Oxidation of olefins by palladium(II). 18. Effect of reaction conditions, substrate structure and chiral ligand on the bimetallic palladium(II) catalyzed asymmetric chlorohydrin synthesis

Article abstract of DOI:10.1016/S0022-328X(02)01580-2

The effect of electronic factors, solvent composition, identity of the chiral bidentate, and olefin structure on the yields and enantioselectivities of the asymmetric chlorohydrin synthesis were investigated. Electronic effects on the chlorohydrin reaction were tested by oxidation of phenyl allyl ether p-substituted by H, Cl, CH₃O and CN. All species gave same similar yields and enantioselectivities indicating that electronic effects are not important. Varying the solvent composition of the THF-H₂O mixtures indicated that the optimal solvent mixture contains more than 85% THF. Variation of added [Cl^-] indicated that the added chloride had to be greater than 0.2 M for high yields and %ee's. Under ideal conditions the enantioselectivities of the chlorohydrins from the phenyl allyl ethers were more than 90%ee. Vinylacetic acid, methyl acrylate and trans-cinnamaldehyde were unreactive under the usual reaction conditions while 2-hydroxy-3-butene and allyl acetate give lower %ee's than did the phenyl allyl ethers. Styrene and α- methylstryrene gives comparable rates of reactions but the %ee's were lower with the latter. (2,6-Diisopropyl)phenyl allyl ether and 2- hydroxy-3-butene give high %ee's indicating that steric hindrance was not a major factor. All of the chiral bridging ligands tested gave satisfactory results except for DACH. A strange case was BZOX which did not give any induction at all. Structural studies showed the ligands are not large enough to bridge both Pd(II) in the bimetallic catalyst so one Pd(II) contained both ligand groups of the bidentate ligand and was thus unreactive. The other Pd(II) of the dimer was reactive but did not contain any chiral ligands to induce optical activity.

Full text of DOI:10.1016/S0022-328X(02)01580-2

Journal of Organometallic Chemistry 656 (2002) 168ꢀ176
/
www.elsevier.com/locate/jorganchem
Oxidation of olefins by palladium(II). 18. Effect of reaction
conditions, substrate structure and chiral ligand on the bimetallic
palladium(II) catalyzed asymmetric chlorohydrin synthesis
Arab K. El-Qisairi 1, Hanan A. Qaseer 2, Patrick M. Henry *
Department of Chemistry, Loyola University of Chicago, Chicago, IL 60626, USA
Received 17 January 2002; received in revised form 9 April 2002; accepted 15 May 2002
Abstract
The effect of electronic factors, solvent composition, identity of the chiral bidentate, and olefin structure on the yields and
enantioselectivities of the asymmetric chlorohydrin synthesis were investigated. Electronic effects on the chlorohydrin reaction were
tested by oxidation of phenyl allyl ether p-substituted by H, Cl, CH3O and CN. All species gave same similar yields and
enantioselectivities indicating that electronic effects are not important. Varying the solvent composition of the THFꢀH2O mixtures
/
indicated that the optimal solvent mixture contains more than 85% THF. Variation of added [Clꢁ] indicated that the added chloride
had to be greater than 0.2 M for high yields and %ee’s. Under ideal conditions the enantioselectivities of the chlorohydrins from the
phenyl allyl ethers were more than 90%ee. Vinylacetic acid, methyl acrylate and trans-cinnamaldehyde were unreactive under the
usual reaction conditions while 2-hydroxy-3-butene and allyl acetate give lower %ee’s than did the phenyl allyl ethers. Styrene and a-
methylstyrene gives comparable rates of reactions but the %ee’s were lower with the latter. (2,6-Diisopropyl)phenyl allyl ether and 2-
hydroxy-3-butene give high %ee’s indicating that steric hindrance was not a major factor. All of the chiral bridging ligands tested
gave satisfactory results except for DACH. A strange case was BZOX which did not give any induction at all. Structural studies
showed the ligands are not large enough to bridge both Pd(II) in the bimetallic catalyst so one Pd(II) contained both ligand groups
of the bidentate ligand and was thus unreactive. The other Pd(II) of the dimer was reactive but did not contain any chiral ligands to
induce optical activity. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Palladium(II); Catalysis; Asymmetric; Olefins; Chlorohydrins
1. Introduction
Sharpless epoxidation is restricted to oxidation of allylic
alcohols. The Jacobson epoxidation procedure does not
suffer from this limitation [2]. Macrocyclic complexes of
Mn(III) prepared from chiral diamines catalyze the
epoxidation of unfunctionalized olefins by hydroper-
oxides. Recent synthetically useful variations of this
chemistry include the kinetic resolution of epoxides by
Presently there are five general methods for the
asymmetric oxygenation of olefins. The first developed
was the Sharpless epoxidation of allylic alcohols with
hydroperoxides catalyzed by titanium(IV)-chiral
diethyltartrate complexes which were discovered in
1980 [1]. Of many asymmetric transformations, one of
the simplest and most useful is the conversion of allyl
alcohol to chiral glycidol. Despite its usefulness, the
reaction with azide (metalꢂ/Cr) to give hydroxy azides
[3], hydrolysis with water (metalꢂ/Co) to give glycols
[4], and carbonylation with CO to give b-hydroxyesters
[5]. The third asymmetric oxidation procedure consists
of the vicinal hydroxylation of olefins by Os(VIII)
catalysts [6]. A well-known reaction is the osmium
tetroxide catalyzed oxidation of olefins by H2O2. The
asymmetric version, as with the previous two systems
discussed, involves the addition of an appropriate chiral
ligand to the coordination sphere of the Os(VIII). This
system does not require another functional group, such
* Corresponding author. Tel.: ꢃ
3086
E-mail address: phenry@luc.edu (P.M. Henry).
/
1-773-508-3139; fax: ꢃ1-773-508-
/
1
Present address: Department of Chemistry, Mu’tah University,
P.O. Box 7, Mu’tah-Karak, Jordan.
2
Present address: Department of Chemistry, Mu’tah University,
P.O. Box 7, Mu’tah-Karak, Jordan.
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 5 8 0 - 2

A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ
/176
169
as OH in the Ti catalyzed epoxidation, to obtain
enantioselectivity. Thus the asymmetric dihydroxylation
is a general reaction, a trait that has made it useful for
the preparation of many chiral biologically active
compounds. The fourth synthesis is the osmium cata-
lyzed aminohydroxylation reaction [7]. Another of the
reactions uncovered by Dr. Sharpless, this synthesis
could be particularly useful in drug manufacture. The
fifth is the chiral Pd(II)-catalyzed allylic acetoxylation
[8]. However the enantioselectivities realized to date
have been very low (B5%).
