Preparation and oxidation of α-phenylselanyl esters

Article abstract of DOI:10.1016/S0040-4020(00)00647-5

Alkylation and selenenylation of selenium-stabilized ester enolates have allowed the preparation of α-phenylselanyl esters 5, 7, 8 and of α,α-bis(phenylselanyl)esters 6, respectively. The competitive selenophilic reaction, leading to an allylic phenylselenide 9, was avoided in the presence of HMPA. α-phenylselanyl α,β-unsaturated esters 15 were prepared by oxidation of compounds 6 and dehydrohalogenation of β-chloroesters 17. Some other transformations: oxidation, transesterification and Grignard reaction were also studied. H₂O₂ oxidation of Z-esters 15 has led to stable E-α-seleninyl esters 20. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00647-5

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 7483–7493
Preparation and Oxidation of a-Phenylselanyl Esters
*
Loic Lebarillier, Francis Outurquin and Claude Paulmier
`
´ ´
´
Laboratoire de Synthese Thio- et Seleno-organique, IRCOF-Universite de Rouen, F-76821 Mont Saint Aignan Cedex, France
Received 7 April 2000; revised 13 July 2000; accepted 25 July 2000
Abstract—Alkylation and selenenylation of selenium-stabilized ester enolates have allowed the preparation of a-phenylselanyl esters 5, 7, 8
and of a,a-bis(phenylselanyl)esters 6, respectively. The competitive selenophilic reaction, leading to an allylic phenylselenide 9, was
avoided in the presence of HMPA. a-phenylselanyl a,b-unsaturated esters 15 were prepared by oxidation of compounds 6 and dehydro-
halogenation of b-chloroesters 17. Some other transformations: oxidation, transesterification and Grignard reaction were also studied. H2O2
oxidation of Z-esters 15 has led to stable E-a-seleninyl esters 20. ᭧ 2000 Elsevier Science Ltd. All rights reserved.
The selenium methodology has now an increasing place in
organic synthesis.1–7 a-Phenylselanyl carbonyl compounds
are important bifunctional selenium synthons. a-Phenyl-
selanyl aldehydes and ketones have been extensively
studied in our laboratory.8 We have recently explored the
synthetic utility of b-phenylselanyl a-oxoesters as pre-
cursors of 2-halo, 2-amino and 2-hydroxy 3-alkylidene-
succinates9 and alkyl aziridine-2-carboxylates.10 The use
of selenium stabilized enolates, formed by a-deprotonation
of a-selanyl carbonyl compounds, is often complicated by
competitive nucleophilic attacks on the selenium atom lead-
ing to mixture of selenenylated products.6 We were able,
however, to prepare b-phenylselanyl enoxysilanes derived
from a-phenylselanyl aldehydes and ketones and to study
their reactivity.11 As a continuation of this work, we were
interested with the reactivity of a-phenylselanyl esters. Four
methods of preparation were proposed more than twenty
years ago but the synthetic use of these esters was not
extensively studied.
The two principal routes involve selenenylation of ester
enolates1,12–15 and reaction of a phenylselenolate anion
with a-haloesters.12 Alkylation of a-phenylselanylester
enolates constitutes a third way.12 The last method concerns
the reaction of a selenium stabilized carbanion with an alkyl
chloroformate.15 In this paper, we present our observations
concerning the methods involving enolates for the prepara-
tion of the a-phenylselanyl esters 2, 5, 7 (Scheme 1) and 8
Scheme 1. (i) LDA, THF, Ϫ78ЊC, PhSeCl. (ii) PhSeSePh, EtOH, NaBH4, 0ЊC. (iii) KH, THF, R2X (XˆI, Br), HMPA, 0ЊC. (iv) LDA, THF, Ϫ78ЊC, PhSeCl.
(v) KH (2 equiv.), THF, Ϫ35ЊC, PhCH2Br (3 equiv.), HMPA, 0ЊC.
1
Keywords: a-phenylselanyl esters; a-b-unsaturated a-phenylselanyl esters; selenoxides; H NMR; 13C NMR.
* Corresponding author. Tel.: ϩ2-35-52-29-50; fax: ϩ2-35-52-29-59; e-mail: claude.paulmier@univ-rouen.fr
0040–4020/00/$ - see front matter ᭧ 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00647-5

7484
L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
Scheme 2. (i) KH, THF, Ϫ35ЊC; Allyl bromide, HMPA, Ϫ35ЊC. (ii) LDA, THF, Ϫ78ЊC; Allyl bromide or methallyl chloride, HMPA, 0ЊC. (iii) KH, THF,
Ϫ35ЊC, allyl bromide (2 equiv.). 8a/10:84/16. (iv) H2O2, pyridine, CHCl3, 0ЊC.
(Scheme 2) and a,a-bis(phenylselanyl)esters 6. Two new
routes for the preparation of a-phenylselanyl-a,b-unsatu-
rated esters 15, and some reactions carried out on these
esters, are also described. The following paper will be
devoted to the formation of dichloro-adducts and to the
synthesis of chloroesters.16
PhSeCl (1 equiv.).12–14 The use of PhSeBr has led to
comparable results. No trace of a,a-bis(phenylselanyl)ester
6 was observed with an excess of base. An important
dilution was needed to minimize a competitive Claisen
condensation. Esters 2a–2i were prepared in good yields
(Table 1, entries 1, 3, 5, 7, 9–13). The sodium phenyl-
selenolate treatment of a-haloesters 3 in ethanol has led to
esters 2 with excellent yields12 (Method B, Table 1, entries
2, 4, 6, 8). The use of borane complexed selenolate anions,
even in excess, avoids a partial deselenenylation which was
observed with free selenolate species.6,20 The non-enolis-
able a-phenylselanyl esters 5a and 5b were prepared by
method A (Table 1, entries 14 and 16) but could also be
synthetized by alkylation of the corresponding a-selanyl
enolate resulting from KH treatment of a-selanyl esters 2
in the presence of HMPA (Method C, Table 1, entries 15,
17–19). On the contrary to ketones,6,11 the cleavage of the
PhSe group, through a selenophilic attack by the enolate
anion was not observed.14 A double alkylation occurred
during benzylation of ester 2a, with formation of ester 7
The preparation of saturated and unsaturated a-selanyl
esters was carried out with the goal to study some addition
and cyclization reactions involving carbon centered radicals
resulting from C–Se bond cleavage and Diels–Alder
cycloadditions carried out with the functionalyzed vinylic
selenides 15 and selenoxides 20. Another objective of this
work was to find the best method allowing the synthesis of
optically active a-phenylselanyl aldehydes and ketones
from chiral a-phenylselanyl esters.17–19
a-Phenylselanyl esters 2 were essentially prepared by
method A (Scheme 1). The enolates, formed by LDA treat-
ment of esters 1, in THF at Ϫ78ЊC, were treated with
Table 1. a-Phenylselanyl esters 2, 5 and a,a-bis(phenylselanyl)esters 6
Entry
Esters 2 and 5
Method
Yield (%)
Esters 6
Yield (%)
No.
R1
R2
No.
1
2
3
4
5
6
7
8
2a
2a
2b
2b
2c
2c
2d
2d
2e
2f
2g
2h
2i
5a
5a
5b
5b
5c
5d
H
H
Me
Me
Et
Et
nPr
nPr
nBu
iPr
Ph
c-C6H11
H
H
H
H
H
H
H
H
H
H
H
H
A
79
87
84
93
76
96
78
95
74
76
60
75
68
78
91
72
71
90
87
6a
57
B (XˆCl)
A
B (XˆCl)
A
6c
96
B (XˆBr)
A
B (XˆBr)
9
A
6e
6f
6g
6h
89
68
40
75
10
11
12
13
14
15
16
17
18
19
A
A
A
A
c-C6H11–CH2
H
Me
Me
Me
Me
Et
Me
Me
Et
Et
Bn
Bn
A
C (XˆI)
A
C (XˆI)
C (XˆBr)
C (XˆBr)
nBu

L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
Table 2. a-Phenylselanyl g,d-unsaturated esters 8 and oxidation products 11 and 12
7485
Entry
No.
R1
R
Method
Yield (%)
Oxidation products
Yield (%)
11/12
1
2
3
4
5
6
7
8
8a
8b
8b
8c
8d
8e
8f
H
H
H
H
H
H
H
H
H
H
H
H
Me
Me
Me
Me
D
C
D
C
C
C
C
D
C
D
C
D
C
D
C
96a
82
75
75
76
76
70
68
81
72
85
75
85
67
72
92
11a
11b/12a:78/22
Me
Me
Et
nPr
nBu
iPr
iPr
Ph
Ph
c-C6H11
H
81b
84
71
11c
11d
8f
9
8g
8g
8h
8i
8j
8j
10
11
12
13
14
15
Me
Me
nBu
80b
11j/12b:37/63
8k
a Two equivalents of LDA were used.
b Overall yield.
(89% yield), when base and benzyl bromide were used in
excess (Scheme 1).
the a position, however, the corresponding a-methylenic
ester 12 was also formed (Scheme 2, Reaction 3; Table 2,
entries 1, 2, 5, 9, 13). The chromatographic separation of
11b from 12a and of 11j from 12b was unsuccessful. It must
be noticed that the deconjugated dienic ester 12 (entry 5,
R1ˆnPr) was not formed when another alkyl substituent was
present on the a carbon in the place of the methyl group.
