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Chiral spiro-β-lactams from 6-diazopenicillanates
- Source :
-
Tetrahedron . May2012, Vol. 68 Issue 19, p3729-3737. 9p. - Publication Year :
- 2012
-
Abstract
- Abstract: Chiral spiro-β-lactam derivatives have been prepared via stereoselective 1,3-dipolar cycloaddition of 6-diazopenicillanates. Using dipolarophiles such as acrylonitrile, acrylates or methyl vinyl ketone spiro-2-pyrazoline-β-lactams were obtained, whereas the cycloaddition with N-substituted-maleimides afforded spiro-1-pyrazoline-β-lactams. 6-Diazopenicillanates also reacted with electron-deficient alkynes to give the corresponding spiro-3H-pyrazole-β-lactam as single product. The observed stereoselectivity can be explained considering that the major product results from the addition to the less sterically hindered α-side of the β-lactam. Microwave-induced denitrogenation of spiro-1-pyrazoline-β-lactams allowed the stereoselective synthesis of novel spirocyclopropyl-β-lactams. The rationalization of the observed selectivity was supported by electronic structure calculations. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 00404020
- Volume :
- 68
- Issue :
- 19
- Database :
- Academic Search Index
- Journal :
- Tetrahedron
- Publication Type :
- Academic Journal
- Accession number :
- 74410501
- Full Text :
- https://doi.org/10.1016/j.tet.2012.03.022