meso-meso, β-β, β-β Triply linked porphyrin arrays (porphyrin tapes) have been extensively studied in the last decade owing to their remarkable physical properties such as extremely red-shifted absorption bands reaching up to IR region and large two-photon absorption cross-sections. Recently, hybrid porphyrin tapes have emerged as novel promising molecular motifs by realizing ample chemical stabilities and good solubilities in common organic solvents. Synthesis of porphyrin-hexaphyrin hybrid tape has been also achieved and the unique property has been revealed. In other cases, various aromatic segments have been fused onto the porphyrin or hexaphyrin periphery to create fused porphyrinoids. These novel fused porphyrinoids are promising molecules as near-infrared(NIR)-absorbing dyes, pointing to future applications such as conducting wire, NIR emitter, photovoltaics, and nonlinear optical materials.
In the course of our mechanistic studies of mycoparasitism between Lambertella spp. (the parasite) and Monilinia fructigena (M. f., the host) on apple fruits, we isolated known lambertellin (1) and new spirobutenolides lambertellols A (2), B (3). Lambertellols were detected only when the host M. f. co-inhabited in the broth of M. f. Lambertellols 2, 3 were readily interconverted and gradually decomposed into 1. Our total syntheses enable the SAR studies to disclose that 1 should be the real active species and 2 and 3 are diffusible precursors. In order to rationally explain these observations, we performed dynamic analyses of the metabolites to disclose a novel alleropathy ‘Lambertellin system’ as described in this article. This mechanism also accords with the progress of ‘Natsu-Nenju’ disease on apple fruits, which is known to be a mysterious phyto-disease because of two unique stages of its lifecycle, anamorphic (asexual) and teleomorphic (sexual). Only organic chemistry based investigations could approach the final conclusion in this particular case.
Functional fullerenes have been used widely as excellent n-type semiconductors in solution processable organic electronics, especially as the unique electron acceptors for organic photovoltaics due to their significant increase in solubility while preserving certain electronic and optical properties of pristine fullerenes. Numerous efforts have been made to develop new fullerene functionalization. In comparison with the traditional methods, such as nucleophilic addition of organometallic reagents, cycloaddition, and addition of free radicals, the transition-metal-catalyzed fullerene functionalization has been proved to exhibit high efficiency and selectivity under mild reaction conditions as well as a high compatibility with a wide range of functional groups. We have been interested in the catalytic generation and reactivity of the fullerene radicals. The account describes our recent achievements for the synthesis of various monosubstituted hydrofullerenes, fullerene cycloadducts, single-bonded fullerene dimers, and amine-substituted 1,4-bisadducts in the presence of cobalt and copper catalysts via the formation of the fullerene monoradical as an active species.
We have established aromatic enamide-ene metathesis to give highly substituted indole derivatives. This is a new method for the preparation of chiral 2-trans-cyclopropyl indoles, which successfully led to our H4 antagonist candidates. Based on this findings, we also designed and synthesized conformationally restricted analogues and regioisomers of the nonsteroidal anti-inflammatory drug indomethacin. Evaluation of the inhibitory effects of these compounds on COX, P-glycoprotein, and multidrug-resistance indicated that NSAIDS modulation of multidrug resistant P-glycoprotein and multidrug-resistant protein-1 is not associated with COX-1 and COX-2 inhibitory activities.
A process development research of renin inhibitor 1 for anti-hypertensive drug candidate is described. This compound consists of three intermediates, and especially the key intermediate is chiral lactone 3 which contains three asymmetric carbons. We developed two different approaches to construct those carbons for the synthesis of the common intermediate 9. Namely, scalable synthetic method was established from d-glucose, and 6 kg of 1 was provided for early clinical studies. Then we also developed a highly efficient alternative synthetic method of 1 for manufacturing from n-butyryl chloride 24 by using Evans stereoselective alkylation, followed by stereoselective bromolactonization as key reactions.
The organophosphorus radicals have drawn much attention in organic chemistry, biological processes, and functional materials due to their high reactivity. Although various species of organophosphorus radicals in solution have been observed by EPR spectroscopy, only a few examples have been isolated in the solid state. By using suitable bulky substituents, isolation of organophosphorus radicals such as dialkylphosphinyl radical, triarylphosphine radical cation, and tetraaryldiphosphine radical cation were achieved. The EPR spectra of those radicals showed the spin density of their radicals are mainly localized on phosphorus atom.
Being universal second messengers in bacteria, cyclic dinucleotides (CDN) such as cyclic dimeric guanosine 3’,5’-monophosphate (c-di-GMP) and cyclic dimeric adenosine 3’,5’-monophosphate (c-di-AMP) are important multi-functional compounds that regulate a diverse range of processes in bacteria. After the discovery of c-di-GMP as a trigger for an innate immune response in mammalian host cells, CDN have been of topical interest as vaccine adjuvants and immunotherapeutics. This review highlights the innovative discovery backed up by the achievement of efficient CDN synthesis and the CDN analogues for the future therapeutics.