Synthesis of stabilized phosphorus ylides from electron-poor alcohols and their applications in the preparation of 2,5-dihydrofuran derivatives
Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by alcohols (2-methanol thiophen, 3-methanol thiophen, 1,1,1,3,3,3-hexafluoro-2-propanol and [4-(trifluoromethyl)-phenyl]methanol) leads to vinyltriphenylphosphonium salts, which undergo Michael addition reaction with conjugate base to produce the corresponding stabilized phosphorus ylides. Wittig reaction of the stabilized phosphorus ylides with ninhydrin leads to the corresponding densely functionalized 2H-indeno[2,1-b]furans in fairly good yields.
KEY WORDS: Electron-poor alcohol, Acetylenic esters, Ninhydrin, Intramolecular Wittig reaction, Vinyltriphenylphosphonium salt
Bull. Chem. Soc. Ethiop. 2012, 26(1), 153-158.