588
J.G. Uranga et al. / Tetrahedron 68 (2012) 584e589
4.2. General methods
131.7; 131.9; 132.6; 132.9; 133.1; 134.6; 154.6; 166.8. HRMS [MH]þ
exact mass calcd for C21H19O3S2: 383.0776, found: 383.0770.
Irradiation was conducted in a reactor equipped with two 400-
W UV lamps emitting maximally at 350 nm (Philips Model HPT,
water-refrigerated).
4.3.5. Methyl 3,6-bis(1-adamantylthio)-2-methoxybenzoate
(10). The product was purified as a white solid by column chro-
matography employing diethyl ether/petroleum ether (2:98). Mp:
4.2.1. Photostimulated reactions of methyl 2,5-dichlorobenzoate with
PhSꢀ ions in liquid ammonia. The following procedure is repre-
sentative of these reactions. PhSH (5 mmol) and t-BuOK (5.1 mmol)
were added to 250 mL of distilled liquid ammonia; PhSꢀ ions were
ready for use. The substrate, methyl 2,5-dichlorobenzoate
(1 mmol), was added to the solution, and the reaction mixture
was irradiated for 2 h. The reaction was then quenched with an
excess of ammonium nitrate (or methyl iodide), and the ammonia
was allowed to evaporate. The solid was dissolved in water, and
HNO3 was added to the water phase to reach pH¼3 before ex-
traction with diethyl ether. Products were isolated by column
chromatography employing silica gel and quantified by GC using
the internal standard method.
188.5e190 ꢂC 1H NMR (400 MHz, CDCl3)
d: 1.54e2.08 (30H, m);
3.92 (3H, s); 3.93 (3H, s); 7.23 (1H, d, J¼8.1 Hz) 7.45 (1H, d,
J¼7.9 Hz). 13C NMR (100 MHz, CDCl3)
d: 30.1; 30.15; 36.06; 36.1;
43.8; 43.9; 50.1; 50.4; 52.3; 63.0; 125.9; 130.5; 133.1; 136.9; 139.8;
159.4; 167.5. HRMS [MNa]þ exact mass calcd for C29H38O3S2:
521.2155, found: 521.2187.
4.3.6. Methyl 2-methoxy-6-(phenylthio)benzoate (17). The product
was purified as yellow oil after chromatographic column employing
petroleum ether (60:80). 1H NMR (400 MHz, CDCl3)
d: 3.84 (3H, s);
3.88 (3H, s); 6.80e6.87 (2H, m); 7.19e7.38 (6H, m). 13C NMR
(100 MHz, CDCl3) d: 52.4; 56.1; 109.9; 124.4; 126.1; 127.4; 129.2;
130.8; 131.6; 134.8; 135.1; 156.7; 167.2. HRMS [MNa]þ exact mass
calcd for C15H14O3S: 297.0556 found: 297.0551.
4.2.2. Dark reactions with PhSꢀ ions in liquid ammonia. This pro-
cedure was similar to that described for the previous reaction, ex-
cept that the reaction flask was wrapped with aluminum foil.
4.4. Computational procedure
All calculations were carried out with DFT methods, as imple-
mented in the Gaussian 03 package,15 by employing the B3LYP1621
functional at the 6-31þG* level of theory. This methodology is
known to be appropriate for the theoretical study of the electronic
and geometric properties of RAs.22 Stationary points were charac-
terized by the normal analysis and obtained with complete ge-
ometry optimization without symmetry restrictions. Potential
energy surfaces (PES) were obtained by varying the CmetaeCl bond
length. The transition state structures were optimized, character-
ized, and confirmed by IRC calculations. In all cases, the B3LYP spin
contamination along the whole fragmentation path was negligible
ðhS2i ¼ 0:750 ꢀ 0:751Þ. For more details see Supplementary data.
4.2.3. Inhibited reactions using PhSꢀ ions in liquid ammonia. This
procedure was similar to that described for the previous reaction,
except that 30 mol % of m-DNB was added to the solution of the
nucleophile prior to the addition of the substrate.
4.3. Isolation and characterization
4.3.1. Methyl 5-chloro-2-(phenylthio)benzoate (3). The product was
purified as a colorless oil by column chromatography employing
diethyl ether/petroleum ether (2:98) 1H NMR (400 MHz, CDCl3)
d:
3.96 (3H, s); 6.73 (1H, d, J¼8.8 Hz); 7.19 (1H, dd, J¼2.4, 8.7 Hz);
7.40e7.58 (5H, m); 7.96 (1H, d, J¼2.4 Hz). 13C NMR (100 MHz,
Supplementary data
CDCl3) d: 52.5; 127.8; 128.7; 129.4; 129.9; 130.2; 130.7; 132.0;
132.3; 135.5; 142.0; 165.8. HRMS [MNa]þ exact mass calcd for
C14H11ClO2S: 301.0066, found: 301.0064.