/
Papers 16 [9] and 17 [10] of this series described the
newest procedure, the asymmetric synthesis of chlor-
ohydrins by the oxidation of olefins using mono- and bi-
metallic Pd(II) complexes containing chiral auxiliaries
(A and B), in the presence of CuCl2 (Scheme 1). The
CuCl2 is necessary for the formation of the chlorohydrin
products. In its absence only ketones and aldehydes are
produced. These studies used a-olefins as the main
substrates.
2. Results and discussion
2.1. Electronic effects, solvent composition and chloride
concentration
Table 1 lists a series of runs which test electronic
effects, chloride concentration and solvent composition
on the yields and enantioselectivity of the chlorohydrin
product.
Catalyst A gave modest to good enantioselectivities
(eeꢂ
/
28ꢀ/82%) while catalyst B generally gave higher
enantioselectivities (50ꢀ/94%). One reason for the lower
enantioselectivities for the monometallic catalysts is the
fact that the ligands were sulfonated to increase
solubility in the reaction media and sulfonation is
known to decrease optical yields [11]. However, mono-
metallic catalysts with ligands that were not sulfonated
still gave lower enantioselectivities than the correspond-
ing bimetallic catalysts.
First, in regard to electronic effect, runs 3, 6, 8 and 10
have about the same [Clꢁ] (0.2ꢀ
/
0.3 M) and % THF
(85ꢀ/92%) but have different para substitutions on the
benzene rings. These include the hydrogen, the electron
withdrawing CN and Cl, and the electron releasing
group CH3O. The yields of 1 were greater than 85% and
the ee varied between 85 and 93% and there is no
systematic dependence on the electron withdrawing or
releasing properties of the substitution. This result is not
surprising since electron effects are apparently not
important in Pd(II) catalytic chemistry. Thus, in the
Wacker oxidation of a-olefins in aqueous solution, both
acetaldehydes and ketones are formed with ketones
predominating [12]. The order of rates for the reaction is
The present paper will explore further the effect of
chiral ligand, substrate structure and reaction conditions
on the oxidation of a-olefins by the bimetallic catalysts,
B. The studies described in paper 17 used (1R,2R)-(ꢁ
1,2-diaminocyclohexane (1R,2R-DACH), (ꢃ)- and
(ꢁ)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphe-
nylphosphino)butane ((ꢃ) and (ꢁ)-DIOP), and (S)-
(ꢁ)-2,2?-bis(diphenylphosphino)-1,1?-binaphthyl {(S)-
BINAP}. The present study will include these ligands
and, in addition, (S)-(ꢁ)-2,2?-bis(ditolylphosphino)-
1,1?-binaphthyl {(S)-Tol-BINAP}, (R)-(ꢃ)-1,1?-bi-
/)-
/
/
/
/
/
etheneꢀ
the reaction of a-olefins with Tl(III) give only ketones
and the order of rates is isobuteneꢀpropeneꢀethene
[14].
/
propeneꢀisobutene [13]. On the other hand,
/
/
/
/
/
naphthyl-2,2?-diamine ((R)-DINDA), 2,2?-methylene-
bis[(4S)-4-tert-butyl-2-oxazoline] ((S)-METBOX), and
The results are summarized in Scheme 2. Since Pd(II)
hydroxypalladation does have any appreciable carboni-
um ion character, it gives both 3 and 4 which decompose
to ketones and acetaldehydes respectively. Since the
reaction is mainly controlled by stereo chemistry factors,
increasing substitution on the double bond retarded the
reaction. On the other hand, the addition of Tl(III) and
hydroxyl to olefins has considerable ionic character.
This results in exclusively Markovnikov addition to give
2,2?-methylenebis[(4S)-4-benzyl-2-oxazoline]
BZOX).
((S)-
Scheme 1. Chlorohydrin reaction.

170
A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ176
/
Table 1
Results for the oxidation of several para-substituted phenyl allyl ethers
Run
L*ÃL*
[LiCl], (M)
Substrate, p-XÃPhOCH2CHÄCH2
% THF
Yield of 1
%ee of 1
b
1
2
(S)-BINAP
(S)-BINAP
(S)-BINAP
0.3
0.3
XꢂH
XꢂH
XꢂH
XꢂCl
XꢂCl
XꢂCl
XꢂCl
XꢂOCH3
XꢂOCH3
XꢂCN
XꢂCN
30
60
92
92
92
85
92
85
85
85
93
82
90
84
80
93
52
75
92
92
88
89
85
94
b
a
3
0.3
92
70
4
(S)-Tol-BINAP
(S)-Tol-BINAP
(S)-BINAP
0.00
0.05
0.24
2.0
b
5
75
ꢀ90
92
6
b
7
(S)-Tol-BINAP
(S)-Tol-BINAP
(S)-Tol-BINAP
(S)-Tol-BINAP
(S)-Tol-BINAP
8
0.3
2.3
ꢀ90
90
9
10
11
0.2
1.7
ꢀ85
ꢀ95
All runs contain 0.05ꢀ
/
0.12 mmoles of chiral catalyst in 20ꢀ
THF mixture containing 54ꢀ93% THF by volume. Catalyst turnovers were between 150 and 200.
Data from reference [10].
/
30 ml of solvent and are 2.1ꢀ3.5 M in CuCl2. Temperatureꢂ25 8C. The solvent was a
/
H2Oꢀ
/
/
a
b
Dioxygen is oxidant; turnovers measured by O2 uptake using gas burets. In calculating turnovers dioxygen is assumed to be a four electron
oxidant.
of the runs contained more than 85% THF to ensure
maximum values of enantiospecificity.
The added [Clꢁ] content to the reaction mixture had
a larger effect than the solvent composition. In runs 4ꢀ
the major variation of the reaction is the added [Clꢁ]
content. Apparently at least ꢁ
0.2 M excess [Clꢁ] must
be added to achieve the maximum %ee. The optical
purity decreased sharply in going to 0.06ꢀ0.00 M added
/
7
/
Scheme 2. Oxidation of olefins by Pd(II), Tl(III) and Hg(II).
/
[Clꢁ]. In such a complicated system it is difficult to
define the exact role of the added [Clꢁ]. In these
heterogeneous reaction mixtures the chloride may be
bringing more cupric chloride into solution as the
CuCl3ꢁ ion. Increasing the added [Clꢁ] above 0.2 M
does not to have any further effect on %ee’s (compare
runs 6 and 7). However, with the p-CN substituted
phenylallyl ether (PAE), [Clꢁ] does seem to make an
appreciable difference.
