AuBr3-catalyzed thiooxime-to-carbonyl conversion: From chiral aliphatic nitro compounds to ketones without racemization

Organic Letters

Volumn 11, Issue 19, 2009, Pages 4414-4417

  Burés, Jordi ^a   Lsart, Carles ^a   Vllarrasa, Jaume ^a  

^a UNIVERSITY OF BARCELONA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 70350151697     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol9017722     Document Type: Article

References (35)

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11. (a) Burés, J.; Vilarrasa, J. Tetrahedron Lett. 2008, 49, 441. This method was based on (what we call) the BMZ reaction,
12. (b) Barton, D. H. R.; Motherwell, W. B.; Zard, S. Z. Tetrahedron Lett. 1984, 25, 3707.
13. 2R' moiety (e.g., for R' = Ar or EWG), but speaking in general the handicap was significant and restricted too much the application of our procedure.
14. Bures, J. Isart, C. Vilarrasa, J. Org. Lett. 2007, 9, 4635. In Table 1, entry 4, the oxime should have been, depicted as the Z isomer.
15. (a) Most of our sulfenylimines underwent hydrolysis on warming with 1 M. HCl or with Amberlite IR-120 (pH 2.2), but racemization or epimerization was then produced, as well as the cleavage of various protecting groups,
16. 3 (and a different mechanism.) has been described: Branchaud, B. P. J. Org. Chem. 1983, 48, 3531.
17. By adding 1 M HCl or 1 M HBr to a THF solution of 2a, hydrolysis to ketone 3a was complete after stirring overnight. However, as mentioned, these conditions did not suit us, as we plan to apply the reaction on acidsensitive polyfunctional substrates.
18. (a) Baes, C. F.; Mesmer, R. E. The Hydrolysis of Cations; Wiley: New York, 1976; pp 279-285.
19. (b) Usher, A.; McPhail, D. C.; Brugger, J. Geochim. Cosmochim. Acta 2009, 73, 3359 (a spectrophotometric study of aqueous Au(III) halide-hydroxide complexes). Also see ref la.
20. On the other hand, oximes PhQ=N-OBn)Me and PhC(=N-OPh)Me are not hydrolyzed under the conditions of entry 24 of Table 1.
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25. Recent review of N-S bond-containing compounds: (e) Davis, F. A. J. Org. Chem. 2006, 71, 8993.
26. 1H NMR, PhSSPh was formed predominantly,
27. 3HnONO alone reacted with la at low pH (1.5 equiv was required to fully decompose la, overnight at rt, pH 4.2), but not at all at pH 7.
28. 3 (10 mol %) at pH 7 did not improve the outcome of entry 28 of Table 1.
29. (a) Hanessian, S.; Shao, Z.; Warner, J. S. Org. Lett. 2006, 8, 4787, and references therein,
30. tBuCHO). See:
31. (c) Isart, C.; Burés, J.; Vilarrasa, J. Tetrahedron Lett. 2008, 49, 5414.
32. Pyrrole formation is unavoidable in most reductions of y-nitro ketones, since the intermediate oximes or imines react in situ with, the CO groups (formation of five-membered rings). Cf. refs 2d and 3b. Zard et al. took advantage of this reaction to prepare various interesting pyrroles: (a) Quiclet-Sire, B.; Thevenot, I.; Zard, S. Z. Tetrahedron Lett. 1995, 36, 9469.
33. (b) Barton, D. H. R.; Motherwell, W. B.; Simon, E. S.; Zard, S. Z. J. Chem. Soc. Perkin Trans. 1 1986, 2243.
34. (c) Barton, D. H. R.; Zard, S. Z. Chem. Commun. 1985, 1098. Under the conditions of Scheme 1, y-nitro acyclic ketones give pyrrole derivatives almost quantitatively.
35. 3, did not affect 2a.