77359-58-1Relevant academic research and scientific papers
Kinetics and Mechanisms of Hydrolysis and Aminolysis of Thioxocephalosporins
Tsang, Wing Y.,Dhanda, Anupna,Schofield, Christopher J.,Page, Michael I.
, p. 339 - 344 (2007/10/03)
The effect of replacing the β-lactam carbonyl oxygen in cephalosporins by sulfur on their reactivity has been investigated. The second-order rate constant for alkaline hydrolysis of the sulfur analogue is 2-fold less than that for the natural cephalosporin. The thioxo derivative of cephalexin, with an amino group in the C7 side chain, undergoes β-lactam ring opening with intramolecular aminolysis by a reaction similar to that for cephalexin itself. However, the rate of intramolecular aminolysis for the S-analogue is 3 orders of magnitude greater than that for cephalexin. Furthermore, unlike cephalexin, intramolecular aminolysis in the S-analogue occurs up to pH 14 with no competitive hydrolysis. The rate of intermolecular aminolysis of natural cephalosporins is dominated by a second-order dependence on amine concentration, whereas that for thioxocephalosporins shows only a first-order term in amine. The Bronsted βnuc for the aminolysis of thioxo-cephalosporin is +0.39, indicative of rate-limiting formation of the tetrahedral intermediate with an early transition state with relatively little C-N bond formation.
Palladium Catalysis in Cephalosporin Chemistry: General Methodology for the Synthesis of Cephem Side Chains
Farina, Vittorio,Baker, Stephen R.,Benigni, Daniel A.,Hauck, Sheila I.,Sapino, Chester
, p. 5833 - 5847 (2007/10/02)
We describe in full the palladium-catalyzed coupling of 3-(triflyloxy)cephems with organotin compounds, leading to the synthesis of 3-alkenyl-, 3-alkynyl-, and 3-arylcephems under exceptionally mild conditions.While this approach was not satisfactory for