Selenylation of the selenium-stabilized enolates derived
from esters 2 was also achieved with success. a,a-Bis-
(phenylselanyl)esters 6 were prepared in good yields except
6g (R1ˆPh, Table 1, entry 11). The first member 6a of this
new family of a-oxoester selenoacetals was previously
prepared by selenenylation of ethyl diazoacetate.21,22
Two other reactions were carried out on a-phenylselanyl
esters 2 (Scheme 3). Transesterification into allyl esters 13
was achieved through a probable O-allylation of the inter-
mediate selenium-stabilized enolate. Allyl esters 13c
(R1ˆEt), 13d (R1ˆnPr), 13e (R1ˆnBu) and 13f (R1ˆiPr)
were prepared with correct yields. Grignard reaction using
allylmagnesium chloride provided the dienols 14a, 14b, 14c
in good yields. (73–85%). In this reaction, no trace of
deselenenylated products was observed.
Allylation of the selenium-stabilized enolates derived from
esters 2 was especially studied (Scheme 2 and Table 2).
Method C (KH, allyl bromide, THF, HMPA) afforded the
expected a-phenylselanyl g-unsaturated esters 8 but trace
amount of allyl phenylselenide 9 (RˆH) was also observed
as for the allylation of selenium-stabilized ketone eno-
lates.11b The formation of this by-product is a consequence
of a competitive alkylation of the selenium atom.23 The
amount of selenide 9a (RˆH) increased in the absence of
HMPA and 9b (RˆMe) was formed when methallyl
chloride was used as reagent. Allylation of lithium enolates
has also allowed the preparation of esters 8 without forma-
tion of 9 (Method D). Starting from 2a, the bis-allylated
ester 10 did not appear besides 8a, even in the presence of
two molar equivalents of LDA (Table 2, entry 1), but was
formed in a minor amount (8a/10:84/16) using method C
(Scheme 2, Reaction 2).
After several experiments with various oxidizing agents,
we have found that sodium periodate treatment of the
a,a-bis(phenylselanyl)esters 6 afforded the a-phenyl-
selanyl-a,b-unsaturated esters 15 in very good yields
without overoxidation into selenoxides 20 (Scheme 4 and
Table 3, entries 1, 6, 11 and 12, Method E). The esters 15a
and 15b (R0ˆH) were isolated as mixture of isomers (15a:
Z/Eˆ85/15; 15b: Z/Eˆ86/14). This reaction constitutes a
new preparative method for this class of compounds. The
first published one involves conjugated LDA addition to
a,b-unsaturated esters, reaction of the intermediate enolate
with PhSeBr and diisopropylamine elimination.24 It was
more recently observed that PhSeCl adds stereospecifically
to unsaturated esters with formation of b-chloro a-phenyl-
Methods C and D were equally effective for the preparation
of the g-unsaturated esters 8. These esters were then
oxidized by H2O2 in the presence of pyridine and 2,4-dienic
esters 11 were isolated. When a methyl group was present at
Scheme 3. (i) NaH, EtOH, THF, D; Allyl bromide, D. (ii) Allylmagnesium chloride (2.2 equiv.), THF, Ϫ78ЊC.

7486
L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
Scheme 4. (i) NaIO4, NaHCO3, EtOH, H2O, 0ЊC!RT (Method E). (ii) PhSeCl, ZnCl2, CH2Cl2, RT. (iii) Et3N, benzene reflux, 5 h (Method F). (iv) K2CO3,
acetone reflux, 6 h (Method G). v) DBU, THF, RT, 20 h (Method H). (vi) H2O2, pyridine, CHCl3, 0ЊC!RT.
selanyl esters as thermodynamic addition products.25,26
With ZnCl2 activation,26 we have prepared esters 17 (anti
or erythro) from E-esters 16, probably through the sele-
niranium intermediate A (Scheme 4). Compounds 17a
(RˆMe), 17b (RˆnPr) and 17c (RˆiPr) were isolated in
84–94% yields. Ethyl cinnamate, however, has led to ethyl
2,3-dichloro-3-phenylpropanoate 18 and ethyl cyclohexyl-
idenepropenoate to ethyl (2-chlorocyclohexylidene)pro-
penoate 19. These results could be explained by a
selenophilic reaction between the adduct 17 and PhSeCl.16
(K2CO3, acetone reflux) provided the E isomer as the
major product (Table 3, entries 4 and 8). Finally, HCl
elimination was achieved by DBU treatment of esters 17a
and 17c in THF at room temperature (Method H). Esters 15a
(Z) and 15c (Z) were isolated in good yields (Table 3, entries
5 and 10). These results show that the two-step sequence:
PhSeCl addition–HCl elimination, on a,b-unsaturated
esters, is also an efficient route to a-phenylselanyl a,b-un-
saturated esters 15 (R0ˆH). The two methods disclosed
here complete those described: reaction of an alkyl chloro-
formate with a-selanylvinyllithiums,27 treatment of
a-diazoesters with benzeneselenenyl iodide,28 condensation
of aldehydes with ethyl bromo(phenylselanyl)acetate29 and
Wittig-type reaction of a-selanylarsonium ylides with
aldehydes.30 Another method, involving dehydrochlorina-
tion of a-chloro-a-phenylselanyl esters was found efficient
for the synthesis of esters 15.16
Dehydrochlorination of b-chloroesters 17 was achieved by
three different ways (Scheme 4, Table 3). Z-Esters 15
(R0ˆH) were obtained by method F, after a prolonged heat-
ing in benzene in the presence of Et3N. The formation of the
kinetic E-ester was observed when the reaction was stopped
after 3 h (15a, Z/Eˆ94/6, Table 3, entry 2). Method G
Table 3. a-Phenylselanyl a,b-unsaturated esters 15 and selenoxides 20
Entry
Substrate
R
Method
Product
Selenoxide 20 (Z)
Yield (%)
74
No.
R0
No.
Yield (%)
Z/E
1
2
3
4
5
6
7
8
6c
17a
17a
17a
17a
6e
17b
17b
17c
17c
6f
Me
Me
Me
Me
Me
nPr
nPr
nPr
iPr
iPr
Me
–(CH2)5–
H
E
F
F
G
H
E
F
G
F
15a
15a
15a
15a
15a
15b
15b
15b
15c
15c
15d
15e
85
83
91
92
91
87
80
94
80
84
82
80
85/15
94/6a
100/0
0/100
100/0
86/14
100/0
10/90
100/0
100/0
–
20a
H
H
H
H
H
H
H
H
H
Me
20b
20c
72
68
9
10
11
12
H
E
E
b
6h
–
a The reaction was stopped after 3 h.
b Unidentified products.

L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
7487
H2O2 oxidation of Z-a-phenylselanyl esters 15 (R0ˆH), in
Preparation of a-phenylselanyl esters 2
the presence of pyridine, has provided the vinylselenoxides
20 (E) isolated in a pure form. A partial decomposition,
however, occurred during the chromatographic purification.
Method A: A solution of iPr2NH (1.11 g, 11 mmol) in
anhydrous THF (20 ml), under argon, was treated with
BuLi (4.4 ml, 11 mmol, 2.5 M in hexane) at 0ЊC for
15 min. Ester 1 (10 mmol) in THF was then added at
Ϫ78ЊC. After 20 min at this temperature, a solution of
PhSeBr (11 mmol) in THF (4 ml) was added quickly. The
mixture was stirred for 15 min at Ϫ78ЊC then quenched with
sat. aq. NH4Cl solution (10 ml) and diluted with ether
(50 ml). The organic layer was washed with water
(3×10 ml), dried, filtered and evaporated to give a crude
product distilled or chromatographed on silica gel (light
petroleum/ethyl acetate:5/1).
1
Examination of the H NMR of 15a (Z) and of the corre-
sponding selenoxide 20a (dH3ˆ7.43 ppm for 15a and
dH3ˆ7.29 ppm for 20a) led us to assign the E stereo-
chemistry for 20a. The isomerisation could be attributed
to a reversible conjugated addition of pyridine. The same
E stereoisomer was also obtained, using the same experi-
mental conditions, from the kinetic unsaturated a-phenyl-
selanyl ester 15a (E)16 (85% yield). As shown in Table 3,
20b (E) and 20c (E) were prepared from 15b (Z) and 15c (Z)
respectively. NaIO4 oxidation of 15a (Z) was unsuccessful
and a partial oxidation was observed using mCPBA in
CH2Cl2. Ethyl cyclohexylidenepropenoate 15e (R0±H) has
led to a complex mixture which was not studied further. Our
unexpected results revealed that the E isomers of 20 (R0ˆH)
can only be isolated.
Method B:12 To a solution of diphenyldiselenide (5 g,
32 mmol) in EtOH (100 ml), NaBH4 (3 g, 32 mmol) was
added with ice-cooling. A solution of ethyl 2-haloester 3
(30 mmol) in EtOH (50 ml) was then introduced. The
mixture was stirred at 0ЊC for 1 h and warmed to room
temperature. Water (200 ml) and diethyl ether (500 ml)
were added. The organic layer was separated, washed with
water (2×50 ml), dried, filtered and concentrated. The crude
oil was purified by silica gel chromatography as above.
Finally, we have checked that esters 15 reacted with allyl-
magnesium chloride (2 equiv.) under the same experimental
conditions that those used for esters 2. Phenylselanyl
trienols 21 were prepared in 63–68% yields.
