With the aid of an in silico method, α-glucosidase inhibitors with far more potent activities than salacinol (1), a potent natural α-glucosidase inhibitor isolated from an Ayurvedic traditional medicine Salacia reticulata, have been developed.

Samarium(II)-mediated spirocyclization by intramolecular addition of aryl radicals onto an aromatic ring was achieved by the reaction of N-(2-iodophenyl)-N-alkylbenzamides with SmI2 in the presence of HMPA, yielding spirocyclic indolin-2-one derivatives. The ether congeners afford spirocyclic benzofuran derivatives in moderate yields by aryl radical addition onto a benzene ring without having an electron-withdrawing group. The reaction with other aryl groups such as naphthalene and indole rings is also described.

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The first total synthesis of the 7,7-dimethylaporphinoid, 4,5-didehydroguadiscine (6), originally isolated from the stems and roots of Hornschuchia oblique (Annonaceae), was achieved by the condensation of homopiperonylamine (7) with an α,α-dimethylphenylacetic acid derivative (8) and subsequent Pschorr reaction of the resulting benzylisoquinoline intermediate (22). The reported (13)C NMR data were partially revised on the basis of the analysis of HMBC spectra measured under different conditions. The melanogenesis inhibitory activity (IC50 = 4.7 μM) of 6 was 40 times stronger than that of arbutin (174 μM), which was used as reference standard. Furthermore, 6 was the most potent natural melanogenesis inhibitor within this class of compounds.

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