Structure and properties of phosphonium ylides obtained by the reaction of 3-phosphorylated 1,4-dichloro-2-aza-1,3-dienes with sodium azide

Synthesis and Reactions of Stabilized Phosphorus Ylides

“…Protonation of the highly reactive 1:1 intermediates produced in the reaction between (1) and (2) by acetylacetone (33) leads to sterically congested phosphorus ylides (34), which undergo an intermolecular Wittig reaction with indane-1,2,3-trione (35) in CH 2 Cl 2 at room temperature producing dialkyl 1,1-diacetyl8a-hydroxy-8-oxo-1,2,8,8a-tetrahydrocyclopenta[a]indene-2,3-carboxylates (37) in fairly high yields. Magnesium sulfate powder has catalytic activity in the intermolecular Wittig reactions of the stabilized phosphorus ylides (34) with indane-1,2,3-trione (35), to produce (37), in solvent-free conditions with ordinary heating, microwave irradiation, or at room temperature (Scheme 9) [64][65][66][67]. The stereochemistry of (37) was proved via single crystal X-ray diffraction [68].…”

“…Protonation of the highly reactive 1:1 adduct intermediates, produced in the reaction between (1) and (2), by 2,2,2-trihaloethanol (120) leads to vinyltriphenylphosphonium salts which undergo a Michael addition reaction with the conjugate base of the alcohol to produce the corresponding halo-containing stabilized phosphorus ylides (121). An intermolecular Wittig reaction of the halo-containing stabilized phosphorus ylides (121) with indane-1,2,3-trione (35) leads to the corresponding significantly electron-deficient halocontaining alkenes (122) (Scheme 31) [152,153]. Catalysts such as silica gel and sodium hydrogen carbonate were found to catalyze the reaction of these phosphoranes (121) with Scheme 29.…”

“…A plausible mechanism for the formation of ylides in this reaction is shown in Scheme 1. The reaction starts from addition of TPP (1) to electron-deficient acetylenic ester (2) to form the zwitterionic intermediate (3) [34][35][36], which is subsequently protonated by the acid (4) to give vinyltriphenylphosphonium cation (5). Then, addition of the conjugate base of the acid (4) to (5) produces ylide (6) (Scheme 1).…”

Preparation of Stabilized Phosphorus Ylides via Multicomponent Reactions and Their Synthetic Applications

“…A plausible mechanism for the formation of ylides in this reaction is shown in Scheme 1. The reaction starts from addition of TPP (1) to electrondeficient acetylenic ester (2) to form the zwitterionic intermediate (3) [39][40][41][42], which is subsequently protonated by the acid (4) to give vinyltriphenylphosphonium cation (5). Then, addition of the conjugate base of the acid (4) to (5) produces ylide (6) (Scheme 1).…”

“…3-Chloropentane-2,4-dione (40) exists in solution almost exclusively as the enol tautomer, which undergoes a complex reaction with (2) in the presence of (1) to produce alkyl 5,5-diacetyl-2-oxo-3-(triphenylphosphoranylidene)tetrahydrofuran-4-carboxylates (44) in moderate to fairly high yield. Compounds (44) apparently result from the initial addition of the phosphine to the acetylenic ester and the concomitant protonation of the 1:1 adduct, followed by attack the enolate anion to form the intermediate (41), which is then converted to the butyrolactone (44) presumably by elimination of HCl and ring closure (Scheme 13) [66].…”