Metalation and alkylation of 4H-1,3-dioxin: a new .beta.-acyl vinyl anion equivalent

Abstract

Supplementary Material Available: NMR data given for 3a-u, 5a,b, and 7a,b (9 pages). Ordering information is given on any current masthead page.(13) The nucleophilic alkyl radical first attacks 1,1-dicyanoethenes rather than allylic stannanes; however, the new radical so produced has an electrophilic nature and attacks allylic stannanes in a manner shown in Scheme II: Fleming, I. Frontier Orbitals and Organic Chemical Reactions•, John Wiley & Sons: London, 1976; Chapter 5.(14) The reactivity of the electron-deficient alkenes decreased in the order: la > 6a > 4a.(15) (£)-1 -Nitro-2-phenylethene, (£)-1 -cyano-2-phenylethene, 1,1-dicyano-2-phenyl-1 -propene, and cyclohexylidenepropanedinitrile were unreactive under similar conditions.

The Dihydroxyacetone Unit—A Versatile C3Building Block in Organic Synthesis

“…[76] Since no mild and versatile synthesis of these dienophiles was known, Funk and co-workers developed a new strategy based on their previous discovery that 4-alkyl 4H-1,3-dioxins undergo facile retrocycloaddition reactions to provide 3-alkyl acroleins and formaldehyde. [77] Starting from dioxanone 33, O acylation upon treatment with triethylamine/DMAP and an anhydride, chloroformate, or carbamoyl halide furnished the 5-acyloxy dioxins 120, all of which underwent smooth retrocycloaddition to yield the desired 2-acyloxy acroleins 121 with the release of acetone (Scheme 34). [76] The retrocycloaddition was induced by heating in the presence of hydroquinone (1 mol %).…”

Die Dihydroxyaceton‐Einheit – ein nützlicher C3‐Baustein in der Organischen Synthese

“…[76] Da es zu jenem Zeitpunkt noch keine milde und flexible Synthese solcher Dienophile gab, entwickelten Funk et al eine neue Strategie, die auf ihrer Beobachtung aufbaute, dass 4-Alkyl-4H-1,3-dioxine sehr leicht eine Retrocycloaddition zu 3-Alkylacroleinen und Formaldehyd eingehen. [77] Ausgehend von Dioxanon 33 wurde zunächst eine O-Acylierung durch Umsetzung mit Triethylamin/DMAP und verschiedenen Anhydriden, Chlorameisensäureestern oder Carbamoylhalogeniden vorgenommen (Schema 34). Alle so erhaltenen 5-(Acyloxy)dioxine 120 gingen eine glatte Retrocycloaddition ein und lieferten die erwünschten 2-(Acyloxy)acroleine 121 unter Abspaltung von Aceton.…”

Largazole and Analogues with Modified Metal-Binding Motifs Targeting Histone Deacetylases: Synthesis and Biological Evaluation

“…Alkylation of 31 with 2-[(2-bromoethyl)sulfanyl]-2-methylpropane 32 via the lithium derivative gave 33 . Compound 33 underwent retro Diels-Alder reaction to give the aldehyde 34 21 which was used in aldol reaction to furnish the alcohol 35 . It was used as described in scheme 5 to make the cyclic core 38 .…”