Application of the octacarbonyldicobalt-catalyzed carbonylation of ethyl diazoacetate for the one-pot synthesis of n-tert-butyl-trans-α- ethoxycmbonyl- β-phenyl-β-lactam

Eszter Fördos, Róbert Tuba, László Párkányl, Tamás Kégl, Ferenc Ungváry

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23 Citations (Scopus)

Abstract

N-tert-Butyl-trans-α-ethoxycarbonyl-β-phenyl-β-lactam has been prepared in 95% yield (GC) by the octacarbonyldicobalt-catalyzed carbonylation of ethyl diazoacetate in dichloromethane in the presence of ZV-tert-butylbenzaldimine at 10 °C and 75 bar pressure of carbon monoxide. The key step of the reaction is the catalytic formation of the highly reactive (ethoxycarbonyl)ketene from both of the intermediary complexes [Co 2(CO)7(CHCO2Et)] and [Co2(CO) 6(CITCO2Et)2], which is in situ scavenged by the imine in a [2+2] cycloaddition reaction. DPT (PBEPBE/6-31G **) calculations revealed that the reaction follows a two-step mechanism via a noncydic intermediate with a reaction free energy of -15.9 kcal/mol and a free-energy barrier of 24.7 kcal/mol for the second rate-limiting step. The computation also shows that the formation of the trans isomer is preferred both kinetically and thermodynamicaily.

Original languageEnglish
Pages (from-to)1994-2002
Number of pages9
JournalEuropean Journal of Organic Chemistry
Issue number12
DOIs
Publication statusPublished - Apr 1 2009

Keywords

  • C-C coupling
  • Carbene ligands
  • Carbonyl ligands
  • Cobalt
  • Density functional calculations
  • Lactams

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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