Supplementary data related to this article can be found online at
4.3.2. Methyl
2-(1-adamantylthio)-5-chlorobenzoate
(4). The
References and notes
product was purified as a white solid by column chromatogra-
~ꢀ~
1. (a) Rossi, R. A.; Pierini, A. B.; Penenory, A. B. Chem. Rev. 2003, 103, 71; (b) Rossi,
phy employing diethyl ether/petroleum ether (2:98). Mp:
~ꢀ~
R. A.; Penenory, A. B. The Photostimulated SRN1 Process: Reaction of Haloarenes
59.0e59.7 ꢂC. 1H NMR (400 MHz, CDCl3)
d: 1.55e2.05 (15H, m);
with Carbanions In CRC Handbook of Organic Photochemistry and Photobiology,
2nd ed.; Horspool, W. M., Lenel, F., Eds.; CRC: Boca Raton, USA, 2004, Chapter 47
pp 1e28; (c) Rossi, R. A. Photoinduced Aromatic Nucleophilic Substitution Re-
actions In Synthetic Organic Photochemistry; Griesbeck, A. G., Mattay, J., Eds.;
Marcel Dekker: New York, NY, 2005; pp 495e527; (d) Rossi, R. A.; Pierini, A. B.;
Santiago, A. N. In Organic Reactions; Paquette, L. A., Bittman, R., Eds.; Wiley:
1999; 54, pp 1e271.
3.91 (3H, s); 7.36 (1H, dd, J¼2.5, 8.3 Hz); 7.51 (1H, d, J¼8.2 Hz); 7.56
(1H, d, J¼2.5 Hz). 13C NMR (100 MHz, CDCl3)
d: 30.1; 36.0; 43.7;
49.9; 52.5; 128.1; 128.6; 130.0; 134.8; 140.3; 141.0; 167.7. HRMS
[MNa]þ exact mass calcd for C18H21ClO2S: 359.3934, found:
359.3934.
2. Bunnett, J. F.; Creary, X. J. Org. Chem. 1974, 39, 3173.
3. Bunnett, J. F.; Creary, X. J. Org. Chem. 1975, 40, 3740.
4.3.3. Methyl 2,5-bis(1-adamantylthio)benzoate (6). The product
was purified as a white solid by column chromatography employing
diethyl ether/petroleum ether (2:98). Mp: 185.5e186.5 ꢂC 1H NMR
4. (a) Pierini, A. B.; Baumgartner, M. T.; Rossi, R. A. J. Org. Chem. 1991, 56, 580; (b)
Baumgartner, M. T.; Pierini, A. B.; Rossi, R. A. J. Org. Chem. 1993, 58, 2593.
5. (a) Beugelmans, R.; Chbani, M. Bull. Soc. Chim. Fr. 1995, 132, 290; (b) Beugel-
mans, R.; Bois-Choussy, M. Tetrahedron 1986, 42, 1381.
6. (a) Pastor, S. D. Helv. Chim. Acta 1988, 71, 859; (b) Nasielski, J.; Moucheron, C.;
Nasielski-Hinkens, R. Bull. Soc. Chim. Belg. 1992, 101, 491; (c) Singh, P.; Arora, G.
Tetrahedron 1988, 44, 2625; (d) Baumgarner, C. D.; Malen, A. H.; Pastor, S. D.;
NabiRahni, M. A. Helv. Chim. Acta 1992, 75, 480.
(400 MHz, CDCl3) d: 1.54e2.08 (30H, m); 3.89 (3H, s); 7.49e7.58
(2H, m); 7.66 (1H, d, J¼1.6 Hz). 13C NMR (100 MHz, CDCl3)
d: 30.2;
30.3; 36.0; 43.6; 43.8; 48.7; 49.8; 52.1; 130.4; 131.7; 136.8; 138.5;
138.6; 139.6; 168.1. HRMS [MH]þ exact mass calcd for C28H36O2S2:
469.2229, found: 469.2233.
7. (a) Bunnett, J. F.; Creary, X. J. Org. Chem. 1974, 39, 3611; (b) Amatore, C.; Beu-
ꢀ
gelmans, R.; Bois-Choussy, M.; Combellas, C.; Thiebault, A. J. Org. Chem. 1989, 54,
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2205; (d) Petrillo, G.; Novi, M.; Garbarino, G.; Dell’Erba, C. Tetrahedron 1986, 42,
4007.
4.3.4. Methyl
2-methoxy-3,6-bis(phenylthio)benzoate
(9). The
product was purified as a yellow oil by column chromatography
8. Shaw, J. E. J. Org. Chem. 1991, 56, 3728.
employing diethyl ether/petroleum ether (2:98). 1H NMR
9. Palacios, S. M.; Alonso, R. A.; Rossi, R. A. Tetrahedron 1985, 41, 4147.
10. Ahbala, M.; Hapiot, P.; Houmam, A.; Jouini, M.; Pinson, J.; Saveant, J. M. J. Am.
Chem. Soc. 1995, 117, 11488.
(400 MHz, CDCl3)
d
: 3.91 (3H,s); 3.94 (3H,s); 6.83 (1H, d, J¼8.5 Hz);
6.87 (1H, d, J¼8.5 Hz); 7.24e7.43 (10H, m). 13C NMR (100 MHz,
~
11. Basso, S. M.; Montanez, J. P.; Santiago, A. N. Lett. Org. Chem. 2008, 5, 633.
~
CDCl3)
d: 52.6; 62.2; 127.7; 128.16; 128.2; 129.3; 129.6; 130.8; 131.0;
12. Montanez, J. P.; Uranga, J. G.; Santiago, A. N. New J. Chem. 2010, 34, 1170.