69556-76-9Relevant academic research and scientific papers
Highly efficient 4-O-alkylations of tetronic acids involving oxyphosphonium intermediates
Paintner, Franz F.,Allmendinger, Lars,Bauschke, Gerd
, p. 83 - 86 (2007/10/03)
4-Alkoxy-5H-furan-2-ones were prepared in fair to high yields by regioselective 4-O-alkylation of tetronic acids with stoichiometric amounts of primary and secondary alcohols. This approach involves the intermediacy of (5-oxo-2,5-dihydrofuran-3-yloxy) phosphonium trifluoromethanesulfonates, which were generated in situ on reaction of tetronic acids with triphenylphosphonium anhydride trifluoromethanesulfonate (Hendrickson's reagent).
Domino syntheses of five-, six- and seven-membered O-, N- and S-heterocycles from α-, β- and γ-substituted carboxylic esters
Loeffler,Schobert
, p. 2799 - 2802 (2007/10/03)
By a one-pot procedure, tetronic acids, tetronates, coumarins, benzoxepinones and their N- and S-analogues are readily accessible from keteneylidene(triphenyl)phosphorane 2 and carboxylic esters bearing OH, NHR or SH groups in an α-, β- or γ-position by an addition/Wittig olefination/(Claisen rearrangement) sequence. This cascade can be controlled by temperature variation. Extension of this procedure by a further addition step yielding annulated bisheterocycles such as the furoquinolone 28 is possible in some cases.
