A. Boto et al. / Tetrahedron Letters 50 (2009) 3974–3977
3977
8757–8760. and references cited therein; For related work, see: (d) Díaz-
Sánchez, B. R.; Iglesias-Arteaga, M. A.; Melgar-Fernández, R.; Juaristi, E. J. Org.
Chem. 2007, 72, 4822–4825; (e) Maruyama, T.; Mizuno, Y.; Shimizu, I.; Suga, S.;
Yoshida, J. I. J. Am. Chem. Soc. 2007, 129, 1902–1903. and references cited
therein; For a review on the modification of amino acids and carbohydrates
through radical chemistry, see: (f) Hansen, S. G.; Skrydstrup, T. Top. Curr. Chem.
2006, 264, 135–162.
43.4 (CH2, 10-C), 52.0 (CH3, OMe), 52.4 (CH2, 5-C), 54.1 (CH, 2-C), 71.0 (CH2,
CH2Ph), 77.5 (CH, 4-C), 127.5 (2 ꢂ CH, Ph), 128.2 (2 ꢂ CH, Ph), 128.5 (2 ꢂ CH,
Ph), 128.6 (3 ꢂ CH, Ph), 132.8 (CH, Ph), 137. 4 (C, Ph), 138.0 (C, Ph), 155.2 (C,
CO2), 199.0 (C, 20-C). As in the previous case, the 1H NMR coupling constants
showed a cis relationship 2-H/3-Hb/4-H and a trans relationship 2-H/3-Ha and
4-H/3-Ha (J3b = 5.4, 8.2 Hz, while J3a = 0.0 Hz).
13. (a) Substrate 17 is known: Renaud, P.; Seebach, D. Helv. Chim. Acta 1986, 69,
9. Unpublished results on the stereoselective scission–alkylation process using
menthyl carbamoyl, camphorsulfonyl, camphanyl, and amino acyl groups as
chiral auxiliaries. In many cases, the stereoselectivity was low or moderate. In
others, unseparable mixtures of the major and minor diastereomers were
formed.
10. Any source of visible light can be used. However, to obtain reproducible results,
we carried out the scission with 80-W tungsten-filament lamps, available in
DIY shops.
1704–1710; ½a lDit
ꢃ
+22.9 (c 1.4, CHCl3); (b) For compound 17: ½a Dobs
ꢃ
+21.2 (c 0.40,
CHCl3). (c) As comparison, for compound 23: [a] +13.6 (c 0.43, CHCl3), while
D
its epimer 24: [
a
]
D
ꢀ17.3 (c 0.45, CHCl3).
14. (a) Passarella, D.; Barilli, A.; Belinghieri, F.; Fassi, P.; Riva, S.; Sacchetti, A.;
Silvani, A.; Danieli, B. Tetrahedron: Asymmetry 2005, 16, 2225–2230; (b) Amat,
M.; Llor, N.; Hidalgo, J.; Escolano, C.; Bosch, J. J. Org. Chem. 2003, 68, 1919–1928.
15. (a) Tirel, P. J.; Vaultier, M.; Carrié, R. Tetrahedron Lett. 1989, 30, 1947–1950; For
a review, see: (b) Bates, R. W.; Kanicha, S. E. Tetrahedron 2002, 58, 5957–5978.
11. General procedure for the scission–rearrangement process: To a solution of the
hydroxyproline derivative (0.1 mmol) in dry dichloromethane (1.5 mL) were
added iodine (13 mg, 0.05 mmol) and DIB (64 mg, 0.2 mmol). The resulting
mixture was stirred for 3 h at 26 °C, under irradiation with visible light (80 W
tungsten-filament lamp). Then the reaction mixture was cooled to 0 °C (ꢀ50 °C
16. (a) For compound 28 [(+)-norconiine methyl carbamate], [
CHCl3). (b) For
very related compound (the (ꢀ)-norconiine t-butyl
carbamate) see: Blarer, S. J.; Seebach, D. Chem. Berich. 1983, 116, 2250–2260;
a
]
+26 (c 0.3,
D
a
[a
]
D
ꢀ34.1 (c 1.1, CHCl3).