Ethyl phenylselanylacetate 2a.13 (79% yield, method A;
87% yield, method B). H NMR d: 7.54–7.60 (2H, m),
In conclusion, we have determined the better experimental
conditions for the synthesis of a-alkyl a-phenylselanyl
esters 5, 7, 8 and a,a-bis(phenylselanyl)esters 6, respec-
tively, achieved by alkylation and selenenylation of
a-selanyl esters enolates. The competitive formation
of allylic phenylselenide 9 was avoided during allylation
of lithium enolates (Method D) and was reduced by addition
of HMPA when potassium enolates were involved (Method
C). NaIO4 oxidation of esters 6 constitutes a new method for
the synthesis of a-phenylselanyl-a,b-unsaturated esters 15.
Z-Esters 15 were oxidized into stable E-a-seleninyl esters
20 by H2O2 treatment in the presence of pyridine. Trans-
esterification of esters 2 into allyl esters 13 and Grignard
reaction achieved on esters 2 and 15 have allowed access to
the selenenylated dienols 14 and trienols 21, respectively.
1
7.26 (3H, m), 4.09 (2H, q, Jˆ7.0 Hz), 3.48 (2H, s), 1.17
(3H, t, Jˆ7.0 Hz).
Ethyl 2-phenylselanylpropanoate 2b.13 (84% yield,
1
method A; 93% yield, method B). H NMR d: 7.54–7.61
(2H, m), 7.22–7.32 (3H, m), 4.06 (2H, q, Jˆ7.0 Hz), 3.74
(1H, q, Jˆ7.1 Hz), 1.51 (2H, d, Jˆ7.1 Hz), 1.14 (3H, t,
Jˆ7.0 Hz).
Ethyl 2-phenylselanylbutanoate 2c. (76% yield, method
1
A; 96% yield method B). H NMR d: 7.54–7.60 (2H, m),
7.22–7.29 (3H, m), 4.06 (2H, q, Jˆ7.2 Hz), 3.50 (1H, m),
1.65–2.02 (2H, m), 1.13 (2H, t, Jˆ7.2 Hz), 0.93 (3H, t,
Jˆ7.3 Hz). 13C NMR d: 172.7, 135.5, 128.8, 128.2, 127.9,
60.7, 45.3, 25.1, 13.9, 12.6. IR (cmϪ1): 1740, 1578. Anal.
Calcd for C12H16O2Se: C, 53.14; H, 5.95. Found: C, 53.23;
H, 6.13.
Experimental
Esters 1, 3, 4 and 16 are commercial compounds except 16c
(E) and 16h prepared by Wittig–Horner reaction using
triethyl phosphonoacetate, butyllithium and isobutanal or
cyclohexanone in 66 and 70% yields respectively. Solvents
and eluents were distilled before use. THF was freshly
distilled from sodium-benzophenone under argon and light
petroleum refers to the fraction with bp 40–60ЊC. GC/mass
spectrometry analysis was performed on a Hewlett–Packard
HP5890 with an HP-1 capillary column (25 m, 0.22 mm, He
carrier gas) at 70 eV. 1H and 13C NMR spectra were
recorded in CDCl3 on a Brucker AC200 spectrometer. Infra-
red spectra were performed on Beckman Acculab 9 and
Perkin–Elmer FTIR 1600 spectrometers. C, H Micro-
analysis was determined with a Carlo–Erba 1106 analyser.
The Z and E-stereochemistry of esters 15 was assigned by
comparison of the chemical shift values of the vinylic
proton (15a Z: dH3ˆ7.43 ppm; 15a E: dH3ˆ6.33 ppm)
with those given in the literature.29
Ethyl 2-phenylselanylpentanoate 2d. (95% yield, method
B). 1H NMR d: 7.54–7.60 (2H, m), 7.22–7.30 (3H, m), 4.05
(2H, q, Jˆ7.0 Hz), 3.57 (1H, m), 1.80 (2H, m), 1.38 (2H,
m), 1.13 (3H, t, Jˆ7.0 Hz), 0.88 (3H, t, Jˆ7.0 Hz). 13C
NMR d: 172.4, 135.0, 128.4, 127.8, 127.6, 60.2, 42.8,
33.4, 20.9, 13.5, 13.1. IR (cmϪ1): 1740, 1578. Anal. Calcd
for C13H18O2Se: C, 54.74; H, 6.36. Found: C, 54.70; H, 6.34.
Ethyl 2-phenylselanylhexanoate 2e. (74% yield, method
A). 1H NMR d: 7.54–7.60 (2H, m), 7.22–7.30 (3H, m), 4.05
(2H, q, Jˆ7.2 Hz), 3.57 (1H, dd, Jˆ6.6, 8.7 Hz), 1.63–2.00
(2H, m), 1.15–1.45 (4H, m), 1.13 (3H, t, Jˆ7.2 Hz), 0.85
(3H, t, Jˆ6.8 Hz). 13C NMR d: 172.9, 135.5, 128.9, 128.4,
127.8, 60.8, 43.7, 31.5, 30.3, 22.2, 14.0, 13.9. IR (cmϪ1):
1727, 1578. Anal. Calcd for C14H20O2Se: C, 56.19; H, 6.74.
Found: C, 56.15; H, 7.68.
Ethyl 3-methyl-2-phenylselanylbutanoate 2f. (76% yield,

7488
L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
method A). 1H NMR d: 7.52–7.57 (2H, m), 7.16–7.24 (3H,
m), 4.00 (2H, q, Jˆ7.1 Hz), 3.33 (1H, d, Jˆ9.4 Hz), 2.06
(1H, m), 1.09 (3H, d, Jˆ6.6 Hz), 1.08 (3H, t, 7.1 Hz), 0.97
(3H, d, Jˆ6.6 Hz). 13C NMR d: 172.5, 135.2, 128.8, 128.6,
128.1, 60.5, 53.0, 30.2, 21.0, 20.7, 13.9. IR (cmϪ1): 1728,
1578. Anal. Calcd for C13H18O2Se: C, 54.74; H, 6.36.
Found: C, 54.87; H, 6.42.
Jˆ7.2 Hz). 13C NMR d:173.4, 137.8, 128.9, 128.5, 127.3,
60.5, 50.4, 31.3, 22.0, 13.9, 9.8. IR (cmϪ1): 1710, 1578.
Anal. Calcd for C13H18O2Se: C, 54.74; H, 6.36. Found: C,
54.76; H, 6.38.
Ethyl 2-benzyl-2-phenylselanylbutanoate 5c. (90%
1
yield). H NMR d: 7.58–7.64 (2H, m), 7.20–7.40 (8H,
m), 4.06 (2H, m), 3.39 (1H, d, Jˆ14.0 Hz), 3.14 (1H, d,
Jˆ14.0 Hz), 1.78 (2H, m), 1.16 (3H, t, Jˆ7.0 Hz), 1.09
(3H, t, Jˆ7.0 Hz). 13C NMR d: 172.9, 137.7, 136.8,
129.9, 129.0, 128.5, 128.2, 127.9, 126.7, 60.7, 56.8, 39.8,
26.0, 13.7, 9.7. IR (cmϪ1): 1718, 1578. Anal. Calcd for
C19H22O2Se: C, 63.15; H, 6.01. Found: C, 62.89; H, 6.31.
Ethyl phenyl(phenylselanyl)acetate 2g. (60% yield,
1
method A). H NMR d: 7.38–7.52 (4H, m), 7.17–7.34
(6H, m), 4.89 (1H, s), 4.09 (2H, q, Jˆ7.1 Hz), 1.15 (3H,
d, Jˆ7.1 Hz). 13C NMR d:170.9, 136.4, 135.6, 129.0, 128.7,
128.6, 128.5, 127.9, 61.4, 48.2, 14.0. IR (cmϪ1): 1730, 1578.
Anal. Calcd for C16H16O2Se: C, 60.19; H, 5.05. Found: C,
60.27; H, 5.09.
Ethyl 2-benzyl-2-phenylselanylhexanoate 5d. (87%
1
yield). H NMR d: 7.58–7.65 (2H, m), 7.15–7.45 (8H,
Ethyl cyclohexyl(phenylselanyl)acetate 2h. (75% yield,
method A). H NMR d: 7.46–7.53 (2H, m), 7.12–7.19
m), 4.04 (2H, qd, Jˆ1.4, 7.1 Hz), 3.38 (1H, d,
Jˆ14.2 Hz), 3.15 (1H, d, Jˆ14.2 Hz), 1.15–1.85 (6H, m),
1.15 (3H, t, Jˆ7.1 Hz), 0.88 (3H, t, Jˆ7.3 Hz). 13C NMR d:
137.7, 136.9, 129.9, 128.9, 128.5, 127.9, 127.2, 126.5, 60.7,
56.0, 40.4, 32.9, 27.3, 22.6, 13.8, 13.7. IR (cmϪ1): 1718,
1577. Anal. Calcd for C21H26O2Se: C, 64.77; H, 6.73.
Found: C, 65.02; H, 6.96.
1
(3H, m), 3.94 (2H, qd, Jˆ1.5, 7.1 Hz), 3.33 (1H, dd,
Jˆ1.7, 9.7 Hz), 2.05–2.20 (1H, m), 1.45–1.80 (4H, m),
1.03 (3H, td, Jˆ2.2, 7.1 Hz), 0.80–1.25 (6H, m). 13C
NMR d:171.8, 134.7, 128.4, 127.5, 59.9, 51.5, 38.7, 30.9,
25.6, 25.4, 13.5. IR (cmϪ1): 1727, 1578. Anal. Calcd for
C16H22O2Se: C, 59.08; H, 6.82. Found: C, 58.98; H, 7.16.
