Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes, a Key Reaction in a Strigol Total Synthesis

Article abstract of DOI:10.1002/ejoc.200200671

Oxidation of 4,6-heptadienoic acid systems with hydrogen peroxide in the presence of a catalytic amount of diphenyl diselenide leads to 5-(3-hydroxypropenyl)dihydrofuran-2-one systems with defined relative configuration at the 4 and 7 positions (carboxylic acid numbering). A system having a six-membered ring as part of the s-trans-diene system was an intermediate in a strigol total synthesis; a second system lacking the six-membered ring is the subject of the present publication. We accomplished a stereoselective synthesis of the diene system by (i) trapping a π-allyl palladium complex with lithium diphenylphosphinite to give an allylic diphenylphosphane oxide and (ii) a subsequent Horner-Wittig reaction. The species that brings about the oxidative 1,4-addition is benzeneperoxyseleninic acid. We also report observations that shed some light on the mechanism. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/ejoc.200200671

FULL PAPER
Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes, a Key Reaction in
a Strigol Total Synthesis
[a]
[a]
[b]
´
´
Anna Galkina, Angelika Buff (nee Kranz), Emmanuelle Schulz (nee Samson),
Lothar Hennig,[a] Matthias Findeisen,[a] Gerd Reinhard,[a] Ramona Oehme,[a] and
Peter Welzel*[a]
Dedicated to Professor Wolfgang Steglich on the occasion of his 70th birthday
Keywords: Oxidation / Olefination / Palladium / Stereochemistry
Oxidation of 4,6-heptadienoic acid systems with hydrogen
peroxide in the presence of a catalytic amount of diphenyl
diselenide leads to 5-(3-hydroxypropenyl)dihydrofuran-2-
one systems with defined relative configuration at the 4 and
7 positions (carboxylic acid numbering). A system having a
the diene system by (i) trapping a π-allyl palladium complex
with lithium diphenylphosphinite to give an allylic di-
phenylphosphane oxide and (ii) a subsequent Horner−Wittig
reaction. The species that brings about the oxidative 1,4-ad-
dition is benzeneperoxyseleninic acid. We also report obser-
six-membered ring as part of the s-trans-diene system was vations that shed some light on the mechanism.
an intermediate in a strigol total synthesis; a second system
lacking the six-membered ring is the subject of the present
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
publication. We accomplished a stereoselective synthesis of 2002)
Introduction
The exchange of chemical information indicated above
raises basic questions, such as (i) which structural features
of the stimulants are essential to elicit a high seed germi-
nation potency, (ii) how is the chemical signal that is re-
leased from the host recognized by the seed, and (iii) how
does the primary chemical signal initiate the biochemical
processes that are involved in germination?
It has been determined that both the absolute and rela-
tive configurations at the individual stereogenic units of
strigol-type compounds have a strong influence on their
biological activity.[8]
Root parasitic flowering plants of the general Striga,
Alectra (Scrophulariaceae), and Orobanche (Orobanchaceae)
and their respective host plants use a very interesting sys-
tem of chemical communication. It has long been known
that germination of the seeds of the parasites is stimulated
by compounds exuded from the roots of their host plant
into the soil.[1] Well-known stimulants are strigol and its
acetate (isolated from Striga hosts[2] and from cotton, Gos-
sypium hirsutum,[3] a non-host), as well as sorgolactone, iso-
lated from the root exudates of Sorghum vulgare,[4] a host
for Striga). Recently, orobanchol, an isomer of strigol, was
isolated by Yokota et al. from root exudates of its host,
Results
Strigolactones are available from the root exudates of the
Trifolium pratense.[4,5] Finally, a compound, alectrol, has host plants only under extreme difficulty. The chemical syn-
been isolated from the root exudates of Vigna unguiculata[6] thesis is, therefore, indispensable for gaining access to these
(host for Striga and Alectra). A structure has been proposed compounds. A number of synthetic routes have been devel-
for this compound that was recently rejected (Figure 1).[7]
oped for strigol that involve the reduction of a keto group
at C-5 (strigol numbering), which leads to a 1:1 mixture of
epimeric 5-alcohols.[8,9] We have developed a synthesis in
which diene 3 is a key intermediate (Scheme 1).[10Ϫ12] An
oxidative 1,4-addition furnished the desired hydroxylactone.
When the oxidizing agent was a peracid, hydrogen peroxide
(slow reaction), or N-phenyloxaziridine, a 1:1 mixture of 5-
alcohols 2a and 2b resulted. We have speculated that the
reaction proceeds via the epimeric allylic epoxides 4 that
[a]
Fakultät für Chemie und Mineralogie, Universität Leipzig,
Johannisallee 29, 04103 Leipzig, Germany
Fax: (internat.) ϩ49-0341-9736551
E-mail: welzel@organik.chemie.uni-leipzig.de
[b]
´
Laboratoire de Catalyse Moleculaire, ICMO, Universite Paris
ˆ
Sud, Bat. 420,
91405 Orsay, France
E-mail: emmaschulz@icmo.u-psud.fr
4640
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DOI: 10.1002/ejoc.200200671
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Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
Figure 1. Naturally occurring strigolactones
are attacked intramolecularly by the carboxylic acid group. trifluoromethylbenzoates. Our idea was to use the Saito
On the other hand, treatment of diene 3 with 30 % H2O2 photochemical deoxygenation method[18] for the reductive
and a catalytic amount of diphenyl diselenide in CH2Cl2 formation of the double bond; these experiments were un-
proceeded stereoselectively with the exclusive formation of successful, however.[19] We were also unable to achieve the
the desired stereoisomer 2a, which was isolated in 70 % olefin formation with samarium diiodide or zincϪcopper
yield. The result was taken as a hint that the formation of couple.[19] Finally, treatment of rac-6c, rac-6d, and rac-9c
2a under these conditions takes a course other than that of with sodium amalgam[20] brought about the desired re-
the oxidation reactions leading to the 1:1 mixture of 2a and ductive β-elimination. Unfortunately, in all cases we ob-
2b. We reasoned that an anhydride intermediate of type 5, tained a mixture of the isomeric dienes rac-7a and rac-10a
formed from 3 with benzeneseleninic acid (the oxidation (GC analysis, ratio ca. 1.5:1). A NOESY cross peak be-
product of diphenyl diselenide[13]), reacts as indicated to tween the proton at the exocyclic double bond and 3-H re-
give 2a and benzeneselenenic acid, which could be reoxid- vealed that rac-10a was the major isomer. Since we were
ized to benzeneseleninic acid (Scheme 1). It was also adum- unable to separate rac-7a and rac-10a, it made no sense to
brated that the peracid anhydride version of 5 would result perform the oxidative cyclization because no information
directly in the formation of benzeneseleninic acid. The s- on the stereoselectivity could be expected.
trans diene system in 3 is incorporated into a system con-
Synthesis of Diphenylphosphane Oxides rac-13b and rac-
14b
taining a six-membered ring. To exclude specific effects in
such systems, such as in the reduction of cyclohexanones[14]
or in SN2Ј reactions,[15] we tried to prepare dienes 7 and 10
(Figure 2) and to submit these compounds to the oxidative
cyclization reaction. Each isomer should lead to a single
hydroxy lactone (8 and 11, respectively).
Phosphane oxide-mediated olefin synthesis, i.e., reaction
of lithium derivatives of alkyl diphenylphosphane oxides
with aldehydes to give β-hydroxyphosphane oxides followed
by separation of the stereoisomers, and stereospecific elim-
ination of Ph2POϪ with a sodium or a lithium base
(HornerϪWittig olefin synthesis[21,22]) seemed to offer a
way out of the difficulties experienced with the non-stereo-
Attempted Synthesis of Dienes rac-7 and rac-10 via
Hydroxysulfones rac-6 and rac-9
The synthesis of the four racemic hydroxysulfones rac-6a/ selective formation of the trisubstituted olefins rac-7 and
b and rac-9a/b (R ϭ α-H and β-H) has been described.[16] rac-10 during the Julia-type reactions described above. Our
We wanted to convert them into the desired dienes making concept was to convert the unsaturated lactone rac-12 into
use of a Julia-type reductive elimination.[17] Thus, the a π-allylϪpalladium complex and to trap this intermediate
hydroxysulfones were converted into the corresponding m- with a nucleophilic precursor of the diphenylphosphane ox-
Scheme 1
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P. Welzel et al.
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Figure 2. Structures of compounds 6Ϫ11
ide substituent. Our investigations started on the basis of a ence of either Pd(acac)2 or Pd(PPh3)4. In all cases the corre-
report by Man˜as et al.[23] who disclosed that cinnamyl acet- sponding sulfones (rac-13c, rac-20b, rac-22b, respectively)
ate (15) in a Pd-mediated reaction with methyl diphenyl- were formed.
phosphinite [Pd(acac)2 in dioxane at 150 °C (pressure ves-
Another method for the preparation of 13a might be the
sel)] furnished the allylic diphenylphosphane oxide 16 in a
oxidation of rac-23, which was obtained by Pd0-mediated
yield of 49 %. By repeating these experiments we found that
reaction of rac-12 with lithium diphenylthiophosphinite[24]
the reaction proceeds equally well in acetonitrile (at 101 °C)
in a yield of 61 % (Scheme 3).
or MeOH solution (at 60 °C) to give 16 in yields of 53 and
68 %, respectively. The use of a pressure vessel is, therefore,
The diastereoisomeric acids rac-13a/rac-14a were con-
not required. Unfortunately lactone rac-12 did not react verted (MeOH/Hϩ) into their methyl esters, which were
with methyl diphenylphosphinite under the conditions used separated by crystallization to give a crystalline and an oily
for the conversion of 15 into 16, neither in dioxane, aceto- stereoisomer, respectively. Their configurational assign-
1
nitrile, or MeOH solution. We reasoned that an external ments were far from trivial; Figures 3 and 4 display the H
nucleophile that would attack the methoxy group could im- NMR spectra of the two compounds. The protons at C-5
prove the reaction. Thus, the reaction was performed in of one stereosiomer give rise to two multiplets at δ ϭ 1.79
MeOH at 60 °C in the presence of LiCl, NaOAc, and and 2.45 ppm. Interpreting these multiplets is complicated
(Bu)4NϩClϪ, respectively, but without success. At this point because of 31P-1H coupling. Upon 31P decoupling, the mul-
we decided to include model compounds 2-cyclopentenyl tiplets collapse to six lines from which, by spin simulation,
acetate (rac-17), cis-3,5-diacetoxycyclopent-1-ene (19), and we derived coupling constants of J1,5a ϭ J4,5a ϭ 4.8 Hz,
3,4-epoxycyclopent-1-ene (rac-21) into the investigations J1,5b ϭ J4,5b ϭ 6.0 Hz, and J5a,5b ϭ 9.0 Hz. We conclude
(Scheme 2) and to use also other nucleophilic diphenyl- from the values of J1,5a/J4,5a and J1,5b/J4,5b, respectively,
phosphane oxide precursors. The results, summarized in that this isomer has the cis configuration, as indicated in
Table 1, demonstrate that only lithium diphenylphosphinite rac-13b. We determined both one- and two-dimensional
was of any use for our purpose. The phosphinite, upon reac- NOEs. In addition to the NOEs summarized in Figure 5,
tion with lactone rac-12 in the presence of Pd(PPh3)4 (Ϫ80 we found a structurally important NOE contact between 5-
°C, 1 h), provided the desired diphenylphosphane oxide in Ha and CH2-COOMe. These NOEs allowed us to assign
67 % yield as a 3:1 mixture (31P NMR) of the two (racemic) the signals of 2-H and 3-H, as well as those of 5-Ha and 5-
diastereoisomers rac-13a and rac-14a; we isolated rac-24 as Hb. We believe that the unexpected small chemical shift of
a side product. Prolonging the reaction time from 1 to 2 h 5-Ha is the result of a shielding effect of the ester CO group
increased the yield to 78 %. To exclude the possibility that and/or an aromatic ring. We observed no NOE contact be-
the intermediate π-allyl-palladium complexes were not tween 1-H and 4-H. The chemical shift difference for the
formed during the unsuccessful trials, rac-12, 19, and rac- olefinic protons at C-2 and C-3 is ca. 0.3 ppm for one iso-
21 were treated with sodium benzenesulfinate in the pres- mer (rac-13b) and 0.6 ppm for the other (rac-14b). This fea-
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Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
Scheme 2
Table 1. Pd-mediated reaction of rac-12, rac-21, 15, and 19 with nucleophilic diphenylphosphane oxide precursors
Nucleophiles
Ph2POSiMe3
[25]
Substrate
Ph2P(O)Me
Ph2POMgCl[26,27]
Ph2POϪLiϩ [28,29]
15
rac-17
19
rac-21
rac-12
16, 68 %
16, 24 %
16, 78 %
rac-18a, 68 %
no reaction[30]
decomposition[30]
no reaction[30]
rac-18a, 28 %
rac-20a, 0 %[30]
rac-22a, 7 %
no reaction[30]
rac-20a, 45 %
rac-22a, 28 %
rac-13a/rac-14a, 78 %
rac-13a/rac-14a, 0 %[30]
ture, which we cannot explain at present, is of high diagnos-
tic value.
