Synthesis of novel 2H,5H-dihydrofuran-3-yl ketones via ISNC reactions
作者:Matthew L. Grandbois、Kelsie J. Betsch、William D. Buchanan、Jetty L. Duffy-Matzner
DOI:10.1016/j.tetlet.2009.08.110
日期:2009.11
Unique 1-[2H,5H-dihydrofur-3-yl]ketones have been synthesized from propargylic nitroethers via intramolecular cycloadditions involving silyl nitronates Various substituent groups were placed on the 2 and 5 positions of the dihydrofuran rings We examined the scope of the long-range Coupling in proton NMR of the oxo-dihydrofuran products The identities of the diastereomers resulting from the Michael addition/cycloaddition reactions were tentatively assigned for the first time CAChe MNDO PM5 and CONFLEX programs were engaged to assist with the identification of these stereoisomers. The reaction times and conditions for those oxo-dihydrofurans were found to be different than that of the published dihydrofuranals. which led us to propose a different mechanism. (C) 2009 Elsevier Ltd. All rights reserved
A Brønsted Acid Mediated Cascade Enone Synthesis from Aldehydes Containing a Tethered Propargylsilane
作者:Rui Ramalho、Peter J. Jervis、Benson M. Kariuki、Alexander C. Humphries、Liam R. Cox
DOI:10.1021/jo702351s
日期:2008.2.1
MeSO3H effects the intramolecular allenylation of a series of aldehydes 1 to provide allenyl alcohol product 3 as a single diastereoisomer. Cyclization proceeds rapidly at −78 °C. However, when the reaction is performed at room temperature, aldehyde 1 provides enone product 7 instead. A mechanism for the formation of this product is proposed in which the initially formed allenyl alcohol 3 undergoes
Diels–Alderreactions of 2-vinylindoles with cyclic carbo- and heterodienophiles, in the presence of suitable Lewis acids, led to uncommon [ c ]-carbo- and furoannulated tetrahydrocarbazoles. The obtained compounds encompass a carbonyl group in an angular position, suitable for further transformations, and represent useful intermediates for the synthesis of more complex structures.