A new synthesis of α-phenylseleno esters and acids from terminal alkynes

Article abstract of DOI:10.1055/s-2001-13370

Alkynyl phenyl selenides, easily prepared from terminal alkynes, react with p-toluenesulfonic acid to afford (Z)-α-(phenylseleno)vinyl p-toluenesulfonates. The reactions of these compounds with phenylselenenyl sulfate in the presence of alcohols or water

Full text of DOI:10.1055/s-2001-13370

706
LETTER
A New Synthesis of -Phenylseleno Esters and Acids from Terminal Alkynes
Marcello Tiecco,* Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini, Claudio Santi
Dipartimento di Chimica e Tecnologia del Farmaco, Sezione di Chimica Organica, Università degli Studi di Perugia, I-06123 Perugia, Italy
Fax 390755855116; E-mail: tiecco@unipg.it
Received 12 February 2001
selenides 613-16 and that these react with p-toluenesulfonic
Abstract: Alkynyl phenyl selenides, easily prepared from terminal
acid to give the (Z)- -(phenylseleno)vinyl p-toluene-
alkynes, react with p-toluenesulfonic acid to afford (Z)- -(phe-
nylseleno)vinyl p-toluenesulfonates. The reactions of these com-
pounds with phenylselenenyl sulfate in the presence of alcohols or
sulfonates 7 (Scheme 2) as the result of a stereospecific cis
addition.17a
water give the corresponding -phenylseleno esters or acids, re-
spectively.
Key words: selenium, electrophilic additions, alkynes, alkenes, es-
ters
Organoselenium chemistry has rapidly developed in re-
cent years and organoselenium reagents are now com-
monly used as very useful and powerful reagents since
they allow the chemo-, regio- and stereoselective intro- Scheme 2
duction of new functional groups into complex organic
molecules under extremely mild experimental conditions.
Compounds 7 present some intereresting chemical prop-
erties. Owing to the different reactivity of the phenylsele-
no and of the p-toluenesulfonate groups, compounds 7
were employed to develop a convenient method for the
stereospecific synthesis of trisubstituted alkenes 8 by tran-
sition metal catalyzed sequential cross coupling reac-
tions.17a,b In these reactions the (Z)- -(phenylseleno)vinyl
p-toluenesulfonates 7 behave as the synthetic equivalents
of the dicationic synthon 9 (Scheme 2). Moreover, com-
pounds 7 are electron rich alkenes which can easily react
with electrophilic reagents.
The fundamental aspects of organoselenium chemistry
have been described in excellent books and review articles
some of which have very recently appeared.1-6 Among the
several selenium compounds which have been described
and investigated, -phenylseleno aldehydes, ketones, and
esters have found useful applications7 mostly as conve-
nient starting products to introduce unsaturated functions
into organic molecules. Particular attention has been de-
voted to the synthesis and reactivity of -phenylseleno es-
ters 1.7
We report in this paper that the reaction of 7 with electro-
philic phenylselenium reagents represents a new and con-
venient method to prepare -phenylseleno esters, as well
as the corresponding acids. The electrophilic reagent em-
ployed was the phenylselenenyl sulfate which was
introduced18 and extensively used19 by our research group
and which is easily produced by diphenyl diselenide and
ammonium persulfate. First experiments were carried out
with the (Z)-1-(phenylseleno)-2-phenylethenyl p-toluene-
sulfonate 7a. The reaction of this compound with phe-
nylselenenyl sulfate was carried out in methanol at 65 °C.
After usual work up and column chromatography of the
reaction mixture the only product obtained, in 55% yield,
was the methyl -phenylseleno ester 12a. The same reac-
tion, carried out in benzyl alcohol, afforded the benzyl
-phenylseleno ester 13a in 47% yield. When a 95:5 mix-
ture of acetonitrile and water was employed as solvent the
reaction afforded the -phenylseleno acid 14a in 72%
yield.