The multiplets of the protons in the 5-position of the
other stereoisomer remain complex, even in the 31P-decou-
pled spectra, which is a situation that indicates that this
compound is the trans isomer, rac-14b. In the NOESY spec-
tra of rac-14b, the following structurally important NOEs,
summarized in Figure 5, were observed, and in addition to
those between 5-Ha and CH2-COOMe.
Scheme 3
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1
The H NMR spectra of rac-23 were analysed less rigor-
ously. They resemble, however, those of rac-13b. We assume,
therefore, that the two substituents at the five-membered
ring of rac-23 are also in a cis relation.[31]
Synthesis of β-Hydroxyphosphane Oxides rac-31 and rac-32
An array of methods exist for the formation of β-
hydroxyphosphane oxides, including the addition of lithi-
ated alkyldiphenylphosphane oxides to carbonyl com-
pounds[32] and their acylation followed by reduction of the
resulting β-oxophosphane oxides.[21,33] We tried the latter
approach first. Compound rac-13b was deprotonated with
LDA and the anion treated at Ϫ80 °C with an excess of
valeroylimidazole. After workup, we isolated only the trans
isomer rac-14b; rac-28 was not formed (Scheme 4). Sequen-
tial treatment of phosphane oxide rac-13b with LDA and
valeroyl chloride and valeraldehyde, respectively, also pro-
ved fruitless.[30] Deprotonation of rac-13b with 2 equiv. of
LDA and subsequent quenching with valeroylimidazole at
Ϫ80 °C led to the formation of the γ-substituted product,
rac-27 (24 %). Again, the recovered material (22 %) was the
trans isomer, rac-14b.
1
Figure 3. H NMR signals of CH2-5 of rac-13b (top: normal spec-
trum; bottom: 31P-decoupled spectrum)
1
The H NMR spectrum of rac-27 displays the 3-H signal
at δ ϭ 6.47 ppm, which is indicative of an α,β-unsaturated
ketone. In rac-13b, this signal appears at δ ϭ 5.55 ppm. We
tried to avoid γ attack by protecting the γ position with a
trimethylsilyl substituent. Thus, deprotonation of rac-13b
and subsequent treatment with trimethylsilyl chloride fur-
nished the silyl derivative rac-29 in 78 % yield.[34] The struc-
ture agrees well with the 1H NMR spectrum (no 4-H signal
and the signal of 2-H at δ ϭ 1.93 ppm). A trans relationship
between the trimethylsilyl unit and the acetic acid side chain
seems reasonable, but has not been proven.
1
Figure 4. H NMR signals of CH2-5 of rac-14b (top: normal spec-
trum; bottom: 31P-decoupled spectrum)
The reaction of rac-29 with LDA and valeroylimidazole
led to the formation of a multitude of reaction products,
but the desired product, rac-30, could not be detected
(Scheme 5).[30] When rac-29 was treated sequentially with
LDA and valeraldehyde, rac-13b was isolated.
It is known that the problem of α vs. γ attack in substi-
tuted allylic anions can be mastered by a sequence of two
SEЈ reactions.[35Ϫ38] Thus, following a report by Murray and
co-workers,[38] rac-13b was deprotonated with LDA in THF
at Ϫ80 °C and then dichlorotitanium diisopropoxide was
added; after keeping this mixture at Ϫ80 °C for 2 h, the
Figure 5. Selected NOE contacts of rac-13b and rac-14b (also see
text)
The NOEs again allowed us to assign the signals of 5- product was trapped with an excess of valeraldehyde.
Ha, 5-Hb, 2-H, and 3-H. Interestingly, we observed a 1-H/ This protocol led to two of the four possible (racemic)
4-H cross peak in the NOESY spectrum of rac-14b that diastereoisomeric α products, rac-31 and rac-32, in a ratio
originates from a relay process (proven by an NOE build- of 74:26 (HPLC) and a combined yield of 73 % (Scheme 6).
ing-up experiment).
The oily β-hydroxyphosphane oxides were separated by pre-
Compound rac-13b constitutes the major component iso- parative HPLC. Their spectra are in agreement with their
lated from the reaction mixture formed from rac-12 and proposed structures, but there are characteristic differences
1
lithium diphenylphosphinite. If the product ratio reflects ki- between these H NMR spectra. The chemical shift of 1-H
netic control, and if the normal anti course for formation of rac-31 is δ ϭ 3.17 ppm, but for rac-32 this signal is found
of the palladium complex is followed, the preferred forma- at δ ϭ 2.39 ppm. The signals of the olefinic protons at C-2
tion of the cis product means that the incoming diphenyl- and C-3 appear at δ ϭ 6.12/5.81 and 5.85/5.40 ppm, respec-
phosphinite behaves as a soft nucleophile attacking C-4 di- tively. The assignment of the relative configuration at C-4
rectly. On equilibration with sodium methoxide in MeOH, and the carbinol carbon atom rests on the outcome of the
rac-13b rearranged into rac-14b.
HornerϪWittig elimination; the relative configuration at C-
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Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
Scheme 4
Scheme 5
Horner؊Wittig Elimination
Compounds rac-31 and rac-32 were treated individually
1 is not relevant. If the reasonable assumption is made that
the side chain at C-1 and the titanium ligand are trans to
one another, the relative configurations of rac-31 and rac- with with KOtBu in THF. Each reaction gave a single (ra-
32 should be as indicated in the formulae. The formation of cemic) diene in a yield of 95 %. The compounds were highly
the β-hydroxyphosphane oxides may proceed as indicated in volatile and were purified by flash chromatography (FC)
Scheme 7 by (i) attack of the titanium reagent at the γ posi- using pentane/diethyl ether as eluent. The NOEDIF spectra
tion and (ii) reaction of the allylic titanium species with the of rac-10a displayed unequivocally an NOE contact be-
aldehyde via a ZimmermanϪTraxler transition state.
tween 1Ј-H and 3-H, whereas rac-7a showed weak NOE
Scheme 6
Scheme 7
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P. Welzel et al.
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signals between 1Ј-H, 5-Ha, and 5-Hb. From this infor- imide, and Steglich’s base in CH2Cl2. Similarly, esters rac-
mation, we deduced the Z configuration of rac-7a and the 35b and rac-35c were oily compounds.[30] Attempts to solve
E configuration of rac-10a and, thereby, the relative con- the structures by low-temperature X-ray crystallography re-
figurations of rac-31 and rac-32, respectively. Hydrolysis of mained unsuccessful.
esters rac-7a and rac-10a was accomplished under mild con-
ditions using barium hydroxide in MeOH at 20 °C. The
very sensitive dienecarboxylic acids formed, rac-7b and rac-
10b, respectively, were used directly in the next step.
Some Observations That May Help to Explain the
Stereochemistry of the Oxidative Cyclization
At first we wanted to identify the selenium species that
brings about the oxidative cyclization. Compound 3 was
treated with benzeneseleninic acid, benzeneseleninic per-
acid, and benzeneselenonic acid in stoichiometric amounts.
In the absence of hydrogen peroxide, benzeneseleninic acid
did not effect the oxidative cyclization, i.e., 3 was stable un-
der the reaction conditions. On the other hand, the ben-
zeneseleninic acid/hydrogen peroxide combination con-
verted 3 with high stereoselectivity into hydroxylactone 2a
when the reaction was performed in CH2Cl2 solution. Fi-
nally, benzeneselenonic acid behaved as a strong acid and
induced cyclization to lactone 2c, a compound that was pre-
viously obtained from 3 upon camphorsulfonic acid-me-
diated cyclization.[12] We conclude from these results that
benzeneseleninic peracid[42] is the species that is responsible
for the conversion of 3 into 2a. All electrophilic reagents
that attack the distal double bond of 3 lead to mixtures of
stereoisomeric 5-substituted bicyclic lactones (vide supra).
Interestingly, reaction of 3 with benzeneseleninic peracid in
a polar solvent, such as MeOH, also gives a 1:1 mixture of
2a and 2b, which indicates that the reaction follows the nor-
mal attack of the peracid onto the distal double bond lead-
ing to the two epoxides 4 that are then opened as described
Oxidative Cyclization of rac-7b and rac-10b
The oxidative cyclization was performed with H2O2 and
cat. diphenyl diselenide in CH2Cl2 solution at 0 °C, i.e., ex-
actly under the conditions used for the conversion of rac-3
into rac-2a. TLC control revealed that rac-7b and rac-10b
reacted completely stereospecifically with each giving a sin-
gle oxidation product, which, by analogy with the results
obtained for the oxidative cyclization of 3, we assume to
be rac-8 and rac-11, respectively. The constitutions of both
compounds are agree well with the spectroscopic data. The
1H NMR spectra of both compounds exhibit signals of the
1Ј-H, 6-H, and 6a-H protons in the range δ ϭ 4Ϫ6 ppm
(Table 2).
1
Table 2. Selected H NMR spectroscopic chemical shifts of 8 and
11
1Ј-H
6-H
6a-H
8
11
4.48
4.20
5.70
5.68
4.70
5.41
Unfortunately, rac-8 and rac-11 are oily compounds. We above. Thus, the mechanism as formulated in 5 (Scheme 1)
tried to obtain crystalline derivatives by ester formation seems to offer an explanation. This mechanism implies that,
with anthracene-2-carboxylic acid, 4-nitro-, and 3,5-dinitro- after electrophilic attack of a selenium species, the 5-OH
benzoic acid (Figure 6). Several simple crystalline esters are group originates from the solvent. This mechanism is, how-
known to derive from anthracene-2-carboxylic acid.[39Ϫ41] ever, not compatible with the following experiment. When
As expected, the isopropyl ester of anthracene-2-carboxylic 3 was treated with benzeneseleninic acid in CH2Cl2 in the
acid, which we prepared as a model compound, was a crys- presence of one equiv. of H2O2 and one equiv. of MeOH,
talline solid.[30] We were unable, however, to get suitable the stereoselectivity was still high, although slightly reduced
crystals from esters rac-34a and rac-35a, which we prepared (4:1 ratio). No methoxy lactone 2d[12] was detected from
from rac-8 and rac-11 by reaction with 2-anthracenecar- this experiment. Thus, it seems reasonable to assume that
boxylic acid, NЈ-(3-dimethylaminopropyl)-N-ethylcarbodi- an anhydride of type 5[43] is formed from 3 and the peracid,
Figure 6. Esters rac-34a and rac-35a
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Scheme 8
COSY): δ ϭ 0.77 (t, 3 H, 5Ј-CH3), 1.29Ϫ1.50 (m, 4 H, 4-CH2, 3Ј-
CH2), 1.42Ϫ1.58 (m, 2 H, 2Ј-CH2), 1.98 (dd, 1 H, 5-Ha), 2.27Ϫ2.43
which then undergoes a cycloaddition to give 36. A sigma-
tropic rearrangement would then lead to 37, from which 2a
is formed by hydrolysis (Scheme 8). The rearrangement of
allylic selenoxides to selenenates is, of course, well
known.[44]
In conclusion, we have found a new oxidation reaction
that converts s-trans-4,6-heptadienoic acid systems stereose-
lectively into 5-(3-hydroxypropenyl)dihydrofuran-2-one sys-
tems. We stress that this reaction is complementary to
(m, 2 H, CH2CO2CH3, AB part of an ABX system, JAB
ϭ
15.3 Hz), 2.90Ϫ3.04 (m, 2 H, 4-H and dd at 2.95, 5-Hb), 3.62 (s, 3
H, OCH3), 5.39 (dd, 1 H, 2-H), 5.84 (dd, 1 H, 1Ј-H), 6.04 (dd, 1
H, 3-H), 7.37Ϫ7.59 (m, 4 H, Ar-H), 7.71Ϫ7.88 (m, 3 H, Ar-H),
8.06Ϫ8.18 (m, 2 H, Ar-H) ppm; J2,3 ϭ 5.6 Hz; J2,4 ϭ 1.7 Hz; J3,4 ϭ
2.1 Hz; J4,5-Ha ϭ 6.2 Hz; J4,5-Hb ϭ 8.1 Hz; J5gem ϭ 14.2 Hz; J4Ј,5Ј
7.1 Hz; J1Ј,2Ј 9.6, J1Ј,2Ј 3.6 Hz. C27H29F3O6S (538.58,
538.1637). EI MS: m/z (%) ϭ 397 (23) [M Ϫ C6H5O2S]ϩ, 366 (4),
ϭ
ϭ
ϭ
Bäckvall’s palladium-mediated oxidative cyclizations of the 208 (17), 207 (100), 173 (47), 147 (29), 145 (17), 91 (16), 77 (13).
corresponding s-cis-systems.[45] We were unable to achieve
(1S*,4S*,1ЈR*)-1-[4-(Methoxycarbonylmethyl)-1-(phenylsulfonyl)-
the oxidative cyclization of 3 under the Bäckvall con-
cyclopent-2-enyl]pentyl 3-Trifluoromethylbenzoate (rac-6c): β-
ditions.[46]
Hydroxysulfone rac-6a was converted into rac-6c as described for
6d. Quantitative yield. IR (CHCl3): ν˜ ϭ 3020, 2950, 1735, 1445,
1325, 1300, 1245, 1170, 1140, 1070 cmϪ1 1H NMR (200 MHz,
.
