Abstract: | By condensation of tert-butyl 3-methyl-7-oxoceph-3-em-4-carboxylate and its 3-acetoxymethyl analog with acetylmethylenetriphenylphosphorane
and 3-trimethylsilylpropyn-2-ylindenetriphenylphosphorane tert-butyl 7Z-acetylmethylene-3-methylceph-3-em-4-carboxylate and
also 7Z-and 7E-isomers of tert-butyl 3-acetoxymethyl-7-(3-trimethylsilylpropyn-2-ylidene)ceph-3-em-4-carboxylates were synthesized.
Oxidation of these compounds with 1 equivalent of meta-chloroperbenzoic acid gave their 1R-and 1S-sulfoxides, and oxidation
with 2 equivalents gave the corresponding sulfones. According to data from 1H NMR spectroscopy, the carbonyl of the β-lactam descreens proton H-9 of the alkylidene group in the 7Z-isomers more strongly
than in the 7E-isomers, shifting their signals to weaker field. Analogous shifts of the H-6 signal to weaker field was observed
in the 1R-sulfoxides in comparison with that for the 1S-sulfoxide. These results were confirmed by X-ray crystallography of
tert-butyl 7Z-acetylmethylene-3-methyl-1S-oxoceph-3-em-4-carboxylate and tert-butyl 7Z-acetylmethylene-3-methyl-1,1-dioxoceph-3-em-4-carboxy-late.
In memory of Professor A.A. Potekhin
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 618–626, April, 2008. |