3 which give ketone as the only carbonyl product. Thus,
since electronic factors predominated, increased substi-
tution increases the rate of the reaction. A similar case is
Hg(II) which produces the stable oxymercuration ad-
ducts 3. As with Tl(III), since only Markovnikov
addition is observed, the rate increased with increasing
substitution on the double bond [15]. The d for the
reaction was found to be ꢁ
expected for a free carbonium ion in the transition state.
Electronic effects do play some role in altering the 3ꢀ
4 ratio. In the study of the oxidation of some p-
substituted styrenes in THFꢀH2O mixtures, it was
/2.77 which is close to that
/
2.2. Effect of olefin structure
/
observed that electron-releasing groups on the aromatic
ring favored phenylacetophenone formation and elec-
tron-withdrawing groups favored phenylacetaldehyde
formation [16]. In the chlorohydrin reaction this direct-
ing influence cannot be a factor since only the 1 isomer
is observed in all cases. However the electronic releasing
p-CH3O group does give some acetaldehyde so the
electronic factor is of some importance in carbonyl
formation.
Table 2 lists the results for the oxidation of several
olefins containing different functional groups and of
different stereo chemistry requirements. The first five
runs test the reactivity of acids, esters, aldehydes and
alcohols. The fact that vinylacetic acid, methyl acrylate
and trans-cinnamaldehyde were inactive was a surprise
although these functional groups had not been tested
previously. The acid and esters groups must deactivate
the double bond to attack of Pd(II) and water.
The composition of the solvent makes a fairly small
On the other hand, the failure of trans-cinnamalde-
hyde was not surprising since aldehydes tend to be poor
candidates for asymmetric synthesis because of side
reactions. To overcome this problem, this reaction was
tested on acrolein benzene-1,2-dimethanol acetal (5), a
masked glyceraldehyde used successfully in the asym-
metric dihydroxylation reaction (Scheme 3). Unfortu-
but appreciably affect on %ee. Thus, in runs 1ꢀ3 the
/
only variation in reaction conditions is the solvent
composition. When the %THF drops from 92 to 60%
the %ee falls to 80%. Reducing the %THF further to
30% does not decrease the %ee further. The reason this
solvent dependance of %ee is not clear but the remainder

A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ
/176
171
Table 2
Effect of olefin structure on rate of dioxygen uptake with (S)-Tol-BINAP as chiral ligand
Run
Substrate
Rate, M hꢁ1, ꢄ103
Yield of 1
%ee
1
2
3
4
5
6
7
8
9
CH2ÄCHCH2CO2H
CH2ÄCHCO2CH3
t-PhCHÄCHCHO
CH2ÄCHCH(OH)CH3
AcOCH2CHÄCH2
Styrene
0
0
0
0
0
0
0
0
0
2.8
1.9
0.74
0.27
0.45
1.4
75
75
70
66
80
84
70
86
a
85
(2,6-diisopropyl)PAE
a-Methyl styrene
2-Methyl-1-butene
ꢀ95
ꢀ90
57
All runs contain 0.05ꢀ
/
0.12 mmol of chiral catalyst in 20ꢀ
/
30 ml of solvent and are 2.1ꢀ
/
3.5 M in CuCl2. Temperatureꢂ25 8C. [LiCl]ꢂ0.3ꢀ
/
0.4 M.
The solvent was a H2Oꢀ
/
THF mixture containing 90% THF by volume. Catalyst turnovers were between 150 and 200.
a
Absolute configuration is R.
about twice as fast as styrene indicating that the phenyl
group exerts more steric influence than two methyl
groups. As expected, (2,6-diisopropyl)PAE and a-
methylstyrene were the slowest reacting olefins.
Scheme 3. Reaction of acrolein benzene-1,2-dimethanol acetal.
2.3. Comparison of various chiral ligands
nately, none of the chlorohydrin was formed. It is
possible that polymerization had occurred.
Table 3 lists the results of oxidations of phenyl allyl
ethers by several chiral ligands. As reported previously,
DIOP was not as effective as BINAP and DACH was
somewhat inferior to both. The newer ligands, DINDA
and METBOX were about as effective at BINAP in
producing high %ee’s. The lower enantioselectivity
displayed with METBOX in the 1-naphthy allyl ether
oxidation is to be expected since that substrate gives
lower %ee’s when oxidized by a catalyst in which
BINAP is the ligand.
The enantioselectivities of 3-hydroxy-2-butene and
allyl acetate were low compared with the ethers in Table
1. This could result from the presence of the hydroxy
and acetate groups. These groups could interact with the
Pd(II) and thus interfere from the olefin forming a good
fit into the pocket formed by the chiral ligand bonded to
the Pd(II). By comparison the oxidation of allyl alcohol
gave low %ee’s and a fair amount of the 2 isomer [10]. In
addition both 1-hydroxyacetone and 3-hydroxypropa-
nal were found in about equal amounts. This suggests
that the hydroxy group have a strong directing effect on
the mode of hydroxypalladation. This directing effect of
the hydroxy group has been observed previously [17].
Possibly the acetate group in allyl acetate also exerts a
directing influence.
What stands out in Table 3 is the result when BZOX
is the ligand. The yield of chlorohydrin product is high
Table 3
Results for the oxidation of phenyl allyl ether (PAE) and substituted
phenyl allyl ethers by several chiral ligands
Runs 6ꢀ9 test the effect of increasing substitution on
/
Run L*ÃL*
Substrate
Yield of 1 %ee
rates and products. Styrene is the least substituted and
thus is a model for comparison with other olefins. (2,6-
diisopropyl)PAE tests the effect of o-substitutions on
the phenyl ring. This type of steric hindrance is
apparently not an important factor since the yields
and %ee’s compare well those in Table 1. Runs 8 and 9
are examples of a-olefins with two substitutions on one
carbon of the double bond. In both runs the yields were
low and with a-methylstyrene the %ee were also lower
than the other three runs of the series. Some dimeric
product was detected in the run. This dimerization is the
predominate reaction in acetic acid [18].
b
1
2
3
4
5
6
7
8
9
(R)-DINDA
PAE
PAE
90
90
90
92
88
40
87
70
90
86
90
0
b
b
(S)-METBOX
(S)-BZOX
(S)-BINAP
PAE
PAE
a
a
a
93
85
60
92
82
86
(ꢁ)-DIOP
PAE
PAE
(ꢁ)-DACH
(R)-DINDA
(S)-METBOX
(ꢁ)-DIOP
(4-CN) PAE
1-naphthyl allyl ether
(4-OMe) PAE
a,b
All runs contain 0.05ꢀ
solvent and are 2.1ꢀ
solvent was a H2OꢀTHF mixture containing 54ꢀ
Catalyst turnovers were between 150 and 200.
a
Data from reference [10].
