢀCH–
CH3–
C6H5–
No reaction (78a)
No reaction (56a)
34 (54a)
No reaction
No reaction
No reaction
34 (57a)
No reaction
42–52 (49a)
No reaction
41 (72a)
10
11
12
13
14
15
16
17
18
19
20
–
–
C6H11
C6H5CHꢀCH–
–
No reaction
a Stage two at reflux (see General Method).
suspension which was then heated under reflux for 18 h.
After work-up, the product 2 was purified by flash
column chromatography (2:1 DCM:Petrol 40–60)
Table 3.
4. Experimental
General experimental procedures have been described
[5].
Substrate 3 was found to be less reactive than methyl
Meldrum’s acid 4, requiring extended heating in the
second step to give acceptable yields. However, the
enantiomeric excesses (determined by chiral shift NMR
spectroscopy) were very low, the highest value being
only 8%. These low e.e. values could be the result of a
number of factors; the stereogenic centre of the ligand
could be too far removed from the lead(IV) centre, or
alternatively it is conceivable that the extended heating
of the second stage either re-establishes a facile ligand
exchange equilibrium, which possibly generates a more
reactive but achiral complex, or overwhelms the small
energy difference of the diastereomeric transition states,
ultimately giving essentially racemic product [5].
5. General procedure for phenylation reactions [9]
5.1. Stage one
The lead(IV) complex (1 eq.), phenylboric acid (1 eq.)
and the catalyst (0.1 eq.) were dissolved in dry CHCl3
(20–40 ml) and stirred at 40°C for 1 h. The resulting
cloudy solution was stirred overnight at room
temperature.
Interestingly, the application of the complexes 22–26,
prepared in an analogous fashion to the previous com-
plexes, containing more than one chiral ligand, failed to
give any arylated product with substrate 4, even when
the reaction was carried out under refluxing conditions.
It would appear that the introduction of too much
steric bulk and/or electron density in close proximity to
the lead(IV) centre does indeed result in substantial
5.2. Stage two
The substrate 3 or 4 (0.91 eq.) in pyridine (3.03 eq.)
was added to the above solution, which was stirred at
40°C for 1 h and at room temperature overnight. The
resulting solution was filtered through Celite® and the
solid was washed with CHCl3 (2–3×25 ml). The com-

82
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
bined organic layers were washed with 3 M H2SO4
(25–50 ml) and the CHCl3 layer was separated. The
aqueous phase was extracted with CHCl3 (2×15 ml),
the combined organic layers were dried (MgSO4) and
the solvent was removed in vacuo to give the crude
product.
1574 s, 1540 s, 1439 s, 1376 s, 1309 s, 1267 s, 1169 s,
1130 m, 1054 m, 1011 m, 816 w, 791 w, 769 m, 733 m,
700 m cm−1; lH (200 MHz, CDCl3) 0.91 (3H, s, CH3),
1.29 (6H, s, 2×CH3), 1.60–1.72 (1H, m, C5HH%),
1.82–1.98 (1H, m, C4HH%), 2.15 (9H, s, (OC(O)CH3)3),
2.15–2.34 (1H, m, C4HH%), 2.45–2.57 (1H, m,
C5HH%), 2.92 (1H, t, J=9.5 Hz, C3H), 5.25 (1H, d,
J=12.5 Hz, C11HH%), 5.26 (1H, d, J=12.5 Hz,
C11HH%), 7.22 (1H, m, C15H), 7.38 (1H, d, J=8.0 Hz,
C13H), 7.73 (1H, m, C14H), 8.61 (1H, d, J=5.0 Hz,
C16H); lC (50.3 MHz, CDCl3) 18.02 ((OC(O)CH3)3),
21.15 (CH3), 22.41 (2×CH3), 22.72 (C4), 33.59 (C5),
47.30 (C2), 52.27 (C3), 56.60 (C1), 66.81 (C11), 122.27
(C13), 123.17 (C15), 137.19 (C14), 149.57 (C16), 155.92
(C12), 173.66 (C10), 180.82 (CꢀO); lPb (52.3 MHz,
CDCl3, 223K) −1877.6, −1883.4 to −1885.0
(broad).
In the case of substrate 3, the crude product was
purified by silica chromatography (3:1 DCM:petrol,
gradient to DCM) to give 2 as a colourless oil (0.70 g,
70%). Rf 0.34 (DCM); wmax (film) 2954 m, 1750 s, 1722
1
s, 1449 m and 1256 s cm−1; H-NMR lH (200 MHz,
CDCl3) 1.82–2.13 (2H, m, CH2), 2.28–2.62 (3H, m,
CH2), 2.83–2.93 (1H, m, CH2), 3.72 (3H, s, CH3) and
7.30–7.41 (5H, m, ArH); lC (50.3 MHz, CDCl3) 19.19,
34.92, 37.75 (3×CH2), 53.00 (CH3), 65.05, 127.54,
127.92, 128.78 (3×ArCH), 136.32 (ArC), 171.52
(CO2Me) and 211.95 (CꢀO); m/z (CI (NH3)) 236 (M+
NH4+, 53%), 219 (100, MH+), 204 (8), 190 (12) and
159 (13).
In the case of 4, the crude product was purified by
flash column chromatography eluting with either i)
1:9-EtOAc:petrol, or ii) 1:3-DCM:petrol, gradient to
100% DCM gave 5-phenyl-2,2,5-trimethyl-1,3-dioxane-
4,6-dione 5, m.p. 133–135°C; Rf 0.44 (100% DCM);
wmax (Nujol) 1776 m, 1735 s, 1302 s, 1159 s, 1070 m
cm−1; lH (200 MHz, CDCl3) 1.27 (3H, s, CH3), 1.74
(3H, s, CH3), 1.88 (3H, s, CH3), 7.33–7.44 (5H, m,
ArCH); lC (50.3 MHz, CDCl3) 26.19, 27.11 and 29.32
(3×CH3), 55.42 (C5), 105.56 (C2), 125.60, 128.77 and
129.68 (3×CH), 136.95 (ipso-C), 167.44 (CꢀO); m/z
(CI(NH3)) 252 (82%, [MNH4+]), 150 (13), 132 (100%),
122 (15), 104 (51), 76 (83).
8. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-trime-
thylcyclopentane-1,3-dicarboxylic acid mono-3-
(2-pyridinylmethyl)ester) 10
LTA (0.076 g, 0.17 mmol), benzoic acid (0.063 g,
0.52 mmol) and ligand 6 (0.050 g, 0.17 mmol) were
reacted according to the General Method to give com-
plex 10 as a yellow foam. [h]2D3+5.1 (c=0.88, CHCl3);
wmax (film) 3060 w, 2966 w, 1732 s, 1592 s, 1488 s, 1440
s, 1388 s, 1315 m, 1274 s, 1156 s, 1117 m, 1070 m, 1024
m, 938 m, 853 m, 761 m, 714 s, 681 s cm−1; lH (200
MHz, CDCl3) 0.95 (3H, s, CH3), 1.32 (6H, s, 2×CH3),
1.62–1.99 (2H, m, C5HH% and C4HH%), 2.17–2.36 (1H,
m, C4HH%), 2.51–2.67 (1H, m, C5HH%), 2.93 (1H, t,
J=9.0 Hz, C3H), 5.26 (1H, d, J=13.5 Hz, C11HH%),
5.30 (1H, d, J=13.5 Hz, C11HH%), 7.27 (1H, t, J=5.0
Hz, C15H), 7.37–7.49 (7H, m, 6×ArH and C13H),
7.58–7.61 (3H, m, 3×ArH), 7.65–7.77 (1H, m,
C14H), 8.11 (6H, d, J=7.5 Hz, 6×ArH), 8.64 (1H, d,
J=5.0 Hz, C16H); lC (50.3 MHz, CDCl3) 21.18 (CH3),
22.47 (2×CH3), 22.76 (C4), 33.53 (C5), 47.35 (C2),
52.34 (C3), 56.64 (C1), 66.34 (C11), 122.52 (C13),
123.44 (C15), 128.76 (ArC), 131.54 (ArC), 134.31
(ArC), 137.74 (C14), 149.16 (C16), 155.78 (C12), 173.73
(C10), 174.68 (CꢀO), 175.37 (CꢀO).
6. General method for the preparation of lead
complexes
LTA (1 equiv), monodentate carboxylic acid A (n
equiv.) and monodentate carboxylic acid B (m equiv.),
(where n+m=4), were combined in dry toluene (20–
40 ml). The solvent was removed in vacuo (20–70
mbar, 20°C) to give a residue which was then redis-
solved in toluene (20–40 ml) and the solvent again
removed in vacuo. This process was continued to re-
1
move acetic acid, as shown by H-NMR spectroscopy.
9. Lead(IV) tris(cyclohexanecarboxylate) mono-
((1R,3S)-1,2,2-trimethylcyclopent-ane-1,3-dicarboxylic
acid mono-3-(2-pyridinylmethyl)ester) 11
7. Lead(IV) triacetate mono((1R,3S)-1,2,2-trimethylcyc-
lopentane-1,3-dicarboxylic acid mono-3-(2-pyridinyl-
methyl)ester) 9
LTA (0.076 g, 0.17 mmol), cyclohexanecarboxylic
acid (0.066 g, 0.52 mmol) and ligand 6 (0.050 g, 0.17
mmol) were reacted according to the General Method
to give complex 11 as a pale yellow foam. [h]2D1+5.4
(c=0.89, CHCl3); wmax (CDCl3) 2979 s, 2858 s, 1732 s,
1704 s, 1311 m, 1285 m, 1268 m, 1230 m, 1171 s, 1138
LTA (0.076 g, 0.17 mmol) and ligand 6 (0.050 g, 0.17
mmol) were reacted according to the General Method
to give complex 9 as a bright yellow foam. [h]2D3−4.5
(c=1.05, CHCl3); wmax (film) 2973 s, 1733 s, 1596 m,

M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
83
m, 1053 m, 1013 m, 950 m, 927 m cm−1; lH (200 MHz,
CDCl3) 0.91 (3H, s, CH3), 1.28–1.96 (38H, m, 2×CH3,
C5HH%, C4HH% and 30×cyclohexyl protons), 2.15–
2.35 (1H, m, C4HH%), 2.50–2.57 (4H, m, C5HH% and
3×C1%H), 2.92 (1H, t, J=9.5 Hz, C3H), 5.26 (1H, d,
J=12.5 Hz, C11HH%), 5.27 (1H, d, J=12.5 Hz,
C11HH%), 7.22–7.29 (1H, m, C15H), 7.39 (1H, d, J=
7.5 Hz, C13H), 7.73 (1H, m, C14H), 8.62 (1H, d,
J=4.5 Hz, C16H); lC (50.3 MHz, CDCl3) 21.22 (CH3),
22.40 (2×CH3), 22.69 (C4), 25.20 (C3%), 25.49 (C4%),
29.53 (C2%), 33.46 (C5), 42.16 (C1%), 47.17 (C2), 52.30
(C3), 56.68 (C1), 66.65 (C11), 122.29 (C13), 123.19
(C15), 137.26 (C14), 149.45 (C16), 155.88 (C12), 173.75
(C10), 175.37 (CꢀO); lPb (52.3 MHz, CDCl3, 223K)
−1876.8 (broad).
(OC(O)CH3)3), 2.39–2.55 (1H, m, C5HH%), 2.76 (1H, t,
J=8.0 Hz, C3H), 3.16 (2H, t, J=7.0 Hz, C11H2),
4.40–4.60 (2H, m, C12H2), 7.18–7.28 (2H, m, C14H
and C16H), 7.65 (1H, m, C15H), 8.58 (1H, d, J=5.0
Hz, C17H); lC (50.3 MHz, CDCl3) 20.69
((OC(O)CH3)3), 24.65, 24.83, 26.10 and 27.93 (3×CH3
and C4), 31.46 (C5), 37.15 (C11), 48.15 (C2), 52.79
(C3), 54.89 (C1), 63.32 (C12), 121.90 (C14), 123.79
(C16), 136.82 (C15), 149.49 (C17), 157.58 (C13), 174.01
(CꢀO); lPb (52.3 MHz, CDCl3, 223 K) −1876.6
(broad), −1882.7 (broad).
12. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-(2-pyridinyl)ethyl)ester) 14
10. Lead(IV) tricinnamate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-pyridinylmethyl)ester) 12
LTA (0.073 g, 0.16 mmol), benzoic acid (0.060 g,
0.49 mmol) and ligand 7 (0.050 g, 0.16 mmol) were
reacted according to the General Method to give com-
plex 14 as a bright orange solid. wmax (film) 2964 m,
1725 s, 1593 m, 1525 s, 1442 m, 1392 s, 1315 m, 1273
m, 1175 m, 1158 m, 1117 w, 1070 m, 1025 m, 851 m,
768 m, 717 s, 682 m cm−1; lH (200 MHz, CDCl3) 0.75
(3H, s, CH3), 1.10–1.25 (6H, s, 2×CH3), 1.29–2.77
(5H, m, C4H2 and C5H2 and C3H), 3.16–3.22 (2H, m,
C11H2), 4.42–4.52 (2H, m, C12H2), 7.17–7.47 (11H, m,
9×ArH, C14H and C16H), 7.62–7.69 (1H, m, C15H),
7.98 (6H, d, J=7.5 Hz, 6×ArH), 8.63–8.65 (1H, m,
C17H); lC (50.3 MHz, CDCl3) 21.09 (CH3), 21.51
(CH3), 22.33 (C4), 22.57 (CH3), 32.37 (C5), 36.60 (C11),
46.56 (C2), 52.76 (C3), 57.10 (C1), 63.48 (C12), 122.30
(C14), 124.14 (C16), 128.31 (ArCH), 130.08 (ArCH),
132.83 (ArCH), 137.55 (C15), 148.91 (C17), 157.86
(C13), 173.62 (CꢀO), 174.34 (CꢀO).
LTA (0.076 g, 0.17 mmol), cinnamic acid (0.076 g,
0.52 mmol) and ligand 6 (0.050 g, 0.17 mmol) were
reacted according to the General Method to give com-
plex 12 as a pale yellow solid. [h]2D5−3.9 (c=0.26,
CHCl3); wmax (CHCl3) 3021 s, 1693 s, 1639 s, 1595 s,
1450 s, 1410 s, 1127 s, 840 m, 798 m, 794 s cm−1; lH
(200 MHz, CDCl3) 0.79–1.09 (3H, m, CH3), 1.14–1.40
(6H, m, 2×CH3), 1.57–1.76 (1H, m, C5HH%), 1.81–
2.11 (1H, m, C4HH%), 2.13–2.38 (1H, m, C4HH%),
2.54–2.72 (1H, m, C5HH%), 2.96 (1H, t, J=9.0 Hz,
C3H), 5.20–5.37 (2H, s, C11H2), 6.64 (3H, d, J=16.0
Hz, 3×CHꢀCHCO2), 7.23–7.29 (1H, m, C15H), 7.34–
7.64 (16H, m, C13H and 15×ArCH), 7.69–7.80 (1H,
m, C14H), 7.88 (3H, d, J=16.0 Hz, 3×CH=
CHCO2), 8.64–8.66 (1H, m, C16H); lC (50.3 MHz,
CDCl3) 21.23 (CH3), 22.49 (CH3), 22.76 (C4), 33.57
(C5), 47.36 (C2), 52.38 (C3), 66.65 (C11), 122.34 (C13),
123.24 (C15), 125.51 and 128.45 (CHꢀCHCO2), 128.70
(CH), 129.22 (CH), 131.19 (CH), 134.28 (C), 137.38
(C14), 149.42 (C16), 155.89 (C12), 173.75 (C10); lPb
(52.3 MHz, CDCl3, 253 K) −1878.6 (broad).
13. Lead(IV) tris(cyclohexanecarboxylate) mono-
((1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarboxylic
acid mono-3-(2-(2-pyridinyl)ethyl)ester) 15
LTA (0.073 g, 0.16 mmol), cyclohexanecarboxylic
acid (0.061 g, 0.48 mmol) and ligand 7 (0.050 g, 0.16
mmol) were reacted according to the General Method
to give complex 15 as a pale yellow/green gum. [h]2D0+
5.9 (c=0.51, CHCl3); wmax (CDCl3) 2937 s, 2858 s, 1727
s, 1538 s, 1452 s, 1350 m, 1285 m, 1230 m, 1177 s, 1021
w cm−1; lH (200 MHz, CDCl3) 0.82 (3H, s, CH3), 1.12
(3H, s, CH3), 1.20–2.00 (35H, m, CH3, C4HH%, C5HH%
and 30×cyclohexyl protons), 2.12–2.30 (1H, m,
C4HH%), 2.43–2.61 (4H, m, C5HH%and 3×C1%H), 2.75
(1H, t, J=9.0 Hz, C3H), 3.16 (2H, t, J=6.5 Hz,
C11H2), 4.44–4.56 (2H, m, C12H2), 7.18–7.28 (2H, m,
C14H and C16H), 7.64 (1H, t, J=7.5 Hz, C15H), 8.59
(1H, d, J=5.0 Hz, C17H); (50.3 MHz, CDCl3) 21.10
(CH3), 21.19 (2×CH3), 22.39 (C4), 25.23 (C4%), 25.51
11. Lead(IV) triacetate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-(2-pyridinyl)ethyl)ester) 13
LTA (0.073 g, 0.16 mmol) and ligand 7 (0.050 g, 0.16
mmol) were reacted according to the General Method
to give complex 13 as a yellow gum. wmax (film) 2971 s,
1727 s, 1636 m, 1595 s, 1571 m, 1541 s, 1476 s, 1458 s,
1374 s, 1308 s, 1174 s, 1119 w, 1057 w, 1013 m, 764 m,
693 m cm−1; lH (200 MHz, CDCl3) 0.80 (3H, s, CH3),
1.12 (3H, s, CH3), 1.25 (3H, s, CH3), 1.56–1.89 (2H, m,
C5HH% and C4HH%), 2.04–2.30 (10H, m, C4HH% and

84
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
(C3%), 29.52 (C2%), 33.40 (C5), 36.95 (C11), 42.37
(C1%), 46.90 (C2), 52.37 (C3), 56.64 (C1), 63.61 (C12),
122.03 (C14), 123.87 (C16), 137.01 (C15), 149.38
(C17), 158.08 (C13), 174.02 (C10), 184.74 (CꢀO); lPb
(52.3 MHz, CDCl3, 223 K) −1875.9 (broad).
16. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(3-(2-pyridinyl)propyl)ester) 18
LTA (0.070 g, 0.16 mmol), benzoic acid (0.059 g,
0.48 mmol) and ligand 8 (0.050 g, 0.16 mmol) were
reacted according to the General Method to give
complex 18 as a yellow gum. [h]2D1+8.6 (c=0.71,
CHCl3); wmax (CHCl3) 3600–3200 br, 2969 m, 1725 br
s, 1593 s, 1533 s, 1416 s, 1228 s, 1203 s, 1178 s, 1125
s, 1072 s, 1027 m cm−1; lH (200 MHz, CDCl3) 0.85–
0.98 (3H, m, CH3), 1.13–1.40 (6H, m, 2×CH3),
1.40–3.06 (9H, m, C5H2, C4H2, C12H2, C11H2 and
C3H), 4.17–4.23 (2H, m, C13H2), 7.11–7.28 (2H, m,
C15H and C17H), 7.42–7.75 (10H, m, 9×ArH and
C16H), 8.12 (6H, d, J=7.0 Hz, 6×ArH), 8.60–8.69
(1H, m, C18H); lC (50.3 MHz, CDCl3) 21.22 (CH3),
22.54 (2×CH3), 22.55 (C4), 28.67 (C12), 33.62 (C5),
33.91 (C11), 47.19 (C2), 52.37 (C3), 56.64 (C1), 63.85
(C13), 121.98 (C15), 123.55 (C17), 128.76 (ArCH),
131.62 (ArCH), 134.28 (ArCH), 137.81 (C16), 148.69
(C18), 160.62 (C14), 174.07 (C10), 175.79 (CꢀO); lPb
(52.3 MHz, CDCl3, 223 K) −1885.6, −1888.0,
−1892.7, −1895.4.
14. Lead(IV) tricinnamate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-(2-pyridinyl)ethyl)ester) 16
LTA (0.073 g, 0.16 mmol), cinnamic acid (0.071 g,
0.48 mmol) and ligand 7 (0.050 g, 0.16 mmol) were
reacted according to the General Method to give
complex 16 as a bright yellow foam. wmax (CDCl3)
3031 m, 2972 m, 1726 s, 1635 s, 1579 s, 1498 s, 1452
s, 1310 m, 1254 s, 1180 s, 1072 m, 982 s, 927 s, 686 s
cm−1; lH (200 MHz, CDCl3) 0.86 (3H, s, CH3), 1.14
(3H, s, CH3), 1.29 (3H, s, CH3), 1.55–1.90 (2H, m,
C4HH% and C5HH%), 2.11–2.35 (1H, m, C4HH%),
2.46–2.65 (1H, m, C5HH%), 2.77 (1H, t, J=8.5 Hz,
C3H), 3.16 (2H, t, J=6.5 Hz, C11H2), 4.44–4.57
(2H, m, C12H2), 6.48 (3H, d, J=16.0 Hz, 3×CH=
CHCO2), 7.18–7.27 (2H, m, C14H and C16H), 7.35–
7.65 (16H, m, C15H and 15×ArCH), 7.90 (3H, d,
J=16.0 Hz, 3×CH=CHCO2), 8.56 (1H, d, J=4.0
Hz, C17H); lC (50.3 MHz, CDCl3) 20.72 (CH3),
22.29 (2×CH3 and C4), 31.48 (C5), 36.88 (C11),
54.89 (C3), 63.33 (C12), 121.04 (C14), 122.12 (CH),
123.99 (C16), 128.44 (CH), 128.53 (CH), 129.12 (CH),
130.82 (CH), 134.49 (C), 137.22 (C15), 149.17 (C17);
lPb (52.3 MHz, CDCl3, 223K) −1879.7, −1881.2
(broad).
17. Lead(IV) tris(cyclohexanecarboxylate) mono
((1R,3S)-1,2,2-trimethylcyclopent-ane-1,3-dicarboxylic
acid mono-3-(3-(2-pyridinyl)propyl)ester) 19
LTA (0.070 g, 0.16 mmol), cyclohexanecarboxylic
acid (0.061 g, 0.48 mmol) and ligand 8 (0.050 g, 0.16
mmol) were reacted according to the General Method
to give complex 19 as a bright yellow gum. [h]2D1+
12.2 (c=0.55, CHCl3); wmax (film) 3600–3100 br, 2933
s, 2856 s, 1729 s br, 1542 s, 1452 s, 1349 s, 1285 m,
1175 s, 1022 m, 950 m, 811 m, 733 m cm−1; lH
(200 MHz, CDCl3) 0.90 (3H, s, CH3), 1.20–1.45
(14H, m, 2×CH3 and 8×cyclohexyl protons), 1.45–
1.83 (16H, m, C5HH%, C4HH% and 14×cyclohexyl
protons), 1.83–2.30 (11H, m, C4HH%, C12H2 and
8×cyclohexyl protons), 2.45–2.68 (4H, m, C5HH%
and 3×C1%H), 2.78 (1H, t, J=9.5 Hz, C3H), 2.88
(2H, t, J=7.5 Hz, C11H2), 4.14 (2H, t, J=6.5
Hz C13H2), 7.11–7.17 (2H, m, C15H and C17H),
7.61 (1H, m, C16H), 8.55 (1H, d, J=5.0 Hz, C18H);
lC (50.3 MHz, CDCl3) 21.24 (CH3), 22.46 (2×
CH3), 22.46 (C4), 25.17 (C3%), 25.45 (C4%), 28.49
(C12), 29.64 (C2%), 33.52 (C5), 34.37 (C11),
41.76 (C1%), 47.03 (C2), 52.31 (C3), 56.57 (C1), 63.89
(C13), 121.56 (C15), 123.14 (C17), 136.97 (C16),
149.35 (C18), 160.91 (C14), 174.09 (C10), 184.93
(CꢀO); lPb (52.3 MHz, CDCl3, 223K) −1877.0
(broad).