Scheme 1
As indicated in Scheme 1, these compounds are generally
obtained either from the reaction of the enolates of esters
28-12 with phenylselenenyl chloride or by the reaction of
the phenylselenolate anion with -haloesters 3.8-12 Com-
pounds 1 can also be obtained by reaction of selenium sta-
bilized carbanions 4 with alkyl chloroformates.11 The
enolates of 1 can be easily alkylated to afford more com-
plex -phenylseleno esters.8
We now report a new simple method for the synthesis of
-phenylseleno esters and acids starting from terminal
alkynes. We have recently reported that these acetylenic
compounds 5 can be easily converted into alkynyl phenyl
As indicated in Scheme 3, the reactions of 7 with phe-
nylselenenyl sulfate very likely proceed through the initial
formation of the seleniranium intermediates 10 which are
Synlett 2001, No. 5, 706–708 ISSN 0936-5214 © Thieme Stuttgart · New York

LETTER
A New Synthesis of -Phenylseleno Esters and Acids from Terminal Alkynes
707
trapped by methanol, benzyl alcohol or water to give the which, very likely, can find several synthetic applications.
Se,O orthoester intermediates 11. Compounds 11 could We are presently investigating the intramolecular version
not be isolated since, under the acidic reaction conditions, of these reactions from which -phenylseleno - or -lac-
they loose the PhSe and the tosyl groups to afford the ob- tones can be prepared starting from alkynes containing in-
served products 12, 13 or 14. The structures of these com- ternal oxygen nucleophiles.
pounds indicate that both the alkoxy- and the hydroxy-
selenenylation of the carbon carbon double bond are re-
giospecific processes.
Acknowledgement
Financial support from MURST, National Project "Stereoselezione
in Sintesi Organica. Metodologie e Applicazioni", the University of
Perugia, Progetti di Ateneo, and CNR, Rome is gratefully acknow-
ledged.
References and Notes
(1) Paulmier, C. Selenium Reagents and Intermediates in Organic
Synthesis, Pergamon Press; Oxford 1986.
(2) Rappoport, Z. The Chemistry of Organic Selenium and
Tellurium Compounds, Wiley: New York 1987.
(3) Liotta, D. Organoselenium Chemistry, Wiley: New York
1987.
Scheme 3
(4) Krief, A.; Hevesi, L. Organoselenium Chemistry, Springer:
Berlin 1988.
(5) Ponthieux, S.; Paulmier, C. Topics in Current Chemistry.
Organoselenium Chemistry: Modern Developments in
Organic Synthesis. Wirth, T. Ed.; Springer: Berlin 2000, 113-
142.
Similar good results were obtained when these reactions
were effected starting from compounds 7 holding differ-
ent substituents. The starting products,20 the reaction
products21 and the yield of the isolated compounds are re-
ported in the Table.
(6) Back, T. G. (Ed); Organoselenium Chemistry. A Pratical
Approach. Oxford: New York 2000.
Two interesting examples are represented by the reactions
carried out on (Z)- -(phenylseleno)vinyl p-toluene-
sulfonates 7e and 7f which contain a phthalimido or a sul-
fonamido substituent. The yields obtained in these cases
are similar to those observed with the other substrates in-
dicating that these substituents are compatible with the re-
action conditions employed. Compounds 12f and 14f
obtained from 7f are an -phenylseleno -N-substituted
amino ester and the corresponding acid, respectively.
These compounds have recently found very useful syn-
thetic applications.23
(7) a) Houllemare, D.; Ponthieux, S.; Outurquin, F.; Paulmier, C.
Synthesis 1997, 101 and references cited therein. b) Paulmier,
C.; Outurquin, F.; Lebarillier, L. Tetrahedron 2000, 56, 7483.
(8) Sharpless, K. B.; Lauer, R. F.; Teranishi, A. Y. J. Am. Chem.
Soc. 1973, 95, 6137.
(9) Brockson, T. G.; Petragnani, N., Rodriguez, R. J. Org. Chem.
1974, 39, 2114.
(10) a) Reich, H. J.; Reich, I. L.; Renga, J. M. J. Am. Chem. Soc.
1973, 95, 5813. b) Reich, H. J.; Reich, I. L. J. Am. Chem. Soc.
1975, 97, 5434.
(11) Denis, J. M.; Dumont, W.; Krief, A. Tetrahedron Lett. 1976,
453.
(12) Clive, D. L. J. Tetrahedron 1978, 34, 1049.
(13) Tingoli, M.; Tiecco, M.; Testaferri, L.; Balducci, R. Synlett
1993, 211.
Table Synthesis of methyl 12 and benzyl 13 -phenylseleno esters
and of -phenylseleno acids 14 from the reaction of 7 with PhSeSePh
and (NH4)2S2O8
(14) Braga, A.; Silveira, C.; Reckziegel, A.; Menezes, P.
