Synthesis of carba analogs of 6-O-(benzyl)-d-allal- and -d-galactal-derived allyl epoxides and evaluation of the regio- and stereoselective behavior in nucleophilic addition reactions

Tetrahedron

Volumn 67, Issue 25, 2011, Pages 4696-4709

  Di Bussolo, Valeria ^a   Frau, Ileana ^a   Checchia, Lorenzo ^a   Favero, Lucilla ^a   Pineschi, Mauro ^a   Uccello Barretta, Gloria ^a   Balzano, Federica ^a   Roselli, Graziella ^b   Renzi, Gabriele ^b   Crotti, Paolo ^a  

^a UNIVERSITY OF PISA   (Italy)

^b UNIVERSITY OF CAMERINO   (Italy)

Author keywords

Allyl epoxides; Glycal carba analogs; Glycomimetics; Nucleophilic addition; Regioselectivity

Indexed keywords

6 (BENZYLOXYMETHYL) 2 ACETOXY 3 CYCLOHEXEN 1 OL; 6 (BENZYLOXYMETHYL) 2 METHYL 3 CYCLOHEXEN 1 OL; 6 (BENZYLOXYMETHYL) 4 ACETOXY 2 CYCLOHEXEN 1 OL; 6 (BENZYLOXYMETHYL) 4 METHOXY 2 CYCLOHEXEN 1 OL; EPOXIDE; GLYCAN DERIVATIVE; NUCLEOPHILE; UNCLASSIFIED DRUG;

ADDITION REACTION; ARTICLE; CONFORMATION; METHANOLYSIS; PRIORITY JOURNAL; STEREOCHEMISTRY; SYNTHESIS;

EID: 79957748403     PISSN: 00404020     EISSN: 14645416     Source Type: Journal    
DOI: 10.1016/j.tet.2011.04.036     Document Type: Article

References (36)