Ethyl 2-benzyl-3-phenyl-2-phenylselanylpropanoate 7.
(89% yield). H NMR d: 7.58–7.65 (2H, m), 7.16–7.42
1
Ethyl 3-cyclohexyl-2-phenylselanylpropanoate 2i. (68%
yield, method A). H NMR d: 7.53–7.60(2H, m), 7.23–
1
(13H, m), 4.06 (2H, q, Jˆ7.1 Hz), 3.37 (2H, d,
Jˆ14.0 Hz), 3.28 (2H, d, Jˆ14.0 Hz), 1.12 (3H, t,
Jˆ7.1 Hz). 13C NMR d: 172.6, 137.7, 136.7, 129.9, 128.8,
128.3, 127.5, 126.3, 60.7, 54.2, 40.9, 13.4. IR (cmϪ1): 1715,
1578. Anal. Calcd for C24H24O2Se: C, 68.08; H, 5.71.
Found: C, 68.12; H, 5.79.
7.30 (3H, m), 4.03 (2H, q, Jˆ7.2 Hz), 3.71 (1H, dd,
Jˆ6.6, 9.1 Hz), 1.50–1.90 (7H, m), 1.05–1.45 (6H, m),
1.11 (3H, t, Jˆ7.2 Hz). 13C NMR d:172.6, 135.0, 128.5,
127.9, 127.7, 60.3, 41.0, 38.7, 35.9, 32.6, 32.4, 26.0, 25.7,
13.6. IR (cmϪ1): 1728, 1578. Anal. Calcd for C17H24O2Se:
C, 60.17; H, 7.13. Found: C, 60.43; H, 7.21.
Preparation of g,d-unsaturated esters 8
Preparation of a-phenylselanyl esters 5 and 7
Esters 8 (except 8a) were prepared by method C using KH,
allyl bromide and HMPA as cosolvent (Table 2). Trace
amount of allyl phenylselenide 9a (RˆH) was detected.
The selenides 9a or 9b (RˆMe) were formed using allyl
bromide or methallyl bromide in the absence of HMPA
(5–10%). A mixture of monoallylated ester 8a and bis-
allylated ester 10 was obtained from 2a (8a/10:84/16).
Method D was used for the preparation of 8a, 8b, 8f, 8g
and 8j.
Compounds 5a and 5b were also prepared by method A.
Method C: KH (250 mg, 35 wt% dispersion in mineral oil)
washed with light petroleum (5×20 ml), dried under argon,
was covered with THF (10 ml) and the suspension was
slowly added to ester 2 (1 mmol) in THF at Ϫ35ЊC. After
stirring for 20 min, alkyl halide (MeI or EtI or BnBr,
3 mmol) in THF (2 ml) and HMPA (0.5 ml) was introduced.
The reaction was brought to room temperature and evapo-
rated under reduced pressure. The oily residue was
dissolved in light petroleum, washed twice with water
(5 ml). The organic layer was concentrated and the crude
product was chromatographed on silica gel (light petroleum/
CH2Cl2:70/30). Dibenzylation of 2a, leading to ester 7, was
achieved by the same method using a double amount of KH.
Method D: A solution of ester 2 (1.8 mmol) in THF (3 ml)
was added dropwise at Ϫ78ЊC, under stirring, to a solution
of LDA (2 mmol) in THF, as for method A. Allyl bromide
or methallyl chloride (2 mmol) dissolved in HMPA (0.5 ml)
was slowly added. The resulting mixture was brought to
0ЊC, stirred for 30 min, quenched with sat. aq. NH4Cl
(10 ml) and diluted with ether (10 ml). The organic layer
was washed with water (3×10 ml), dried, filtered and
evaporated providing an oily product purified by silica gel
chromatography (light petroleum/CH2Cl2:70/30).
Ethyl 2-methyl-2-phenylselanylpropanoate 5a.13 (78%
yield, method A; 91% yield, method C). 1H NMR d:
7.54–7.60 (2H, m), 7.23–7.38 (3H, m), 4.06 (2H, q,
Jˆ7.1 Hz), 1.55 (6H, s), 1.16 (3H, t, Jˆ7.1 Hz). 13C NMR
d: 174.1, 137.7, 129.0, 128.5, 127.7, 60.7, 45.1, 26.2, 13.9.
IR (cmϪ1): 1770, 1578.
Ethyl 2-phenylselanylpent-4-enoate 8a. (64% yield,
1
method C; 96% yield, method D). H NMR d: 7.54–7.62
(2H, m), 7.20–7.34 (3H, m), 5.76 (1H, m), 5.00–5.15 (2H,
m), 4.07 (2H, q, Jˆ7.2 Hz), 3.65 (1H, m), 2.55 (2H, m), 1.14
(3H, t, Jˆ7.0 Hz). 13C NMR d: 173.2, 135.6, 133.2, 128.9,
128.4, 127.2, 117.5, 60.8, 42.3, 38.4, 35.8, 13.9. IR (cmϪ1):
Ethyl 2-methyl-2-phenylselanylbutanoate 5b. (72% yield,
method A; 71% yield, method C). H NMR d: 7.53–7.59
(2H, m), 7.22–7.38 (3H, m), 4.04 (2H, m), 1.65–2.07 (2H,
m), 1.46 (3H, s), 1.15 (3H, td, Jˆ0.5, 7.1 Hz), 0.90 (3H, t,
1

L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
7489
1730, 1578. Anal. Calcd for C13H16O2Se: C, 55.13; H, 5.69.
Found: C, 55.29; H, 5.82.
4.16 (2H, m), 2.86 (2H, m), 1.18 (3H, t, Jˆ7.0 Hz). 13C
NMR d: 171.9, 140.2, 137.5, 133.6, 128.7, 128.0, 127.5,
127.2, 126.8, 118.2, 61.3, 40.5, 13.7. IR (cmϪ1): 1722,
1578. Anal. Calcd for C19H20O2Se: C, 63.51; H, 5.61.
Found: C, 63.19; H, 5.36.
Ethyl 2-(prop-2-enyl)-2-phenylselanylpent-4-enoate 10.
1
(10% yield, method C, separated from 8a). H NMR d:
7.53–7.59 (2H, m), 7.23–7.38 (3H, m), 5.72–5.94 (2H,
m), 5.04–5.16 (4H, m), 4.05 (2H, q, Jˆ7.1 Hz), 2.57 (4H,
m), 1.15 (3H, t, Jˆ7.1 Hz). 13C NMR d: 173.0, 137.9, 133.3,
132.0, 129.2, 128.7, 118.8, 60.9, 38.4, 13.9. IR (cmϪ1):
1720, 1578. Anal. Calcd for C16H20O2Se: C, 59.44; H,
6.24. Found: C, 59.69; H, 6.26.
Ethyl 2-cyclohexyl-2-phenylselanylpent-4-enoate 8h. (85%
yield, method C). 1H NMR d: 7.53–7.59 (2H, m), 7.20–7.35
(3H, m), 6.02 (1H, m), 5.00–5.15 (2H, m), 4.06 (2H, m),
2.56 (2H, m), 2.00–2.15 (1H, m), 1.00–1.80 (13H, m). 13C
NMR d: 172.8, 137.9, 135.5, 128.9, 128.4, 127.4, 117.1,
60.6, 59.9, 43.4, 37.5, 29.5, 28.3, 26.8, 26.6, 26.3, 13.9.
IR (cmϪ1): 1716, 1578. Anal. Calcd for C19H26O2Se: C,
62.46; H, 7.17. Found: C, 62.65; H, 7.31.
Ethyl 2-methyl-2-phenylselanylpent-4-enoate 8b. (82%
yield, method C; 75% yield, method D). 1H NMR d:
7.55–7.62 (2H, m), 7.20–7.38 (3H, m), 5.64–5.86 (1H,
m), 5.04–5.14 (2H, m), 4.06 (2H, qd, Jˆ2.2, 7.1 Hz), 2.60
(2H, m), 1.49 (3H, s), 1.15 (3H, td, Jˆ2.3, 7.1 Hz). 13C
NMR d: 173.1, 137.8, 133.4, 129.0, 128.5, 127.1, 118.7,
60.7, 48.4, 42.8, 22.5, 13.9. IR (cmϪ1): 1722, 1578. Anal.
Calcd for C14H18O2Se: C, 56.57; H, 6.10. Found: C, 56.55;
H, 6.09.
Ethyl 4-methyl-2-phenylselanylpent-4-enoate 8i. (75%
1
yield, method C). H NMR d: 7.56–7.64 (2H, m), 7.22–
7.34 (3H, m), 4.75 (2H, m), 4.03 (2H, q, Jˆ7.1 Hz), 3.80
(1H, dd, Jˆ6.1, 9.7 Hz), 2.55 (2H, m), 1.70 (3H, s), 1.12
(3H, t, Jˆ7 Hz). 13C NMR d: 172.3, 142.0, 135.6, 128.8,
128.4, 127.8, 112.5–60.7, 41.2, 39.7, 22.3, 13.9. IR (cmϪ1):
1728, 1578. Anal. Calcd for C14H18O2Se: C, 56.57; H, 6.10.
Found: C, 56.87; H, 6.31.
