M. Tingoli et al. / Tetrahedron Letters 47 (2006) 7529–7531
7531
chloride, (1.0 g, 5.2 mmol) dispersed in 3 ml of anhydrous
hexane. Dry CH2Cl2 (20 ml) was then added and to this
stirred solution, under Ar atmosphere, solid silver saccha-
rin (1.45 g, 5.0 mmol) was added portionwise, at room
temperature. The initial red brown solution decolorized
and after 3 h stirring, a consistent amount of white AgCl
was separated and a pale yellow solution appeared. As
described in the test the precipitate can be filtered off and
the resulting solution is ready for use. In order to better
characterize NPSSac 1, after the evaporation of the
solvent, the solid obtained (1.3 g, 81% yield) was in part
crystallized from a mixture of CH2Cl2–hexane to obtain a
stable solid. Compound 1: colorless crystals; mp 151–
154 °C (dec); IR (CCl4), cm1: 3010 (w), 1747 (s), 1342 (s),
1180 (s); 1H NMR (400 MHz, CD3CN): d = 8.05–7.90 (m,
4H, aromatic nucleus of saccharin), 7.90–7.85 (m, 2H,
ortho-aromatic PhSe), 7.67–7.63 (m, 3H, meta- and para-
aromatic PhSe); 13C NMR (100 MHz, CD3CN): d = 160.0
(s); 148.1 (s); 139.4 (s); 135.6 (d); 134.7 (d); 132.3 (d); 129.4
(d); 127.5 (s); 125.8 (d), 125.1 (d); 120.9 (d); 77Se NMR
(76.28 MHz, THF-d8): d = 734.
Briefly as reported in Table 1, using NPSSac, it is possi-
ble to functionalize terminal or internal olefins, entries
from 1 to 5, in the presence of different nucleophiles like
H2O, MeOH or NaN3, entry 1.
The cyclofunctionalization of alkenes bearing an inter-
nal nucleophiles (entries 6 and 7) or the phenylselenenyl-
ation of activated aromatic substrates (entries 8 and 9)
were also realized in a high yield. Finally, the direct
a-phenylselenenylation of an enolizable ketone or an
aldehyde (entries 10 and 11) is possible, leaving these
reactions running for a longer time, but still obtaining
a high reaction conversion.10,11
The representative examples reported in this letter show
the ability of our new reagent to produce the electro-
philic PhSe group, starting from cheap and easily avail-
able materials like AgNO3 and saccharin.8 Moreover,
the almost neutral reaction conditions generated can
be adjusted on demand by adding a catalytic amount
of camphorsulfonic acid.
10. The reactions described were carried out in CH2Cl2 or in
CH3CN on a 0.5 mmol scale. The external nucleophile was
added in a slight excess (30%) referred to the amount of
the starting material. Unless the preparation of the
phenylseleno-azide starting from styrene, entry 1, product
1c, all the reactions proceeded in the presence of 5% of
camphorsulfonic acid. After the time indicated in Table 1
the reactions were quenched with water extracted with
CH2Cl2 and washed with a dilute solution of sodium
bicarbonate. The longer reaction time observed for both
carbonyl derivatives, Table 1 entries 10 and 11, is probably
due to the initial equilibrium reaction that produces the
more reactive, enol forms.
11. All the compounds are stable enough to be purified by
standard flash chromatography, using a mixture of hex-
ane–tert-butyl methyl ether as eluant. Products 1a,12 1b,3
1c,13 2a,2 3a,14 4a,2 5a,15 6a,4 7A,4 8a,16 9a17 and 11a18
have spectral data consistent with those previously
reported. Compound 10a is fully characterized.19
12. Engman, L. J. Org. Chem. 1987, 52, 4086–4094.
13. Hassner, A.; Amarasekara, A. S. Tetrahedron Lett. 1987,
28, 5185–5188.
It is important to observe that the properties and the
reactivity of NPSSac are very similar to those showed
by the commercially available N-phenylselenophthal-
imide (NPSP).2 It is our opinion, however, that the sil-
ver salt of saccharin can potentially combine with all
the alkyl- or aryl-selenyl chloride or bromide generated
from the corresponding dialkyl- or diaryl-diselenide
derivatives and for these reasons our method should
be considered for wide applications in organic
synthesis.
Acknowledgments
The Consorzio CINMPIS is thanked for a postdoctoral
fellowship (R.D.). The authors are indebted to Dr. Pel-
legrino Conte and Dr. Claudio Santi (University of
Perugia), for some NMR facilities.
14. Tiecco, M.; Testaferri, L.; Tingoli, M.; Chianelli, D.;
Bartoli, D. Tetrahedron 1988, 44, 2261–2272.
References and notes
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Petrovskii, P. V. J. Organomet. Chem. 2000, 605, 96–
101.
1. Wirth, T. Organoselenium Chemistry: Modern develop-
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19. Physical data of compound 10a: 1H NMR (200 MHz,
CDCl3): d = 7.80–7.20 (m, 9H), 4.2 (dd, J1 = 7.6 Hz,
J2 = 2.7 Hz, 1H), 3.65 (dd, J1 = 18.1 Hz, J2 = 7.6 Hz, 1H),
3.15 (dd, J1 = 18.1 Hz, J2 = 2.7 HZ, 1H); 13C NMR
(CDCl3, 50 MHz): d 203.2 (s, C–O); 152.2 (s); 135.5;
135.3; 135.0; 129.0; 128.4; 127.7; 127.5; 126.2; 124.4; 43.3
(d); 35.1 (t); GC–EIMS: m/z 288 (M+) (19), 207 (13), 157
(11), 131 (93), 103 (55), 77 (100), 51 (74). Anal. Calcd.
for C15H12OSe: C, 62.72; H, 4.21. Found: C, 62.69; H,
4.25.
8. Dolenc, D. Synlett 2000, 544–546.
9. N-Phenylselenosaccharin 1: In a 150 ml RB 3-necked flask
equipped with an argon inlet was placed phenylselenenyl