Experimental Section
CDCl3, H,H COSY): δ ϭ 0.88 (t, 3 H, 5Ј-CH3), 1.20Ϫ1.50 (m, 4
H, 4Ј-CH2, 3Ј-CH2), 1.66Ϫ1.99 (m, 2 H, 2Ј-Ha and dd at 1.93, 5-
Ha), 2.12Ϫ2.43 (m, 3 H, 2Ј-Hb and AB part of an ABX system,
JAB ϭ 15.8 Hz, CH2CO2CH3), 2.65Ϫ2.83 (m, 1 H, 4-H), 2.94 (dd,
1 H, 5-Hb), 3.65 (s, 3 H, OCH3), 5.63 (dd, 1 H, 3-H), 5.84 (dd, 1
H, 2-H), 5.87 (dd, 1 H, 1Ј-H), 7.42Ϫ7.70 (m, 4 H, Ar-H),
Thin-layer chromatography (TLC) was carried out using pre-coated
aluminium plates (Kieselgel 60 F254, Merck) that were visualized
using a phosphomolybdateϪceric sulfate reagent.[47] Flash column
chromatography (FC) was performed on silica gel (Kieselgel 60,
Merck 40Ϫ63 µm). Melting points were determined in capillary
tubes using a Büchi (B-540) apparatus. IR spectra were determined
on an FTIR spectrometer (ATI Mattson, Genesis series). 1H and
13C NMR spectra were obtained on Varian Gemini 200, Gemini
2000, and Gemini 300 and Bruker DRX-400 and DRX-600 spec-
trometers, with CDCl3 as the solvent unless otherwise stated. The
signals of CHCl3 (δ ϭ 7.26 ppm) and CDCl3 (δ ϭ 77.16 ppm) were
used as internal references. J values are given in Hz. Signals were
assigned by means of 2D protonϪproton (COSY) and
protonϪcarbon (HMQC, HMBC) shift-correlation spectra. Mass
spectra were recorded on a VG ZAB-HSQ (VG Analytics) using 3-
nitrobenzyl alcohol as the matrix (FAB MS) and by FT ICR (MS,
7 T APEX II, Bruker-Daltonics) in a positive or negative mode
(ESI MS). Analytical HPLC was performed on a HPLC system
containing a pump PU-980 (Jasco), a multiwave UV detector MD-
910 (Jasco), and a solvent mixing system LG 980Ϫ02 (Uniflows).
Preparative HPLC was performed on an HPLC system containing
a pump PU-987 (Jasco) and a multiwave UV detector 875-UV (Ja-
sco).
7.77Ϫ7.93 (m, 3 H, Ar-H), 8.10Ϫ8.40 (m, 2 H, Ar-H) ppm; J2,3
5.9 Hz; J2,4 ϭ 1.8 Hz; J3,4 ϭ 2.2 Hz; J4,5-Ha ϭ 7.0 Hz; J4,5-Hb
8.0 Hz; J5gem ϭ 15.0 Hz; J4Ј,5Ј ϭ 7.0 Hz; J1Ј,2Ј ϭ 10.6, J1Ј,2Ј
ϭ
ϭ
ϭ
2.6 Hz. C27H29F3O6S (538.58, 538.1637), EI MS: m/z (%) ϭ 397
(21) [M Ϫ C6H5O2S]ϩ, 366 (5) [397 Ϫ OCH3], 208 (15), 207 (100),
173 (47), 147 (25), 145 (20), 91 (17), 77 (12).
(1R*,4S*,1ЈR*)-1-[4-(Methoxycarbonylmethyl)-1-(phenylsulfonyl)-
cyclopent-2-enyl]pentyl 3-Trifluoromethylbenzoate (rac-9c): rac-9a
was converted into rac-9c as described for rac-6d. Yield: quantita-
tive. IR (CHCl3): ν˜ ϭ1735, 1440, 1330, 1300, 1250, 1160, 1130
1
cmϪ1. H NMR (200 MHz, CDCl3, HH COSY): δ ϭ 0.84 (t, 3 H,
5Ј-CH3), 1.18Ϫ1.40 (m, 4 H, 4Ј-CH2, 3Ј-CH2), 1.50Ϫ1.67 (m, 2 H,
2Ј-CH2), 2.27Ϫ2.44 (m, 3 H, containing dd of 5-Ha and AB of
ABX, CH2CO2CH3), 2.82 (dd, 1 H, 5-Hb), 3.20Ϫ3.40 (m, 1 H, 4-
H), 3.71 (s, 3 H, OCH3), 5.51 (dd, 1 H, 3-H), 5.86 (dd, 1 H, 1Ј-H),
6.11 (dd, 1 H, 2-H), 7.41Ϫ7.63 (m, 4 H, Ar-H), 7.77Ϫ7.93 (m, 3
H, Ar-H), 8.08Ϫ8.21 (m, 2 H, Ar-H) ppm; J2,3 ϭ 5.9 Hz; J2,4
2.2 Hz; J3,4 ϭ 2.2 Hz; J4,5-Hb ϭ 9.2 Hz; J5gem ϭ 15.8 Hz; J4Ј,5Ј
ϭ
ϭ
6.6 Hz; J1Ј,2Ј
ϭ 8.2, J1Ј,2Ј ϭ 5.0 Hz. C27H29F3O6S (538.58,
(1S*,4S*,1ЈS*)-1-[4-(Methoxycarbonylmethyl)-1-(phenylsulfonyl)-
cyclopent-2-enyl]pentyl 3-Trifluoromethylbenzoate (rac-6d): A solu-
tion of DMAP (27.1 mg, 0.239 mmol) in pyridine (1 mL) and 3-
(trifluoromethyl)benzoyl chloride (135 µL, 0.888 mmol) were added
to a solution of β-hydroxysulfone rac-6b (81.4 mg, 0.222 mmol) in
pyridine (1 mL). The mixture was stirred at 20 °C for 19 h. Satu-
538.1637), EI MS: m/z (%) ϭ 397 (4) [M Ϫ C6H5O2S]ϩ, 381 (22),
311(12), 208 (20), 207 (100), 173 (71), 147 (33), 145 (25), 91 (28),
77 (19).
(1R*,4S*,1ЈS*)-1-[4-(Methoxycarbonylmethyl)-1-(phenylsulfonyl)-
cyclopent-2-enyl]pentyl 3-Trifluoromethylbenzoate (rac-9d): rac-9b
rated aqueous NH4Cl was added. Usual workup (CH2Cl2), solvent was converted into rac-9d as described for rac-6d. Yield: quantita-
evaporation and FC (petroleum ether/EtOAc, 7:1) provided rac-6d tive. IR (CHCl3): ν˜ ϭ 3020, 2920, 1735, 1440, 1325, 1300, 1250,
1
(118.6 mg, 99 %). IR (CHCl3): ν˜ ϭ 3020, 2970, 1735, 1445, 1325, 1160, 1130 cmϪ1. H NMR (200 MHz, CDCl3, H,H COSY): δ ϭ
1300, 1245, 1170, 1140 cmϪ1
.
1H NMR (400 MHz, CDCl3, H,H
0.87 (t, 3 H, 5Ј-CH3), 1.16Ϫ1.45 (m, 4 H, 4Ј-CH2, 3Ј-CH2),
4647
Eur. J. Org. Chem. 2003, 4640Ϫ4653
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

P. Welzel et al.
FULL PAPER
1.60Ϫ1.90 (m, 1 H, 2Ј-Ha), 1.95-2.32 (m, 4 H, containing AB of (EtOAc) provided rac-16 (0.056 g, 68 %). The spectroscopic data
ABX, CH2CO2CH3, 2Ј-Hb and dd at 2.21, 5-Ha), 2.57 (dd, 1 H, 5-
Hb), 3.10Ϫ3.30 (m, 1 H, 4-H), 3.68 (s, 3 H, OCH3), 5.77 (dd, 1 H,
3-H), 5.81 (dd, 1 H, 1Ј-H), 5.94 (dd, 1 H, 2-H), 7.41Ϫ7.60 (m, 4
H, Ar-H), 7.72Ϫ7.87 (m, 3 H, Ar-H), 8.04Ϫ8.13 (m, 2 H, Ar-H)
ppm; J2,3 ϭ 5.5 Hz; J2,4 ϭ 2.2 Hz; J3,4 ϭ 2.2 Hz; J4,5-Ha ϭ 5.9 Hz;
J4,5-Hb ϭ 8.8 Hz; J5gem ϭ 15.8 Hz; J4Ј,5Ј ϭ 6.8 Hz; J1Ј,2Ј ϭ 9.5,
(1H and 31P NMR) were in agreement with ref.[48]
Treatment of rac-12 with Methyl Diphenylphosphinite in the Pres-
ence of Cat. Pd(acac)2: The reactions were performed in dioxane,
MeCN, and MeOH solution exactly as described for the formation
of rac-16 and also in MeOH in the presence of LiCl, NaOAc, or
(Bu)4NCl. According to TLC and NMR spectra, rac-13 did not
form.
J
1Ј,2 ϭ 1.8 Hz. C27H29F3O6S (538.58, 538.1637), EI MS: m/z (%) ϭ
397 (20) [M Ϫ C6H5O2S]ϩ, 381 (14), 311 (27), 208 (93), 207 (100),
173 (59), 147 (29), 145 (20), 91 (14), 77 (14).
1-(Diphenylphosphanoyl)cyclopent-2-ene (rac-18a): Methyl di-
phenylphosphinite (0.316 mL, 1.6 mmol) and Pd(acac)2 (12 mg,
0.04 mmol) were added under Ar to a stirred solution of 2-cyclo-
pentene-1-yl acetate (17; 100 mg, 0.8 mmol) in MeOH (2 mL). The
mixture was heated at 60 °C for 24 h. After cooling to room tem-
perature, water was added. The aqueous suspension was extracted
with CH2Cl2 (3 ϫ). The combined organic fractions were dried
(Na2SO4), evaporated under reduced pressure, and then purified by
FC (CHCl3/MeOH, 9:1) to give 18a (146 mg, 68 %). M.p.: 126Ϫ128
°C (EtOAc/petroleum ether). IR (KBr): ν˜ ϭ 1714, 1436, 1170, 1116,
752 cmϪ1. 1H NMR (200 MHz, CDCl3, HMQC, HMBC): δ ϭ 2.41
(m, 4 H, 4-H, 5-H), 3.72 (m, 1 H, 1-H), 5.55 (m, 1 H, 3-H), 5.95
Reaction of rac-9c, rac-6c, rac-6d with Sodium Amalgam: a) Sodium
amalgam (2 % sodium, 76.3 mg) in MeOH (0.5 mL) was cooled to
Ϫ20 °C. A solution of rac-9c (15.2 mg, 0.028 mmol) in THF
(1.5 mL) was added and the mixture was stirred for 22 h at Ϫ20
°C and then for 8 h at 0 °C. Water was added. The usual workup
(CH2Cl2) gave a solution of a 1:1.6 mixture (determined by GC) of
the very volatile dienes rac-7b and rac-10b. b) Compound rac-6c
(101.8 mg) was treated with sodium amalgam (1.087 g) as described
above. According to GC, rac-7a and rac-10a were formed in a 1:1.7
ratio. The reaction products were purified by FC (pentane). The
spectroscopic data were obtained from this sample. c) Compound
rac-6d (118.6 mg) was treated with sodium amalgam (1.282 g) as
described above to give a 1:2.2 mixture of rac-7a and rac-10a (GC).
