Yuichi Sugimoto

Dicationic dithiocarbamate carbapenems with anti-MRSA activity.

A new class of 1 beta-methylcarbapenems bearing a doubly quaternarized 1,4-diazabicyclooctane (DABCO) substituted dithiocarbamate moiety at the C-2 side chain was prepared, and the biological profiles of the compounds, including in vitro and in vivo anti-MRSA activity and DHP-I susceptibility, were evaluated to identify a carbapenem derivative that was superior to BO-3482 (1). As a result, we discovered a 1 beta-methyl-2-[4-(4-carbamoylmethyl-1,4-diazabicyclo[2,2,2]octanediium-1-yl)methyl-1,2,3,6-tetrahydropyridinylthiocarbonylthio]carbapenem, 14a showing greater than 2-fold better anti-MRSA activity in a mouse infection model and 3-fold better DHP-I susceptibility as compared with BO-3482 (1).

IPC synthase as a useful target for antifungal drugs.

Inositol phosphorylceramide (IPC) synthase is a common and essential enzyme in fungi and plants, which catalyzes the transfer of phosphoinositol to the C-1 hydroxy of ceramide to produce IPC. This reaction is a key step in fungal sphingolipid biosynthesis, therefore the enzyme is a potential target for the development of nontoxic therapeutic antifungal agents. Natural products with a desired biological activity, aureobasidin A (AbA), khafrefungin, and galbonolide A, have been reported. AbA, a cyclic depsipeptide containing 8 amino acids and a hydroxyl acid, is a broad spectrum antifungal with strong activity against many pathogenic fungi such as Candida spp., Cryptococcus neoformans, and some Aspergillus spp. Khafrefungin, an aldonic acid ester with a C22 long alkyl chain, has antifungal activity against C. albicans, Cr. Neoformans, and Saccharomyces cerevisiae. Galbonolide A is a 14-membered macrolide with fungicidal activity against clinically important strains, and is especially potent against Cr. neoformans. These classes of natural products are potent and specific antifungal agents. We review current progress in the development of IPC synthase inhibitors with antifungal activities, and present structure-activity relationships (SAR), physicochemical and structural properties, and synthetic methodology for chemical modification.

A novel method for the generation of 2,3-naphthoquinodimethanes utilizing samarium(II) iodide-promoted allene synthesis

Abstract 2,3-Naphthoquinodimethanes are easily generated from o-bis(α-acetoxypropargyl)benzene derivatives with SmI 2 in the presence of palladium catalyst under mild conditions. The reactions of the quinodimethane intermediates were found to follow the different paths depending on the acetylenic substituents of substrates.

A novel class of cycloalkano[b]pyridines as potent and orally active opioid receptor-like 1 antagonists with minimal binding affinity to the hERG K+ channel.

A series of compounds based on 7-{[4-(2-methylphenyl)piperidin-1-yl]methyl}-6,7,8,9-tetrahydro-5 H-cyclohepta[ b]pyridine-9-ol ( (-)-8b), a potent and selective opioid receptor-like 1 (ORL1) antagonist, was prepared and evaluated using structure-activity relationship studies with the aim of removing its affinity to human ether-a-go-go related gene (hERG) K (+) channel. From these studies, 10l was identified as an optimized structure with respect to ORL1 antagonist activity, and affinity to the hERG K (+)channel. Furthermore, 10l showed good in vivo antagonism with a wide therapeutic index in regards to adverse cardiovascular effects.

Stereoselective Synthesis of a Broad Spectrum 1β-Methylcarbapenem, J-114,870

Abstract An ultra-broad spectrum carbapenem, J-114,870 (1), was synthesized from the corresponding C-2 side chain and 1β-methylcarbapenem enolphosphate. Synthesis of the C-2 side chain was accomplished by installation of the benzene part to (4R)-hydroxy-2-pyrrolidone 3, affording 2-phenylpyrrolidine 8a, and asymmetric Michael addition of chiral amine to α,β-unsaturated ester derived from 8a.

