Application of the intramolecular PIFA-mediated amidation of alkynes to the synthesis of substituted indolizidinones
摘要:
The construction of the title compounds has been achieved from properly substituted linear alkynylamides through the suitable combination of two key cyclization steps. First, an intramolecular PIFA-mediated alkyne amidation protocol leads to the creation of the pyrrolidinone nucleus, which under proper manipulation of the generated keto carbonyl group permits the assembling of the indolizidinone skeleton by the introduction of a subsequent ring closing olefin metathesis step. Finally, its transformation into a series of substituted mono- and trihydroxylated indolizidinone derivatives is achieved by manipulation of the remaining unsaturated fragment under hydrogenation and dihydroxylation conditions. (C) 2012 Elsevier Ltd. All rights reserved.
8-naphthyridin-2(1H)-ones have been synthesized with the inverseelectron-demandDiels-Alderreaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecularinverseelectron-demandDiels-Alderreaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones