Alkyl groups on the metal enhance the reactivity of the 'classical' zirconium enolate of 1-methoxycyclohexanone

Tetrahedron Asymmetry

Volumn 7, Issue 11, 1996, Pages 3079-3082

  Giacobbe, Simone A ^a   Rossi, Tino ^a  

^a GSK   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

BETA LACTAM ANTIBIOTIC; SANFETRINEM; TRINEM DERIVATIVE;

ARTICLE; CATALYSIS; DRUG SYNTHESIS; PRIORITY JOURNAL; REACTION ANALYSIS;

EID: 0030575810     PISSN: 09574166     EISSN: None     Source Type: Journal    
DOI: 10.1016/0957-4166(96)00402-8     Document Type: Article

References (27)

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2. 2. This class of compounds was formerly referred to as the tribactams. See Gaviraghi, G.Eur. J. Med. Chem. 1995, 30, 467.
3. 3. a) Di Modugno, E.; Erbetti, I.; Ferrari, L.; Galassi, G. L.; Hammond, S. M.; Xerri, L. Antimicrob. Agents Chemother. 1994, 38, 2362 and references cited therein.
4. 4. (3r,4R,1'R)-(+)-4-Acetoxy-3-[1'-(tert-butyldimethylsilyl)oxy]ethyl-2-azetidinone is commercially available from Aldrich Chemical Company Inc.,Milwakee, WI.
5. 5. For a review on the topic see Wild, H. In The Organic Chemistry of β-Lactams; Georg, G. I. Ed.; VCH Publisher: New York, NY, 1993; chapter 2.
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11. 9. Kim, C. U.; Luh, B.; Partyka, R.A. Tetrahedron Lett. 1987, 28, 507.
12. 10. Endo, M. Can. J. Chem. 1987, 65, 2140.
13. 11. It is for this reason that in his paper Endo introduces the 4-chloro analogue of 3.
14. 12. Kowalski, C.; Creary, X.; Rollin, A. J.; Burke, C. M. J. Org. Chem. 1978, 43, 2601.
15. 13. Andreotti, D.; Rossi, T.; Gaviraghi, G.; Donati, D.; Marchioro, C.; Di Modugno, E.; Perboni, A. Bioorg. Med. Chem. Lett. 1996, 6, 491.
16. 14. Ghiron, C.; Piga, E.; Pecunioso, A. UK Patent Application GB 2,287,709 A
17. 15. a) Rossi, L.; Pecunioso, A. Tetrahedron Lett. 1994, 35, 5285
18. b) Ghiron, C.; Piga, E.; Rossi, T.; Tamburini, B.; Thomas, R. J. Tetrahedron Lett. 1996, 37, 3891.
19. 16. Since we never observed products derived from attack of the regioisomeric enolate onto azetidinone 3, we assume that both transmetallations proceed with retention of configuration of the enolate.
20. 4Cl (20 ml). After standard crude isolation, pure 2 was isolated by column chromatography (Cyclohexane/Ethyl acetate 6/4).
21. 18. a) Schwartz, J.; Labinger, J. A. Angew. Chem. Int. Ed. Engl. 1976, 15, 333.
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25. 20. Method B. A solution of 5 (476 mg, 2.8 mmol) in THF (30 ml) was treated at -10°C with MeLi (2.8 eq, 2 ml) for 15 min. After cooling to -78°C neat zirconocene dichloride (820 mg, 2.8 mmol) was added and stirring continued for 1 h. MeLi (2.8 eq, 2 ml) was then added very slowly so that the temperature of the solution never increased above -65°C; after stirring for 1h, neat 3 (400 mg, 1.4 mmol) followed by the appropriate amount of base were added, as indicated in Table I. For quenching and workup see ref 17.
26. 21. a) Williard, P.G., Nintze, M.J., J. Am. Chem. Soc., 1990, 112, 8602.
27. b) Gilchrist, J.H., Collum, D.B., J. Am. Chem. Soc., 1992, 114, 794.