17. (a) Iminosugars: from Synthesis to Therapeutic Applications; Compain, P.; Martin,
O.R., Eds.; Wiley-VCH: Chichester, ISBN: 978-0-470-03391-3, 2007.; For
pyrrolidine-based iminosugars, see: (b) Doddi, V. R.; Vankar, Y. D. Eur. J. Org.
Chem. 2007, 5583–5589; (c) Hakansson, A. E.; van Ameijde, J.; Guglielmini, L.;
Horne, G.; Nash, R. J.; Evinson, E. L.; Kato, A.; Fleet, G. W. J. Tetrahedron:
Asymmetry 2007, 18, 282–289; (d) Zhou, X.; Liu, W. J.; Ye, J. L.; Huang, P. Q.
Tetrahedron 2007, 63, 6346–6357.
when substrate 12 was used) and then BF3ꢁOEt2 (25
lL, 29 mg, 0.2 mmol) and
the nucleophile (3 equiv) were added. The mixture was stirred for 1 h; then
was poured into 10% aqueous Na2S2O3/saturated aqueous NaHCO3 (1:1,
10 mL), and extracted with CH2Cl2. The organic layer was dried on sodium
sulfate, filtered, and evaporated under vacuum. The residue was purified by
chromatography on silica gel (hexanes/ethyl acetate mixtures) to give the
products.
18. For a review article, see: (a) Yokoyama, M.; Momotake, A. Synthesis 1999,
ˇ
12. (a) All the products were characterized using NMR, HRMS, and elemental
analysis. The proposed stereochemistry was deduced from the value of the 1H
NMR coupling constants and it was supported by NOESY experiments. As
representative examples, the NMR experiments for the allyl compound 15 and
1541–1554; For articles on the subject: (b) Kocalka, P.; Pohl, R.; Rejman, D.;
Rosenberg, I. Tetrahedron 2006, 62, 5763–5774; (c) Evans, G. B.; Furneaux, R.
H.; Hausler, H.; Larsen, J. S.; Tyler, P. C. J. Org. Chem. 2004, 69, 2217–2220; (d)
Kamath, V. P.; Ananth, S.; Bantia, S.; Morris, P. E., Jr. J. Med. Chem. 2004, 47,
1322–1324; (e) Deng, L.; Scharer, O. D.; Verdine, G. L. J. Am. Chem. Soc. 1997,
119, 7865–7866; (f) Mayer, A.; Häberli, A.; Leumann, C. J. Org. Biomol. Chem.
2005, 3, 1653–1658.
the phenone derivative 19 are described; (b) Product 15: [a] +20.6 (c 1.11,
D
CHCl3); 1H NMR (500 MHz, CDCl3 with TMS, 70 °C) dY 1.97 (ddd, J = 3.8, 3.8,
13.6 Hz, 3-Ha), 2.05 (ddd, J = 6.0, 8.2, 13.6 Hz, 1H, 3-Hb), 2.38 (ddd, J = 7.9, 9.1,
13.6 Hz, 1H, 10-Ha), 2.64 (m, 1H, 10-Hb), 3.42 (dd, J = 3.8, 12 Hz, 1H, 5-Ha), 3.67
(s, 3H, OMe), 3.70 (m, 1H, 5-Hb), 3.90 (m, 1H, 2-H), 4.06 (m, 1H, 4-H), 4.47 (d,
J = 12.2 Hz, 1H, CHaPh), 4.50 (d, J = 12.6 Hz, 1H, CHbPh), 5.04 (J = 10 Hz, 1H, 30-
Ha), 5.06 (J = 17 Hz, 1H, 30-Hb), 5.75 (m, 1H, 20-H), 7.26–7.34 (m, 4H, Ph), 7.24
(m, 1H, Ph); 13C NMR (125.7 MHz, CDCl3, 70 °C) dC 35.2 (CH2, 3-C), 38.9 (CH2,
10-C), 52.0 (CH3, OMe), 52.2 (CH2, 5-C), 56.6 (CH, 2-C), 71.3 (CH2, CH2Ph), 77.2
(CH, 4-C), 117.0 (CH2, 30-C), 127.5 (2 ꢂ CH, Ph), 127.6 (CH, Ph), 128.4 (2 ꢂ CH,
Ph), 135.2 (CH, 20-C), 138.3 (C, Ph), 155.4 (C, CO2). The NOESY experiment
showed strong spatial interactions between the benzylic protons (dY 4.50/4.47)
and the 10-H2 (dY 2.64/2.38), between the 10-H2 and the 3-Ha (dY 1.97) and a
weaker spatial interaction between 2-H (dY 3.90) and 4-H (dY 4.06). The 1H
NMR coupling constants also showed a cis relationship 2-H/3-Hb/4-H and a
trans relationship 2-H/3-Ha and 4-H/3-Ha (J3b = 6.0, 8.2 Hz, while J3a = 3.8,
19. For related compounds and their uses, see: Murruzzu, C.; Riera, A. Tetrahedron:
Asymmetry 2007, 18, 149–154.
