A new and versatile synthetic route to Securinega alkaloids is reported. The first synthesis of allosecurinine has been accomplished in seven steps and 40% yield, starting from (+)-menisdaurilide, using a vinylogous Mannich reaction as the key transformation. Similarly, viroallosecurinine has been synthesized from (-)-menisdaurilide.

The synthesis and characterization of a new family of catechol derivatives designed to behave as fluorescent chemosensors for wide-range pH detection has been described. These compounds were prepared by covalently coupling a catechol unit with other aromatic rings, thus obtaining pi-delocalized systems with both pH-responsive groups and fluorescent behavior. In the case of a pyridine-catechol derivative, this leads to up to three different protonation states with distinct optical properties in organic media, as corroborated by density functional theory calculations. By applying dual-wavelength detection techniques, this compound shows complementary "off-on-off" and "on-off-on" emission profiles upon pH variation, a behavior that can be exploited to perform acidity detection over a broad pH range.

Alkaloids U 0600Diastereoselective Synthesis of Allosecurinine (III) and Viroallosecurinine from Menisdaurilide. -The title compound is prepared in 42% overall yield starting from (+)-menisdaurilide (I). Following the same sequence, its enantiomer viroallosecurinine is available from (-)-(I). -(BARDAJI, G. G.; CANTO, M.; ALIBES, R.; BAYON, P.; BUSQUE*, F.; DE MARCH*, P.; FIGUEREDO, M.; FONT, J.; J.

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