135560-63-3Relevant academic research and scientific papers
Diastereofacial selectivity in the reaction of chiral N-trimethylsilyl imines with ester enolates: Preparation of trans-azetidin-2-ones in high stereocontrolled fashion
Cainelli,Panunzio,Bandini,Martelli,Spunta
, p. 1685 - 1698 (2007/10/03)
Highly efficient chiral ester enolate-imine condensation, giving 3,4-disubstituted β-lactams with excellent trans-syn or trans-anti diastereoselectivity, is reported. The chiral information is included in the electrophilic partner of the condensation, nominally chiral α-, β-silyloxy- or alkoxy-N-trimethylsilyl-imines. The high diastereofacial selectivity is determined by the correct choice of the metal cations present in the reaction medium and the very nature of the hydroxy protecting group. By this procedure a number of azetidinones, intermediates in the synthesis of commercially interesting β-lactam antibiotics have been obtained. Fully assigned 1H and 13C NMR spectra of the so obtained azetidinones are reported.
β-Lactams from Ester Enolates and Silylimines: Enantioselective Synthesis of the trans-Carbapenem Antibiotics (+)-PS-5 and (+)-PS-6
Andreoli, Patrizia,Cainelli, Gianfranco,Panunzio, Mauro,Bandini, Elisa,Martelli, Giorgio,Spunta, Giuseppe
, p. 5984 - 5990 (2007/10/02)
A new synthetic route to the antibiotics (+)-PS-5 and (+)-PS-6 is described.The preparation involves a fully stereocontrolled reaction between the enantiomerically pure N-trimethylsilylimine of lactic or mandelic aldehyde and the lithium enolate of the tert-butyl butanoate or tert-butyl isovalerate, respectively.Conversion of the azetidinones obtained to 4-acetoxy derivatives via oxidative cleavage of the hydroxyethyl or hydroxybenzyl side chain and introduction of the necessary appendage in the position 4 of the azetidinone ring, followed by assemlage of the bicyclic ring system, afforded the natural trans-carbapenems (+)-PS-5 and (+)-PS-6.