1. O. Arjona, A.M. Gómez, J.C. López, and J. Plumet Chem. Rev. 107 2007 1919 2036
2. J. Marco-Contelles, M.T. Molina, and S. Anjum Chem. Rev. 104 2004 2857 2900
3. I. Cumpstey Carbohydr. Res. 344 2009 2285 2310
4. V. Di Bussolo, M. Caselli, M.R. Romano, M. Pineschi, and P. Crotti J. Org. Chem. 69 2004 7383 7386
5. V. Di Bussolo, M. Caselli, M.R. Romano, M. Pineschi, and P. Crotti J. Org. Chem. 69 2004 8702 8708
6. For the corresponding results from 6-deoxy derivatives of 6α and 6β, see: V. Di Bussolo, L. Favero, M.R. Romano, M. Pineschi, and P. Crotti Tetrahedron 64 2008 8188 8201
7. V. Di Bussolo, M.R. Romano, M. Pineschi, and P. Crotti Tetrahedron 63 2007 2482 2489 and references therein
8. V. Di Bussolo, L. Checchia, M.R. Romano, M. Pineschi, and P. Crotti Org. Lett. 10 2008 2493 2496. Corresponding 4-amino-substituted and 'mixed' oligosaccharides were also synthesized by reiterative application of the same glycosylation process to aziridine 2α
9. Unpublished results from our laboratory.
10. Epoxides 6α and 6β were prepared as corresponding racemic mixtures, considering that it was not necessary to have them as pure enantiomers for these preliminary studies on their reactivity.
11. S. Ogawa, K. Nishi, and Y. Shibata Carbohydr. Res. 206 1990 352 360
12. H. Tsunoda, and S. Ogawa Liebigs Ann. 1995 267 277
13. S. Ogawa, I. Kasahara, and T. Suami Bull. Chem. Soc. Jpn. 52 1979 118 123
14. S. Ogawa, T. Toyokuni, T. Kondoh, Y. Hattori, S. Iwasaki, M. Suetsugu, and T. Suami Bull. Chem. Soc. Jpn. 54 1981 2739 2746
15. H. Kotsuki, K. Asao, and H. Ohnishi Bull. Chem. Soc. Jpn. 57 1984 3339 3340
16. A. Balsamo, P. Crotti, B. Macchia, and F. Macchia Tetrahedron 29 1973 2183 2188
17. Evidently, the corresponding allyl trans-hydroxy acetate 18, the primary reaction product, is hydrolyzed in the reaction mixture to trans diol 13.
18. 2) in the presence of TsOH, the reactions are not regioselective, affording a 7:3 (hydrolysis) and 8:2 mixture (methanolysis) of the corresponding anti-1,2-addition product and 1,4-addition products (vide infra and see Table 1).
19. Obviously, the opening reactions of epoxides carried out in the gas-phase have no synthetic valence. They can only give information about the intrinsic reactivity of epoxides unperturbed by the effects of solvation and ion-pairing which affect, to a variable extent, the corresponding processes carried out in solution. Accordingly, this information can often be useful for the rationalization of the regio- and stereoselective behavior of the same epoxides in opening reactions carried out in the condensed phase. See, as an example: P. Crotti, V. Di Bussolo, F. Macchia, L. Favero, M. Pineschi, L. Lucarelli, G. Roselli, and G. Renzi J. Phys. Org. Chem. 18 2005 321 328 and references therein
20. +, the necessary gaseous catalyst of the reaction. The crude reaction product was examined by GC/MS (see Experimental section).
21. 4/MeOH).
22. These results would indicate that in epoxide 6β, the C(2) oxirane carbon is largely the more reactive center of the allyl system, to the point that in the presence of a low amount of O-nucleophile, it becomes the only reactive one.
23. The result obtained by AcOH/TsOH under protocol B reaction conditions (entry 8, Table 1) turned out to be particularly useful for the synthesis of epoxide 6α (see Scheme 7).
24. 1H NMR conformational analysis. A similar result was previously obtained by a theoretical conformational analysis carried out on the corresponding 6-methyl substituted epoxides, see: P. Crotti, V. Di Bussolo, C.S. Pomelli, and L. Favero Theor. Chem. Account 122 2009 245 256
25. The possibility that a corresponding syn-1,2-addition process of epoxide 6α can occur by an equatorial opening of the oxirane ring through the less stable conformer 6α″-H cannot reasonably be ruled out (Scheme 13). However, it was demonstrated that, in nucleophilic opening reactions, the 'axial cleavage' of 1,2-epoxycyclohexanes is easier than the corresponding 'equatorial cleavage' and favours the syn stereoselectivity of the addition process. See: C. Battistini, P. Crotti, D. Damiani, and F. Macchia J. Org. Chem. 44 1979 1643 1647 and references therein.
26. As previously demonstrated in the case of 2-aryl-oxiranes, we think that the syn-1,2-addition process leading to cis-2-acetoxy alcohol 27 derives from a nucleophile-separated ion-dipole pair, such as 34, followed by nucleophilic pseudoequatorial attack on the partially developed C(2) carbocation with retention of configuration (Scheme 13). See Ref. 12 and P. Crotti, G. Dell'Omodarme, M. Ferretti, and F. Macchia J. Am. Chem. Soc. 109 1987 1463 1469
27. 2 which are rapidly transformed into the furane derivative 1-F (unpublished results from our laboratory; for the sake of simplicity, only epoxide 1β is shown). For the formation of 1-F, see: Zamojski, A.; Chmielewski, M.; Konowal, A. Tetrahedron 1970, 26, 183-189.
28. N2′ pathway, previously observed in the gas-phase-acid-induced methanolysis of allyl alcohols. See: G. Renzi, A. Lombardozzi, E. Dezi, A. Pizzabiocca, and M. Speranza Chem. Eur. J. 2 1996 316 322
29. 3 was added, was a fast formation of ketone 39 observed.
30. P. Crotti, V. Di Bussolo, F. Bertolini, and M. Pineschi Curr. Org. Synth. 6 2009 290 324
31. J.P. Marino, and D.M. Floyd Tetrahedron Lett. 20 1979 675 678
32. Actually, epoxide 6α can react also by means of the less stable conformer 6α″. However, in the discussion, the attention was directed toward the more stable conformer 6α′ because only in this conformer a more favorable axial opening of the oxirane ring can occur (see Ref. 17a ).
33. N. Yoshikai, S.-L. Zhang, and E. Nakamura J. Am. Chem. Soc. 130 2008 12862 12863
34. J.-B. Langlois, and A. Alexakis Adv. Synth. Catal. 352 2010 447 457
35. F. Bertozzi, P. Crotti, F. Macchia, M. Pineschi, and B.L. Feringa Angew. Chem., Int. Ed. 40 2001 930 932
36. For a review on this topic, see also: M. Pineschi New J. Chem. 28 2004 657 665