Ethyl 2-ethyl-2-phenylselanylpent-4-enoate 8c. (75%
1
yield, method C). H NMR d: 7.52–7.58 (2H, m), 7.20–
7.38 (3H, m), 5.85 (1H, m), 5.06–5.18 (2H, m), 4.06 (2H, q,
Jˆ7.2 Hz), 2.54 (2H, m), 1.79 (2H, m), 1.16 (3H, t,
Jˆ7.0 Hz), 0.93 (3H, t, Jˆ7.0 Hz). 13C NMR d: 172.9,
137.7, 133.4, 128.9, 128.5, 126.8, 118.1, 60.6, 54.9, 37.6,
26.8, 13.8, Ϫ9.2. IR (cmϪ1): 1719, 1579. Anal. Calcd for
C15H20O2Se: C, 57.88; H, 6.48. Found: C, 57.87; H, 6.51.
Ethyl 2,4-dimethyl-2-phenylselanylpent-4-enoate 8j. (85%
yield, method C; 67% yield, method D). 1H NMR d: 7.54–
7.60 (2H, m), 7.15–7.35 (3H, m), 4.80 (1H, m), 4.65 (1H,
m), 4.04 (2H, q, Jˆ7.0 Hz), 2.95 (1H, d, Jˆ14.0 Hz), 2.43
(1H, d, Jˆ14.0 Hz), 1.60 (3H, s), 1.46 (3H, s), 1.15 (3H, t,
Jˆ7 Hz). 13C NMR d: 172.0, 141.7, 137.9, 129.2, 128.6,
127.1, 114.9, 60.8, 48.3, 46.6, 23.2, 22.4, 13.8. IR (cmϪ1):
1719, 1577. Anal. Calcd for C15H20O2Se: C, 57.88; H, 6.48.
Found: C, 58.27; H, 6.53.
Ethyl 2-n-propyl-2-phenylselanylpent-4-enoate 8d. (76%
yield, method C). 1H NMR d: 7.52–7.58 (2H, m), 7.22–7.38
(3H, m), 5.86 (1H, m), 5.06–5.16 (2H, m), 4.06 (2H, q,
Jˆ7.0 Hz), 2.51–2.58 (2H, m), 1.20–1.85 (4H, m), 1.16
(3H, t, Jˆ7.0 Hz), 0.87 (3H, t, Jˆ7.2 Hz). 13C NMR d:
173.0, 137.7, 133.5, 129.0, 128.1, 126.9, 118.1, 60.6, 54.2,
38.1, 36.1, 18.1, 14.0, 13.8. IR (cmϪ1): 1720, 1578. Anal.
Calcd for C16H22O2Se: C, 59.07; H, 6.82. Found: C, 59.13;
H, 6.85.
Ethyl 2-n-butyl-4-methyl-2-phenylselanylpent-4-enoate
1
8k. (72% yield, method C). H NMR d: 7.50–7.60 (2H,
m), 7.15–7.40 (3H, m), 4.71 (1H, m), 4.82 (1H, m), 4.02
(2H, q, Jˆ7.0 Hz), 2.76 (1H, d, Jˆ14.1 Hz), 2.54 (1H, d,
Jˆ14.1 Hz), 1.05–1.90 (9H, m), 1.14 (3H, t, Jˆ7.1 Hz),
0.87 (3H, m). 13C NMR d: 173.4, 141.5, 137.8, 129.0,
128.5, 126.0, 114.5, 60.7, 55.3, 42.5, 33.2, 27.0, 23.4,
22.8, 13.8. IR (cmϪ1): 1720, 1578. Anal. Calcd for
C18H26O2Se: C, 61.18; H, 7.42. Found: C, 60.97; H, 7.56.
Ethyl 2-n-butyl-2-phenylselanylpent-4-enoate 8e. (76%
1
yield, method C). H NMR d: 7.50–7.57 (2H, m), 7.22–
7.36 (3H, m), 5.85 (1H, m), 5.10 (2H, m), 4.06 (2H, q,
Jˆ7.0 Hz), 2.53 (2H, m), 1.60–1.85 (2H, m), 1.15–1.45
(4H, m), 1.15 (3H, t, Jˆ7.0 Hz), 0.86 (3H, t, Jˆ7.0 Hz).
13C NMR d: 173.0, 137.8, 133.5, 129.0, 128.8, 127.0,
118.2, 60.7, 54.3, 38.1, 33.7, 28.9, 22.7, 13.8. IR (cmϪ1):
1721, 1578. Anal. Calcd for C17H24O2Se: C, 60.17; H, 7.13.
Found: C, 60.05; H, 7.18.
Allyl phenylselenide 9a.11c 1H NMR d: 7.48 (2H, m), 7.27
(3H, m), 6.04–5.84 (1H, m), 5.01–4.91 (2H, m), 3.51 (2H,
m). 13C NMR d: 134.1, 116.2, 30.3.
2-Methyl-3-prop-2-enyl phenylselenide 9b.11c 1H NMR d:
7.49 (2H, m), 7.27 (3H, m), 4.68 (2H, m), 3.51 (2H, s), 1.85
(3H, s).
Ethyl 2-isopropyl-2-phenylselanylpent-4-enoate 8f. (70%
yield, method C; 68% yield, method D). 1H NMR d: 7.55–
7.60 (2H, m), 7.22–7.35 (3H, m), 6.00 (1H, m), 5.02–5.14
(2H, m), 4.04 (2H, m), 2.55 (2H, m), 2.17 (1H, m), 0.95–
1.20 (9H, m). 13C NMR d: 173.0, 138.0, 135.3, 129.0, 128.5,
117.3, 60.7, 37.2, 32.9, 19.1, 18.2, 13.9. IR (cmϪ1): 1719,
1578. Anal. Calcd for C16H22O2Se: C, 59.07; H, 6.81.
Found: C, 59.09; H, 6.92.
Preparation of a,a-bis(phenylselanyl)esters 6
Ester 2 (2 mmol) in THF (1 ml) was added dropwise to a
solution of LDA (4.8 mmol) in anhydrous THF (3 ml), at
Ϫ78ЊC under argon. The reaction was stirred for 10 min and
treated with PhSeCl (932 mg, 4.8 mmol) dissolved in
HMPA (2 ml) and THF (6 ml). The mixture was warmed
to 0ЊC, stirred for 30 min, quenched with sat. aq. NH4Cl.
After dilution with ether, the organic layer was washed with
water (2×5 ml), dried and concentrated. The crude product
Ethyl 2-phenyl-2-phenylselanylpent-4-enoate 8g. (81%
yield, method C; 72% yield, method D). 1H NMR d:
7.08–7.32 (10H, m), 5.92 (1H, m), 5.02–5.14 (2H, m),

7490
L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
was rectified by Kugelrohr distillation and chromatography
on silica gel (light petroleum/ethyl acetate:97/3).
(E)-Ethyl 2-methylpenta-2,4-dienoate 11b.32 (mixture
11b/12a, 81% Yield).1H NMR d: 7.14 (1H, dd, Jˆ11.3,
0.6 Hz,), 6.63 (1H, dt, Jˆ16.8, 11.3, 10.0 Hz,), 5.54 (1H,
dd, Jˆ16.8, 0.9 Hz), 5.43 (1H, dt, Jˆ10.0, 0.6 Hz), 4.19
(2H, q, Jˆ7.0 Hz), 1.93 (3H, s), 1.28 (3H, t,
Jˆ7.0 Hz).13C NMR d: 168.1, 138.0, 132.0, 125.0, 123.8,
60.4, 14.1, 12.4. IR (cmϪ1): 1709.
Ethyl bis(phenylselanyl)acetate 6a.22 (57% yield). 1H
NMR d: 7.55–7.63 (4H, m), 7.22–7.35 (6H, m), 4.78
(1H, s), 4.08 (2H, q, Jˆ7.0 Hz), 1.12 (3H, t, Jˆ7.0 Hz).
13C NMR d: 169.8, 134.5, 129.0, 128.8, 128.4, 61.5, 38.7,
13.6. IR (cmϪ1): 1723, 1577.
Ethyl 2-methylidenepent-4-enoate 12a.33 1H NMR d: 6.15
(1H, d, Jˆ1.0 Hz), 5.65–5.95 (1H, m) 5.52 (1H, m), 5.02–
5.10 (2H, m), 4.20 (2H, q, Jˆ7.0 Hz), 3.02 (2H, m), 1.28
(3H, t, Jˆ7.0 Hz). 13C NMR d: 166.8, 142.6, 138.5, 125.5,
112.2, 60.4, 39.5, 22.0, 13.9. IR (cmϪ1): 1720,1630.
Ethyl 2,2-bis(phenylselanyl)butanoate 6c. (96% yield). 1H
NMR d: 7.65–7.73 (4H, m), 7.24–7.44 (6H, m), 4.11 (2H,
q, Jˆ7.0 Hz), 1.70 (2H, q, Jˆ7.0 Hz), 1.18 (3H, t,
Jˆ7.0 Hz), 0.94 (3H, t, Jˆ7.0 Hz). 13C NMR d: 170.5,
137.5, 129.3, 128.9, 128.4, 61.8, 56.6, 29.4, 13.9. IR
(cmϪ1): 1715, 1576. Anal. Calcd for C18H20O2Se2: C,
50.72; H, 4.73. Found: C, 51.02; H, 4.68.
(E)-Ethyl 2-n-propylpenta-2,4-dienoate 11c.34 (84%
1
Yield). H NMR d: 7.15 (1H, d, Jˆ11.4 Hz), 6.62 (1H,
ddd, Jˆ16.7, 11.4, 9.9 Hz), 5.54 (1H, dd, Jˆ16.7, 1.6 Hz),
5.42 (1H, dd, Jˆ9.9, 1.6 Hz), 4.19 (2H, q, Jˆ7.0 Hz), 2.37
(2H, t,), 1.44 (2H, m), 1.29 (3H, t, Jˆ7.0 Hz), 0.89 (3H, t).