/
0.12 mmoles of chiral catalyst in 20ꢀ
3.5 M in CuCl2. Temperatureꢂ25 8C. The
93% THF by volume.
/
30 ml of
/
/
/
The rates of the reactions in Table 2 are noteworthy
mainly because they vary over a short range, a factor of
only ten. As expected, they are, in general, faster for the
monosubstituted olefins. However 2-methyl-1-butene is
b
Dioxygen is oxidant; turnovers measured by O2 uptake using gas
burets. In calculating turnovers dioxygen is assumed to be a four
electron oxidant.

172
A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ176
/
but there was absolutely no chiral induction. METBOX
and BZOX are similar in structure with the latter having
one less CH2 groups separating the two nitrogen donors.
This suggests that the METBOX catalyst have the
structure B while the BZOX catalyst C. The Pd(II)
which contains the bidentate ligand has no labile
coordinate sites and is thus inactive. The other Pd(II)
has two labile coordinate sites and is thus reactive but it
gives no chiral induction since it has no chiral ligand. To
test this possibility both catalysts were prepared using
the symmetric triketone, 2,4,6-heptanetrione. The two
terminal CH3 had an identical signal at 1.76 ppm in the
1H-NMR for the METBOX containing catalyst indicat-
ing a symmetrical structure. However the signals for the
terminal methyl groups in the BZOX catalyst had
different values (2.00 and 2.19 ppm) indicating the
non-symmetrical structure C. Note that BZOX might
a very effective ligand for a monometallic catalyst.
spectrometer. Melting points were recorded on a La-
boratory Devices Mel-Temp apparatus using a cali-
brated thermometer. Elemental analyses were
performed by M-H-W Laboratories, Phoenix, AZ.
GLC analyses were carried out on a GOW-MAC gas
chromatograph (Model 350) or a Perkinꢀ
system XL GC. Optical rotations were measured using a
PerkinꢀElmer Model 341 polarimeter.
(ꢃ)- And (ꢁ)-2,3-O-isopropylidene-2,3-dihydroxy-
1,4-bis(diphenylphosphino)butane (DIOP), (1R,2R)-
/Elmer Auto-
/
/
/
(ꢁ
/
)-1,2-diaminocyclohexane (1R,2R-DACH), (R)-
(ꢃ
/
)-1,1?-binaphthyl-2,2?-diamine (R)-DINDA), 2,2?-
methylenebis[(4S)-4-tert-butyl-2-oxazoline] ((S)-MET-
BOX), and 2,2?-methylenebis[(4S)-4-benzyl-2-oxazoline]
((S)-BZOX). tris[3-(heptafluoropropyl-hydroxymethy-
lene)-(ꢃ
/
)-camphoratol],
europium(III)
derivative
(Eu(hfc)3), sodium hydride (60% dispersion in mineral
oil), styrene, methyl acrylic, acrolein, vinylacetic acid,
trans-cinnamaldehyde, 3-buten-2-ol, a-methylstyrene, 2-
methyl-1-butene, 2,4-pentanedione a-styrene oxide and
dehydroacetic acid were obtained from Aldrich Chemi-
cal Co. (S)-(ꢁ)-2,2?-bis(diphenylphosphino)-1,1?-bi-
/
naphthyl {(S)-BINAP} was obtained either from
Fisher Scientific or Strem Chemicals. (S)-Tol-BINAP
and tetrakis(acetonitrile)palladium(II) tetrafluorobo-
rate, 98%, were obtained either from Strem Chemicals
or Aldrich. Allyl phenyl ether was obtained from Fluka
Chemical Corp. All chemicals were used as received.
The preparation of 1-phenyl-1,3,5-hexanetrione (PHT),
2,4,6-heptanetrione (HpT) and allyl-a-naphthyl ether
was described previously [10]. Solvents were reagent
grade. Dichloromethane, diethyl ether, tetrahydrofuran,
and acetonitrile were dried over calcium hydride (CaH2)
and distilled and stored under argon. The preparation of
the polyketones required moisture exclusion techniques.
All reaction glassware was dried overnight at 110 8C
before use. The apparatus was assembled and lightly
flamed while passing argon through the system. Moist-
ure sensitive solvents and solutions were transferred via
cannulas and/or syringes. Reflux reactions under nitro-
gen or argon were normally performed in a three-neck
round bottom flask fitted with a condenser, an inert gas
adapter and a suba seal septum. Reagents were intro-
duced through the neck with the septum. The reactions
were accomplished under a slight positive pressure of the
inert gas.
3. Conclusions
The conditions which favor the high yields and
enantioselectivity in the chlorohydrin reaction by bime-
tallic catalysts in THFꢀ
/
H2O mixtures are further
defined. They include high THF content (ꢀ
/85%) and
[Clꢁ] of at least 0.2 M. A series of runs with p-
substituted phenyl allyl ethers confirm that electronic
effects are not importance in yield and purity of the
product. Several bidentate chiral ligands were found to
be effective in producing chlorohydrins of high optical
purity. However the chain between the two ligands must
be long enough to bridge both of the two Pd(II)’s or an
inactive catalyst will result. Aldehydes and acids and
their esters are unreactive but alcohol and the esters are
reactive. With simple a-olefins steric hindrance does not
play a major role.
The %ee was determined by using 1H- or 13C-NMR in
4. Experimental
the presence of chiral Eu(hfc)3. A range of 0.1ꢀ0.3 mol
/
4.1. General
ratio of Eu(hfc)3 with respect to the chiral material was
used.
1
All H-, 13C-, 31P-NMR spectra were recorded on a
Varian VXR 400S NMR spectrometer. Chemical shifts
4.2. Preparation of reactants and ligands
1
for H and 13C are relative to (CH3)4Si. 31P chemical
shifts are relative to 85% H3PO4 at 0.0 ppm. IR spectra
4.2.1. Preparation of 4-substituted phenyl allyl ether
These substrates were prepared by a literature proce-
dure [19] according to Scheme 4.
were recorded on a Perkinꢀ
spectrometer or an ATI Mattson Genesis series FT-IR
/
Elmer Model 1310 Infrared

A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ
/176
173
3H) ppm. 13C-NMR (CDCl3): dꢂ
116.84, 123.96, 124.56, 134.12, 141.87, 153.37 ppm.
/24.06, 26.49, 75.41,
Scheme 4. Preparation of 4-substituted phenyl allyl ethers.