15. Lead(IV) triacetate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(3-(2-pyridinyl)propyl)ester) 17
LTA (0.070 g, 0.16 mmol) and ligand 8 (0.050 g,
0.16 mmol) were reacted according to the General
Method to give complex 17 as a bright orange gum.
wmax (film) 2964 s, 1729 s, 1592 m, 1475 m, 1436 m,
1364 m, 1259 m, 1173 s, 1117 m, 1053 m, 1019 m,
768 m cm−1; lH (200 MHz, CDCl3) 0.90 (3H, s,
CH3), 1.27 (6H, s, 2×CH3), 1.44–2.62 (15H, m,
(OC(O)CH3)3, C5H2, C4H2 and C12H2), 2.73–2.91
(3H, m, C3H and C11H2), 4.10–4.16 (2H, m,
C13H2), 7.13–7.29 (2H, m, C15H and C17H), 7.58–
7.65 (1H, m, C16H), 8.54 (1H, d, J=4.0 Hz, C18H);
lC (50.3 MHz, CDCl3) 18.04 ((OC(O)CH3)3), 21.16
(CH3), 22.43 (2×CH3), 22.58 (C4), 28.49 (C12), 33.58
(C5), 34.34 (C11), 47.11 (C2), 52.29 (C3), 56.50 (C1),
63.92 (C13), 121.56 (C15), 123.16 (C17), 137.01 (C16),
149.30 (C18), 160.91 (C14), 173.98 (C10), 180.66
(CꢀO).

M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
85
20. Lead(IV) bis(cyclohexanecarboxylate) bis((1R,3S)-
1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-(2-pyridinyl)ethyl)ester) 23
18. Lead(IV) tricinnamate mono((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(3-(2-pyridinyl)propyl)ester) 20
LTA (0.073 g, 0.16 mmol), cyclohexanecarboxylic
acid (0.042 g, 0.33 mmol) and ligand 7 (0.100 g, 0.33
mmol) were reacted according to the General Method
to give the complex 23 as a pale yellow/green gum.
[h]2D0+8.1 (c=0.35, CHCl3); wmax (CHCl3) 2937 s,
2858 s, 1725 s, 1534 s, 1453 s, 1392 s, 1350 s, 1228 s,
1176 s cm−1; lH (200 MHz, CDCl3) 0.79 (6H, s,
2×CH3), 1.22–2.09 (36H, m, 4×CH3, 2×C4HH%,
2×C5HH% and 20×cyclohexyl protons), 2.14–2.35
(2H, m, 2×C4HH%), 2.40–2.61 (4H, m, 2×C5HH%
and 2×C1%H), 2.73 (2H, t, J=9.0 Hz, 2×C3H),
3.14 (4H, t, J=6.5 Hz, 2×C11H2), 4.39–4.61 (4H,
m, 2×C12H2), 7.18–7.29 (4H, m, 2×C14H and 2×
C16H), 7.58–7.65 (2H, m, 2×C15H), 8.55 (2H, d,
J=4.5 Hz, 2×C17H); lC (50.3 MHz, CDCl3) 21.16
(CH3), 21.40 (2×CH3 and C4), 25.25 (C3%), 25.65
(C4%), 29.21 (C2%), 32.95 (C5), 36.94 (C11), 41.06
(C1%), 46.67 (C2), 52.56 (C3), 56.64 (C1), 63.52 (C12),
122.02 (C14), 123.87 (C16), 137.01 (C15), 149.34
(C17), 158.08 (C13), 174.18 (C10), 184.10 (CꢀO); lPb
(52.3 MHz, CDCl3, 223 K) −1875.7.
LTA (0.070 g, 0.16 mmol), cinnamic acid (0.070 g,
0.47 mmol) and ligand (0.050 g, 0.16 mmol) were
reacted according to the General Method to give
complex 20 as a pale yellow solid. wmax (CHCl3) 3029
m, 2968 m, 1733 s, 1698 s, 1654 m, 1636 s, 1283 s,
1232 s, 1158 m cm−1; lH (200 MHz, CDCl3) 0.97
(3H, s, CH3), 1.32 (6H, s, 2×CH3), 1.47–1.99 (2H,
m, C5HH% and C4HH%), 2.04–2.27 (3H, m, C4HH%
and C12H2), 2.50–2.65 (1H, m, C5HH%), 2.81 (1H, t,
J=9.5 Hz, C3H), 2.91 (2H, t, J=7.5 Hz, C11H2),
4.15 (2H, t, J=6.5 Hz, C13H2), 6.47 (3H, d, J=16.0
Hz, 3×CHꢀCHCO2), 7.13–7.20 (2H, m, C15H and
C17H), 7.27–7.66 (16H, m, C16H and 15×ArH),
7.86 (3H, d, J=16.0 Hz, 3×CHꢀCHCO2), 8.58 (1H,
d, J=4.5 Hz, C18H); lC (50.3 MHz, CDCl3) 21.28
(CH3), 22.46 (C4), 22.59 (2×CH3), 28.49 (C12),
33.70 (C5), 34.08 (C11), 47.13 (C2), 52.44 (C3),
63.85 (C13), 121.82 (C15), 123.40 (C17), 125.49 and
128.45 (CHꢀCHCO2), 128.61, 129.18, 131.00, 134.40,
137.48 (C16), 149.94 (C18), 160.75 (C14), 174.15
(C10); lPb (52.3 MHz, CDCl3, 253K) −1878.4
(broad).
