Helical chiral 2-aminopyridinium ions were designed as a significantly more acidic (active) dual hydrogen-bonding catalyst than commonly used (thio)urea-based systems. The helicene framework was specifically utilized to position an inherently chiral barrier on the hydrogen-bonding side of the catalyst. The catalyst reactivity and enantioselectivity were successfully demonstrated in additions of 4,7-dihydroindoles to nitroalkenes (0.5−2 mol % catalyst loadings, up to 98:2 er).

Helical Chiral 2-Aminopyridinium Ions: A New Class of Hydrogen Bond Donor Catalysts

Alstonia boonei De Wild is a herbal medicinal plant of West African origin, popularly known as God's tree or “Onyame dua”. Within West Africa, it is considered as sacred in some forest communities; consequently the plant parts are not eaten. The plant parts have been traditionally used for its antimalarial, aphrodisiac, antidiabetic, antimicrobial, and antipyretic activities, which have also been proved scientifically. The plant parts are rich in various bioactive compounds such as echitamidine, Nα-formylechitamidine, boonein, loganin, lupeol, ursolic acid, and β-amyrin among which the alkaloids and triterpenoids form a major portion. The present paper aims at investigating the main research undertaken on the plant in order to provide sufficient baseline information for future work and for commercial exploitation.

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A Review of the Ethnobotany and Pharmacological Importance of Alstonia boonei De Wild (Apocynaceae)

Alstonia scholaris (L.) R. Br. and Alstonia macrophylla Wall. ex G. Don: A comparative review on traditional uses, phytochemistry and pharmacology.

Indole alkaloids from Ervatamia chinensis

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A new family of chiral pyridines has been designed and synthesized for use in asymmetric organocatalysis. Thus, helical-chiral pyridines induce high enantioselectivity in a range of mechanistically unrelated, synthetically significant transformations, including Friedel-Crafts alkylation with nitroalkenes, periselective Diels-Alder reactions with nitroalkenes, the ring-opening of epoxides with a chloride nucleophile, and the propargylation of aldehydes.

Applications of helical-chiral pyridines as organocatalysts in asymmetric synthesis.

Alasmontamine A, A first tetrakis monoterpene indole alkaloid from Tabernaemontana elegans.

A novel tetrakis monoterpene indole alkaloid, alasmontamine A (1) consisting of bis-vobtusine-type skeletons, was isolated from the leaves of Tabernaemontana elegans. The structure including the relative stereochemistry was elucidated on the basis of spectroscopic data. Alasmontamine A (1) exhibited moderate cell growth inhibitory activity against HL-60 cells.

Alasmontamine A, a first tetrakis monoterpene indole alkaloid from Tabernaemontana elegans

A new indole alkaloid, akuammidine-N-oxide (1) was isolated from the leaves of Alstonia scholaris (Apocynaceae) together with akuammidine (2), and the structure was elucidated by NMR spectral analysis and chemical correlation. Akuammidine (2) showed a moderate antiplasmodial activity.

Saori Miyama

Papers

Alasmontamine A, A first tetrakis monoterpene indole alkaloid from Tabernaemontana elegans.

Alasmontamine A, a first tetrakis monoterpene indole alkaloid from Tabernaemontana elegans

Indole alkaloids from the leaves of Alstonia scholaris

Indole Alkaloids from the Leaves of Alstonia scholaris

Alasmontamine A, a First Tetrakis Monoterpene Indole Alkaloid from Tabernaemontana elegans.