4.2.3. Preparation of 3-vinyl-1,5-dihydro-3H-2,4-
benzodioxepine [20]
4.2.1.1. XꢂCl. 4-Chlorophenol (10.0 g, 0.078 mol),
/
A solution of 1,2-benzenedimethanol (6, 4.14 g, 30.0
mmol), trimethylorthoformate (3.18 g, 30.0 mmol), and
a trace amount of p-toluene sulfonic acid in 1,2-
dimethoxy ethane (DME) (15 ml) was stirred at room
temperature (r.t.) for 1 h (Scheme 5). The reaction
mixture was diluted with Et2O and washed with sodium
bicarbonate. The ether layer was dried over anhydrous
MgSO4. Solvent was removed by rotary evaporator, and
1H-NMR for the residue indicated compound 7 ob-
tained. The residue was redissolved in 15 ml DME. To
this solution was added, acrolein (2.0 ml, 30 mmol) and
a trace amount of p-toluene sulfonic acid. The reaction
mixture was stirred for 1 h at r.t. Same work up was
used as in preparation of compound 7. Compound 5 was
14.1 g (0.117 mol) of allyl bromide, and 16.2 g (0.117
mol) of potassium carbonate were mixed together in 60
ml acetone and refluxed for 2 h. Acetone was removed
by rotary evaporator and the residue extracted with
Et2O (3ꢄ50 ml). The ether layer was dried over
/
anhydrous MgSO4 and then evaporated. The residue
was charged on a silica gel column chromatography.
The column was eluted with 10% EtOAcꢀ
afford a yellow oil product. The yield was 83%; 400
MHz; 1H-NMR (CDCl3): dꢂ
4.50 (dd, 2H, Jꢂ3.00,
5.26 Hz), 5.28 (dd, 1H, Jꢂ1.38, 10.49 Hz), 5.38 (dd, 1H,
Jꢂ1.59, 17.27 Hz), 6.05 (m, 1H), 6.84 (dd, 2H, Jꢂ 2.14,
6.73 Hz) and 7.22 (dd, 2H, Jꢂ
2.21, 6.80 Hz) ppm. 13C-
NMR (CDCl3): dꢂ68.90, 104.82, 115.90, 119.76,
129.43, 135.40, and 156.82 ppm.
/
Hexane to
/
/
/
/
/
/
1
/
obtained in 70% yield; 400 MHz; H-NMR (CDCl3):
dꢂ
10.53 Hz), 5.50ꢀ
(m, 1H), 7.13ꢀ
7.25 (m, 4H) ppm. 13C-NMR (CDCl3):
dꢂ69.96, 104.20, 118.40, 126.10, 127.20, 134.60, 138.71
/
4.85ꢀ
/
4.97 (q, 4H), 5.33ꢀ
/
5.37 (dd, 2H, Jꢂ/1.46,
/
5.56 (d, 1H, Jꢂ
/
17.36 Hz), 5.89ꢀ/5.99
/
4.2.1.2. Xꢂ
4.2.1.1, except 4-cyanophenol allyl ether used. The yield
was 85%; 400 MHz; 1H-NMR (CDCl3): dꢂ
4.57 (d, 2H,
Jꢂ5.18 Hz), 5.29ꢀ5.44 (ddd, 2H, Jꢂ1.37, 10.35, 17.27
Hz), 6.00 (m, 1H), 6.96 (d, 2H, Jꢂ8.80 Hz) and 7.57 (d,
2H, Jꢂ 68.94,
8.80 Hz) ppm. 13C-NMR (CDCl3): dꢂ
/
CN. Same procedure was used as in Section
/
ppm.
/
/
/
/
/
4.3. Catalyst preparation
/
/
103.97, 115.33, 118.29, 119.00, 131.93, 133.77 and
161.63 ppm.
The procedure for catalyst preparation have been
described [10].
4.3.1. [Pd2(MeCN)2(PHT)(Tol-BINAP)](BF4)2
The yield was 83%. Anal. Calc. for Pd2C64H58-
N2O3P2B2F8: C, 56.87; H, 4.33; N, 2.07; P, 4.58. Found:
C, 56.27; H, 4.23; N, 2.10; P, 4.52%. 1H-NMR (DMSO):
4.2.1.3. XꢂMeO. Same procedure was used as in
Section 4.2.1.1, except 4-methoxyphenol allyl ether
used. The yield was 87%. 400 MHz; 1H-NMR
/
(CDCl3): dꢂ
Hz), 5.24 (dd, 1H, Jꢂ
1.50, 17.30 Hz), 6.03 (m, 1H) and 6.83 (m, 4H) ppm.
13C-NMR (CDCl3): dꢂ
69.40, 70.21, 115.88, 119.76,
/
3.75 (s, 3H), 4.46 (dt, 2H, Jꢂ/1.50, 5.30
dꢂ
Jꢂ
Jꢂ
(m), 7.92 (m), 8.18 (br.s) ppm. 13C-NMR (DMSO): dꢂ
/
1.77 (s), 2.02 (s), 2.37 (s), 2.47 (s), 6.21 (s), 6.55 (dd,
4.0, 9.6 Hz), 6.65 (br), 6.86 (d, Jꢂ2.0 Hz), 7.22 (t,
6.8 Hz), 7.40 (t, Jꢂ7.6 Hz), 7.56 (br.t), 7.77ꢀ7.89
/
1.50, 10.50 Hz), 5.36 (dd, 1H, Jꢂ
/
/
/
/
/
/
/
/
129.43, 135.50, 152.52 and 154.30 ppm.
1.2, 20.9, 21.1, 110.2, 113.6, 113.7, 120.7, 121.3, 124.0,
125.8, 126.8, 127.5, 128.2, 128.6, 129.1, 129.3, 129.8,
131.3, 132.2, 134.4, 135.2, 139.0, 142.3, 143.5, 162.5,
4.2.2. Preparation of 2,6-diisopropylphenyl allyl ether
An 13.9 g (0.078 moles) sample of 2,6-diisopropyl-
phenol, 14.1 g (0.117 moles) of allyl bromide, and 16.2 g
(0.117 moles) of potassium carbonate were mixed
together in 60 ml acetone and refluxed for 24 h. Acetone
was removed by rotary evaporator and the residue
165.8, 178.8, 180.4, 185.9 ppm. 31P-NMR (DMSO): dꢂ
/
31.3 ppm
4.3.2. [Pd2(MeCN)2(PHT)(DINDA)](BF4)2
The yield was 85%. Anal. Calc. for Pd2C36H34-
N4O3B2F8: C, 45.18; H, 3.58; N, 5.85. Found: C,
extracted with Et2O (3ꢄ50 ml). The ether layer was
/
dried over anhydrous MgSO4 and then evaporated. The
residue was charged on a silica gel column chromato-
graphy. The column was eluted with 5% EtOAcꢀ
to afford a yellow oil product. The yield was 95%; 400
MHz; 1H-NMR (CDCl3): dꢂ
1.25 (d, 12H, Jꢂ6.8 Hz),
3.36 (septet, 1H, Jꢂ6.98, 13.89 Hz), 4.30 (dt, 2H, Jꢂ
1.59, 3.50 Hz), 5.30 (dt, 1H, Jꢂ1.27, 10.48 Hz), 5.47
(dt, 1H, Jꢂ 1.59, 17.15 Hz), 6.13 (m, 1H) and 7.11 (s,
/
hexane
/
/
/
/
/
/
Scheme 5. Preparation of 3-vinyl-1,5-dihydro-3H-2,4-benzodioxepine.

