Nachweis behinderter rotation bei stabilen triphenylphosphinalkylenen.

On the structure and reactivity of a stabilized phosphorane: methyl (triphenylphosphoranylidene) acetate

“…It has been nearly 20 years since stabilized ylides were investigated (4)(5)(6)(7)(8) by 'H NMR. The results of these studies may be summarized as follows: at -40°C or lower, ylide 1 gives the signals of two distinct forms, with signal coalescence above room temperature.…”

One-pot synthesis of stable phosphorus ylides using aldehyde phenylhydrazone derivatives

“…[28][29][30][31] The 1 H NMR spectrum of compound 3a exhibited two singlets (δ 3.06 and 3.87) arising from the methoxy group in the Z-isomer, and two singlets at 3.42 and 3.78 ppm for that in the E-isomer. The methyl group at 3.06 in the Z-isomer is shielded due to the anisotropic effect of a phenyl group of the triphenylphosphine unit.…”

A facile synthesis, dynamic 1H NMR and theoretical study the novel stable heterocyclic phosphorus ylides containing tetrazole

“…The assignments of E-4 (d, e) and Z-4 (d, e) isomers as the major or minor form in phosphorus ylides have been reported previously. [34][35][36][37][38] The 1 H NMR spectrum of 4d exhibited two singlets (δ 3.17 and 3.73 ppm) arising from the methoxy group in the Z-isomer, and two singlets at 3.59 and 3.70 ppm for that in the E-isomer. The methyl group at 3.17 in the Z-isomer is shielded due to the anisotropic effect of a phenyl group of triphenylphosphine.…”

“…In addition, products 4d and 4e displayed 13 C NMR resonances at δ 163.77 ppm and δ 163.99 ppm, respectively for the N=C-S unit. 16,34 For the 13 C NMR spectroscopy the anisotropic effect could not be reported for the methoxy group in the Z-isomer because of the small different of their chemical shifts. The carbonyl region of these compounds 4a-e exhibited absorption bands for each compound.…”