Novel method for the synthesis of β-lactams by the reaction of α-bromocarboxylic acids with imines mediated by triphenylphosphine

Heterocycles

Volumn 68, Issue 3, 2006, Pages 453-457

  Kikuchi, Satoshi ^a   Hashimoto, Yukihiko ^a  

^a UNIVERSITY OF TOKYO   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33744524697     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/COM-05-10661     Document Type: Article

References (21)

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15. The reaction was also carried out under reflux conditions in other solvents, toluene and MeCN. However, the best results were obtained under benzene reflux condition.
16. We investigated the effects of the several substituents on the nitrogen atom of the imine. Then, p-methoxyphenyl group was found to be the best substituent to achieve the highest yield and selectivity.
17. Walker D., and Leib J. J. Org. Chem. 27 (1962) 4455
18. Palomo C., Ontoria J.M., Odriozola J.M., Alzpurua J.M., and Ganboa I. J. Chem. Soc., Chem. Commun. (1990) 248. Although there was the possibility that the reaction proceeded via the formation of ketenes, the product was obtained with trans-selectivity even in the reaction of 2-bromopropionic acid (Entry 7). So, this reaction mechanism was thought as that illustrated in Scheme 1. The cis-selective β-lactam formation of alkyl ketenes with imines was reported
19. 3): trans-isomer; δ 7.25-7.38 (m, 11H), 6.84 (d, 2H, J=8.7 Hz), 4.88 (d, 1H, J=1.8 Hz), 4.21 (d, 1H, J=1.8Hz), 3.74 (s, 3H). cis-isomer; δ 7.33 (d, 2H, J=9.0 Hz), 6.98-7.12 (m, 9H), 6.83 (d, 2H, J=9.3 Hz), 5.39 (d, 1H, J=6.3Hz), 5.00 (d, 1H, J=6.3Hz), 3.77 (s, 3H). IR(KBr): 3100-2900, 1740, 1510, 1490, 830, 820.
20. Regen S.L., and Lee D.P. J. Org. Chem. 40 (1975) 1669
21. Bernard M., and Ford W.T. J. Org. Chem. 48 (1983) 326