Fibrinolysis

Are the known Δ2‐cephems inactive as antibiotics because of an unfavourable steric orientation of their 4α‐carboxylic group? Synthesis and biology of two Δ2‐cephem‐4β‐carboxylic acids

“…Thus, it has to be concluded that an activity model based solely on a good fit of the P-lactam compound with the active site of the transpeptidase fails to explain the above mentioned biological results. On the other hand, we feel it incorrect to reject, because of the biological inactivity of the two P-oriented A'-cephem acids, the conclusions about geometrical requirements for antibacterial activity of P-lactam antibiotics as presented in the quoted paper by Cohen [5]. Considering this failure of the steric model on the one hand, and the difficulties encountered with the reactivity model on the other hand, we now tend to believe ~ this somewhat contrarily to the conclusions of FrPre et al [4] that for a good antibiotic activity a subtle combination of both features, namely a 3-D recognition and a sufficient chemical reactivity of the P-lactam, are necessary.…”

“…), 3050, 1754, 1680, 1625, 1535, 1496, 1442, 1387, 1355, 1236, 1085. 'H-NMR (400 MHz, CD30D): 7.29~-6.96 (m. 5 H); 6.28 (d, J = 10, 1 H); 5.83 (d, J = 10, I H); 5.48 (d, J = 4, 1 H); 5 Benzhydryl 3a-Hydroxy-48-methyl-78-(2-phenoxyacetamido)cepham-4a-carbo.xylate 6, (14). Reduction of 6.25 g (1 1.8 mmol) of 4 in a way similar to that described above for the preparation of 6 (60 ml of DMF, 15 ml of AcOH, 840 mg of NaBH,; 90 min at 0") gave, after chromatography of the crude product on 300 g of Merck silica gel 60 with toluene/AcOEt 19:1, 3.48 g (55.5%) of 14.…”

“…565(5) 4.472 (5) 4). 325 (5) 0.066(5) 0.087(5) 0.12 1 ( 5 ) 0.259(5) 0.402(5) 0.448 (5) 0.358 (5) 0.216 (5)…”

The Harmony of Molecules

“…C is a normalization constant. An example is given in the work of Cohen [29]. On the basis of our cited work, we used two descriptors to divide these molecules in two groups.…”