10.1039/c39870000081
The research details the preparation of penicillin-2-carboxylate systems and their conversion into 2-methylene penam and 2-methyl penem systems through a decarboxylative Pummerer reaction. The purpose of this study was to synthesize the 2-exomethylene penam system, which serves as a structural bridge between penicillin and clavulanic acid, and was previously unknown. The researchers successfully synthesized this system and demonstrated its conversion to other penicillin derivatives. Key chemicals used in the process included penicillin V, various oxidants, dimethyl sulphoxide (DMSO), oxalyl chloride, pyridine, 2,6-lutidine, molecular sieves, and phosphorus tribromide in dimethylformamide (DMF). The conclusions drawn from the study indicated that the synthesized compounds, including the 2-exomethylene penam system and the dicarboxylate (12), showed comparable antibacterial activity to penicillin V, while the amide (21) exhibited an order of magnitude lower in activity.
10.1016/S0040-4039(01)81957-2
The study presents a novel, high-yield synthesis of the 1-carbapenam ring system, a precursor to thienamycin and clavulanic acid analogs. The entire carbon framework is introduced in a single step from simple precursors. Benzyl sorbate is isomerized to 3,5-hexadienoate, which reacts with chlorosulfonyl isocyanate to form B-lactam. This compound is then converted to an iodo-hydrin, reduced to an alcohol, and oxidized to a ketoester. The ketoester undergoes diazo group transfer and rhodium-catalyzed ring closure to form the final product. The study also explores the synthesis of o-nitrobenzyl ester derivatives and attempts to convert these compounds to the corresponding acids, though these attempts were unsuccessful due to decomposition. The synthesized compounds are analyzed using various techniques, including IR, NMR, and mass spectrometry.