Several amines have been tested as chiral auxiliaries in the stereoselective synthesis of beta-lactams by condensation of the titanium enolates of 2-pyridyl thioesters with chiral imines. The amines were selected among the following classes of compounds: benzylic amines, beta-aminoalcohols, beta-heterosubstituted alpha-aminoesters. Inexpensive and available in both enantiomeric forms alpha-methylbenzylamine was identified as the chiral auxiliary that generally combines good reactivity and satisfactory levels of stereocontrol. To illustrate the potential of the method a precursor of a component of a renin inhibitor was prepared. A tentative rationalization of the stereochemical results is presented.
STEREOSELECTIVE SYNTHESIS OF BETA-LACTAMS BY CONDENSATION OF TITANIUM ENOLATES OF 2-PYRIDYL THIOESTERS WITH IMINES BEARING A CHIRAL AUXILIARY / R. ANNUNZIATA, M. BENAGLIA, M. CINQUINI, F. COZZI, L. RAIMONDI. - In: TETRAHEDRON. - ISSN 0040-4020. - 50:31(1994), pp. 9471-9486.
STEREOSELECTIVE SYNTHESIS OF BETA-LACTAMS BY CONDENSATION OF TITANIUM ENOLATES OF 2-PYRIDYL THIOESTERS WITH IMINES BEARING A CHIRAL AUXILIARY
R. ANNUNZIATAPrimo
;M. BENAGLIASecondo
;M. CINQUINI;F. COZZIPenultimo
;L. RAIMONDIUltimo
1994
Abstract
Several amines have been tested as chiral auxiliaries in the stereoselective synthesis of beta-lactams by condensation of the titanium enolates of 2-pyridyl thioesters with chiral imines. The amines were selected among the following classes of compounds: benzylic amines, beta-aminoalcohols, beta-heterosubstituted alpha-aminoesters. Inexpensive and available in both enantiomeric forms alpha-methylbenzylamine was identified as the chiral auxiliary that generally combines good reactivity and satisfactory levels of stereocontrol. To illustrate the potential of the method a precursor of a component of a renin inhibitor was prepared. A tentative rationalization of the stereochemical results is presented.Pubblicazioni consigliate
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