The synthesis and structure-activity relationships of a series of orally absorbed O-2-isocephems are described. These compounds possessed a D-[(p-hydroxyphenyl)glycyl]amino substituent at the 7-position while the substituent at the 3-position was varied. Relative to the analogous cephems, the O-2-isocephems exhibited comparable to better activity against Gram-positive organisms. Against Gram-negative organisms, their activity was variable but did indicate a lower beta-lactamase stability. Following oral administration, the O-2-isocephems generally exhibited longer half-lives but lower Cmax's and urinary recoveries.

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Racemic and enantiomeric p-nitrobenzyl carbapen-2-em-3-carboxylates 3, 3a, and 3b were prepared starting from inexpensive sorbic acid through the key intermediates, azetidinone esters 4, thus establishing a total synthesis of the p-nitrobenzyl ester of a natural product SQ 27,860. Optical resolution was achieved readily on azetidinone menthyl esters, 12. The absolute configurations were also established.

Die Reaktion zwischen dem Methylester (I) und dem Ester (III) dient als Ausgangspunkt zur Synthese des Racemats (V).