174
A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ
/176
1
45.12; H, 3.64; N, 5.75%. H-NMR (DMSO): dꢂ
(s), 2.06 (s), 2.37 (s), 3.56ꢀ3.63 (br.s), 6.21 (s), 6.80 (s),
6.84 (d, Jꢂ2.0 Hz), 6.92 (d, Jꢂ
Hz), 7.43 (d, Jꢂ8.4 Hz), 7.57 (q, Jꢂ
Jꢂ8.8 Hz), 7.91 (dd, Jꢂ2.0, 8.0 Hz), 8.10 (d, Jꢂ
Hz), 8.20 (d, Jꢂ8.8 Hz), 8.23 (d, Jꢂ
NMR (DMSO): dꢂ1.1, 18.0, 110.1, 113.6, 118.1, 120.7,
/
1.77
In all runs the gas uptake was a linear function of time.
For the runs in which the dioxygen uptake was
measured, the yields were based on dioxygen consumed.
For the others it was based on recovered starting
material.
/
/
/
8.4 Hz), 7.38 (t, Jꢂ
/7.6
/
/
6.8 Hz), 7.76 (d,
/
/
/
8.4
/
/
8.4 Hz) ppm. 13C-
The products were extracted with Et2O (3ꢄ
and then dried over anhydrous MgSO4. Ether was
evaporated and the volume reduced to ꢁ1.0 ml. This
volume was charged on a silica gel (60ꢀ200 mesh)
/
50 ml)
/
121.4, 121.8, 124.8, 125.8, 127.5, 128.7, 129.1, 131.1,
131.4, 132.0, 133.0, 136.7, 163.9, 176.8, 179.5, 183.6
ppm.
/
/
column chromatography. The column was eluted with
80% petroleum ether in CH2Cl2 to elute starting
material and carbonyl product. Then, the column was
eluted with 20% petroleum ether in CH2Cl2 to give the
4.3.3. [Pd2(MeCN)2(HpT)(BZOX)](BF4)2
The yield was 87%. Anal. Calc. for Pd2C31H36N4-
O5B2F8: C, 40.00; H, 3.90; N, 6.02. Found: C, 40.02; H,
1
chlorohydrin. The %ee was determined by H-NMR in
the presence of chiral Eu(hfc)3.
3.87; N, 6.08%. 1H-NMR (CDCl3): dꢂ
/
1.39 (d, Jꢂ
6.4), 2.00 (s), 2.19 (s), 2.71 (s), 3.03 (m), 3.12
(m), 3.36 (m), 3.68 (m), 4.49ꢀ4.76 (m), 5.90 (s), 6.00 (s),
7.26ꢀ 1.9, 18.0,
7.42 (m) ppm. 13C-NMR (CDCl3): dꢂ
/6.4),
1.45 (d, Jꢂ
/
/
4.4.1.1. Oxidation of allyl phenyl ether. The oxidation
has been described [10]. The spectra data (1H-NMR,
13C-NMR) of the 1-chloro-3-phenoxy-2-propanol pro-
duct were identical with those reported [22].
/
/
20.1, 30.4, 38.4, 38.8, 43.4, 55.4, 63.3, 63.4, 78.2, 103.9,
113.6, 118.1, 120.7, 127.6, 128.5, 128.8, 129.2, 129.4,
129.6, 129.9, 134.6, 161.6, 174.5, 178.4, 196.5 ppm.
4.4.1.2. Oxidation of (4-chloro)phenyl allyl ether. The
ketone product was confirmed to be (4-chloro)-1-phe-
4.3.4. [Pd2(MeCN)2(HpT)(METBOX)](BF4)2
The yield was 87%. Anal. Calc. for Pd2C26H42N4-
O5B2F8: C, 35.60; H, 4.83; N, 6.39. Found: C, 36.01; H,
1
noxyacetone; 400 MHz; H-NMR (CDCl3): dꢂ
/
2.28 (s,
9.0 Hz), 7.22 (d, 2H,
7.35 Hz) ppm. 13C-NMR (CDCl3): dꢂ
26.59, 73.28,
115.81, 129.50, 143.03, 156.25, 204.90 ppm.
4.87; N, 6.48%.1H-NMR (DMSO): dꢂ
/
0.93 (s), 0.99 (s),
1.09 (s), 1.25(s), 1.26 (s), 1.28 (s), 1.76 (s), 2.20 (t, Jꢂ7.6
Hz), 2.65 (t, Jꢂ7.6 Hz), 3.14 (m), 3.62 (m), 6.69 (br s),
7.29 (br s), 8.16 (br s) ppm. 13C-NMR (DMSO): dꢂ
1.3,
3H), 4.02 (s, 2H), 6.82 (d, 2H, Jꢂ
/
Jꢂ
/
/
/
/
The major product was confirmed to be (4-chloro)-1-
phenoxy-3-chloro-2-propanol; 400 MHz; 1H-NMR
/
18.0, 20.1, 25.6, 26.0, 26.3, 26.8, 41.8, 53.6, 67.8, 70.7,
71.5, 103.4, 104.0, 105.6, 118.9, 161.9, 166.3, 166.7,
171.6, 177.9 ppm.
(CDCl3): dꢂ
5.38, 11.27, 18.20 Hz), 4.05ꢀ
Hz), 4.22 (m, 1H), 6.86 (d, Jꢂ
2H, Jꢂ
1.95, 7.35 Hz) ppm. 13C-NMR (CDCl3) dꢂ
/
2.55 (s.br, OH), 3.73ꢀ
4.07 (dd, 2H, Jꢂ
9.0 Hz), 7.23-7.26 (dd,
/
3.81 (ddd, 2H, Jꢂ
/
/
/1.17, 5.21
/
/
/
4.4. Oxidation reactions
45.94, 68.96, 69.83, 115.86, 129.39, 135.41, 156.75
ppm. Anal. Calc. For C9H10Cl2O2: C: 48.90; H: 4.56;
4.4.1. Oxidation procedure
Cl: 32.07. Found: C: 49.24; H: 4.60; Cl: 31.95%. [a]2D0ꢂ
/
To provide good gas liquid mixing, the reactions were
run in creased flasks at 25 8C at a constant pressure of
one atmosphere of dioxygen. The progress of some of
the oxidations was followed by dioxygen uptake mea-
sured by gas burets thermostated at 25 8C. The reaction
vessel was a 250 ml two-necked coned shaped flask with
the sided indented at four places to increase stirring
efficiency. The apparatus is similar to that previously
ꢃ
/
0.518 (cꢂ
/
3.33, CH2Cl2) (eeꢂ92%).