(m, 1 H, 2-H), 7.47 (m, 6 H, Ar-H), 7.84 (m, 4 H, Ar-H) ppm. 13
C
ϭ
4
NMR (50.3 MHz, CDCl3): δ ϭ 23.96 (C-5), 32.80 (C-4, d, JC,P
3 Hz), 46.37 (C-1, d, 1JC,P ϭ 72 Hz), 125.56 (C-2, d, 3JC,P ϭ 6 Hz),
136.14 (C-3, d, JC,P ϭ 11 Hz), 128.43Ϫ131.83 (Ar-C) ppm. 31P
2
Methyl (Z)- and (E)-(1R*)-(4-Pentylidenecyclopent-2-enyl)acetate
(rac-7a and rac-10a): C13H20O (208.30, 208.1463), GC MS: m/z
(%) ϭ 208 (33), 165 (38) [M Ϫ CH3CH2CH2]ϩ, 135 (38), 134 (45),
105 (100), 91 (53), 79 (45). 1H NMR of the E isomer (200 MHz,
CDCl3, H,H COSY, NOESY): δ ϭ 0.90 (t, 3 H, 5Ј-CH3), 1.22Ϫ1.43
(m, 4 H, 4Ј-CH2, 3Ј-CH2), 1.94Ϫ2.22 (m, 3 H, 2Ј-CH2, 5-Ha),
2.24Ϫ2.52 (m, 2 H, CH2CO2CH3, AB of ABX, JAB ഠ 15 Hz),
2.66Ϫ2.86 (m, 1 H, 5-Hb), 3.11Ϫ3.34 (m, 1 H, 1-H), 3.69 (s, 3 H,
OCH3), 5.26Ϫ5.39 (m, 1 H, 1Ј-H), 5.88 (dd, 1 H, 2-H), 6.11 (dd, 1
H, 5-H) ppm; J1,2 ϭ 2.4 Hz; J1,3 ϭ 1.8 Hz; J2,3 ϭ 5.5 Hz. NOESY
cross peak between 1Ј-H and 3-H. 1H NMR of the Z isomer
(200 MHz, CDCl3, H,H COSY, NOESY): δ ϭ 0.88 (t, 3 H, 5Ј-
CH3), 1.22Ϫ1.43 (m, 4 H, 4Ј-CH2, 3Ј-CH2), 1.94Ϫ2.22 (m, 3 H, 2Ј-
CH2 and 5-Ha), 2.24Ϫ2.52 (m, 2 H, CH2CO2CH3, AB of ABX,
JAB ഠ 15 Hz), 2.66Ϫ2.86 (m, 1 H, 5-Hb), 3.11Ϫ3.34 (m, 1 H, 1-
H), 3.68 (s, 3 H, OCH3), 5.10Ϫ5.22 (m, 1 H, 1Ј-H), 5.96Ϫ6.03 (m,
1 H, 2-H), 6.37Ϫ6.44 (m, 1 H, 3-H).
NMR (80.9 MHz, CDCl3): δ ϭ 35.15 ppm. C17H17OP (268.30,
268.1017), FAB MS: m/z ϭ 269.1 [M ϩ H]ϩ, 283.1 [M ϩ Na]ϩ.
Conversion of rac-12 into [4-(Phenylsulfonyl)cyclopent-2-enyl]acetic
Acid (rac-13c and rac-14c):
A solution of rac-12 (100 mg,
0.81 mmol) in THF (1 mL) and a solution of Pd(acac)2 (12 mg,
0.004 mmol) in THF (1 mL) were added under Ar to a suspension
of sodium benzenesulfinate (330 mg, 2.01 mmol) in THF (2 mL).
After stirring for 5 h at 60 °C, the mixture was cooled to room
temperature, and 5 % HCl was added until pH 3. The aqueous
suspension was extracted with CH2Cl2 (3 ϫ). The combined or-
ganic fractions were dried (Na2SO4), evaporated under reduced
pressure and purified by FC (petroleum ether/EtOAc, 1:2) to give
a mixture of rac-13c and rac-14c (117 mg, 55 %). 1H NMR and 13
C
NMR spectroscopic data agreed with that of ref.[49]
Conversion of 17 into 3-(Phenylsulfonyl)cyclopent-1-ene (18b): The
reaction was performed as described for rac-13c and rac-14c. FC
(petroleum ether/EtOAc, 1:2) provided 18b (55 %) as a colourless
oil. IR (KBr): ν˜ ϭ 1301, 1141 cmϪ1. 1H NMR (200 MHz, CDCl3):
δ ϭ 2.23 (m, 4 H, 4-CH2, 5-CH2), 4.26 (m, 1 H, 1-H), 5.66 (m, 1
H, 3-H), 6.09 (m, 1 H, 2-H), 7.56 (m, 3 H, Ar-H), 7.88 (m, 2 H,
Ar-H) ppm. 13C NMR, (50 MHz, CDCl3): δ ϭ 24.55 (ϩ, C-4),
31.97 (ϩ, C-5), 72.46 (Ϫ, C-1), 77.25 (ϩ, C-4), 123.82 (Ϫ, C-2),
133.64 (Ϫ, C-3), 128.98, 129.15, 131.66, 140.26 (Ar-C) ppm.
C11H12O2S (208.28, 208.0558), MS (EI): m/z (%) ϭ 208.0 (5) [Mϩ·],
143.0 (25) [PhO2Sϩ].
Pd-Mediated Conversion of Cinnamyl Acetate and Methyl Diphenyl-
phosphinite into 3-(Diphenylphosphanoyl)-1-phenylprop-1-ene (rac-
16). a) Reaction in Dioxane: Cinnamyl acetate (2.07 mL, 0.12 mol),
Pd(acac)2 (0.15 g, 0.05 mol), and methyl diphenylphosphinite
(1.15 mL, 0.10 mol) were added in that order under Ar to anhy-
drous dioxane (100 mL). The mixture was heated at 150 °C in a
pressure reactor for 22 h. The precipitate that formed was filtered
off and the solvent was evaporated. The residue was purified by
FC (EtOAc) to provide rac-16 (1.69 g, 49 %).
b) Reaction in MeCN: Cinnamyl acetate (0.095 mL, 0.57 mmol),
Pd(acac)2 (0.008 g, 0.027 mmol), and methyl diphenylphosphinite
(0.280 mL, 1.420 mmol) were added in that order and under Ar to
MeCN (10 mL). The mixture was heated at 101 °C in a pressure
reactor (Büchi mini clave) for 22 h. The precipitate that formed was
filtered off and the solvent was evaporated. FC (EtOAc) provided
rac-16 (0.096 g, 53 %).
Conversion of 21 into 4-(Phenylsulfonyl)cyclopent-2-en-1-ol (rac-
22b): The reaction was performed as described above. FC (petro-
leum ether/EtOAc, 1:2) provided rac-22b (57 %) as a colourless oil.
1
IR (KBr): ν˜ ϭ 3492, 1306, 1165, 783 cmϪ1. H NMR (200 MHz,
CDCl3, H,H COSY): δ ϭ 2.21 (m, 1 H, 5-Ha), 2.40 (m, 1 H, 5-
Hb), 4.15 (m, 1 H, 1-H), 4.71 (m, 1 H, 4-H), 5.75 (m, 1 H, 2-H),
6.36 (m, 1 H, 3-H), 7.65 (m, 3 H, Ar-H), 7.90 (m, 2 H, Ar-H).
C11H12O3S (224.27, 224.0507) MS (FAB): m/z ϭ 225.0 [M ϩ H]ϩ,
247.0 [M ϩ Na]ϩ.
c) In MeOH: Cinnamyl acetate (0.047 mL, 0.280 mmol), Pd(acac)2
(4.0 mg, 0.013 mmol) and methyl diphenylphosphinite (0.14 mL,
0.71 mmol) were added in that order under Ar to MeOH (10 mL).
The mixture was heated at 60 °C for 22 h. The precipitate that
Conversion of cis-3,5-Diacetoxycyclopent-1-ene (19) into 4-(Phenyl-
formed was filtered off and the solvent was evaporated. FC sulfonyl)cyclopent-2-ene-1-yl Acetate (rac-20b): The reaction was
4648  2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjoc.org
Eur. J. Org. Chem. 2003, 4640Ϫ4653

Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
performed as described above. FC (petroleum ether/EtOAc, 1:2)
NMR (80.96 MHz, CDCl3): δ ϭ 33.19 (75 %), 31.25 (25 %).
provided rac-20b (63 %) as a colourless oil. IR (KBr): ν˜ ϭ 3056, C17H17O3P (326.33, 326.1071). FAB MS: m/z ϭ 327.1 [M ϩ H]ϩ.
1255, 1160, 750 cmϪ1 1H NMR (200 MHz, CDCl3, H,H COSY,
.
[2-(Diphenylphosphanoyl)cyclopent-2-enyl]acetic Acid (rac-24): 1H
NMR (300 MHz, CDCl3, H,H COSY, HMQC, HMBC): δ ϭ 2.19
(m, 4 H, 5-CH2, CH2COOMe), 3.09 (m, 3 H, 4-CH2, 1-H), 3.76
(m, 1 H, 4-H), 5.39 (m, 1 H, 3-H), 7.48 (m, 6 H, Ar-H), 7.74 (m,
4 H, Ar-H) ppm. 13C NMR (50 MHz, CDCl3, APT): δ ϭ 24.31
HMQC, HMBC): δ ϭ 1.89 (s, 3 H, CH3), 2.17 (m, 1 H, 5-Ha), 2.64
(m, 1 H, 5-Hb), 4.24 (m, 1 H, 4-H), 5.54 (m, 1 H, 1-H), 6.09 (m, 2
H, 3-H, 4-H), 7.63 (m, 3 H, Ar-H), 7.86 (m, 2 H, Ar-H) ppm. 13C
NMR (50 MHz, CDCl3, APT): δ ϭ 21.00 (Ϫ, CH3), 31.03 (ϩ, C-
5), 70.43 (Ϫ, C-4), 77.52 (Ϫ, C-1), 129.83 (Ϫ, C-3), 137.00 (Ϫ, C-
2), 129.11, 129.50, 134.01, 136.89 (Ϫ, Ar-C), 170.58 (ϩ, CO) ppm.
C13H14O4S (266.31, 266.0612), MS (EI): m/z (%) ϭ 266.0 (ca. 1)
[Mϩ·], 124.9 (20) [PhOS]ϩ, 83.1 (100).
2
(ϩ, C-5), 35.33 (ϩ, CH2COOMe, d, JC,P ϭ 2 Hz), 36.73 (ϩ, C-4,
2
1
d, JC,P ϭ 2 Hz), 46.37 (Ϫ, C-1, d, JC,P ϭ 72 Hz), 123.48 (Ϫ, C-
2, d, JC,P ϭ 3 Hz), 128.83Ϫ132.21 (C-Ar), 141.83 (ϩ, C-3, d,
2JC,P ϭ 11 Hz), 171.02 (CO) ppm. 31P NMR (80.96 MHz, CDCl3):
δ ϭ 32.65 ppm. C17H17O3P (326.33, 326.1071), FAB MS: m/z ϭ
327.1 [M ϩ H]ϩ.
Pd-Mediated Reaction of Cinnamyl Acetate with Chloromagnesium
Diphenylphosphinite: Cinnamyl acetate (0.1 mL, 0.27 mmol), Pd(a-
cac)2 (8.0 mg, 0.03 mmol) and a solution of chloromagnesuim di-
phenylphosphinite (78 mg, 0.30 mmol) in THF (2 mL) was stirred
at 50 °C for 24 h under Ar. The mixture was cooled to room tem-
perature and water was added. The aqueous suspension was ex-
tracted with CH2Cl2 (3 ϫ). The combined organic fractions were
dried (Na2SO4), evaporated under reduced pressure and purified
by FC (EtOAc then EtOAc/MeOH, 6:1) to give of rac-16 (20 mg,
24 %).
(Diphenylphosphanoyl)-2-cyclopenten-4-ol (rac-22a) by Pd-Mediated
Reaction of 3,4-epoxycyclopent-1-ene (rac-21) with Lithium Di-
phenylphosphinite: A solution of freshly prepared lithium diphenyl-
phosphinite (1.2 mmol) was slowly added to a solution of rac-21
(100 mg, 1.2 mmol) and Pd(acac)2 (8.0 mg, 0.12 mmol) in THF
(2 mL) at 0 °C. The mixture was stirred for 1 h at 0°C and then for
8 h at room temperature. The mixture was acidified with 5 % HCl
and extracted with CH2Cl2. The combined organic layers were
dried and the solvent was evaporated. FC (CHCl3/EtOAc, 4:1, then
CHCl3/MeOH, 10:1) gave rac-22a (95 mg, 28 %). IR (KBr): ν˜ ϭ
Pd-Mediated Reaction of Cinnamyl Acetate with Lithium Diphenyl-
phosphinite: A mixture of cinnamyl acetate (0.20 mL, 0.57 mmol)
and Pd(acac)2 (17 mg, 0.06 mmol) in THF (2 mL) was cooled to 0
°C under Ar. A solution of freshly prepared lithium diphenylphos-
phinite (0.57 mmol) in THF was added slowly and the mixture was
then stirred for 1 h at 0 °C followed by 6 h at room temperature.
The mixture was neutralized with 5 % HCl and extracted with
CH2Cl2. The combined organic layers were dried and the solvent
was evaporated. Pure rac-16 (110 mg, 78 %) was obtained upon
crystallisation from EtOAc. M.p.: 192Ϫ193 °C (ref.[50] 193Ϫ193.5
°C)
1
3313, 1295, 1120 cmϪ1. H NMR (400 MHz, CDCl3, H,H COSY,
HMQC, HMBC): δ ϭ 2.01 (m, 1 H, 5-Ha), 2.79 (m, 1 H, 5-Hb),
5.28 (m, 1 H, 1-H), 5.47 (m, 1 H, 4-H), 6.04 (m, 2 H, 2-H, 3-H),
7.46 (m, 6 H, Ar-H), 7.91 (m, 4 H, Ar-H) ppm. 13C NMR
2
(50 MHz, CDCl3): δ ϭ 39.04 (C-5, d, JC,P ϭ 4 Hz), 77.35 (C-1),
4
77.54 (C-4, d, JC,P ϭ 6 Hz), 128.53Ϫ131.83 (Ar-C), 134.31 (C-3),
135.93 (C-2, d, 1JC,P ϭ 2 Hz) ppm. 31P NMR (80.96 MHz, CDCl3):
δ ϭ 30.95 ppm. C17H17O2P (284.29, 284.0966). FAB MS: m/z ϭ
285.1 [M ϩ H]ϩ.
Pd-Mediated Reaction of rac-21 with Chloromagnesium Diphenyl-
phosphinite: A solution of Ph2POMgCl (337 mg, 1.2 mmol) was ad-
ded to a solution of rac-21 (100 mg, 1.2 mmol) and Pd(acac)2
(8.0 mg, 0.12 mmol) in THF (2 mL). The mixture was stirred for
24 h at 50 °C. Water was added and the aqueous suspension was
extracted with CH2Cl2 (3 ϫ). The combined organic fractions were
dried, evaporated under reduced pressure and purified by FC
(EtOAc/MeOH, 6:1) to give rac-22a (26 mg, 7 %).
Pd-Mediated Reaction of 2-Cyclopentene-1-yl Acetate (rac-17) with
Chloromagnesium Diphenylphosphinite: The reaction was per-
formed as described above. FC (EtOAc/MeOH, 6:1) gave of rac-
18a (7 %).
Pd-Mediated Reaction of rac-17 with Lithium Diphenylphosphinite:
The reaction was performed as described above. FC (CHCl3/
EtOAc, 4:1, then CHCl3/MeOH, 10:1) gave rac-18a (28 %).
Pd-Mediated Reaction of rac-12 with Lithium Diphenylphosphinite:
A solution of lithium diphenylphosphinite (0.5 mmol) was added
slowly to a solution of rac-12 (58 mg, 0.5 mmol) and Pd(acac)2
(10 mg, 0.09 mmol) in THF (2 mL) at 0 °C. The mixture was stirred
for 1 h at 0 °C and then for 6 h at room temperature. The mixture
was neutralised with 1  NaOH and extracted with CH2Cl2 (3 ϫ).
The aqueous phase was acidified with 5 % HCl and again extracted
with CH2Cl2. These organic layers were dried and the solvent was
evaporated. FC (CHCl3/EtOAc, 4:1, then CHCl3/MeOH, 10:1) pro-
vided a mixture of rac-13a and rac-14a (110 mg, 67 %) and rac-24
(13 mg, 8 %) as a by-product.
4-(Diphenylphosphanoyl)-2-cyclopentene-1-yl Acetate (rac-20a) by
Pd-Mediated Reaction of 19 with Lithium Diphenylphosphinite: A
solution of freshly prepared lithium diphenylphosphinite
(0.54 mmol) was slowly added at 0 °C under Ar to a solution of
19 (100 mg, 0.54 mmol) and Pd(acac)2 (16 mg, 0.05 mmol) in THF
(2 mL). The mixture was stirred for 1 h at 0 °C and then for 8 h at
room temperature. A usual workup (CH2Cl2) followed by FC
(CHCl3/EtOAc, 4:1, then CHCl3/MeOH, 10:1) gave rac-20a
(80 mg, 45 %). IR (KBr): ν˜ ϭ 1731, 1245, 1120 cmϪ1 1H NMR
.
(400 MHz, CDCl3, H,H COSY, HMQC, HMBC): δ ϭ 2.01 (m, 1
H, 5-Ha), 2.06 (s, 3 H, CH3), 2.79 (m, 1 H, 5-Hb), 5.28 (m, 1 H, 1-
H), 5.47 (m, 1 H, 4-H), 6.04 (m, 2 H, 2-H, 3-H), 7.46 (m, 6 H, Ar-
H), 7.91 (m, 4 H, Ar-H) ppm. 13C NMR (50 MHz, CDCl3): δ ϭ
[4-(Diphenylphosphanoyl)cyclopent-2-enyl]acetic Acid (rac-13a and
rac-14a): M.p.: 178Ϫ180 °C (EtOAc/petroleum ether). IR (KBr):
2
21.25 (CH3), 39.04 (C-5, d, JC,P ϭ 4 Hz), 77.35 (C-1), 77.54 (C-4,
1
ν˜ ϭ 3365, 2954, 1737, 1257 cmϪ1. H NMR (200 MHz, CDCl3,):
4
d, JC,P ϭ 6 Hz), 128.53Ϫ131.83 (C-Ar), 134.31 (C-2), 135.93 (C-
δ ϭ 1.83 (m, 1 H, 5-Ha), 2.40 (m, 3 H, 5-Hb, CH2COOMe), 3.20
1
3, d, JC,P ϭ 2 Hz), 170.79 (CO) ppm. 31P NMR (80.96 MHz,
(m, 1 H, 1-H), 3.67 (m, 1 H, 4-H), 5.39 (m, 1 H, 3-H), 5.84 (m, 1
CDCl3): δ ϭ 30.95. C19H19O3P (326.33, 326.1071). FAB MS:
H, 2-H), 7.41 (m, 6 H, Ar-H), 7.67 (m, 4 H, Ar-H) ppm. 13C NMR
m/z ϭ 327.1 [M ϩ H]ϩ.
4
of the main isomer (50 MHz, CDCl3): δ ϭ 29.72 (C-5, d, JC,P
ϭ
3 Hz), 40.31 (CH2COOMe), 42.60 (C-1, d, 2JC,P ϭ 3 Hz), 46.17 (C- [4-(Diphenylthiophosphanoyl)cyclopent-2-enyl]acetic Acid (rac-23)
1
3
4, d, JC,P ϭ 72 Hz), 125.41 (C-2, d, JC,P ϭ 6 Hz), 139.41 (C-3, d, by Pd-Mediated Reaction of rac-12 with Lithium Diphenylthiophos-
2JC,P ϭ 11 Hz), 128.74Ϫ132.97 (C-Ar), 175.06 (CO) ppm. 31P phinite: The reaction was performed as described above. FC
Eur. J. Org. Chem. 2003, 4640Ϫ4653
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4649

P. Welzel et al.
FULL PAPER
(CHCl3/MeOH, 10:1) gave rac-23 (120 mg, 61 %). M.p.: 101Ϫ103
1 H, 5-Ha), 2.56 (m, 3 H, 2Ј-CH2, 5-Ha), 2.82 (m, 2 H,
CH2COOMe) 3.51 (m, 1 H, 1-H), 3.60 (s, 3 H, CH3), 3.84 (m, 1
1
°C (EtOAc/petroleum ether). IR (KBr): ν˜ ϭ 1764, 1706 cmϪ1. H
NMR (200 MHz, CDCl3): δ ϭ 1.90 (m, 1 H, 5-Ha), 2.45 (m, 3 H, H, 4-H), 6.47 (m, 1 H, 3-H), 7.47 (m, 6 H, Ar-H), 7.73 (m, 4 H,
5-Hb, CH2COOMe), 3.25 (m, 1 H, 1-H), 4.10 (m, 1 H, 4-H), 5.43
Ar-H) ppm. 13C NMR (50 MHz, CDCl3): δ ϭ 14.01 (C-5Ј), 22.51
1
(m, 1 H, 3-H), 5.90 (m, 1 H, 2-H), 7.45 (m, 6 H, Ar-H), 7.88 (m, (C-4Ј), 26.66 (C-3Ј), 30.68 (C-2Ј), 38.02 (C-5, d, JC,P ϭ 6 Hz),
4 H, Ar-H) ppm. 31P NMR (80.96 MHz, CDCl3): δ ϭ 48.55 ppm. 39.33 (CH2COOMe), 41.25 (C-1, d, JC,P ϭ 3 Hz), 47.64 (C-4, d,
4
C19H19O2PS (342.39, 342.0843). EI MS: m/z (%) ϭ 341.9 (40)
1JC,P ϭ 67 Hz), 51.49 (CH3), 76.30 (C-OH), 127.17 (C-2, d, 3JC,P ϭ
[Mϩ·], 234.9 (40), 218.0 (100).
6 Hz), 132.30 (C-3, d, JC,P ϭ 11 Hz), 128.83Ϫ131.49 (C-Ar),
2
173.35 (C-1Ј) ppm. 31P NMR (80.96 MHz, CDCl3): δ ϭ 29.97 ppm.
C24H27O4P (424.48, 424.1803). FAB MS: m/z ϭ 425.1 [M ϩ H]ϩ.
Esterification of rac-13a and rac-14a: A drop of thionyl chloride
was added to
a solution of rac-13a and rac-14a (220 mg,
0.68 mmol) in MeOH (5 mL). The mixture was stirred for 1 h.
Workup (CH2Cl2) and subsequent recrystallisation from EtOAc/
petroleum ether yielded solid rac-13b and, from the filtrate, rac-14b
as a colourless oil in quantitative yield.
Conversion of rac-13b into Methyl [4-(Diphenylphosphanoyl)-2-tri-
methylsilylcyclopent-3-enyl]acetate (rac-29): A solution of nBuLi
(1.6  in hexane, 0.230 mL, 0.32 mmol) and trimethylchlorosilane
(0.04 mL, 0.33 mmol) were added to a solution of rac-13b (100 mg,
0.29 mmol) cooled to Ϫ80 °C in THF (2 mL). The mixture was
warmed and water was added. Usual workup (CH2Cl2) followed
by FC (EtOAc) furnished rac-29 (93 mg, 78 %) as a colourless oil.
Methyl cis-[4-(Diphenylphosphanoyl)cyclopent-2-enyl]acetate (rac-
13b): M.p.: 124Ϫ125 °C (EtOAc/petroleum ether). IR (KBr): ν˜ ϭ
1727, 1174 cmϪ1 1H NMR (200 MHz, CDCl3, H,H COSY,
.
IR (KBr): ν˜ ϭ 2948, 1733, 1172 cmϪ1 1H NMR (400 MHz,
.