21. Lead(IV) bis(cyclohexanecarboxylate) bis((1R,3S)-
1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(3-(2-pyridinyl)propyl)ester) 24
19. Lead(IV) bis(cyclohexanecarboxylate) bis((1R,3S)-
1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid mono-
3-(2-pyridinylmethyl)ester) 22
LTA (0.069 g, 0.16 mmol), cyclohexanecarboxylic
acid (0.040 g, 0.31 mmol) and ligand 8 (0.100 g, 0.31
mmol) were reacted according to the General Method
to give complex 24 as a pale yellow gum. [h]2D0+9.2
(c=0.25, CHCl3); wmax (CHCl3) 3600–3200 br, 2936
s, 2857 m, 1723 s, 1593 m, 1452 m, 1403 s, 1228 s,
1206 s, 1174 s cm−1; lH (200 MHz, CDCl3) 0.91
(6H, s, 2×CH3), 1.21–2.28 (42H, m, 4×CH3, 2×
C12H2, 2×C4H2, 2×C5HH% and 20 cyclohexyl pro-
tons), 2.45–2.74 (4H, m, 2×C5HH% and 2×C1%H),
2.78 (2H, t, J=9.5 Hz, 2×C3H), 2.88 (4H, t, J=
7.5 Hz, 2×C11H2), 4.14 (4H, t, J=6.5 Hz, 2×
C13H2), 7.11–7.20 (4H, m, 2×C15H and 2×C17H),
7.61 (2H, dt, J=7.5, 1.5 Hz, 2×C16H), 8.55 (2H, d,
J=4.5 Hz, 2×C18H); lC (50.3 MHz, CDCl3) 21.37
(CH3), 21.63 (CH3), 22.45 (C4), 22.91 (CH3),
25.48 (C3%), 25.71 (C4%), 28.55 (C12), 29.20 (C2%),
32.41 (C5), 34.23 (C11), 41.15 (C1%), 46.64 (C2), 52.82
(C3), 63.74 (C13), 121.65 (C15), 123.25 (C17), 137.15
(C16), 149.19 (C18), 160.88 (C14), 174.49 (C10),
184.24 (CꢀO); lPb (52.3 MHz, CDCl3, 223 K)
−1876.4.
LTA (0.076 g, 0.17 mmol), cyclohexanecarboxy-
lic acid (0.044 g, 0.34 mmol) and ligand 6 (0.100 g,
0.34 mmol) were reacted according to the General
Method to give complex 22 as a pale yellow/green
gum. [h]2D0+9.1 (c=0.81, CHCl3); wmax (CHCl3) 2937
s, 2858 m, 1732 s, 1703 s, 1454 s, 1228 s, 1170 s, 909
m cm−1; lH (200 MHz, CDCl3) 0.89 (6H, s, 2×
CH3), 1.25 and 1.28 (2×6H, 2×s, 4×CH3), 1.08–
2.85
(30H,
m,
2×C5H2,
2×C4H2
and
22×cyclohexyl protons), 2.90 (2H, t, J=9.5 Hz, 2×
C3H), 5.24 (2H, d, J=14.0 Hz, 2×C11HH%), 5.25
(2H, d, J=14.0 Hz, 2×C11HH%), 7.21–7.26 (2H, m,
2×C15H), 7.37 (2H, d, J=7.5 Hz, 2×C13H), 7.71
(2H, m, 2×C14H), 8.60 (2H, d, J=5.0 Hz, 2×
C16H); lC (50.3 MHz, CDCl3) 21.23 (CH3), 21.63
(CH3), 22.53 (CH3), 22.77 (C4), 25.38 (C3%), 25.67
(C4%), 29.05 (C2%), 32.61 (C5), 45.21 (C1%), 46.79 (C2),
52.75 (C3), 66.43 (C11), 122.33 (C13), 123.21 (C15),
137.37 (C14), 149.34 (C16), 155.95 (C12), 174.06
(C10), 183.92 (CꢀO); lPb (52.3 MHz, CDCl3, 223 K)
−1876.1.

86
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
22. Lead(IV) diacetate bis((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-pyridinyl-
methyl)ester) 25
reacted according to the General Method to give the title
compound 27 as a deep yellow foam. wmax (film) 3600–
3300 br, 2967 m, 1734 s, 1559 m, 1497 m, 1439 m, 1376
m, 1222 m, 1162 s, 1050 m, 1015 m, 852 m, 772 m, 669
m cm−1; lH (200 MHz, CDCl3) 0.81–1.02 (3H, m, CH3),
1.20–1.41 (6H, m, 2×CH3), 1.56–2.79 (13H, m, C5H2,
C4H2 and (OC(O)CH3)3), 2.87–3.04 (1H, m, C3H),
5.25–5.54 (2H, m, C11H2), 7.25–7.54 (3H, m, C13H,
C14H and C15H), 8.38–8.45 (1H, m, C16H).
LTA (0.076 g, 0.17mmol) and ligand 6 (0.100 g, 0.34
mmol) were reacted according to the General Method to
give the complex 25 as a pale yellow/green gum. [h]2D0+
7.2 (c=0.20, CHCl3); wmax (CHCl3) 2972 s, 1732 s, 1596
m, 1537 m, 1439 s, 1392 m, 1311 m, 1228 s, 1170 s, 1053
m, 997 m, 815 w, 794 w, 723 m, 700 m cm−1; lH (200
MHz, CDCl3) 0.92 (6H, s, 2×CH3), 1.28–1.30 (2×6H,
2×s, 2×C6H3 and 2×C8H3 or C7H3), 1.61–1.72 (2H,
m, 2×C5HH%), 1.82–2.38 (10H, m, 2×C4H2 and
2×OC(O)CH3), 2.46–2.60 (2H, m, 2×C5HH%), 2.93
(2H, t, J=9.5 Hz, 2×C3H), 5.26 (2H, d, J=12.5 Hz,
2×C11HH%), 5.27 (2H, d, J=13.5 Hz, 2×C11HH%),
7.20–7.31 (2H, m, 2×C15H), 7.39 (2H, d, J=7.5 Hz,
2×C13H), 7.74 (2H, m, 2×C14H), 8.61 (2H, d, J=4.5
Hz, 2×C16H); lC (50.3 MHz, CDCl3) 21.44, 21.73,
22.62 and 22.99 (3×Me, (O2CCH3)3 and C4), 31.67 (C5),
46.81 (C2), 52.78 (C3), 66.55 (C11), 122.10 (C13), 122.94
(C15), 136.96 (C14), 149.22 (C16), 155.70 (C12), 173.80
(C10), 180.32 (CꢀO); lPb (52.3 MHz, CDCl3, 223 K)
−1877.6.
25. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-methyl-
pyridine-N-oxide)ester) 28
LTA (0.072 g, 0.16 mmol), benzoic acid (0.059 g, 0.49
mmol) and (1R,3S)-1,2,2-trimethylcyclopentane-1,3-di-
carboxylic acid mono-3-(2-methylpyridine-N-oxide)ester
[11] (0.050 g, 0.16 mmol) were reacted according to the
General Method to give the title compound 28 as a bright
yellow foam. wmax (film) 3061 w, 2966 w, 2630 w, 1712
s, 1593 s, 1529 s, 1444 m, 1392 s, 1316 m, 1269 m, 1217
s, 1175 m, 1119 m, 1070 m, 1025 m, 938 m, 849 m, 770
m, 681 m cm−1; lH (200 MHz, CDCl3) 0.75–1.02 (3H,
m, CH3), 1.20–1.51 (7H, m, 2×CH3 and C5HH%),
1.61–2.95 (4H, m, C5HH%, C4H2 and C3H), 5.45–5.63
(2H, m, C11H2), 7.20–7.59 (12H, m, C13H, C14H,
C15H, 6×ArH and 3×ArH), 8.05 (6H, d, J=7.5 Hz,
6×ArCH), 8.49–8.56 (1H, m, C16H).
23. Lead(IV) tetra((1R,3S)-1,2,2-trimethylcyclo-
pentane-1,3-dicarboxylic acid mono-3-(2-pyridinyl-
methyl)ester) 26
LTA (0.069 g, 0.16 mmol) and ligand 6 (0.180 g, 0.62
mmol) were reacted according to the General Method to
give the complex 26 as a pale yellow gum. [h]2D3−2.5
(c=0.40, CHCl3); wmax (CHCl3) 1733 s, 1702 s, 1170 s
cm−1; lH (200 MHz, CDCl3) 0.83 (12H, s, 4×CH3), 1.19
and 1.24 (2×12H, 2×s, 8×CH3), 1.56–1.76 (4H, m,
4×C5HH%), 1.75–1.97 (4H, m, 4×C4HH%), 2.03–2.37
(4H, m, 4×C4HH%), 2.48–2.71 (4H, m, 4×C5HH%),
2.87 (4H, t, J=9.5 Hz, 4×C3H), 5.23 (4H, d, J=14.0
Hz, 4×C11HH%), 5.25 (4H, d, J=14.0 Hz, 4×
C11HH%), 7.21–7.26 (4H, m, 4×C15H), 7.36 (4H, d,
J=7.5 Hz, 4×C13H), 7.69 (4H, m, 4×C14H), 8.58
(4H, d, J=3.0 Hz, 4×C16H); lC (50.3 MHz, CDCl3)
21.13 (CH3), 21.62 (CH3), 22.56 (CH3), 22.78 (C4), 32.48
(C5), 46.85 (C2), 52.67 (C3), 66.63 (C11), 122.34 (C13),
123.17 (C15), 137.23 (C14), 149.54 C16), 156.00 (C12),
174.06 (C10); lPb (52.3 MHz, CDCl3, 223 K) −1877.9.
26. Lead(IV) triacetate mono((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-ethyl-
pyridine-N-oxide)ester) 29
LTA (0.069 g, 0.16 mmol) and (1R,3S)-1,2,2-trimethy-
lcyclopentane-1,3-dicarboxylic acid mono-3-(2-ethylpy-
ridine-N-oxide)ester [11] (0.050 g, 0.16 mmol) were reac-
ted according to the General Method to give the title com-
pound 29 as a bright yellow foam. wmax (film) 3600–3200
br, 2968 m, 1727 s, 1559 s, 1492 m, 1441 s, 1376 s, 1213
s, 1171 s, 1115 m, 1056 m, 1015 m, 852 m, 772 m, 669
m cm−1; lH (200 MHz, CDCl3) 0.70–0.87 (3H, m, CH3),
1.04–1.29 (6H, m, 2×CH3), 1.54–1.68 (1H, m, C5HH%),
1.70–2.62 (12H, m, C5HH%, C4H2 and (OC(O)CH3)3),
2.65–2.80 (1H, m, C3H), 3.25–3.41 (2H, m, C11H2),
4.45–4.63 (2H, m, C12H2), 7.22–7.37 (3H, m, C14H,
C15H and C16H), 8.44 (1H, d, J=6.0 Hz, C17H).
24. Lead(IV) triacetate mono((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-methyl-
pyridine-N-oxide)ester) 27
27. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-ethyl-
pyridine-N-oxide)ester) 30
LTA (0.072 g, 0.16 mmol) and (1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-methyl-
pyridine-N-oxide)ester [11] (0.050 g, 0.16 mmol) were
LTA (0.037 g, 0.08 mmol), benzoic acid (0.031 g, 0.25
mmol) and (1R,3S)-1,2,2-trimethylcyclopentane-1,3-di-

M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
87
carboxylic acid mono-3-(2-ethylpyridine-N-oxide)ester
30. Phenylation of methyl Meldrum’s acid with
isolation of PhPbL3 intermediate
[11] (0.027 g, 0.08 mmol) were reacted according to the
General Method to give the title compound 30 as a
bright yellow gum. wmax (film) 3068 w, 2971 w, 1728 s,
1643 m, 1601 s, 1531 s, 1496 s, 1448 s, 1392 s, 1315 s,
1290 s, 1208 s, 1176 s, 1118 m, 1070 m, 1036 m, 940 m,
850 m, 719 s cm−1; lH (200 MHz, CDCl3) 0.86 (3H, s,
CH3), 1.16 (3H, s, CH3), 1.27 (3H, s, CH3), 1.59–1.88
(2H, m, C5HH% and C4HH%), 2.09–2.24 (1H, m,
C4HH%), 2.42–2.69 (1H, m, C5HH%), 2.74 (1H, t, J=
8.0 Hz, C3H), 3.33 (2H, t, J=6.0 Hz, C11H2), 4.53
(2H, t, J=6.0 Hz, C12H2), 7.22–7.33 (3H, m, C14H,
C15H and C16H), 7.40–7.64 (9H, m, 6×ArH and
3×ArH), 8.10 (6H, d, J=7.5 Hz, 6×ArH), 8.45 (1H,
d, J=5.5 Hz, C17H).
Lead(IV) triacetate mono((1R,3S)-1,2,2-trimethylcy-
clopentane-1,3-dicarboxylic acid mono-3-(2-methyl-
pyridine)ester) 9 (0.338 g, 0.50 mmol), phenylboric acid
(0.067 g, 0.55 mmol) and HgCl2 (0.136 g, 0.50 mmol)
were dissolved in dry CHCl3 (15 ml) and stirred 40°C
for 2 h. The reaction mixture was then filtered through
Celite®, and the solid washed with CHCl3 (3×20 ml).