/
4.4.1.3. Oxidation of (4-methoxy)phenyl allyl ether. The
first fraction was obtained in a 8% yield and found to be
a mixture of (4-methoxy)-1-phenoxyacetone and (4-
methoxy)-3-phenoxypropanal. Their ratio was obtained
by 1H-NMR and found to be 69%: 31% respectively; 400
described [21]. In a typical run the flask containing 30ꢀ
/
MHz; 1H-NMR (CDCl3): dꢂ
2.25 (s, 3H), 2.85 (m, 2H),
/
50 ml of reaction mixture was placed in a constant
temperature bath and connected to the gas buret. The
system was then evacuated for 10 min on the vacuum
line with stirrer running. The stirring was stopped and
the system pressurized to 1.0 atm with dioxygen. The
mercury in the gas buret and the leveling bulb were
equalized and a reading taken. The stirrer was then
activated. Atmospheric pressure was maintained by
continuously leveling the mercury in the gas buret.
The volume of dioxygen consumed was measured at
regular time intervals (t) to give a series of readings (Vt).
3.73 (s, 3H), 3.75 (s, 3H), 4.25 (d, 2H), 4.47 (s, 2H), 6.80
(s, 8H), 9.84 (t, 1H) ppm. The second fraction was
obtained in ꢀ
phenoxy-3-chloro-2-propanol; 400 MHz; 1H-NMR
(CDCl3): dꢂ2.54 (d, OH, Jꢂ5.7 Hz), 3.71ꢀ3.80 (m,
2H), 3.75 (s, 3H), 4.01ꢀ4.03 (dd, 2H, Jꢂ1.53, 5.00 Hz),
/
90% yield and found to be (4-methoxy)-1-
/
/
/
/
/
4.16 (m, 1H), 6.83 (s, 4H) ppm. 13C-NMR (CDCl3): dꢂ
/
46.02, 55.78, 69.40, 70.00, 114.72, 115.63, 152.63, 154.29
ppm. Anal. Calc. For C10H13ClO3: C: 55.44; H: 6.05; Cl:
16.36. Found: C: 56.83; H: 5.95; Cl: 15.83%. [a]2D0ꢂ
/
ꢃ
/
0.708 (cꢂ
/
1.6, CH2Cl2) (eeꢂ86%).
/

A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ
/176
175
4.4.1.4. Oxidation of (4-cyano)phenyl allyl ether. The
first fraction contained 25% of the original starting
material. The second fraction contained a 75% conver-
4.4.1.8. Oxidation of 2-methyl-1-butene. The chlorohy-
drin product was obtained in a 60% yield based on
oxygen uptake and found to be a mixture of 2-methyl-1-
chloro-2-butanol and 2-methyl-2-chloro-1-butanol. The
ratio of these two was obtained by GC and found to be
sion to (4-cyano)-1-phenoxy-3-chloro-2-propanol; 400
1
MHz; H-NMR (CDCl3): dꢂ
/
2.50 (d, OH, Jꢂ
5.38, 11.27, 18.20 Hz), 4.14ꢀ
1.17, 5.21 Hz), 4.26 (m, 1H), 6.98 (d,
9.0 Hz), 7.61 (d, 2H, Jꢂ
7.35 Hz) ppm. 13C-
NMR (CDCl3): dꢂ45.84, 68.86, 69.60, 104.89, 115.27,
/
5.7 Hz),
1
3.71ꢀ
4.24 (dd, 2H, Jꢂ
2H, Jꢂ
/
3.81 (ddd, 2H, Jꢂ
/
/
95:5% respectively; 400 MHz; H-NMR (CDCl3) for 2-
/
methyl-1-chloro-2-butanol (major product): dꢂ
3H, Jꢂ7.40 Hz), 1.18 (s, 3H), 1.52 (q, 2H, Jꢂ7.6 Hz),
2.36 (br., OH), 3.65(s, 2H) ppm. 13C-NMR (CDCl3) dꢂ
/0.90 (t,
/
/
/
/
/
/
118.77, 134.02, 161.34 ppm. Anal. Calc. For
C10H10ClNO2: C: 56.75; H: 4.76; Cl: 16.75, N: 6.62.
8.52, 15.19, 28.58, 36.28, 67.68 ppm.
Found: C: 57.88; H: 4.63; Cl: 16.50; N: 6.31%. [a]2D0ꢂ
/
ꢃ
/
4.4.1.9. Oxidation of a-methyl styrene. Two fractions
were collected by column chromatography. The first
fraction was found to be the starting material and some
Diels Alder products. The second fraction was obtained
in a 40% conversion relative to starting material and
found to be 1-chloro-2-phenyl-2-propanol; 400 MHz;
90.38 (cꢂ
/
0.35, CH2Cl2) (eeꢂ94%).
/
4.4.1.5. Oxidation of (2,6-diisopropyl)phenyl allyl ether.
The first fraction contained 40% of the starting material.
The second fraction contained a 60% conversion to (2,6-
diisopropyl)-1-phenoxy-3-chloro-2-propanol; 400 MHz;
1H-NMR (CDCl3): dꢂ
11.4 Hz), 4.48 (s, OH), 7.33ꢀ
2H, Jꢂ
7.2 Hz) ppm. 13C-NMR (CDCl3): dꢂ
54.59, 70.54, 126.40, 128.40, 128.52, 141.47 ppm.
/
2.11 (s, 3H), 4.04 (q, 2H, Jꢂ
7.41 (m, 3H), 7.56ꢀ7.58 (d,
28.20,
/
1H-NMR (CDCl3): dꢂ
(d, OH, Jꢂ5.7 Hz), 3.30 (septet, 2H, Jꢂ
(dd, 2H, Jꢂ5.55, 9.68 Hz), 3.88 (t, 1H, Jꢂ
4.06 (m, 1H), 4.23 (m, 1H), 7.14 (s, 3H) ppm. 13C-NMR
(CDCl3): dꢂ23.99, 24.05, 26.40, 26.44, 45.69, 70.49,
/
1.24 (d, 12H, Jꢂ
6.99 Hz), 3.81
5.24 Hz),
/
7.2 Hz), 2.60
/
/
/
/
/
/
/
/
4.4.1.10. Oxidation of allyl acetate. The first fraction
contained recovered starting material. The second was
1
pure 3-chloro-2-hydroxypropyl acetate. 400 MHz H-
/
74.17, 124.15, 125.04, 141.59, 152.06 ppm.