HMQC, HMBC): δ ϭ 1.79 (1 H, 5-Ha, for J values, see general
part), 2.30Ϫ2.40 (AB of ABX, JAX ϭ 7, JBX ϭ 8, JAB ϭ 16 Hz, m,
2 H, CH2COOMe), 2.45 (1 H, 5-Hb, for J values, see general part),
3.17 (m, 1 H, 1-H), 3.67 (s, OCH3), 3.75 (m, 1 H, 4-H), 5.55 (m, 1
H, 3-H), 5.86 (m, 1 H, 2-H), 7.41 (m, 6 H, Ar-H), 7.67 (m, 4 H,
Ar-H) ppm. 13C NMR (50 MHz, CDCl3): δ ϭ 29.92 (C-5, d,
CDCl3, H,H COSY, HMBC, HMQC): δ ϭ 0.00 (s, 9 H, Si-CH3),
1.93 (m, 1 H, 2-H), 2.31 (m, 3 H, 5-Ha, CH2COOMe), 2.78 (m, 2
H, 5-Hb, 1-H), 3.60 (s, 3 H, CH3), 6.35 (m, 1 H, 3-H), 7.45 (m, 6
H, Ar-H), 7.67 (m, 4 H, Ar-H) ppm. 13C NMR (APT, 75 MHz,
2
CDCl3): δ ϭ Ϫ2.87 (Ϫ, CH3-Si), 36.91 (ϩ, C-1, d, JC,P ϭ 3 Hz),
39.95 (ϩ, C-5, d, 2JC,P ϭ 2 Hz), 41.68 (ϩ, CH2COOMe), 45.10 (Ϫ,
4
2JC,P ϭ 2 Hz), 39.68 (CH2COOMe, d, JC,P ϭ 2 Hz), 42.48 (C-1,
3
C-2, d, JC,P ϭ 6 Hz), 51.38 (Ϫ, CH3), 128.29Ϫ131.62 (Ϫ, Ar-C),
2
1
d, JC,P ϭ 3 Hz), 45.03 (C-4, d, JC,P ϭ 72 Hz), 51.52 (OCH3),
149.73 (Ϫ, C-3, d, 2JC,P ϭ 11 Hz), 172.56 (ϩ, CO) ppm. 31P NMR
(80.9 MHz, CDCl3): δ ϭ 21.87 ppm. C23H29O3PSi (412.54, 412.16).
EI MS: m/z (%) ϭ 412.0 (20, [M]ϩ·), 339 (100, [M Ϫ Me3Si]ϩ).
3
2
126.25 (C-3, d, JC,P ϭ 6 Hz), 138.40 (C-2, d, JC,P ϭ 11 Hz),
128.44Ϫ131.83 (C-Ar), 173.20 (CO) ppm. 31P NMR (80.96 MHz,
CDCl3): δ ϭ 30.45. C20H21O3P (340.36, 340.1228). FAB MS:
m/z ϭ 341.1 [M ϩ H]ϩ, 363.1 [M ϩ Na]ϩ.
Treatment of rac-29 with Valeraldehyde: A freshly prepared solution
of LDA (0.23 mmol) in THF and valeraldehyde (1.17 mL,
1.1 mmol) were added to a solution of rac-29 (93 mg, 0.22 mmol)
cooled to Ϫ80 °C in THF (2 mL). The mixture was stirred 1 h at
Ϫ80 °C. Usual workup (CH2Cl2) followed by FC (EtOAc) fur-
nished rac-13b (21 mg, 23 %).
Methyl trans-[4-(Diphenylphosphanoyl)cyclopent-2-enyl]acetate (rac-
1
14b): H NMR (300 MHz, CDCl3): δ ϭ 2.34 and 2.48 (2 m, 2 H,
5-CH2), 2.62Ϫ2.80 (AB of ABX, JAX ϭ 7, JBX ϭ 8, JAB ϭ 17.0 Hz
m, 2 H, CH2COOMe), 3.17 (m, 1 H, 1-H), 3.42 (s, OCH3), 3.77
(m, 1 H, 4-H), 5.40 (m, 1 H, 3-H), 6.03 (m, 1 H, 2-H), 7.46 (m, 6
H, Ar-H), 7.78 (m, 4 H, Ar-H) ppm. 13C NMR (75 MHz, CDCl3):
Conversion of rac-13b into rac-31 and rac-32 with Valeraldehyde in
the Presence of Dichlorotitanium Diisopropoxide: A freshly prepared
solution of LDA (0.48 mmol) in THF was added slowly to a solu-
tion of rac-13b (137 mg, 0.40 mmol) in THF (2 mL) cooled to Ϫ80
°C. The mixture was stirred at Ϫ80 °C for 0.5 h and then a solution
of [Ti(iOPr)2Cl2] (0.48 mmol) in THF was added. After stirring for
2 h at Ϫ80 °C, valeraldehyde (0.128 mL, 1.206 mmol) was added.
After stirring for 1 h the mixture was slowly warmed to 20 °C.
Sat. aq. NH4ClϪKF (5 mL) was added. A usual workup (CH2Cl2)
followed by FC (EtOAc) and HPLC (EtOAc/pentane, 2:1; flow
rate: 10 mL/min) furnished rac-31 (70 mg, 52 %) and rac-32 (36 mg,
21 %) as colourless oils and the starting material rac-13b (7 mg).
2
4
δ ϭ 29.94 (C-5, d, JC,P ϭ 2 Hz), 35.72 (CH2COOMe, d, JC,P
ϭ
2
1
2 Hz), 38.63 (C-1, d, JC,P ϭ 3 Hz), 47.67 (C-4, d, JC,P ϭ 70 Hz),
3
51.38 (CH3), 126.80 (C-3, d, JC,P ϭ 6 Hz), 128.52Ϫ131.07 (C-Ar),
135.87 (C-2, d, JC,P ϭ 11 Hz), 173.21 (CO) ppm. 31P NMR
2
(80.96 MHz, CDCl3): δ ϭ 26.93. C20H21O3P (340.36, 340.1228).
FAB MS: m/z ϭ 341.1 [M ϩ H]ϩ, 363.1[M ϩ Na]ϩ.
Treatment of rac-13b with Pentanoyl-1H-imidazole: A solution of
freshly prepared LDA [Ϫ80 °C, 0.29 mmol in THF/hexane (1 mL)]
and pentanoyl-1H-imidazole (221 mg, 1.45 mmol) was added to a
solution of rac-13b (100 mg, 0.29 mmol) in THF (2 mL) cooled to
Ϫ80 °C. The mixture was stirred for 1 h at Ϫ80 °C before the cool-
ing bath was removed and sat. aq. NH4Cl was added. Usual
workup (CH2Cl2) followed by FC (EtOAc) furnished rac-14b
(53 mg, 53 %).
(1S*, 4R*, 1ЈS*)-[4-(Diphenylphosphanoyl)-4-(1-hydroxypentyl)-
cyclopent-2-enyl]acetic Acid (rac-31): IR (KBr): ν˜ ϭ 3543, 1754,
1
1227, 1116 cmϪ1. H NMR (400 MHz, CDCl3, H,H COSY): δ ϭ
Methyl [4-(Diphenylphosphonyl)-2-pentanoylcyclopent-2-enyl]acet-
0.81 (t, 3 H, CH3-5Ј), 1.21 (m, 2 H, CH2-4Ј), 1.28 (m, 3 H, CH2-
ate (rac-27) by Treatment of rac-14b with Pentanoyl-1H-imidazole 3Ј, 2Ј-Ha), 1.51 (m, 1 H, 2Ј-Hb), 1.58 and 1.92 (AB of ABX, JAX ϭ
in the Presence of 2 Equiv. of LDA: A solution of freshly prepared
LDA [Ϫ80 °C, 0.58 mmol in THF/hexane (1 mL)] and pentanoyl-
1H-imidazole (221 mg, 1.45 mmol) was added to a solution of rac-
13b (100 mg, 0.29 mmol) in THF (2 mL) at Ϫ80 °C. The mixture
was stirred and after 1 h the cooling bath was removed and sat. aq.
NH4Cl (2 mL) was added. Usual workup (CH2Cl2) followed by FC
7, JBX ϭ 8, JAB ϭ 17.0 Hz, m, 2 H, CH2COOMe), 1.52 (m, 1 H,
5-Ha), 2.26 (m, 1 H, 5-Hb), 3.17 (m, 1 H, 1-H), 3.61 (m, 3 H, CH3),
3.92 (dt, JH,H ϭ 10, JP-H ϭ 3 Hz, 1 H, 1Ј-H), 5.90 (m, 1 H, 3-H),
6.19 (m, 1 H, 2-H), 7.67 (m, 5 H, Ar-H), 7.74 (m, 2 H, Ar-H), 7.92
(m, 2 H, Ar-H) ppm. 13C NMR (50 MHz, CDCl3): δ ϭ 14.18 (C-
5Ј), 22.86 (C-4Ј), 28.51 (C-3Ј), 31.74 (C-2Ј, d, 2JC,P ϭ 9.5 Hz), 35.13
(EtOAc) furnished rac-27 (29 mg, 22 %) and rac-14b (23 mg, 22 %). (C-5, d, 2JC,P ϭ 6 Hz), 39.46 (CH2COOMe, d, 3JC,P ϭ 3 Hz), 42.74
IR (film): ν˜ ϭ 2921, 1735, 1442, 1247, 1143 cmϪ1
.
1H NMR
(C-1, d, JC,P ϭ 2 Hz), 51.73 (CH3), 61.58 (C-4), 76.05 (C-1Ј),
3
3
2
(200 MHz, CDCl3, H,H COSY, HMQC, HMBC): δ ϭ 0.88 (t, 3 129.24 (C-3, d, JC,P ϭ 7.5 Hz), 138.24 (C-3, d, JC,P ϭ 11 Hz),
H, 5Ј-CH3), 1.26 (m, 2 H, 4Ј-CH2), 1.53 (m, 2 H, 3Ј-CH2), 1.95 (m, 128.15Ϫ132.24 (C-Ar), 172.66 (CO) ppm. 31P NMR (80.96 MHz,
4650
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4640Ϫ4653

Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
CDCl3): δ ϭ 35.57 ppm. C25H31O4P (426.49, 426.1803). ESI MS:
m/z ϭ [C25H31O4P ϩ H]ϩ calcd. 427.2033, found 427.2037.
Ar), 172.54 (CO) ppm. 31P NMR (80 MHz, CDCl3): δ ϭ 29.93
ppm. C25H31O4P (426.49, 426.1803). FAB MS: m/z ϭ 427.1 [M ϩ
H]ϩ, 449.0 [M ϩ Na]ϩ.
(1S*,4R*,1ЈR*)-[4-(Diphenylphosphanoyl)-4-(1-hydroxy-
pentyl)cyclopent-2-enyl]acetic Acid (rac-32): IR (KBr): ν˜ ϭ 3543,
Methyl (Z)-(1R*)-(4-Pentylidenecyclopent-2-enyl)acetate (rac-7a):
A solution of KOtBu (9 mg, 0.07 mmol) in THF (1 mL) was added
slowly under Ar to a solution of rac-31 (26 mg, 0.06 mmol) in THF
(3 mL). The mixture was stirred for 0.5 h and then water was ad-
ded. A usual workup (Et2O) followed by FC (pentane/Et2O,1:1)
furnished rac-7a (11 mg, 95 %). 1H NMR (400 MHz, CD3OD, H,H
COSY, NOEDIF): δ ϭ 0.90 (t, 3 H, 5Ј-CH3), 1.34 (m, 4 H, 4Ј-
CH2, 3Ј-CH2), 2.14 (m, 3 H, 2Ј-CH2, 5-Ha), 2.26 and 2.39 (AB of
ABX, JAX ϭ 6, JBX ϭ 7, JAB ϭ 16 Hz, m, 2 H, CH2COOMe) 2.73
(m, 1 H, 5-Hb), 3.12 (m, 1 H, 1-H), 3.66 (s, 3 H, CH3), 5.14 (t, 1
H, 1Ј-H), 6.00 (m, 1 H, 2-H), 6.41 (m, 1 H, 3-H) ppm. C13H2O2
(208.30, 208.1463).
1
1756, 1227, 1117 cmϪ1. H NMR (400 MHz, CDCl3, H,H COSY,
HMQC, HMBC): δ ϭ 0.82 (t, 3 H, 5Ј-CH3), 1.20 (m, 2 H, 4Ј-CH2),
1.24 (m, 3 H, 3Ј-CH2, 2Ј-Ha), 1.51 (m, 1 H, 2Ј-Hb), 1.58 and 1.92
(AB of ABX, JAX ϭ 7, JBX ϭ 8, JAB ϭ 17.0 Hz, m, 2 H,
CH2COOMe), 1.52 (m, 1 H, 5-Ha), 2.24 (m, 1 H, 5-Hb), 3.17 (m,
1 H, 1-H), 3.61 (m, 3 H, CH3), 3.90 (dt, JH,H ϭ 10, JP-H ϭ 3 Hz,
1 H, 1Ј-H), 5.97 (m, 1 H, 3-H), 6.19 (m, 1 H, 2-H), 7.67 (m, 5 H,
Ar-H), 7.74 (m, 2 H, Ar-H), 7.92 (m, 2 H, Ar-H) ppm. 13C NMR
(50 MHz, CDCl3): δ ϭ 14.14 (C-5Ј), 22.67 (C-4Ј), 28.61 (C-2Ј),
32.00 (C-3Ј), 35.26 (C-5), 39.52 (CH2COOMe), 42.83 (C-1), 51.65
1
3
(CH3), 76.18 (C-1Ј, d, JC,P ϭ 32 Hz), 128.93 (C-3, d, JC,P
ϭ
2
7.5 Hz), 138.17 (C-3, d, JC,P ϭ 11 Hz), 128.15Ϫ132.24 (C-Ar),
172.60 (CO) ppm. 31P NMR (80.96 MHz, CDCl3): δ ϭ 34.51 ppm.
