Torquoelectronic effect in the control of the stereoselectivity of ketene-imine cycloaddition reactions

Theoretical study of the conformational and electrostatic properties of C4-monosubstituted 2-azetidinones

“…The conformational preferences of I have been investigated at both semiempirical [11] and ab initio [12] levels, in the latter using the medium size 6-3 IG basis set. On the other hand, the mechanism of the ketene-imine cycloaddition reaction, which is one of the methods leading to the formation of ~-lactams, has been investigated using high-level quantum mechanical calculations [13][14][15][16][17]. Furthermore, the effect of solvation on the mechanism of this reaction has been examined using a self-consistent reaction-field (SCRF) procedure [17].…”

Facile synthesis of 3-(1-(4'-(3-chloro-2-(substituted phenyl)-4-oxoazetidin-1-yl)biphenyl-4-yl)-5-oxo-2-phenyl-1H-imidazol-4(5H)-ylidene)indolin-2-ones: β-Lactam derivatives as antimicrobes

“…These compounds were purified with column chromatography and the yields mentioned are of the major isolable fractions which were characterized by different spectroscopic techniques. The title compounds, 3-(1-(4'-(3-chloro-2-(substituted phenyl)-4-oxoazetidin-1-yl)biphenyl-4-yl)-5-oxo-2-phenyl-1H-imidazol-4(5H)-ylidene)indolin-2-ones (6a-e) and 3-(1-(3-chloro-2-(substituted phenyl)-4-oxoazetidin-1-yl)-5-oxo-2-phenyl-1H-imidazol-4(5H)-ylidene) indolin-2-ones (7a-e), were obtained by the treatment of 4a-e and 5a-e with chloroacetyl chloride in dioxane in presence of triethylamine and were found to have cis geometry [22][23]. IR and 1 H NMR spectra of these compounds were well in agreement with the structures assigned.…”

Synthesis and antimicrobial evaluation of novel benzo[b]thiophenes comprising β-lactam nucleus

“…The cistrans stereochemistry depends mainly upon the substituents on the ketene parts as the imine (azomethines) is usually presumed to exist in the more stable E-configuration. The stereochemical outcome can be explained involving the (Rondan and Houk, 1985), and later utilized by Lopez et al (Lopez et al, 1993). Based on this concept, the preference of donor (alkoxy, aryloxy) or acceptor (thioalkoxy, thioaryloxy, chloride) groups on the ketene would decide about the structure of the involved intermediate ( …”