20. Choubdar, N.; Pinto, B. M. Carbohydr. Res. 2008, 343, 1766–1777.
21. Product 31: 1H NMR (500 MHz, CD3OD, 70 °C) dY 0.96 (dd, J = 7.4, 7.7 Hz, 30-H3),
1.39–1.45 (m, 2H, 20-H2), 1.69 (m, 1H, 10-Ha), 1.82 (m, 1H, 10-Hb), 3.00 (dd,
J = 7.9, 11.2 Hz, 5-Ha), 3.17 (ddd, J = 7.5, 7.5, 7.6 Hz, 4-H), 3.58 (m, 1H, 2-H),
3.69 (s, 3H, OMe), 3.71 (m, 1H, 3-H), 3.88 (dd, J = 7.2, 11.2 Hz, 1H, 5-Hb); 13C
NMR (125.7 MHz, CD3OD, 26 °C) Rotamer mixture: dC 13.1 (CH3, 30-C), 17.8
(CH2, 20-C), 33.6/34.5 (CH2, 10-C), 50.9/51.6 (CH3, 5-C), 56.6 (CH, 4-C), 63.9 (CH,
2-C), 80.7/81.4 (CH, 3-C).
22. (a) Kamal, A.; Reddy, D. R.; Reddy, P. S. M. M. Bioorg. Med. Chem. Lett. 2007, 17,
803–806; (b) Mandal, A. K.; Hines, J.; Kuramochi, K.; Crews, C. M. Bioorg. Med.
Chem. Lett. 2005, 15, 4043–4047; (c) Doi, M.; Nishi, Y.; Kiritoshi, N.; Iwata, T.;
Nago, M.; Nakano, H.; Uchiyama, S.; Nakazawa, T.; Wakamiya, T.; Kobayashi, Y.
Tetrahedron 2002, 58, 8453–8459; (d) Gómez-Vidal, J. A.; Silverman, R. B. Org.
Lett. 2001, 3, 2481–2484; (e) Bellier, B.; McCort-Tranchepain, I.; Ducos, B.;
Danascimento, S.; Meudal, H.; Noble, F.; Garbay, C.; Roques, B. P. J. Med. Chem.
1997, 40, 3947–3956.
3.8 Hz); (c) Product 19: [a]
+14.1 (c 0.23, CHCl3); 1H NMR (500 MHz, CDCl3
D
with TMS, 70 °C) dY 2.13 (br d, J = 14.2 Hz, 3-Ha), 2.22 (ddd, J = 5.4, 8.2, 14.0 Hz,
1H, 3-Hb), 3.37 (m, 1H, 10-Ha), 3.64 (m, 2H, 5-H2), 3.68 (br b, 1H, 10-Hb), 3.69 (s,
3H, OMe), 4.15 (m, 1H, 4-H), 4.48 (m, 1H, 2-H), 4.51 (s, 2H, CH2Ph), 7.23–7.31
(m, 5H, Ph), 7.43 (dd, J = 7.3, 8.0 Hz, 2H, Ph), 7.52 (dd, J = 6.8, 7.2 Hz, Ph), 7.95
(br d, J = 7.4 Hz, 2-H, Ph); 13C NMR (125.7 MHz, CDCl3, 70 °C) dC 36.2 (CH2, 3-C),