Tetrahedron Lett. 1993, 34, 8041.
(15) Stang, P. J.; Zhdankin, V. V. In Comprehensive Organic
Functional Group Transformations. Katritzky, A. R.;
Methcohn, O.; Rees, C. W. Ed. Pergamon, Elsevier Science;
Oxford 1995, Vol. 2, chapter 2.21, 1011.
(16) Stang, P. J.; Murch, P. Synthesis 1997, 1378.
(17) a) Tingoli, M.; Tiecco, M.; Testaferri, L.; Temperini, A.;
Pelizzi, G.; Bacchi, A. Tetrahedron1995, 51, 4691. b) Gerard,
J.; Bietlot, E.; Hevesi, L. Tetrahedron Lett. 1998, 39, 8735.
(18) Tiecco, M.; Testaferri, L.; Tingoli, M.; Chianelli, D.; Bartoli,
D. Tetrahedron Lett. 1989, 30, 1417.
(19) Tiecco, M.; Testaferri, L.; Tingoli, M.; Bagnoli, L.; Marini, F.;
Santi, C.; Temperini, A. Gazz. Chim. Ital. 1996, 126, 635.
(20) All new compounds were fully characterized by MS, 1H and
13C NMR spectroscopy and by combustion analysis.
(Z)- -(Phenylseleno)vinyl p-toluenesulfonates 7 were
prepared using our previously reported17a procedure slightly
modified. A mixture of the alkynyl phenyl selenide (1 mmol)
and anhydrous p-toluenesulfonic acid (4 mmol), dried in
vacuum over P2O5, in CH2Cl2 (10 ml) was stirred at 40-50 °C.
Solid K2CO3 and CH2Cl2 were added and the mixture was
a) With phenylselenenyl triflate22 12a was obtained in 46% yield.
In conclusion, we have described a new method to obtain
-phenylseleno esters and acids which favourably com-
pares with those already described in the literature and
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M. Tiecco et al.
LETTER
filtered trough a celite pad. The filtrate was dried, evaporated
and purified by flash chromatography. Physical, spectral and
analytical data of some selected compounds are reported
below.
2-[(2)-6-[(4-Methylphenyl)sulfonyloxy]-6-(phenylseleno)5
hexenyl] 1,3-dioxoisoindoline 7e (74% yield); Oil; 1H NMR
: 7.9-7.75 (m, 2H), 7.75-7.6 (m, 4H), 7.35-7.1 (m, 7H), 5.88
(t, 2H, J = 7.6 Hz), 3.62 (t, 2H, J = 6.8 Hz); 2.4 (s, 3H), 2.23
(q, 2H, J = 7.6 Hz), 1.7-1.2 (m, 4H). 13C NMR : 168.3 (2C),
145.2, 138.2, 133.9 (3C), 133.0, 132.0, 131.9 (2C), 129.6
(3C), 129.2 (2C), 128.6 (2C), 127.4, 123.1 (3C), 37.6, 29.6,
28, 25.9, 21.7. Anal. Calcd. for C27H25NO5SSe: C, 58.49; H,
4.54; N, 2.53. Found: C, 58.40, H, 4.65; N, 2.70.
(Z)-1-(Phenylseleno)-3-(phenylsulfonamido)-1-propenyl-
4-ethyl-1-benzenesulfonate 7f (74% yield); Oil; 1H NMR
m, 2H), 7.7-7.46 (m, 5H); 7.43-7.06 (m, 7H), 5.85
(t, 1H, J = 7.0 Hz), 5.05 (t, 1H, J = 6.5 Hz), 3.74 (t, 2H, J = 7
and 6.5 Hz), 2.41 (s, 3H). 13 C NMR : 145.5, 141.2, 139.7,
133.2 (2C), 132.7, 129.7 (3C), 129.3, 129.1 (2C), 128.4 (3C),
128.0, 127.3 (2C), 126.9 (2C), 42.6, 21.6. IR, 3291, 1374,
1178, 735 cm-1. Anal. Calcd. for C22H21NO5S2Se: C, 50.58; H,
4.05; N, 2.68. Found: C, 50.65; H, 4.00; N, 2.80.
: 171.3, 136.2, 135.5 (2C), 131.5, 128.9 (2C), 128.6 (3C),
128.4 (2C), 127.8, 52.3, 48.1; MS m/z (relative intensity): 306
(35), 149 (97), 121 (100), 91 (25), 77 (33). Anal. Calcd. for
C15H14O2Se: C, 59.04; H, 4.62. Found: C, 59.00, H, 4.57.