13C NMR d: 167.9, 138.3, 132.8, 132.0, 129.9, 60.3, 28.7,
22.7, 14.0, 13.6. IR (cmϪ1): 1709.
Ethyl 2,2-bis(phenylselanyl)hexanoate 6e. (89% yield).
1H NMR d: 7.65–7.73 (4H, m), 7.24–7.44 (6H, m), 4.09
(2H, q, Jˆ7.0 Hz), 1.64 (2H, m), 1.40 (2H, m), 1.16 (3H, t,
Jˆ7.0 Hz), 0.98–1.20 (2H, m), 0.74 (3H, t, Jˆ7.0 Hz). 13C
NMR d: 170.8, 137.5, 129.4, 128.7, 128.5, 61.8, 55.7, 36.0,
28.6, 22.2, 13.9. IR (cmϪ1): 1718, 1577. Anal. Calcd for
C20H24O2Se2: C, 52.87; H, 5.32. Found: C, 53.12; H, 5.39.
(E)-Ethyl 2-phenylpenta-2,4-dienoate 11d. (71% Yield).
1H NMR d: 7.43(1H, d, Jˆ11.3 Hz), 7.38–7.15 (5H, m),
6.37(1H, ddd, Jˆ16.9, 11.3, 10.0 Hz), 5.63 (1H, dd, Jˆ16.9,
1.6 Hz), 5.38(1H, dd, Jˆ10.0, 1.6 Hz), 4.23 (2H, q,
Jˆ7.1 Hz), 1.27 (3H, t, Jˆ7.1 Hz). 13C NMR d: 167.2,
140.2, 133.2, 130.0, 127.8, 127.6, 125.4, 118.5, 60.9, 14.2.
IR (cmϪ1): 1712. Anal. Calcd for C13H14O2: C, 77.20; H,
6.98. Found: C, 76.95; H, 6.95.
Ethyl 3-methyl-2,2-bis(phenylselanyl)butanoate 6f. (68%
yield). 1H NMR d: 7.68–7.75 (4H, m), 7.22–7.44 (6H, m),
3.92 (2H, q, Jˆ7.0 Hz), 2.34 (1H, m), 1.12 (6H, d,
Jˆ6.7 Hz), 1.06 (3H, t, Jˆ7.0 Hz). 13C NMR d: 170.7,
137.6, 129.1, 128.9, 128.6, 64.0, 61.6, 35.8, 20.1, 13.8. IR
(cmϪ1): 1709, 1577. Anal. Calcd for C19H22O2Se2: C, 51.83;
H, 5.04. Found: C, 52.05; H, 4.96.
Ethyl 2,4-dimethylpenta-2,4-dienoate 11e.35 (mixture
1
11e/12b, 80% Yield). H NMR d: 7.03 (1H, m), 5.14–
Ethyl phenyl[bis(phenylselanyl)]acetate 6g. (40% yield).
1H NMR d: 7.02–7.40 (15H, m), 4.10 (2H, q, Jˆ7.0 Hz),
1.09 (3H, t, Jˆ7.0 Hz). IR (cmϪ1): 3056, 3027, 1714, 1578.
Anal. Calcd for C22H20O2Se2: C, 55.71; H, 4.25. Found: C,
56.02; H, 4.32.
5.00 (2H, m), 4.14 (2H, q, Jˆ7.0 Hz), 1.95 (3H, d,
Jˆ1.4 Hz), 1.87 (3H, s), 1.24 (3H, t, Jˆ7.0 Hz). 13C NMR
d: 168.5, 140.6, 140.2, 127.4, 119.4, 60.4, 22.6, 14.1, 13.6.
IR (cmϪ1): 1716.
Ethyl 4-methyl-2-methylidenepent-4-enoate 12b.33 (80%
Yield).1H NMR d: 6.15 (1H, m), 5.48 (1H, m), 4.75–4.66
(2H, m), 4.14 (2H, q, Jˆ7.0 Hz), 2.94 (2H, s), 1.66 (3H, s),
1.23 (3H, t, Jˆ7.0 Hz).13C NMR d: 166.8, 142.6, 138.5,
125.5, 112.2, 60.4, 39.5, 22.0, 13.9. IR (cmϪ1): 1716.
Ethyl cyclohexyl[bis(phenylselanyl)]acetate 6h. (75%
1
yield). H NMR d: 7.68–7.75 (4H, m), 7.22–7.40 (6H,
m), 3.94 (2H, q, Jˆ7.1 Hz), 1.02–2.02 (11H, m), 1.06
(3H, t, Jˆ7.1 Hz). 13C NMR d: 170.3, 137.6, 129.1,
128.5, 63.7, 61.4, 45.8, 30.4, 26.7, 26.3, 13.8. IR (cmϪ1):
1717, 1578. Anal. Calcd for C22H26O2Se2: C, 55.01; H, 5.46.
Found: C, 55.37; H, 5.16.
Transesterification of esters 2
NaH (100 mg, 4 mmol, 60% dispersion in mineral oil) was
added to a solution of ester 2 (1 mmol) in THF (3 ml) and
ethanol (0.5 ml). The stirred mixture was heated at reflux for
20 min. Allyl bromide (242 mg, 2 mmol) was then added
and the solution was heated at reflux for 16 h. Water (10 ml)
was introduced after cooling and the allyl ester 13 was
extracted with CH2Cl2 (3×5 ml). The organic layer was
dried, evaporated and the oily residue was chromatographed
on silica gel (light petroleum/CH2Cl2: 75/25).
Oxidation of g,d-unsaturated esters 8
A solution of ester 8 (1 mmol) and pyridine (158 mg,
2 mmol) in chloroform (10 ml) was treated dropwise with
H2O2 (0.7 ml, 8 mmol) at 0ЊC. The reaction was stirred at
the same temperature for 1 h. The solution was washed
twice with water, dried and concentrated. The oily product
was purified by Kugelrohr distillation.
(E)-Ethyl penta-2,4-dienoate 11a.31 (92% Yield). 1H NMR
(CDCl3) d: 7.16 (1H, dd, Jˆ15.4, 10.8 Hz), 6.35 (1H, dddd,
Jˆ16.5, 10.8, 9.9, 0.6 Hz), 5.80 (1H, dd, Jˆ15.4, 0.6 Hz),
5.49 (1H, dd, Jˆ16.5, 0.6 Hz), 5.37 (1H, dt, Jˆ9.9, 0.6 Hz),
4.11 (2H, q, Jˆ7.0 Hz), 1.19 (3H, t, Jˆ7.0 Hz).13C NMR d:
166.6, 144.5, 134.6, 125.3, 122.1, 60.2, 14.1. IR (cmϪ1):
1716.
Allyl 2-phenylselanylbutanoate 13c. (68%Yield).1H NMR
d: 7.54–7.60 (2H, m), 7.20–7.35 (3H, m), 5.70–5.95 (1H,
m), 5.06–5.85 (2H, m), 4.52 (2H, m), 3.54 (1H, dd, Jˆ6.7,
8.5 Hz), 1.65–2.00 (2H, m), 0.98 (3H, t, Jˆ7.2 Hz). 13C
NMR d: 172.0, 135.4, 128.8, 128.2, 118.1, 65.2, 45.0,
25.0, 12.5. IR (cmϪ1): 1729, 1578. Anal. Calcd for
C13H16O2Se: C, 55.13; H, 5.69. Found: C, 55.02; H, 5.61.

L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
7491
Allyl 2-phenylselanylpentanoate 13d. (67% Yield). 1H
NMR d: 7.54–7.60 (2H, m), 7.20–7.35 (3H, m), 5.70–
5.95 (1H, m), 5.10–5.33 (2H, m), 4.51 (2H, m), 3.62 (1H,
dd, Jˆ6.6, 8.7 Hz), 1.60–2.00 (2H, m), 1.25–1.55 (2H, m),
0.88 (3H, t, Jˆ7.2 Hz). 13C NMR d: 172.6, 135.5, 128.8,
128.3, 127.8, 118.1, 65.3, 43.0, 33.7, 18.1, 13.5. IR (cmϪ1):
1732, 1575. Anal. Calcd for C14H18O2Se: C, 56.57; H, 6.10.
Found: C, 56.43; H, 6.19.
Anal. Calcd for C16H26OSe: C, 64.08; H, 7.77. Found: C,
64.16; H, 7.65.
3-Phenylselanyl-4-(prop-2-enyl)hepta-2, 6-dien-4-ol 21a.
1
(65% yield). H NMR d: 7.10–7.35 (5H, m), 6.43 (1H, q,
Jˆ7.0 Hz), 5.60–5.82 (2H, m), 4.95–5.15 (4H, m), 2.25–
2.70 (5H, m), 1.82 (3H, d, Jˆ6.8 Hz). 13C NMR d: 137.7,
133.8, 133.4, 131.1, 129.4, 128.8, 125.8, 118.6, 77.5, 43.8,
18.2. IR (cmϪ1): 3443, 1578. Anal. Calcd for C16H20OSe: C,
62.54; H, 6.56. Found: C, 62.72; H: 6.58.