NMR (CDCl3): dꢂ
(dd, 2H, Jꢂ 5.4, 9.4 Hz), 4.06 (m, 1H), 4.19 (d, 2H, Jꢂ
5.2 Hz) ppm. 13C-NMR (CDCl3) dꢂ
20.80, 45.97,
/
2.09 (s, 3H), 2.36 (s, OH), 3.58ꢀ3.63
/
4.4.1.6. Oxidation of 3-vinyl-1,5-dihydro-3H-2,4-benzo-
dioxepine. 1H and 13C-NMR analysis of the product
indicated that no chlorohydrin was present. It might be
a polymerized product obtained and no further investi-
gation was taken.
/
/
/
65.29, 69.62, 71.09 ppm.
Acknowledgements
4.4.1.7. Oxidation of styrene. The first fraction was
obtained in a ꢁ
of acetophenone and 2-phenyl acetaldehyde in a ratio of
2:1 respectively; 400 MHz; H-NMR (CDCl3): dꢂ
(s, 3H), 3.67 (d, 2H, Jꢂ6.80 Hz), 7.20ꢀ7.60 (m, 10H),
9.75 (t, 1H, Jꢂ5.24 Hz). The second fraction was
/
5% yield and found to be a mixture
This work was supported by the Petroleum Research
Fund, administered by the American Chemical Society,
and the National Science Foundation (CHE-9727526).
1
/
2.15
/
/
/
obtained in a 85% yield and found to be 1-phenyl-2-
chloro ethanol. The spectra data (1H-NMR, 13C-NMR)
of the 1-chloro-3-phenoxy-2-propanol product were
identical with those reported [23].
References
[1] T. Katsuki, K.B. Sharpless, J. Am. Chem. Soc. 102 (1980) 5974.
[2] A. Aith, in: E.N. Jacobsen, I. Ojima (Eds.), Catalytic Asymmetric
Synthesis (Chapter 4.2), VCH, New York, NY, 1993.
[3] J.F. Larrow, S.E. Schaus, E.N. Jacobsen, J. Am. Chem. Soc. 118
(1996) 7420.
A sample from 2-chloro-1-phenylethanol (styrene
chlorohydrin) was reacted with 2 ml 30ꢀ40% NaOH
/
solution at r.t. The reaction mixture was stirred for 30
min. Styrene oxide was extracted with CDCl3. The
spectra date (1H-NMR, 13C-NMR) were identical with
those reported [24]. The %ee was determined by 1H-
NMR in the presence of chiral Eu(hfc)3 and found to be
78%. The absolute configuration of styrene oxide was
determined by comparison with 1H-NMR of the
authentic sample of (R)-styrene oxide in the presence
of 0.2 mol ratio of Eu(hfc)3. The configuration was
found to be (S)-styrene oxide. Since the configuration
was reversed in forming the oxide the starting chlor-
ohydrin was (R).
[4] M. Tokunaga, J.F. Larrow, F. Kakiucha, E.N. Jacobsen, Science
277 (1997) 936.
[5] K. Hinterding, E.N. Jacobsen, J. Org. Chem. 64 (1999) 2164.
[6] R.A. Johnson, K.B. Sharpless, Reference [2], Chapter 4.4.
[7] L. Guigen, C. Han-Ting, K.B. Sharpless, Angew. Chem. Int. Ed.
Engl. 35 (1996) 451.
[8] (a) H. Yang, M.A. Khan, K.M. Nicholas, J. Mol. Catal. 91 (1994)
319;
(b) N.Y. Kozitsyna, M.N. Vargaftik, I.I. Moiseev, J. Organomet.
Chem. 593-594 (2000) 274.
[9] O. Hamed, P.M. Henry, Organometallics 17 (1998) 5184.
[10] A. El-Qisairi, P.M. Henry, J. Organomet. Chem. 603 (2000) 50.
[11] J. Bakos, A. Orosz, B. Heil, M. Laghmari, P. Lhoste, D. Sinou, J.
Chem. Soc., Chem. Commun. (1991) 1684.

176
A.K. El-Qisairi et al. / Journal of Organometallic Chemistry 656 (2002) 168ꢀ176
/
[12] For general discussion and references see: P.M. Henry, Palladium
Catalyzed Oxidation of Hydrocarbons, D. Reidel, Doordrecht,
(f) O. Hamed, P.M. Henry, J. Thompson, J. Org. Chem. 64 (1999)
7745.
Holland, 1980, pp. 41ꢀ
/
84.
[18] P.M. Henry, Palladium Catalyzed Oxidation of Hydrocarbons,
[13] P.M. Henry, J. Am. Chem. Soc. 88 (1966) 1595.
[14] P.M. Henry, J. Am. Chem. Soc. 87 (1965) 4423.
[15] J. Halpern, H.B. Tinker, J. Am. Chem. Soc. 89 (1967) 6427.
[16] T. Okada, T. Noma, Y. Katsuyama, H. Hashimoto, Bull. Chem.
Soc. Jpn. 41 (1968) 1395.
Reidel, Doordrecht, Holland, 1980, pp. 184ꢀ191.
[19] S. Marcinkiewicz, J. Green, P. Mamalis, Tetrahedron 14 (1961)
208.
/
[20] N. Machinaga, C. Kibayashi, Tetrahedron Lett. 30 (1989)
4165.
[17] (a) K. Zaw, P.M. Henry, J. Org. Chem. 55 (1990) 1842;
(b) K. Zaw, P.M. Henry, Organometallics 11 (1992) 2008;
(c) J. Francis, P.M. Henry, Organometallics 11 (1992) 2832;
(d) J.W. Francis, P.M. Henry, Organometallics 10 (1991) 3498;
(e) O. Hamed, P.M. Henry, Organometallics 16 (1997) 4903;
[21] For a similar apparatus see: ref [12], p. 57.
[22] H. Kotsuki, T. Shimanouchi, R. Ohshima, S. Fujiwara, Tetra-
hedron 54 (1998) 2709.
[23] Aldrich Library of 13C and 1H FT NMR Spectra, 1(2), 329A.
[24] Aldrich Library of 13C and 1H FT NMR Spectra, 1(2), 219C.