Estrogen receptor beta-subtype selective tetrahydrofluorenones: use of a fused pyrazole as a phenol bioisostere

Synthesis of a series of fused pyrazole tetrahydrofluorenone analogs which are potent, ERbeta subtype selective ligands is described. Analogs possessing subnanomolar ERbeta binding, greater than 100-fold ERbeta-selectivity, and oral bioavailability are reported.

The discovery of tetrahydrofluorenones as a new class of estrogen receptor beta-subtype selective ligands

Synthesis and derivatization of a series of substituted tetrahydrofluorenone analogs giving potent, ERbeta subtype selective ligands are described. Several analogs possessing ERbeta binding affinities comparable to 17beta-estradiol but with greater than 75-fold selectivity over ERalpha are reported.

Synthesis and activity of 2-(sulfonamido)methyl-carbapenems: discovery of a novel, anti-MRSA 1,8-naphthosultam pharmacophore

A series of 1beta-methyl carbapenems substituted at the 2-position with lipophilic, acyclic and cyclic (sulfonamido)methyl groups was prepared and evaluated for activity against resistant gram-positive bacteria. From these studies, the 1,8-naphthosultamyl group emerged as a novel, PBP2a-binding, anti-MRSA pharmacophore worthy of further exploration.

Synthesis and properties of 2-(naphthosultamyl)methyl-carbapenems with potent anti-MRSA activity: discovery of L-786,392

A series of 1beta-methyl-2-(naphthosultamyl)methyl-carbapenems bearing dicationic groups on the naphthosultamyl moiety was prepared and evaluated for activity against resistant gram-positive bacteria. Based on a combination of excellent in vitro antibacterial activity, acceptable mouse acute toxicity, and a desirable fragmentation pattern on beta-lactam ring opening, the analog 2g (L-786,392) was selected for extended evaluation.

Reduced immunotoxicity and preservation of antibacterial activity in a releasable side-chain carbapenem antibiotic

A carbapenem antibiotic, L-786,392, was designed so that the side chain that provides high-affinity binding to the penicillin-binding proteins responsible for bacterial resistance was also the structural basis for ameliorating immunopathology. Expulsion of the side chain upon opening of the beta-lactam ring retained antibacterial activity while safely expelling the immunodominant epitope. L-786,392 was well tolerated in animal safety studies and had significant in vitro and in vivo activities against methicillin- and vancomycin-resistant Staphylococci and vancomycin-resistant Enterococci.

Heteroaryliumthio substituted carbapenem derivatives: synthesis and in vitro activity of 1 beta-methyl-2-(dihydropyrrolotriazoliumthio)carbapenems

The syntheses of five thiols, including three dihydropyrrolotriazoliumthiol salts, 1,4-dimethyl-5-mercaptomethyl-1,2,4-triazolium trifluoromethanesulfonate, and 6-mercapto-6,7-dihydro-5H-pyrazolo[1,2-a][1,2,4]triazolium chloride; and the addition of these thiols to 4-nitrobenzyl (1R,5R,6S)-2-(diphenylphosphono)oxy-6-[1(R)-hydroxyethyl]-1-met hylcarbapen-2-em-3-carboxylate and the subsequent hydrogenolysis of the addition products is described. The latter thiol provides a new route towards the preparation of L-627 (LJC 10,627). The compounds were evaluated in vitro against a panel of Gram-positive and Gram-negative bacteria and their antibacterial activities compared with imipenem. The compounds were measured for their hydrolytic stability to dehydropeptidase I (DHP-I) relative to imipenem. The five compounds generally had poorer Gram-positive and Pseudomonas activity than imipenem, although their Gram-negative activity was variably improved. The monocyclic triazolium analog was nearly comparable in overall activity to the four bicyclic heterarylium analogs evaluated, including L-627 (LJC 10,627). All compounds were more stable to DHP-I than imipenem, although minor differences existed among them.

Preparation and antibacterial activity of delta 1-thienamycin

delta 1-Thienamycin (2), a double-bond isomer of thienamycin, was prepared by isomerizing N-[[(p-nitrobenzyl)oxy]-carbonyl]thienamycin p-nitrobenzyl ester (5b) with DBU in Me2SO followed by hydrogenolysis of the protecting groups. When evaluated in a disc-diffusion antibacterial assay, delta 1-thienamycin was found to be essentially devoid of activity. The lack of antibacterial activity was ascribed to a chemically less reactive beta-lactam amide bond than that found in thienamycin.

A stereocontrolled, enantiomerically specific total synthesis of thienamycin

A versatile stereocontrolled total synthesis of thienamycin starting from L-aspartic acid is reported. Stereocontrol is achieved by potassium tri-sec-butylborohydride reduction of a thermodynamically formed 3 alpha-acetylazetidinone intermediate. The key [3.2.0] bicyclic ring system is prepared by a metal catalyzed carbene insertion reaction.