Allyl 2-phenylselanylhexanoate 13e. (70% Yield). 1H
NMR d: 7.54–7.60 (2H, m), 7.20–7.35 (3H, m), 5.70–
5.95 (1H, m), 5.10–5.32 (2H, m), 4.51 (2H, m), 3.54 (1H,
dd, Jˆ6.6, 8.7 Hz), 1.15–1.95 (6H, m), 0.86 (3H, t,
Jˆ7.2 Hz). 13C NMR d: 172.6, 135.5, 131.8, 128.6, 128.3,
127.8, 118.3, 65.3, 43.4, 31.4, 30.1, 22.1, 13.7. IR (cmϪ1):
1730, 1578. Anal. Calcd for C15H20O2Se: C, 57.88; H, 6.48.
Found: C, 57.79; H, 6.39.
5-Phenylselanyl-4-(prop-2-enyl)nona-1,5-dien-4-ol 21b.
1
(68% yield). H NMR d: 7.10–7.40 (5H, m), 6.30 (1H, t,
Jˆ7.0 Hz),5.73 (2H, m),5.06 (4H, m), 2.15–2.70 (7H, m),
1.37 (2H, m), 0.84 (3H, d, Jˆ7.0 Hz). 13C NMR d: 139.3,
136.3, 131.4, 129.4, 128.6, 125.7, 118.3, 77.3, 43.8, 34.3,
21.9, 13.5. IR (cmϪ1): 3508, 1579. Anal. Calcd for
C18H24OSe: C, 64.47; H, 7.21. Found: C, 64.62; H, 7.42.
Allyl 3-methyl-2-phenylselanylbutanoate 13f. (67%
Yield). H NMR d: 7.56–7.61 (2H, m), 7.22–7.30 (3H,
1
7-Methyl-5-phenylselanyl-4-(prop-2-enyl)octa-1,5-dien-
4-ol 21c. (63% yield). H NMR d: 7.32–7.40 (2H, m),
1
m), 5.70–5.90 (1H, m), 5.14–5.31 (2H, m), 4.49 (2H, m),
3.39 (1H, d, Jˆ9.4 Hz), 2.11 (1H, m), 1.14 (3H, d,
Jˆ6.7 Hz), 1.01 (3H, t, Jˆ6.6 Hz). 13C NMR d: 172.2,
135.2, 131.7, 129.0, 128.4, 128.1, 118.2, 65.2, 52.9, 30.1,
20.9, 20.7. IR (cmϪ1): 1731, 1578. Anal. Calcd for
C14H18O2Se: C, 56.57; H, 6.10. Found: C, 56.77; H, 6.24.
7.12–7.22 (3H, m), 6.06 (1H, d, Jˆ10.0 Hz), 5.58–5.80
(2H, m), 4.97–5.12 (4H, m), 2.85 (1H, m), 2.30–2.64
(5H, m), 0.93 (6H, d, Jˆ6.6 Hz). 13C NMR d: 146.9,
133.6, 133.4, 131.8, 129.9, 128.9, 126.0, 118.6, 77.1, 44.0,
32.3, 22.3. IR (cmϪ1): 3468, 1578. Anal. Calcd for
C18H24OSe: C, 64.47; H, 7.21. Found: C, 64.44; H, 7.26.
Preparation of dienols 14 and trienols 21
Preparation of a-phenylselanyl a,b-unsaturated esters
Allylmagnesium chloride (2 M solution in THF, 1.1 ml,
2.2 mmol) was added to ester 8 (or 15) (1 mmol) dissolved
in THF (10 ml) at Ϫ78ЊC. The reaction was stirred for
30 min and sat. aq. NH4Cl (10 ml) was then introduced.
The product was extracted with ether (2×10 ml). The
organic layer was washed with water, dried and evaporated.
The oily residue was chromatographed on silica gel (light
petroleum/CH2Cl2:75/25).
15
(1) Oxidation of esters 6 (Method E): NaIO4 (129 mg,
0.6 mmol) was added to a stirred solution of ester 6
(0.5 mmol) in ethanol (10 ml) containing sodium bicarbo-
nate (42 mg, 0.5 mmol) at 0ЊC. The reaction was stirred for
1.5 h, brought to room temperature, filtered and diluted with
CH2Cl2 (15 ml). The organic layer was washed twice with
water, dried and evaporated. The crude product was purified
by silica gel chromatography (light petroleum/CH2Cl2:70/
30).
1-Phenylselanyl-2-(prop-2-enyl)pent-4-en-2-ol 14a. (85%
Yield). 1H NMR d: 7.48–7.56(2H, m), 7.19–7.29 (3H,
m),5.68–5.90 (2H, m),5.00–5.15 (4H, m), 3.10 (2H, s)
2.33 (5H, m). 13C NMR d: 133.0, 132.4, 130.5, 128.8,
126.6, 118.8, 73.1, 43.3, 39.9. IR (cmϪ1): 3480, 1578.
Anal. Calcd for C14H18O1Se: C, 59.43; H, 6.41. Found: C,
59.21; H, 6.33.
(2) Synthesis of b-chloro-a-phenylselanyl esters 17:26
ZnCl2 (1 M ether solution, 0.1 ml) was added dropwise to
a solution of PhSeCl (192 mg, 1 mmol) in CH2Cl2 (8 ml) at
room temperature. After stirring for 10 min, the unsaturated
ester 16 (1 mmol) was slowly added. The resulting mixture
was stirred for 30 min and water was added. After dilution
with CH2Cl2 (10 ml), the organic layer was washed with
water, dried, evaporated. The crude product 17 was purified
by chromatography as in method A. The formation of the
erythro isomer was only observed.
3-Phenylselanyl-4-(prop-2-enyl)hepta-6-en-4-ol 14c. (82%
Yield). 1H NMR d: 7.50–7.62 (2H, m), 7.15–7.27 (3H, m),
5.75–6.00 (2H, m), 4.95–5.16 (4H, m), 3.15 (1H, dd,
Jˆ12 Hz, Jˆ2 Hz), 2.75 (1H, bs), 2.12–2.60 (4H, m),
I.40–2.05 (2H, m), 1.07 (3H, t, Jˆ7.1 Hz). 13C NMR d:
133.5, 133.2, 133.1, 131.5, 128.8, 126.8, 118.4, 117.7,
75.2, 64.2, 42.4, 41.2, 25.2, 13.4. IR (cmϪ1): 3479, 1578.
Anal. Calcd for C16H22OSe: C, 62.13; H, 7.17. Found: C,
62.27; H, 7.20.
Erythro-ethyl 3-chloro-2-phenylselanylbutanoate 17a.
(94% yield). H NMR d: 7.56–7.62 (2H, m), 7.22–7.38
1
(3H, m), 4.32 (1H, dq, Jˆ6.6, 11.0 Hz), 4.11 (2H, q,
Jˆ7.0 Hz), 3.68 (1H, d, Jˆ11.0 Hz), 1.72 (3H, d,
Jˆ6.6 Hz), 1.19 (3H, t, Jˆ7.0 Hz). 13C NMR d: 170.1,
135.7, 129.2, 61.2, 56.6, 52.0, 23.2, 15.6, 13.9. IR (cmϪ1):
1726, 1578. Anal. Calcd for C12H15O2ClSe: C, 47.15; H,
4.95. Found: C, 47.32; H, 5.13.
5-Phenylselanyl-4-(prop-2-enyl)non-1-en-4-ol 14e. (73%
1
Yield). H NMR d: 7.50–7.60 (2H, m), 7.20–7.26 (3H,
m),5.75–6.00 (2H, m),4.95–5.17 (4H, m), 3.23 (1H, dd,
Jˆ2.0, 12.0 Hz), 2.76 (1H, s), 2.15–2.60 (4H, m), 1.10–
1.93 (6H, m), 0.83 (3H, t, Jˆ7.0 Hz). 13C NMR d: 133.5,
133.2, 133.2, 131.5, 128.8, 126.9, 118.5, 117.8, 75.2, 62.2,
42.5, 41.1, 31.7, 30.8, 22.1, 13.8. IR (cmϪ1): 3479, 1578.
Erythro-ethyl 3-chloro-2-phenylselanylhexanoate 17b.
(92% yield). H NMR d: 7.56–7.62 (2H, m), 7.22–7.35
1

7492
L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
(3H, m), 4.24 (1H, m), 4.10 (2H, q, Jˆ7.1 Hz), 3.75 (1H, d,
Jˆ11.2 Hz), 2.22 (1H, m), 1.71 (1H, m), 1.46 (2H, m), 1.15
(3H, t, Jˆ7.2 Hz), 0.89 (3H, t, Jˆ7.2 Hz). 13C NMR d:
170.1, 135.7, 129.1, 128.9, 127.1, 61.6, 61.0, 50.3, 36.9,
18.8, 13.9, 13.3. IR (cmϪ1): 1732, 1578. Anal. Calcd for
C14H19O2ClSe: C, 50.39; H, 5.74. Found: C, 50.71; H, 5.95.
34.4, 21.5, 13.6. MS: Mϩˆ298. IR (cmϪ1): Z isomer:
1709, 1577. E isomer: 1709, 1577.
Ethyl 4-methyl-2-phenylselanylpent-2-enoate 15c.29 (80%
yield, method F; 84% yield, method H, Z isomer). 1H NMR
d:7.32–7.39 (2H, m), 7.13–7.26 (3H, m), 7.14 (1H, d,
Jˆ9.8 Hz), 4.07 (2H, q, Jˆ7.1 Hz), 3.06 (1H, m), 1.06
(3H, t, Jˆ7.1 Hz), 1.04 (6H, d, Jˆ7.0 Hz). 13C NMR d:
167.1, 158.8, 131.1, 130.9, 128.8, 126.4, 121.8, 61.2, 31.9,
21.5, 13.7. IR (cmϪ1): 3059, 1709, 1609, 1579.
