Redox-Triggered CC Coupling of Diols and Alkynes: Synthesis of β,γ-Unsaturated α-Hydroxyketones and Furans by Ruthenium-Catalyzed Hydrohydroxyalkylation
作者:Emma L. McInturff、Khoa D. Nguyen、Michael J. Krische
DOI:10.1002/anie.201311130
日期:2014.3.17
ruthenium‐catalyzed CCcoupling of alkynes and vicinal diols to form β,γ‐unsaturated ketones occurs with complete levels of regioselectivity and good to complete control over the alkene geometry. Exposure of the reaction products to substoichiometric quantities of p‐toluenesulfonic acid induces cyclodehydration to form tetrasubstituted furans. These alkyne‐diolhydrohydroxyalkylations contribute to a
The reaction of tributyltinenolates with α-halogenoketones gave substituted furans which were not derived from the normal cross-coupling products, 1,4-diketones, but were formed instead through addition of the tin enolate to the α-halogenoketones.
Hydrogen peroxide oxidation of polysubstituted pyrylium salts: formation of enol esters and furans
作者:Teodor Silviu Balaban、Monika Hiegemann
DOI:10.1016/s0040-4020(01)92277-x
日期:1992.11
2,4,6-Trialkylsubstituted pyrylium salts 1 have been known lo afford 2-acyl-3,5-dialkyl-furans 2 in moderate yields (30 - 45%). Oxidation of these salts in buffer solutions (pH = 3 - 4.5) increased the yields of acylfurans to 75%. In contrast, tetra- and penta-substituted pyrylium salts are mainly converted into enol esters with a delta-keto group and furans all originating presumably by C-O bond cleavages in a common intermediate. This intermediate may result by a C-O acyl shift as inferred from analogous compounds with deuterium labelling.
Novel Ruthenium- and Platinum-Catalyzed Sequential Reactions: Synthesis of Tri- and Tetrasubstituted Furans and Pyrroles from Propargylic Alcohols and Ketones