Synthesis of aplysiatoxin: stereoselective synthesis of key fragments

Abstract Stereoselective synthesis of key fragments for the synthesis of aplysiatoxin has been achieved. All the stereogenic carbons contained in fragments B≈E were elaborated on the basis of [2,3] Wittig rearrangement and titanium-mediated asymmetric epoxidation.

Design, synthesis, and biological evaluations of novel 7-[7-amino-7-methyl-5-azaspiro[2.4]heptan-5-yl]-8-methoxyquinolines with potent antibacterial activity against respiratory pathogens.

Novel 7-[7-amino-7-methyl-5-azaspiro[2.4]heptan-5-yl]-6-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]- 8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid 2a and 2b were designed and synthesized to obtain potent antibacterial drugs for the treatment of respiratory tract infections. Among these, compound 2a possessing (S)-configuration for the asymmetrical carbon on the pyrolidine moiety at the C-7 position of the quinolone scaffold exhibited potent in vitro antibacterial activity against respiratory pathogens including gram-positive (Streptococcus pneumoniae and Staphylococcus aureus), gram-negative (Haemophilus influenzae and Moraxcella catarrhalis), and atypical strains (Chalmydia pneumoniae and Mycoplasma pneumoniae), as well as multidrug-resistant Streptococcus pneumoniae and quinolone-resistant and methicillin-resistant Staphylococcus aureus). Furthermore, compound 2a showed excellent in vivo activity against the experimental murine pneumonia model due to multidrug resistant Streptococcus pneumoniae (MDRSP) and favorable profiles in preliminary toxicological and nonclinical pharmacokinetic studies.

One-carbon extrusion from carbohydrates via C1-alkoxy radical fragmentation. An easy access to erythrose and threose

Abstract Generation and fragmentation of the C1-alkoxy radicals of pyranose derivatives are nicely promoted by (diacetoxyiodo)benzene or lead tetraacetate in the presence of iodine catalyst under mild conditions to give the corresponding mixed-acetal formates which are further converted to the furanose derivatives by acid-catalysed transacetalization.

Synthesis and biological evaluation of imidazole derivatives as novel NOP/ORL1 receptor antagonists: Exploration and optimization of alternative pyrazole structure

Nonpeptidic small-molecule NOP/ORL1 receptor antagonists with an imidazole scaffold were designed and synthesized to investigate alternatives to the pyrazole analog. Systematic modification of the original pyrazole lead [Kobayashi et al., Bioorg. Med. Chem. Lett.2009, 19, 3627; Kobayashi et al., Bioorg. Med. Chem. Lett., in press] to change the heterocyclic core, substituted side chain, and pendant functional group demonstrated that examining the structure-activity relationship for novel templates allowed the identification of potent, fully substituted 4-aminomethyl-1H-imidazole and 2-aminomethyl-1H-imidazole. These compounds exhibited excellent potency for ORL1 receptor with minimal P-gp efflux and/or reduced hERG affinity.

Structure–Activity Relationships of 1β-Methyl-2-(5-phenylpyrrolidin-3-ylthio)carbapenems

Structure--activity relationship studies of 1beta-methyl-2-[(3S,5R)-5-(4-aminomethylphenyl)pyrrolidin-3-ylthio]carbapenems, especially those pertaining to the relationship between antibacterial activity and side-chain structure were conducted. These studies suggested that the trans-(3S,5R)-5-phenylpyrrolidin-3-ylthio side-chain and the aminomethyl group at the 4-position of the phenyl ring play a key role in enhancing the antibacterial activity against the MRSA and Pseudomonas aeruginosa strains. In particular, the basicity of a substituent at the 4-position of the phenyl ring were shown to greatly contribute to the antibacterial activity against MRSA and methicillin-resistant Staphyloccocus epidermidis strains. In contrast, the amidine group was shown to lead to potent antibacterial activity against P. aeruginosa strains comparable to that of imipenem, however, a good correlation between the basicity of the 4-substituent and antipseudomonal activity was not observed. In conclusion, the 4-aminomethyl or methylaminomethyl group on the phenyl ring was the best substituent for antipseudomonal activity.