Methyl 6-(1,3-dioxo-2,3-dihydro-1H-2-isoindolyl)-2-
(phenyl seleno)hexanoate 12e. Oil. 1H NMR : 7.75-7.65 (m,
2H), 7.65-7.55 (m, 2H), 7.5-7.4 (m, 2H), 7.25-7.1 (m, 3 H),
3.65-3.4 (m, 3 H), 3.5 (s, 3H), 1.95-1.45 (m, 4H), 1.45-1.1 (m,
2H). 13C NMR : 173.3, 168.3 (2C), 135.6 (2C), 133.9 (3C),
132.0, 129.0 (2C), 128.5, 124.5, 123.1 (2C), 52.0, 43.1, 37.6,
31.3, 28.0, 25.3. MS m/z (relative intensity): 242(7)M-189,
174(19), 160(100), 104(14), 94(54), 81(17). Anal. Calcd. for
C21H21NO4Se: C, 58.62; H, 4.92; N, 3.26. Found: C, 58.70, H,
4.82; N, 3.18.
Methyl 2-(phenylseleno)-
3(phenylsulfonamido)propanoate 12f. Oil. 1H NMR :
7.86-7.74 (m, 2H), 7.64-7.42 (m, 5H), 7.42-7.18 (m, 3H), 5.29
(t, 1H, J = 6.6 Hz), 3.78 (dd, 1H, J = 7.8 and 6.6 Hz), 3.63 (s,
3H), 3.32 (dd, 1H, J = 8.1 and 6.6 Hz). 13C NMR : 171.5,
139.7, 135.6, 132.5, 129.0 (2C), 128.9 (2C), 128.8 (2C),
128.3, 126.7 (2C), 52.2, 43.9, 41.7. MS m/z (relative
intensity): 242 (47) (M-157), 183 (100), 157 (30), 91 (31), 77
(52), 51 (27). IR 3285, 1729, 1447, 1330, 1162, 714 cm-1.
Anal. Calcd. for C16H17NO4SSe: C, 48.25; H, 4.30; N, 3.52.
Found: C, 48.18, H, 4.26; N, 3.63.
(21) Synthesis of -phenylseleno esters 12, 13 and acids 14.
General Procedure. A solution of diphenyl diselenide
(0.6 mmol), ammonium persulfate (0.8 mmol) and the (Z)- -
(phenylseleno)vinyl p-toluenesulfonate 7 (1 mmol) in
methanol or benzyl alcohol or acetonitrile and water (95:5)
was stirred at 65-70 °C. The progress of the reaction was
monitored by TLC. Reaction times ranged from 2 h to 24 h. In
the case of esters the reaction mixture was poured into 10%
Na2CO3 solution and extracted with CH2Cl2. The organic
layer was dried (Na2SO4) and evaporated. Chromatography of
the residue through a silica gel column afforded the reaction
products in pure form. In the case of acids the reaction mixture
was evaporated and the residue was directly chromato-
graphed. Physical, spectral and analytical data of some
selected compounds are reported below.
2-Phenyl-2-(phenylseleno)acetic acid 14a. mp. 78-80 °C; 1H
NMR : 10.8 (br s, 1H), 7.6-7.0 (m, 10H), 4.84 (s, 1H); 13
C
NMR : 177.1, 135.7, 135.5 (2C), 129.0 (2C), 128.7 (4C),
128.5 (2C), 128.0, 48.0; MS m/z (relative intensity): 292 (23),
234 (41), 154 (89), 135 (100), 107 (24), 91 (38), 77 (51). Anal.
Calcd. for C14H12O2Se: C, 57.76; H, 4.15; Found: C, 57.80; H,
4.20.
(22) Murata, S.; Suzuki, T. Tetrahedron Lett. 1987, 28, 4297.
(23) Hanessian, S.; Yang, H.; Schaum, R. J. Am. Chem. Soc. 1996,
118, 2507.
Methyl 2-phenyl-2-(phenylseleno)acetate 12a. Oil; 1H
NMR : 7.52-7.12 (m, 10H), 4.9 (s, 1H), 3.6 (s, 3H); 13C NMR
Article Identifier:
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Synlett 2001, No. 5, 706–708 ISSN 0936-5214 © Thieme Stuttgart · New York