Stereoselective synthesis of 4-amino-2, 3-unsaturated-N-Cbz-imino-O- glycosides via new diastereoisomeric N-Cbz-imino glycal-derived allyl N-nosyl aziridines

Organic Letters

Volumn 11, Issue 12, 2009, Pages 2675-2678

  Bussolo, Valeria Di ^a   Fiasella, Annalisa ^a   Favero, Lucilla ^a   Bertolini, Ferruccio ^a   Crotti, Paolo ^a  

^a UNIVERSITY OF PISA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

ALCOHOL DERIVATIVE; AMINOGLYCOSIDE; AZIRIDINE DERIVATIVE; GLYCOSIDE; IMINOSUGAR;

ARTICLE; CHEMICAL STRUCTURE; CHEMISTRY; GLYCOSYLATION; STEREOISOMERISM; SYNTHESIS;

ALCOHOLS; AMINOGLYCOSIDES; AZIRIDINES; GLYCOSIDES; GLYCOSYLATION; IMINO SUGARS; MOLECULAR STRUCTURE; STEREOISOMERISM;

EID: 67149136455     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol900742p     Document Type: Article

References (25)

1. Di Bussolo, V.; Fiasella, A.; Romano, M. R.; Favero, L.; Pineschi, M.; Crotti, P. Org. Lett. 2007, 9, 4479.
2. Afarinkia, K.; Bahar, A. Tetrahedron: Asymmetry 2005, 16, 1239.
3. Dihydroxylation of the double bond of O-glycosides 7 and 8 should reasonably occur in the opposite direction to the substituents on C(1) and C(4) and lead to azapyranosides 9 and 10, respectively, which can be transformed into the corresponding 4-amino-l-deoxy-azasugars 11 and 12 by deprotection of the N-Cbz group. See, for example: Tschamber, T.; Backenstrass, F.; Neuburger, M.; Zehnder, M.; Streith, J. Tetrahedron 1994, 50, 1135.
4. A β-stereoselective introduction of a - NHAc group on C(4) of an iminosugar precursor has been recently described: Toumieux, S.; Compain, P.; Martin, O. R. J. Org. Chem. 2008, 73, 2155.
5. (a) Comins, D. L.; Joseph, S. P.; Goehring, R. R. J. Am. Chem. Soc. 1994, 116, 4719
6. (b) Comins, D. L.; Goehring, R. R.; Joseph, S. P.; O'Connor, S. J. Org. Chem. 1990, 55, 2574
7. (c) Comins, D. L.; Brown, J. D. Tetrahedron Lett. 1986, 27, 4549
8. (d) Comins, D. L.; Fulp, A. B. Tetrahedron Lett. 2001, 42, 6839.
9. 2OBn group on the C(5) of a glycal-derived allyl oxirane system with the simpler methyl group has no influence on the completely regio- and stereoselective glycosylation of O-nucleophiles or on the conformational equilibrium of these systems: Di Bussolo, V.; Favero, L.; Romano, M. R.; Pineschi, M.; Crotti, P. Tetrahedron 2008, 64, 8188, and references therein. The same behavior can reasonably be expected with the 6-deoxy aziridines 5 and 6 and the related 6-OBn-substituted aziridines 3 and 4. As a consequence, the results which are obtained with aziridines 5 and 6 can reasonably be extended to aziridines 3 and 4 too,
10. 5a
11. Luche, J.-L.; Gemal, A. L. J. Am. Chem. Soc. 1979, 101, 5848.
12. 2) to a-mesyloxy ketone 20 (89% yield).
13. 3 for aziridines) of the corresponding stable precursor and made to react immediately with a nucleophile,
14. The recycling of diacetate 25 and diol 24 makes the overall yield of the desired trans-hydroxy acetate 26 more acceptable.
15. 6
16. Zou, W.; Sandbhor, M.; Bhasin, M. J. Org. Chem. 2007, 72, 1226.
17. The azidolysis of epoxide 19 by TMGA is not completely stereoselective, leading to an 8:2 mixture of trans-azido alcohol t-32 and diastereoisomeric cis-azido alcohol c-32. Separation by flash chromatography afforded pure trans-azido alcohol t-32.
18. 3 (3 equiv).
19. In the reaction of aziridine 6 with t-BuOH, the corresponding β-O-glycoside 44β is accompanied by a certain amount (about 20%) of an unidentified nonaddition product (see Supporting Information).
20. The result obtained with aziridine 5 in the presence of a large amount of MeOH could be due to a certain intrinsic tendency of iminoglycal systems towards a product-dependent selectivity.
21. In the reaction of aziridine 6 with diacetone-D-glucose, β-O-glycoside 47β is obtained as a mixture of corresponding D.L-diastereoisomers (see Supporting Information).
22. 1H NMR spectra and appropriate NOE experiments.
23. Theoretical calculations, carried out on appropriate, simplified models (5-Ac and 6-Ac), indicated that aziridines 5 and 6 exist as the only corresponding conformer 5A and 6B, respectively, with the methyl group axial (Scheme 7) (see Supporting Information).
24. Di Bussolo, V.; Romano, M. R.; Pineschi, M.; Crotti, P. Tetrahedron 2007, 63, 2482, and references therein.
25. 3) can reasonably be applied to all the other 4-(N-nosylamino)-O-glycosides synthesized (Scheme 6).