Yoshihiro Harigaya

Dry reaction of indoles with carbonyl compounds on montmorillonite K10 clay: a mild, expedient synthesis of diindolylalkanes and vibrindole A

Abstract Dry reaction of indoles 1a – c with aldehydes 2a – i , ketones 2j – o and an acetal 2p on M. K10 clay at room temperature furnished 3,3′-diindolylalkanes (DIAs: 3a – h , j – r ). The novel formation of tris(3-indolyl)methane 4 from 2i through tandem reactions and of the DIAs 6 and 8 from 1d through Plancher rearrangements were also observed.

Naturally occurring triterpenoid saponins.

Naturally occurring new triterpenoid saponins reported from mid‐1996 to March, 2007 are reviewed including their physical constants and plant sources, and are compiled in Table 1. New saponins are arranged in Table 1 on the basis of the skeletal structures of their aglycones, e.g., oleanane type, ursane type, lupane type, hopane type, taraxastane type, cycloartane type, lanostane type, tirucallane type, dammarane type, cucurbitane type, and holostane type. The known triterpenoid saponins and prosapogenins of the new saponins, the biological and pharmacological activities of which were published during 1996–2007, are also reviewed together with their plant sources listed in Table 2 according to the skeletal structures of their aglycones in the same fashion as in Table 1. The plant and animal sources of both new and known bioactive triterpenoid saponins are collected in Table 3 in alphabetical order. The biological and pharmacological activities such as antiallergic, antiatherosclerosis and antiplatelet, antibacterial, anticomplementary, antidiabetic, contraceptive, antifungal, anti‐inflammatory, antileishmanial, antimalarial/antiplasmodial, anti‐obesity, anti‐proliferative, antipsoriatic, antispasmodic, antisweet, antiviral, cytotoxic/antitumor, detoxication, gastroprotective, haemolytic, hepatoprotective, immunomodulatory, anti‐enzyme, anti‐osteoporotic, insecticidal, insulin‐like, membrane‐porosity, molluscicidal, neuropharmacological, anti‐endothelial dysfunction, snake venom antidote, and sweet activities of these saponins or derived prosapogenins are discussed briefly after Table 3.

Absolute Configuration of Staurosporine By X-Ray Analysis

Abstract The stereostructure of staurosporine ( 1 ) was determined absolutely to be 2′ S , 3′ R , 4′ R , 6′ R -configurations by means of X-ray crystallographic analysis of 4′- N -methylstaurosporine methiodide ( 2 )

Application of sulfamic acid as an eco-friendly catalyst in an expedient synthesis of benzimidazoles

Sulfamic acid, an eco-friendly and zwitterionic solid, proved to be a very efficient catalyst for the reaction of ortho-phenylenediamine with aryl aldehydes in ethanol at room temperature to furnish both 1-arylmethyl-2-aryl- and 2-arylbenzimidazoles in very good to excellent overall yields.

Carbazole alkaloids from Murraya koenigii

Two new alkaloids, 9-carbethoxy-3-methylcarbazole and 9-formyl-3-methylcarbazole, and a known metabolite, 3-methyl-carbazole were isolated from the roots of Murraya koenigii. All three compounds were identified by detailed spectral analyses including 2D NMR studies and their structures confirmed by synthesis. Of the two new metabolites, the 9-formyl compound displayed weak cytotoxicity against both mouse melanoma B16 and adriamycin-resistant P388 mouse leukemia cell lines.

Pinellic acid from the tuber of Pinellia ternata Breitenbach as an effective oral adjuvant for nasal influenza vaccine

This study describes the isolation, purification, characterization, and adjuvant activity of an orally active adjuvant substance from the tuber of Pinellia ternata, as an active herbal component of the traditional Japanese herbal (Kampo) medicine, Sho-seiryu-to (SST, Chinese name: Xiao-Qing-Long-Tang), which has been reported to show oral adjuvant activity for nasally administered influenza HA vaccine [Int. J. Immunopharmacol. 16 (1994) 605]. The active compound was identified as 9S, 12S, 13S-trihydroxy-10E-octadecenoic acid using infrared spectra, proton magnetic resonance, mass spectrometry, and circular dichroism, and named pinellic acid. Oral administration of pinellic acid (1 microg) to BALB/c mice given primary and secondary intranasal inoculations of influenza HA vaccine (1 microg) enhanced antiviral IgA antibody (Ab) titers 5.2- and 2.5-fold in nasal and bronchoalveolar washes, respectively, and antiviral IgG Ab titers 3-fold in bronchoalveolar wash and serum. Intranasal administration of pinellic acid (1 microg) with influenza HA vaccine (1 microg) slightly enhanced antiviral IgG Ab titers in bronchoalveolar wash and serum but not antiviral IgA Ab titers in nasal and bronchoalveolar washes. Pinellic acid showed no hemolytic activity. The results of this study suggest that pinellic acid may provide a safe and potent oral adjuvant for nasal influenza HA vaccine.

Total synthesis of (-)-borrelidin.

The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is SmI2-mediated intramolecular Reformatsky-type reaction for macrocyclization after esterification between two segments. The two key segments were synthesized through chelation-controlled carbotitanation, chelation-controlled hydrogenation, stereoselective Reformatsky reaction, and MgBr2·Et2O-mediated chelation-controlled allylation.

A sojourn in the synthesis and bioactivity of diindolylalkanes

The different synthetic routes to diindolylalkanes (DIAs), an important class of synthetic and natural products, their merits and demerits and the properties of the bioactive DIAs have been presented in this review which is the first of its kind in this field. The synthesis of the bioactive DIAs (3), streptindole (4), vibrindole A (6), 10 and 11 has also been included in this review.

Convenient synthesis of 7' and 6'-bromo-D-tryptophan and their derivatives by enzymatic optical resolution using D-aminoacylase

Abstract Compounds 7′ and 6′-bromo- d -tryptophan ( 1 and 2 ) which are important derivatives for the synthesis of the chloropeptin and kistamycin A, respectively, were conveniently synthesized by optical resolution from N-acetyl-7′ and 6′-bromo- dl -tryptophan ((RS)-5 and (RS)-14 ) using d -aminoacylase.

Total Synthesis of Salinosporamide A

The total synthesis of salinosporamide A has been achieved through enzymatic desymmetrization, diastereoselective aldol reaction, intramolecular aldol reaction, and intermolecular Reformatsky-type reaction followed by 1,4-reduction as key reactions.