C25H31O4P (426.49, 426.1803). ESI MS: m/z ϭ [C25H31O4P ϩ H]ϩ
calcd. 427.2033, found 427.2037.
Methyl (E)-(1R*)-(4-Pentylidenecyclopent-2-enyl)acetate (rac-10a):
rac-32a was converted into rac-10c as described for 7a. Yield:
1
11 mg, (95 %). H NMR (300 MHz, CDCl3/CD3OD, H,H COSY,
NOEDIF): δ ϭ 0.86 (t, 3 H, 5Ј-CH3), 1.28 (m, 4 H, 4Ј-CH2, 3Ј-
CH2), 2.00 (m, 3 H, 2Ј-CH2, 5-Ha), 2.28 and 2.39 (AB of ABX,
JAX ϭ 6, JBX ϭ 7, JAB ϭ 16 Hz, m, 2 H, CH2COOMe), 2.71 (m,
1 H, 5-Hb), 3.20 (m, 1 H, 1-H), 3.66 (s, 3 H, CH3), 5.28 (t, 1 H,
1Ј-H), 5.82 (dd, 1 H, 2-H), 6.06 (dd, 1 H, 3-H) ppm. C13H2O2
(208.30, 208.1463).
Reaction of rac-13b with Valeraldehyde in the Presence of Chlorotit-
anium Triisopropoxide:
A freshly prepared solution of LDA
(0.43 mmol) in THF was added slowly to a solution of rac-13b
(450 mg, 0.40 mmol) in THF (2 mL) cooled to Ϫ80 °C. The mix-
ture was stirred at Ϫ80 °C for 0.5 h and a solution of [Ti(iOPr)3Cl]
(3.44 mL, 0.48 mmol, THF) was added. After stirring for 2 h at Saponification of rac-7a: A solution of barium hydroxide (143 mg,
Ϫ80 °C, valeraldehyde (0.13 mL, 1.2 mmol) was added. After stir-
0.52 mmol) in MeOH (1 mL) was added under Ar to a solution of
ring for 1 h, the mixture was warmed slowly to room temp. Sat. aq. rac-7a (11 mg, 0.052 mmol) in MeOH (2 mL). The mixture was
NH4ClϪKF (5 mL) was added. Usual workup (CH2Cl2) followed stirred for 3 h and then 0.1  HCl (3 mL) was added. A usual
by FC (EtOAc) and HPLC (EtOAc/pentane, 2:1; flow rate: 10 mL/
workup (Et2O) and concentration under vacuum under Ar gave the
min) furnished rac-31 (53 mg, 33 %, based on consumed rac-13b) crude product rac-7b (7.4 mg, 85 %), which was used in the next
and rac-32 (46 mg, 38 %, based on consumed rac-13b) as colourless
oils and starting material rac-13b (287 mg).
step without purification. Compound rac-10a was converted into
rac-10b as described for 7b. Yield: 80 % (7.5 mg).
(3aR*,6aS*,1ЈS*)-5-(1-Hydroxypentyl)-3,3a,4,6a-tetrahydrocyclo-
penta[b]furan-2-one (rac-8) by Oxidation of rac-7b with H2O2/Di-
phenyl Diselenide: A solution of diphenyl diselenide (1 mg, 3.8
µmol) in CH2Cl2 (1 mL) and aq. 50 % H2O2 (4 µL) were added
under Ar to a solution of rac-7b (7.5 mg, 38 µmol) in CH2Cl2
(0.5 mL) at 0 °C. The mixture was stirred at 0 °C for 4 h and then
extracted with Et2O. The organic phase was washed with aq. 5 %
NaHCO3 (2 ϫ), dried (Na2SO4), filtered, and the solvents were
evaporated. FC (EtOAc) gave rac-8 (5 mg, 61 %). 1H NMR
(400 MHz, CDCl3, H,H COSY, HMQC, HMBC): δ ϭ 0.91 (t, 3
H, CH3), 1.36 (m, 4 H, 4Ј-CH2, 3Ј-CH2), 1.84 (m, 2 H, 4Ј-CH2),
2.20 (m, 2 H, 2-Ha, 4-Ha), 2.86 (m, 2 H, 2-Hb, 4-Hb), 3.20 (m, 1
H, 3a-H), 4.48 (br. s, 1 H, 1Ј-H), 4.70 (dd, J ϭ 1, J ϭ 6 Hz, H, 6a-
H), 5.70 (m, 1 H, 6-H). C12H18O3 (210.27, 210.1255), FAB MS:
m/z ϭ 211.2 [M ϩ H]ϩ.
(1S*,4R*,1ЈR*)-[4-(Diphenylphosphanoyl)-4-(1-hydroxypentyl)-
cyclopent-2-enyl]acetic Acid (rac-31): IR (KBr): ν˜ ϭ 3543, 1754,
1227, 1116 cmϪ1 1H NMR (600 MHz, CDCl3, H,H COSY,
.
HMQC, HMBC): δ ϭ 0.81 (t, 3 H, CH3-5Ј), 1.23 (m, 6 H, 4Ј-CH2,
3Ј-CH2, 2Ј-CH2), 1.93 (m, 1 H, 5-Ha), 2.21 (m, 2 H, CH2COOMe),
2.39 (m, 2 H, 5-Hb, 1Ј-H), 3.61 (s, 3 H, CH3), 4.13 (dt, JC,H ϭ 10,
JP-H ϭ 3 Hz, 1 H, 1Ј-H), 5.47 (m, 1 H, 3-H), 5.88 (m, 1 H, 2-H),
7.44 (m, 6 H, Ar-H), 7.90 (m, 4 H, Ar-H) ppm. 13C NMR
(50 MHz, CDCl3): δ ϭ 14.14 (C-5Ј), 22.91 (C-4Ј), 28.48 (C-3Ј),
2
31.17 (C-5, d, JC,P ϭ 6 Hz), 32.22 (C-2Ј, d, 2JC,P ϭ 9.5 Hz), 39.81
(CH2COOMe, d, 3JC,P ϭ 3 Hz), 41.82 (C-1, d, 3JC,P ϭ 2 Hz), 51.63
1
(CH3), 61.60 (C-4, d, JC,P ϭ 68 Hz), 71.92 (C-1Ј), 129.91 (C-3, d,
3JC,P ϭ 7.5 Hz), 138.72 (C-3, d, 2JC,P ϭ 11 Hz), 128.15Ϫ132.24 (C-
Ar), 172.46 (CO) ppm. 31P NMR (80.96 MHz, CDCl3): δ ϭ 21.00
ppm. C25H31O4P (426.49, 426.1803). FAB MS: m/z ϭ 427.0 [M ϩ
H]ϩ, 448.7 [M ϩ Na]ϩ.
(3aR*,6aS*,1ЈR*)-5-(1-Hydroxypentyl)-3,3a,4,6a-tetrahydrocyclo-
penta[b]furan-2-one (rac-11) by Oxidation of rac-10b with H2O2/Di-
phenyl Diselenide: rac-10b was converted into rac-11 as described
for rac-8. Yield: 5 mg (61 %). 1H NMR (400 MHz, CDCl3, H,H
COSY, HMQC, HMBC): δ ϭ 0.84 (t, 3 H, CH3), 1.28 (m, 4 H, 4Ј-
CH2, 3Ј-CH2), 1.51 (m, 2 H, 4Ј-CH2), 2.28 (m, 2 H, 2-Ha, 4-Ha),
2.76 (m, 2 H, 2-Hb, 4-Hb), 3.11 (m, 1 H, 3a-H), 4.20 (t, 1 H, 1Ј-H),
5.41 (m, 1 H, 6a-H), 5.68 (m, 1 H, 6-H) ppm. 13C NMR (100 MHz,
CDCl3): δ ϭ 12.95 (C-5Ј), 21.51 (C-4Ј), 26.47 (C-3Ј), 34.07 (C-2Ј),
34.46 (C-3a), 35.15 (C-2), 37.11 (C-4), 69.90 (C-1Ј), 88.28 (C-6a),
121.94 (C-6), 158.96 (CO) ppm. C12H18O3 (210.27, 210.1255). FAB
MS: m/z ϭ 211.2 [M ϩ H]ϩ, 193.1 [C12H8O2].
(1S*,4R*,1ЈR*)-[4-(Diphenylphosphanoyl)-4-(1-hydroxypentyl)-
cyclopent-2-enyl]acetic Acid (rac-32): IR (KBr): ν˜ ϭ 3543, 1754,
1227, 1116 cmϪ1 1H NMR (300 MHz, CDCl3, H,H COSY,
.
HMQC, HMBC): δ ϭ 0.83 (t, 3 H, 5Ј-CH3), 1.18 (m, 6 H, 4Ј-CH2,
3Ј-CH2, 2Ј-Ha), 1.47 (m, 2 H, 5-Ha and probably 2Ј-Hb), 1.73 (m,
2 H, CH2COOMe), 2.71 (m, 1 H, 5-Hb), 3.14 (m, 1 H, 1-H), 3.61
(s, 3 H, CH3), 3.99 (dt, JC,H ϭ 10, JP-H ϭ 3 Hz, 1 H, 1Ј-H), 5.45
(m, 1 H, 3-H), 5.85 (m, 1 H, 2-H), 7.44 (m, 6 H, Ar-H), 7.90 (m,
4 H, Ar-H) ppm. 13C NMR (50 MHz, CDCl3): δ ϭ 14.13 (C-5Ј),
2
22.87 (C-4Ј), 28.53 (C-3Ј), 30.84 (C-2Ј), 31.74 (C-5, d, JC,P
ϭ
3
9.5 Hz), 39.24 (CH2COOMe,), 43.14 (C-1, d, JC,P ϭ 4 Hz), 51.61
3
(CH3), 61.56 (C-4, d, JC,P ϭ 72 Hz), 72.44 (C-1Ј), 129.84 (C-3, d,
Oxidative Cyclization of rac-3 with a Catalytic Amount of Diphenyl
Diselenide and Hydrogen Peroxide: A solution of diphenyl diselen-
3JC,P ϭ 7.5 Hz), 138.77 (C-2, d, 2JC,P ϭ 11 Hz), 128.15Ϫ132.24 (C-
Eur. J. Org. Chem. 2003, 4640Ϫ4653
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P. Welzel et al.
FULL PAPER
ide (3.4 mg, 0.01 mmol) in CH2Cl2 (2 mL) was added at 0 °C to a
solution of rac-3 (21.8 mg, 0.11 mmol) in CH2Cl2 (1 mL). After
slow addition of hydrogen peroxide (45 µL, 31 wt.% solution in
water), the mixture was stirred for 1 h and then warmed to room
temperature. After dilution with CH2Cl2 (5 mL), the solution was
extracted with 10 % aq. NaHCO3 (10 mL). A usual workup
(CH2Cl2) and LC (petroleum ether/EtOAc, 1:1) yielded rac-2a
(18.3 mg, 78 % yield) containing a trace of the corresponding trans-
diastereoisomer rac-2b.
[1]
[2]
[3]
For leading references, see: J. R. Vyvyan, Tetrahedron 2002,
58, 1631Ϫ1646.
B. A. Siame, Y. Weerasuriya, K. Wood, G. Ejeta, L. G. Butler,
J. Agric. Food Chem. 1993, 41, 1486Ϫ1491.
C. E. Cook, L. P. Whichward, B. Turner, M. E. Wall, G. H.
Egley, Science 1966, 154, 1189Ϫ1193; C. E. Cook, L. P. Which-
ard, M. E. Wall, G. H. Egley, P. Coggon, P. A. Luhan, A. T.
McPhail, J. Am. Chem. Soc. 1972, 94, 6198Ϫ6199.
C. Hauck, S. Mueller, H. Schildknecht, J. Plant. Physiol. 1992,
139, 474Ϫ478.
For structure and synthesis, see: K. Hirayama, K. Mori, Eur. J.
Org. Chem. 1999, 2211Ϫ2217; A. Reizelman, B. Zwanenburg,
Synthesis 2000, 1952Ϫ1955, and references cited therein.
S. Mueller, C. Hauck, H. Schildknecht, J. Plant Growth Regul.
1992, 11, 77Ϫ81.
K. Mori, J. Matsui, M. Bando, M. Kido, Y. Takeuchi, Tetra-
hedron Lett. 1998, 39, 6023Ϫ6026.
For leading references, see: P. Welzel, S. Röhrig, Z. Milkova,
Chem. Commun. 1999, 2017Ϫ2022.
A. Reizelman, M. Scheren, G. H. L. Nefkens, B. Zwanenburg,
Synthesis 2000, 1944Ϫ1951, and references cited therein.
U. Berlage, J. Schmidt, U. Peters, P. Welzel, Tetrahedron Lett.
1987, 28, 3091Ϫ3094.
U. Berlage, J. Schmidt, Z. Milkova, P. Welzel, Tetrahedron Lett.
1987, 28, 3095Ϫ3098.
[4]
[5]
Oxidative Cyclization of rac-3 with a Stoichiometric Amount of Ben-
zeneseleninic Acid and Hydrogen Peroxide in CH2Cl2: Benzeneselen-
inic acid (24.8 mg, 0.13 mmol) in CH2Cl2 (1 mL) was added to a
solution of rac-3 (26.4 mg, 0.13 mmol) in CH2Cl2 (1 mL). Hydro-
gen peroxide (13 µL, 31 wt.% solution in water) was then added
slowly at 0 °C under vigorous stirring. The mixture was stirred for
2 h. A usual workup (aq. NaHCO3 and CH2Cl2), followed by LC
(petroleum ether/EtOAc, 1:1) yielded an 8:1 mixture (determined
[6]
[7]
[8]
1
by H NMR spectroscopy) of 2a (major component) and 2b (65 %
[9]
total yield).
[10]
[11]
[12]
Oxidative Cyclization of rac-3 Acid with a Stoichiometric Amount
of Benzeneselenonic Acid in CH2Cl2: rac-3 (15.3 mg, 0.07 mmol) in
CH2Cl2 (2 mL) was added at 0 °C to benzeneselenonic acid
(16.7 mg, 0.08 mmol) as a suspension in CH2Cl2 (1 mL). Water (3
µL) was added and the mixture was stirred for 3 h. A usual workup
(CH2Cl2) and LC (petroleum ether/EtOAc, 1:1) yielded the cycliza-
tion product rac-2c (11.3 mg, 74 % yield). 1H NMR (400 MHz,
CDCl3): δ ϭ 1.06 (s, 3 H), 1.08 (s, 3 H), 1.31Ϫ1.39 (ddd, 1 H),
1.43Ϫ1.49 (ddd, 1 H), 1.58Ϫ1.74 (m, 2 H), 1.85Ϫ2.03 (m, 2 H),
2.08Ϫ2.16 (d, 1 H), 2.27Ϫ2.35 (dd, 1 H), 2.53Ϫ2.62 (dd, 1 H),
2.72Ϫ2.82 (dd, 1 H), 2.94Ϫ3.04 (m, 1 H), 5.42Ϫ5.47 (d, 1 H) ppm.
13C NMR (100.6 MHz, CDCl3): δ ϭ 19.54, 26.68, 28.03, 28.35,
32.16, 34.75, 36.49, 39.21, 42.56, 90.46, 140.21, 141.76, 177.90 ppm.
IR (CHCl3): ν˜ ϭ 1760, 1170 cmϪ1. HR MS: calcd. for C13H18O2
206.1307, found 206.1308.
K. Frischmuth, E. Samson, A. Kranz, P. Welzel, H. Meuer, W.
S. Sheldrick, Tetrahedron 1991, 47, 9793Ϫ9806.
T. Hori, K. B. Sharpless, J. Org. Chem. 1978, 43, 1689Ϫ1697.
A. Cieplak, Chem. Rev. 1999, 99, 1265Ϫ1336.
R. M. Magid, Tetrahedron 1980, 36, 1901Ϫ1930.
A. Kranz, E. Samson-Schulz, L. Hennig, P. Welzel, M. Mueller,
H. Mayer-Figge, W. Sheldrick, Tetrahedron 1996, 52,
14827Ϫ14840.
[13]
[14]
[15]
[16]
[17]
M. Julia, C. H. Du Pehnoat, Tetrahedron 1986, 42, 4807Ϫ4816,
and references cited therein.
[18] [18a]
A. G. Myers, K. R. Condorski, J. Am. Chem. Soc. 1993,
115, 7926Ϫ7927. [18b] M. Suzuki, H. Koyano, R. Hojori, J. Org.
Chem. 1987, 52, 5583Ϫ5588. [18c] S. Saito, H. Skehira, R. Kasa-
tani, M. Wotanake, T. Matsunra, J. Am. Chem. Soc. 1986,
108, 3115Ϫ3117.
Oxidative Cyclization of rac-3 with Benzeneseleninic Acid, Hydrogen
Peroxide and MeOH in CH2Cl2: Benzeneseleninic acid (23.0 mg,
0.12 mmol) in CH2Cl2 (1 mL) was added to a solution containing
rac-3 (24.9 mg, 0.12 mmol) and MeOH (5 µL) in CH2Cl2 (1 mL).
Hydrogen peroxide (12.2 µL, 31 wt.% solution in water) was added
at 0 °C and the mixture was stirred for 1 h. A usual workup (aq.
NaHCO3 and CH2Cl2) followed by LC (petroleum ether/EtOAc,
1:1) yielded a 4:1 mixture (1H NMR) of rac-2a and rac-2b (68 %
total yield), with rac-2a as the major diastereoisomer. The corre-
sponding methoxylactones (rac-2d and its diastereoisomer) were
not observed.
[19]
[20]
[21]
A. Kranz, PhD Thesis, Leipzig, 1996.
M. Julia, J. M. Paris, Tetrahedron Lett. 1973, 49, 4833Ϫ4836.
Review: J. Clayden, S. Warren, Angew. Chem. 1996, 108,
261Ϫ291, Angew. Chem. Int. Ed. Engl. 1996, 35, 241Ϫ270.
T. Boesen, N. Feeder, M. D. Eastgate, D. J. Fox, J. A. Medlock,
C. R. Tyzak, S. Warren, J. Chem. Soc., Perkin Trans. 1 2001,
118Ϫ126, and references cited therein.
R. Malet, M. Moreno-Man˜as, P. Pleixats, Synth. Commun.
1992, 22, 2219Ϫ2228.
B. Bildstein, F. Sladky, Phosphorus, Sulfur, Silicon Relat. Elem.
1990, 47, 341Ϫ347.
N. A. Bondarenko, E. N. Tsvetkov, J. Gen. Chem. USSR (Engl.
Transl.) 1989, 59, 1361Ϫ1364.
L. Horner, P. Beck, V. G. Toscano, Chem. Ber. 1961, 94,
1317Ϫ1322.
P. F. Cann, S. Warren, M. R. Williams, J. Chem. Soc., Perkin
Trans. 1 1972, 2377Ϫ2382.
Y. Miyamoto, M. Yamashita, T. Oshikawa, Bull. Chem. Soc.
Jpn. 1992, 65, 2004Ϫ2006.
A. Schmidpeter, G. Burget, H. G. von Schnering, D. Weber,
Angew. Chem. 1984, 96, 795Ϫ796, Angew. Chem. Int. Ed. Engl.
1984, 23, 817Ϫ818.
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
Oxidative Cyclization of rac-3 with Benzeneseleninic Acid, Hydrogen
Peroxide in MeOH: A mixture of benzeneseleninic acid (20.9 mg,
0.11 mmol), rac-3 (22.6 mg, 0.11 mmol), and hydrogen peroxide
(11.1 µL, 31 wt.% solution in water) in MeOH (1 mL) was stirred
for 1 h at 0 °C. Usual workup (aq. NaHCO3 and CH2Cl2) followed
by LC (petroleum ether/EtOAc, 1:1) yielded a 1.2:1 mixture (1H
NMR) of rac-2a and rac-2b (35 % total yield). The methoxylactone
2d and its stereoisomer were not observed.
[30]
[31]
A. Galkina, PhD Thesis, Leipzig, 2002.
See: J. C. Fiaud, J. Y. Legros, J. Org. Chem. 1987, 52,
1907Ϫ1911, and references cited therein.
D. R. Armstrong, D. Barr, M. G. Davidson, G. Hutton, P.
O’Brien, R. Snaith, S. Warren, J. Organomet. Chem. 1997, 529,
29Ϫ33, and references cited therein.
Acknowledgments
We wish to thank Prof. S. Berger for recording the NOE spectra of
13b. Financial support by the Deutsche Forschungsgemeinschaft
(Graduiertenkolleg ‘‘Mechanistische und Anwendungsaspekte
nichtkonventioneller Oxidationsreaktionen’’) and the Fonds der
Chemischen Industrie is gratefully acknowledged.
[32]
[33] [33a]
J. Elliott, D. Hall, S. Warren, Tetrahedron Lett. 1989, 30,
4652
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www.eurjoc.org Eur. J. Org. Chem. 2003, 4640Ϫ4653

Studies on an Oxidative 1,4-Addition to s-trans-1,3-Dienes
FULL PAPER
L. Syper, J. Mlochowski, Tetrahedron 1987, 43, 207Ϫ213; J.
Mlochowski, Phosphorus, Sulfur, Silicon Relat. Elem. 1998,
136, 137, 138, 191Ϫ204.
It has been demonstrated that benzeneperoxyselenicic acid re-
acts readily with a nucleophile (water); see ref.[42]
For leading references, see: M. Koprowski, E. Krawczyk, A.
Skowronska, M. McPartlin, N. Choi, S. Radojevic, Tetrahedron
2001, 57, 1105Ϫ1118.
J. E. Bäckvall, Pure Appl. Chem. 1996, 68, 535Ϫ539, and refer-
ences cited therein.
[33b]
[42]
601Ϫ604.
A. D. Buss, S. Warren, J. Chem. Soc., Perkin
Trans. 1 1985, 2307Ϫ2326. [33c] A. Nelson, S. Warren, J. Chem.
Soc., Perkin Trans. 1 1999, 14, 1963Ϫ1982. [33d] M. Beckmann,
H. Hildebrandt, E. Winterfeldt, Tetrahedron: Asymmetry 1990,
1, 335Ϫ345.
[43]
[44]
[34]
M. D. Ironside, A. W. Murray, Tetrahedron Lett. 1989, 30,
1691Ϫ1694.
[35]
[36]
J. A. Marschall, Chem. Rev. 1996, 96, 31Ϫ35.
J. S. Corey, T. S. Coulter, T. J. Hallet, R. J. Maguire, A. H.
McNeil, S. J. Stanway, A. Teerawutgulrad, P. J. Thomas, Pure
Appl. Chem. 1996, 68, 707Ϫ710.
D. Behnke, S. Hamm, L. Henning, P. Welzel, Tetrahedron Lett.
1997, 38, 7059Ϫ7062.
E. F. Birse, A. McKenzie, A. W. Murray, J. Chem. Soc., Perkin
Trans. 1 1998, 1038Ϫ1042.
J. L. Ferrari, I. M. Hursberger, H. S. Gutowsky, J. Am. Chem.
Soc. 1965, 87, 1247Ϫ1251.
[45]
[46]
[47]
[48]
[49]
[50]
E. Samson-Schulz, PhD Thesis, Universite Claude Bernard Ϫ
Lyon I, 1992.
D. Kritchevsky, M. R. Kirk, Arch. Biochem. Biophys. 1952,
35, 346Ϫ351.
[37]
[38]
[39]
A. Nelson, S. Warren, J. Chem. Soc., Perkin Trans. 1 1997,
2645Ϫ2658.
V. K. Aggarwal, N. Monteiro, G. Tarver, R. McCague, J. Org.
Chem. 1997, 62, 4665Ϫ4671.
T. Savage, J. Chem. Soc., C 1966, 1842Ϫ1844.
Received November 29, 2002
[40]
[41]
A. Sonoda, Bull. Chem. Soc. Jpn. 1962, 35, 853Ϫ856.
A. P. Schaap, P. A. Burns, K. A. Zaklika, J. Am. Chem. Soc.
1977, 99, 1270Ϫ1272.
Eur. J. Org. Chem. 2003, 4640Ϫ4653
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4653