Stereoselective synthesis of a new enantiopure tricyclic β-lactam derivative via a tricarbonyl(η6-arene)chromium(0) complex
作者:Paola Del Buttero、Clara Baldoli、Giorgio Molteni、Tullio Pilati
DOI:10.1016/s0957-4166(00)00137-3
日期:2000.5
tricyclic β-lactam 5 has been synthesized both in racemic and enantiopure form starting from the enantiomericallypuretricarbonylchromium(0) complex 1. The synthetic sequence involves the stereoselective [2+2] cycloaddition of 1 with acetoxyacetylketene, followed by intramolecular aromatic nucleophilic substitution of the fluorine atom. Mechanistic pathways leading to 5 are discussed.
Lipase-catalyzed resolution of 4-aryl-substituted β-lactams: effect of substitution on the 4-aryl ring
作者:Jason A Carr、Talal F Al-Azemi、Timothy E Long、Jeung-Yeop Shim、Cristina M Coates、Edward Turos、Kirpal S Bisht
DOI:10.1016/j.tet.2003.09.057
日期:2003.11
reactions occurred with high enantioselectivity and substrate conversion. The effect of substitution on the C-4 aryl ring on lipase hydrolytic activity was dependent upon the steric and electronic nature of the substituent and its position on the aryl ring. The stereopreference of the lipase PS-30 for the (3S,4R) enantiomer was rationalized using a known active site model. Absolute stereochemistry of the