The organic layer was washed with H2O (1×50 ml),
the aqueous layer being further extracted with CHCl3
(2×25 ml). The combined organic fractions were again
filtered through Celite® and then concentrated to a
volume of 10 ml. Petrol (60 ml) was added to the
solution which was then stored at 0°C overnight. Filtra-
tion of the resulting precipitate gave a pale yellow
crystalline solid, phenyl lead(IV) diacetate mono((1R,
3S)-1,2,2-trimethyl-cyclopentane-1,3-dicarboxylic acid
mono-3-(2-methylpyridine)ester) 21 (0.135g, 39%) wmax
(film) 1729 s, 1546 m, 1432 s, 1382 m, 1264 m, 1162 s,
990 m, 725 s, 692 m, 666 s cm−1; lH (200 MHz,
CDCl3) 0.89 (3H, s, C7H3 or C8H3), 1.28 and 1.31
(2×3H, 2×s, 2×CH3), 1.51–1.74 (1H, m, C5HH%),
1.76–1.99 (1H, m, C4HH%), 2.11 (6H, s, 2×
OC(O)CH3), 2.12–2.35 (1H, m, C4HH%), 2.49–2.70
(1H, m, C5HH%), 2.93 (1H, t, J=9.5 Hz, C3H), 5.27
(1H, d, J=14.0 Hz, C11HH%), 5.28 (1H, d, J=14.0
Hz, C11HH%), 7.23–7.66 (7H, m, C15H, C13H and
C6H5), 7.69–7.78 (1H, m, C14H), 8.60 (1H, d, J=5.0
Hz, C16H); lC (125.8 MHz, CDCl3) 21.24, 21.42, 21.78
and 22.38 (3×CH3 and C4), 22.72 (OC(O)CH3), 32.65
(C5), 47.10 (C2), 52.60 (C3), 56.19 (C1), 66.76 (C11),
122.25 (C13), 123.00 (C15), 129.48, 131.23 and 135.97
(3×ArCH), 136.94 (C14), 149.41 (C16), 155.84 (C12),
173.65 (C10).
28. Lead(IV) triacetate mono((1R,1S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-propyl-
pyridine-N-oxide)ester) 31
LTA (0.044 g, 0.10 mmol) and (1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-3-(2-
propylpyridine-N-oxide)ester [11] (0.033 g, 0.10 mmol)
were reacted according to the General Method to give
the title compound 31 as a bright yellow/orange gum.
wmax (film) 3600–3300 br, 2963 m, 1727 s, 1539 s, 1493
m, 1441 s, 1408 s, 1210 s, 1159 s, 1115 m, 1067 m, 1019
m, 877 m, 846 m, 772 s, 728 m cm−1; lH (200 MHz,
CDCl3) 0.83–0.96 (3H, m, CH3), 1.12–1.25 (6H, m,
2×CH3), 1.31–1.48 (1H, m, C5HH%), 1.54–2.91 (15H,
m, C5HH%, C4H2, C12H2, C3H and (OC(O)CH3)3),
3.01–3.11 (2H, m, C11H2), 4.12–4.21 (2H, m, C13H2),
7.19–7.36 (3H, m, C15H, C16H and C17H), 8.39 (1H,
d, J=6.0 Hz, C18H).
Phenyl lead(IV) diacetate mono ((1R,3S)-1,2,2-
trimethylcyclopentane-1,3-dicarboxylic acid mono-3-(2-
methylpyridine)ester) 21 (0.103 g, 0.15 mmol) was
dissolved in dry CHCl3 (10 ml). Methyl Meldrum’s acid
4 (0.024 g, 0.15 mmol) in pyridine (0.035 g, 0.45 mmol)
was added to the above stirring solution, which was
then heated under reflux for 5 h. The reaction mixture
was filtered through Celite® and the solid residue
washed with CHCl3 (3×25 ml). The combined organic
fractions were then concentrated in vacuo. Purification
by flash column chromatography (eluting 100% DCM)
gave the phenylated product 6 (0.016g, 46%).
29. Lead(IV) tribenzoate mono((1R,3S)-1,2,2-trimethyl-
cyclopentane-1,3-dicarboxylic acid mono-3-(2-propyl-
pyridine-N-oxide)ester) 32
LTA (0.066 g, 0.15 mmol), benzoic acid (0.055 g,
0.45 mmol) and (1R,3S)-1,2,2-trimethylcyclopentane-
1,3-dicarboxylic acid mono-3-(2-propylpyridine-N-ox-
ide)ester [11] (0.050 g, 0.15 mmol) were reacted
according to the General Method to give the title
compound 32 as a yellow foam. wmax (film) 2964 m,
1725 s, 1548 s, 1445 s, 1208 s, 1071 m, 1018 m, 849 m,
728 m cm−1; lH (200 MHz, CDCl3) 0.89–0.97 (3H, m,
CH3), 1.20–1.29 (6H, m, 2×CH3), 1.51–2.37 (5H, m,
C5HH%, C4H2 and C2H2), 2.49–2.68 (1H, m, C5HH%),
2.74–2.86 (1H, m, C3H), 3.03–3.15 (2H, m, C11H2),
4.12–4.22 (2H, m, C13H2), 7.24–7.59 (12H, m, C15H,
C16H, C17H, 9×ArH), 8.06 (6H, d, J=7.5 Hz, 6×
Aru), 8.52 (1H, d, J=6.0 Hz, C18H); lPb (52.3 MHz,
CDCl3, 223 K) −1883.8, −1888.2, −1893.5.
Acknowledgements
We thank DTI, EPSRC and Associated Octel Com-
pany for funding of studentships to D.R.P. and E.W.,
and we wish to gratefully acknowledge the use of the
EPSRC’s Chemical Database Service at Daresbury [19]

88
M.G. Moloney et al. / Journal of Organometallic Chemistry 560 (1998) 77–88
Chem. 35 (1997) 159.
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and the EPSRC Mass Spectrometric Service Centre at
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obtaining 207Pb-NMR spectra.
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[11] M.G. Moloney, D.R. Paul, E. Wright, R.M. Thompson, Tetra-
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