Addition of tricthylamine to a mixture of 2-pyridylthioesters and SnCl4 or SnBr4 affords the corresponding tin(IV) enolates that add to imines to give beta-lactams in fair to good yields and with various degree of trans/cis stereoselectivity. Examples of highly diastereofacially selective reactions carried out on a chiral thioester and on a chiral imine are also reported. The results are compared with those obtained in the condensations promoted by TiCl4 and TiBr4.
SYNTHESIS OF BETA-LACTAMS BY CONDENSATION OF THE TIN ENOLATES OF 2-PYRIDYLTHIOESTERS WITH IMINES - A COMPARISON BETWEEN TITANIUM AND TIN ENOLATES / R. ANNUNZIATA, M. BENAGLIA, M. CINQUINI, F. COZZI, L. RAIMONDI. - In: TETRAHEDRON. - ISSN 0040-4020. - 50:19(1994), pp. 5821-5828.
SYNTHESIS OF BETA-LACTAMS BY CONDENSATION OF THE TIN ENOLATES OF 2-PYRIDYLTHIOESTERS WITH IMINES - A COMPARISON BETWEEN TITANIUM AND TIN ENOLATES
R. ANNUNZIATAPrimo
;M. BENAGLIASecondo
;M. CINQUINI;F. COZZIPenultimo
;L. RAIMONDIUltimo
1994
Abstract
Addition of tricthylamine to a mixture of 2-pyridylthioesters and SnCl4 or SnBr4 affords the corresponding tin(IV) enolates that add to imines to give beta-lactams in fair to good yields and with various degree of trans/cis stereoselectivity. Examples of highly diastereofacially selective reactions carried out on a chiral thioester and on a chiral imine are also reported. The results are compared with those obtained in the condensations promoted by TiCl4 and TiBr4.
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