RESUMEN
A new synthetic route to (±)-lycorine, starting from the endo-cycloadduct of 3,5-dibromo-2-pyrone and (E)-ß-borylstyrene, is reported. Boronate oxidation and a set of reactions including face-selective epoxidation provided the pivotal C1-OH group and C3/C3a double bond.
Asunto(s)
Alcaloides de Amaryllidaceae/síntesis química , Fenantridinas/síntesis química , Pironas/química , Estirenos/química , Estructura Molecular , Oxidación-Reducción , EstereoisomerismoRESUMEN
New synthetic routes to (±)-α-lycorane and (±)-1-deoxylycorine were exploited. The endo-cycloadduct of 3,5-dibromo-2-pyrone with styrene-type dienophile provided the pivotal intermediate for the syntheses of the titled natural products.
Asunto(s)
Alcaloides de Amaryllidaceae/síntesis química , Productos Biológicos/síntesis química , Fenantridinas/síntesis química , Alcaloides de Amaryllidaceae/química , Productos Biológicos/química , Estructura Molecular , Fenantridinas/química , EstereoisomerismoRESUMEN
A new synthetic route to (±)-pancratistatin was devised utilizing ß-silyl styrene as a dienophile in the cycloaddition with 3,5-dibromo-2-pyrone. The TMS group incorporated in the cycloadduct permitted a facile elimination process for the eventual installation of the C(1)-OH function. Subsequent transformations including Curtius rearrangement and Bischler-Napieralski reactions completed the total synthesis of (±)-pancratistatin.