Stereoselective synthesis of α- And β-C-glycosides by addition of titanium enolates to glycals

Synlett

Volumn , Issue 18, 2009, Pages 2982-2986

  Gálvez, Erik ^a   Larrosa, Igor ^a   Romea, Pedro ^a   Urpí, Fèlix ^a  

^a UNIVERSITY OF BARCELONA   (Spain)

Author keywords

C glycosidations; Glycals; Stereoselective reactions; Thiazolidinethiones; Titanium enolates

Indexed keywords

GLYCOSIDE; TITANIUM;

ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; CHIRALITY; GLYCOSIDATION; STEREOCHEMISTRY; SYNTHESIS;

EID: 72049098809     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0029-1218279     Document Type: Article

References (30)

1. Current address: School of Biological and Chemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, UK
2. (a)Ravishankar R, Surolia A, Vijayan M, Lim S, Kishi Y, J. Am. Chem. Soc. 1998 120 11297
3. (b)Mikkelsen L M., Hernaiz M J., Martín-Pastor M, Skrydstrup T, Jiménez-Barbero J, J. Am. Chem. Soc. 2002 124 14940
4. (c)Yang G, Schmieg J, Tsuji M, Franck R W., Angew. Chem. Int. Ed. 2004 43 3818
5. (a)Faul M M., Huff B E., Chem. Rev. 2000 100 2407, Yeung K.-S
6. (b)Paterson I, Chem. Rev. 2005 105 4237
7. (c)Nakata T, Chem. Rev. 2005 105 4314
8. (d)Clarke P A., Santos S, Eur. J. Org. Chem. 2006 2045
9. (e)Larrosa I, Romea P, Urpí F, Tetrahedron 2008 64 2683
10. (a)Du Y, Linhardt R J., Vlahov I R., Tetrahedron 1998 54 9913
11. (b)Ferrier R J., Zubkov O A., Org. React. 2003 62 569
12. (c)Postema M H. D., Piper J L., Komanduri V, Betts R L., ACS Symposium Series 2005 896 23; and references therein
13. For additions of metal enolates to five-membered oxocarbenium ions, see:,(a)Jalce G, Seck M, Franck X, Hocquemiller R, Figadère B, J. Org. Chem. 2004 69 3240
14. (b)Pilli R A., Riatto V B., J. Braz. Chem. Soc. 2008 19 583
15. (c)Jalce G, Franck X, Figadère B, Eur. J. Org. Chem. 2009 378
16. As occurs in the greater part of C-glycosidation methodo-logies, those described in reference 5 are unable to provide both stereochemistries from a single glycosyl donor. For an exception, see:, Allwein S P., Cox J M., Howard B E., Johnson H W. B., Rainier J D., Tetrahedron 2002 58 1997
17. (a)Larrosa I, Romea P, Urpí F, Balsells D, Vilarrasa J, Font-Bardia M, Solans X, Org. Lett. 2002 4 4651
18. (b)Larrosa I, Romea P, Urpí F, Org. Lett. 2006 8 527
19. Unsubstituted enolates usually provide poorer levels of stereocontrol than the related substituted counterparts in carbon-carbon bond forming reactions. See, for instance, the aldol paradigm: Modern Aldol Reactions, Mahrwald R, Wiley-VCH Weinheim 2004
20. (a)For the synthesis of N -acyl-1,3-thiazolidine-2-thiones, see:, Baiget J, Cosp A, Gálvez E, Gómez-Pinal L, Romea P, Urpí F, Tetrahedron 2008 64 5637
21. (b)Gálvez E, Romea P, Urpí F, Org. Synth. 2009 86 70
22. The a- and b-stereochemistry of C-glycosides was established through NMR studies, involving NOESY experiments that uncovered diagnostic interactions (Figure 1).