Erythro-ethyl 3-chloro-4-methyl-2-phenylselanylpentano-
ate 17c. (84% yield). 1H NMR d: 7.58–7.64 (2H, m), 7.24–
7.40 (3H, m), 4.27 (1H, m), 4.58 (2H, dq, Jˆ7.1 Hz), 3.82
(1H, d, Jˆ12.0 Hz), 2.50 (1H, m), 1.17 (3H, d, Jˆ7.1 Hz),
1.04 (3H, d, Jˆ7.0 Hz). 0.77 (3H, d, Jˆ7.0 Hz). 13C NMR
d: 170.2, 135.7, 129.0, 128.7, 126.7, 68.2, 61.0, 48.8, 29.4,
20.8, 14.1, 13.7. IR (cmϪ1): 1735, 1578. Anal. Calcd for
C14H19O2ClSe: C, 50.39; H, 5.75. Found: C, 50.35; H, 5.72.
Ethyl 3-methyl-2-phenylselanylbut-2-enoate 15d.28 (82%
yield, method E). 1H NMR d: 7.40–7.46 (2H,m), 7.18–7.26
(3H, m), 3.99 (2H, q, Jˆ7.2 Hz), 2.06 (3H, s), 2.04 (3H, s),
1.05 (3H, t, Jˆ7.2 Hz). 13C NMR d: 166.1, 148.4, 131.5,
130.2, 128.7, 126.6, 60.7, 24.9, 22.9, 13.6. IR (cmϪ1): 1718,
1577. Anal. Calcd for C13H16O2Se: C, 55.13; H, 5.69.
Found: C, 54.91; H: 5.27.
(3) Dehydrohalogenation of esters 17
Method F: A solution of b-chloro-a-phenylselanylester 17
(1 mmol), triethylamine (225 mg, 2.5 mmol) in benzene
(10 ml) was heated at reflux for 5 h. Water (10 ml) and
CH2Cl2 (20 ml) were then added. The organic layer was
washed with water (3×5 ml), dried and concentrated. The
crude product was purified by silica gel chromatography
(light petroleum/CH2Cl2:70/30).
Ethyl cyclohexylidene(phenylselanyl)acetate 15e. (80%
yield, method E). H NMR d: 7.42–7.47 (2H,m), 7.16–
1
7.24 (3H, m), 3.99 (2H, q, Jˆ7.1 Hz), 2.53 (2H, m), 2.41
(2H, m), 1.50–1.66 (6H, m), 1.07 (3H, t, Jˆ7.1 Hz). 13C
NMR d: 166.1, 154.5, 131.6, 130.7, 128.8, 126.7, 60.7, 34.7,
33.7, 27.9, 27.6, 26.0, 13.8. IR (cmϪ1): 1715, 1578. Anal.
Calcd for C16H20O2Se: C, 59.44; H, 6.24. Found: C, 59.15;
H, 6.11.
Method G: A solution of ester 17 (1 mmol) in acetone
(10 ml), containing potassium carbonate (0.138 g,
1 mmol), was heated at reflux for 6 h. The mixture was
then treated with water and extracted twice with CH2Cl2.
The organic layer was washed with water, dried and
evaporated. The ester 15 was purified as described for
method B.
Oxidation of esters 15
H2O2 (0.18 ml, 2 mmol) was added to a solution of
a-phenylselanylester 15a (Z) (0.5 mmol) and pyridine
(2 mmol, 158 mg) in CHCl3 (5 ml) at 0ЊC. The mixture
was stirred for 1 h at 0ЊC, diluted with CH2Cl2 (10 ml),
washed with water (4×1 ml), dried and concentrated. The
crude selenoxide 20a (E) was purified by silica gel chroma-
tography (light petroleum/CH2Cl2:70/30). By the same
procedure, 15a (E)16 has led to 20a (E) in 85% yield. Selen-
oxides 20b (E) and 20c (E) were obtained from 15b (Z) and
15c (Z).
Method H: A solution of ester 17 (1 mmol) and DBU
(0.161 g, 1 mmol) in THF (5 ml) was stirred at room
temperature for 20 h. After addition of water and extraction
with CH2Cl2, the organic layer was treated as above.
Ethyl 2-phenylselanylbut-2-enoate 15a. (85% yield, Z/E:
85/15, method E; 91% yield, Z/E:100/0, method F; 92%
yield, Z/E:0/100, method G; 91% yield, Z/E:0/100, method
E-Ethyl 2-phenylseleninylbut-2-enoate 20a. (74% yield).
1H NMR d: 7.63–7.70 (2H, m), 7.40–7.45 (3H, m), 7.35
(1H, t, Jˆ7.4 Hz), 4.18 (2H, dq, Jˆ1.0, 7.1 Hz), 2.22 (3H, d,
Jˆ7.4 Hz), 1.17 (3H, t, Jˆ7.1 Hz). 13C NMR d: 162.9,
145.5, 142.1, 134.2, 131.1, 129.1, 126.3, 61.4, 15.7, 13.8.
IR (cmϪ1): 1722, 1579. Anal. Calcd for C12H14O3Se: C,
50.53; H, 4.95. Found: C, 50.26; H, 4.86.
1
H). H NMR d: Z isomer: 7.43 (1H, q, Jˆ6.9 Hz), 7.32–
7.39 (2H, m), 7.16–7.24 (3H, m), 4.10 (2H, q, Jˆ7.1 Hz),
2.03 (3H, d, Jˆ6.9 Hz), 1.10 (3H, t, Jˆ7.1 Hz). E isomer:
7.45–7.52 (2H, m), 7.15–7.35 (3H, m), 6.34 (1H, q,
Jˆ7.3 Hz), 4.14 (2H, q, Jˆ7.0 Hz), 1.99 (3H, d,
Jˆ7.3 Hz), 1.16 (3H, t, Jˆ7.0 Hz). 13C NMR d: Z and E
isomers: 164.8, 147.8, 130.7, 128.8, 126.4, 125.7, 59.9,
18.4, 13.7. IR (cmϪ1): Z isomer: 1708, 1578. E isomer:
1716, 1578. Anal. Calcd for C12H14O2Se: C, 53.53; H,
5.20. Found: C, 53.64; H, 5.52.
E-Ethyl 2-phenylseleninylhex-2-enoate 20b. (72% yield).
1H NMR d: 7.62–7.69 (2H, m), 7.37–7.44 (3H, m), 7.27
(1H, t, Jˆ7.7 Hz), 4.16 (2H, dq, Jˆ1.0, 7.1 Hz), 2.71 (2H,
m), 1.55 (2H, m), 1.21 (3H, d, Jˆ7.1 Hz), 0.91 (3H, t,
Jˆ7.3 Hz). 13C NMR d: 162.4, 149.7, 141.8, 133.2, 130.6,
128.7, 126.0, 61.0, 30.9, 21.3, 13.4, 13.2. IR (cmϪ1): 1722,
1579. Anal. Calcd for C18H14O3Se: C, 53.68; H, 5.79.
Found: C, 53.47; H, 6.01.
Ethyl 2-phenylselanylhex-2-enoate 15b.29 (87% yield,
Z/E:86/14, method E; 80% yield, Z/E:100/0, method F;
1
94% yield, Z/E:10/90, method G). H NMR d: Z isomer:
7.32–7.38 (2H,m), 7.33 (1H, t, Jˆ7.3 Hz), 7.15–7.22 (3H,
m), 4.08 (2H, q, Jˆ7.1 Hz), 2.43 (2H, m), 1.49 (2H, m), 1.08
(3H, t, Jˆ7.1 Hz), 0.93 (3H, t, Jˆ7.3 Hz). E isomer: 7.44–
7.52 (2H, m), 7.18–7.30 (3H, m), 6.27 (1H, t, 7.3 Hz), 4.12
(2H, q, 7.0 Hz), 2.42 (2H, m), 1.41 (2H, m), 1.15 (3H, t,
Jˆ7.0 Hz), 0.87 (3H, t, Jˆ7.3 Hz). 13C NMR d: Z and E
isomers: 165.5, 152.6, 130.9, 128.8, 126.4, 124.7, 61.2,
E-Ethyl 4-methyl-2-phenylseleninylpent-2-enoate 20c.
1
(68% yield). H NMR d: 7.72–7.76 (2H, m), 7.37–7.47
(3H, m), 7.22 (1H, d, Jˆ11.1 Hz), 4.03–4.23 (3H, m),
1.18 (3H, t, Jˆ7.1 Hz), 1.04 (3H, d, Jˆ6.6 Hz) 0.75 (3H,
d, Jˆ6.6 Hz). 13C NMR d: 163.1, 131.2, 130.0, 129.8,

L. Lebarillier et al. / Tetrahedron 56 (2000) 7483–7493
7493
126.6, 62.4, 25.1, 22.6, 22.1, 14.4. IR (cmϪ1): 1726, 1578.
Anal. Calcd for C14H18O3Se: C, 53.68; H, 5.79. Found: C,
53.79; H, 5.81.
observed during the aqueous work-up after DIBALH reduction
into a-phenylselanyl aldehydes.18
18. Shea, R. G.; Fitzner, J. N.; Fankhauser, J. E.; Spaltenstein, A.;
Carpino, P. A.; Peevey, R. M.; Pratt, D. V.; Tenge, B. V.; Hopkins,
P. B. J. Org. Chem. 1986, 51, 5243; Danishefsky, S. J.; Dennino,
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