Synthesis of Stable Carbamate Phosphorus Ylides by a Four-Component Reaction And Dynamic ¹H-Nmr Study of the Energy Barriers for the Rotation around the Carbon–Nitrogen Single Bond and the Carbon–Carbon Double Bond

Abstract

A stable phosphorus ylide is obtained in high yield by a four component reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of the intermediate product formed from phenyl isocyanate and substituted phenols in dichloromethane at room temperature. This stable phosphorus ylide exists in solution as a mixture of two geometrical isomers resulting from restricted rotation around the carbon-carbon partial double bond due to conjugation of the ylide moiety with the adjacent carbonyl group. Dynamic effects are observed in 1 H NMR spectra that are attributed to restricted rotation around the carboncarbon double bond and the carbon-nitrogen single bond. These effects are used to calculate the free activation energy (ΔG ‡ ) and other activation parameters such as ΔH ‡ , ΔS ‡ and E a .

Chemo‐Selective Synthesis of Tetrazole‐Containing Cyclopentenyl Phosphanylidene Dicarboxylates

“…For example, in the IR spectrum of compound 5 a , the N−H functional group stretching bond has been observed at 3441 cm −1 . Based on previous experiments, in the synthesis of ylide structures by triphenylphosphine and acetylenic esters in the presence of N−H acids and the comparison of 1 H‐NMR spectroscopic data, we assume that compound 6 has not been formed in the current protocol.…”

“…The generated zwitterionic species can be used to produce the carbocyclic systems in a Michael's reaction mode . We have involved in chemo‐selective reactions with substrates variable and present herein the selective reaction of triphenylphosphine (TPP) and alkyl 3‐phenyl‐2‐(1 H ‐tetrazol‐5‐yl)acrylates 3 in the presence of dialkyl acetylenedicarboxylates (DAAD) 4 to afford tetrazole containing triphenylphosphanylidene cyclopentene dicarboxylates 5 (Scheme ).…”

Separation of OH-containing compounds from the essential oil mixture via a one-pot synthesis of carbamates, antimicrobial evaluation and dynamic 1H NMR study of their derivatives

“…In continuation of our studies about the carbamates (Marandi et al 2015) we reported examinations on conformational behaviours of synthesized carbamates. We observed that the compound 7d shows dynamic effects on its 1 H NMR spectrum.…”

Synthesis of novel organophosphorus compounds via reaction of substituted 2-oxoindoline-3-ylidene with acetylenic diesters and triphenylphosphine or triphenyl phosphite

“…1). Herein, according to our investigations [27][28][29][30] , due to the importance of organophosphorus compounds and isatin cores, we describe the synthesis of functionalized 2-oxoindoline-3-ylidene containing novel organophosphorus compounds. Therefore, we have performed a facile one-pot reaction between 2-oxoindoline-3-ylidene derivatives and triphenyphosphine or triphenyl phosphite in the presence of acetylenic esters.…”