23. Representative procedure: Neat TiCl4 (0.12 mL, 1.1 mmol)was added dropwise to a solution of 2 (203 mg, 1.0 mmol) in CH2Cl2 (8 mL), at 0 °C under N2. The yellow suspension was stirred for 5 min at 0 °C, cooled to -78 °C, and a solution of i-Pr2NEt (0.19 mL, 1.1 mmol) in CH2Cl2 (1.5mL) was added. The dark-red enolate solution was stirred for 30 min at -78 °C and 2 h at -50 °C. Then, 1 M SnCl4 in CH2Cl2 (1.1 mL, 1.1 mmol) followed by tri-O-acetylgalactal (a; 136 mg, 0.5 mmol) in CH2Cl2 (1.5 mL) were successively added dropwise at -78 °C. The resulting mixture was stirred at -78 °C for 30 min and kept at -20 °C for 72 h. The reaction was cooled at -78 °C and quenched by the addition of saturated NH4Cl (6 mL) with vigorous stirring. The layers were separated, the aqueous layer was re-extracted with CH2Cl2, and the combined organic extracts were dried (Na2SO4), filtered and concentrated. Analysis of the resultant oil by HPLC and 1H NMR showed the presence of a single diastereomer. The product was then purified by column chromatography on deactivated (2.5% Et3N) silica gel (CH2Cl2-EtOAc, 95:5), to afford b-C-glycoside 6a (159mg, 0.38 mmol, 76% yield) as a viscous yellow oil. Rf = 0.7 (CH2Cl2-EtOAc, 95:5). [a]D -181 (c 0.9, CHCl3). IR (film): 2964, 1738, 1699, 1369, 1235, 1170, 1044 cm-1. 1H NMR (400 MHz, CDCl3): d = 6.08 (dd, J = 10.0, 1.2 Hz, 1H, CH=CHCHOAc), 6.03 (ddd, J = 10.0, 4.9, 2.0 Hz, 1 H, CH=CHCHOAc), 5.16-5.11 (m, 1 H, NCH), 5.10-5.06 (m,1 H, CHOAc), 4.75-4.68 (m, 1 H, OCHCH=CH), 4.22-4.16 (m, 2 H, CH2OAc), 3.92 (td, J = 6.4, 2.4 Hz, 1 H,OCHCH2OAc), 3.60-3.46 (m, 3 H, SCHxHy and COCH2),3.04 (dd, J = 11.6, 1.2 Hz, 1 H, SCHxHy), 2.44-2.32 [m, 1 H,CH(CH3)2], 2.08 (s, 3 H, CH3CO), 2.06 (s, 3 H, CH3CO),1.07 (d, J = 6.8 Hz, 3 H, CH3), 0.99 (d, J = 6.8 Hz, 3 H,CH3). 13C NMR (100.6 MHz, CDCl3): d = 202.9, 170.7,170.6, 170.4, 135.1, 123.2, 73.8, 71.7, 71.6, 63.8, 62.8, 43.3,30.8 (-2), 21.0, 20.8, 19.1, 17.8. HRMS (+FAB): m/z [M +H]+ calcd for C18H26NO6S2: 416.1202; found: 416.1200.
24. Moreira I De P.R., Bofill J M., Anglada J M., Solsona J G., Nebot J, Romea P, Urpí F, J. Am. Chem. Soc. 2008 130 3242
25. Configurations of 7a and 7b were secured by comparison with data published in the literature, see:(a)Procopio A, Dalpozzo R, DeNino A, Nardi M, Russo B, Tagarelli A, Synthesis 2006 332
26. (b)Wipf P, Uto Y, Yoshimura E, Chem. Eur. J. 2002 8 1670
27. Adducts 9 and 10 were isolated in low yields because of the sensitivity of the 1,3-thiazolidine-2-thione auxiliary. Yields reported in Table 2 were not optimized.
28. For an insightful analysis into the mechanisms of glycosidation processes on six-membered cyclic systems, see:(a)Ayala L, Lucero C G., Romero J A. C., Tabacco S A., Woerpel K A., J. Am. Chem. Soc. 2003 125 15521
29. (a)Shenoy S R., Smith D M., Woerpel K A., J. Am. Chem. Soc. 2006 128 8671
30. (c)Krumper J R., Salamant W A., Woerpel K A., Org. Lett. 2008 10 4907