Cyclic-Phenoxaphosphinine-Based Mixed Phosphonium-Iodonium Ylides with Electron-Withdrawing Substituents - Synthesis and Structural Features

A series of phosphonium ylides and mixed phosphonium-iodonium ylides based on cyclic phenoxaphosphinine has been synthesized, representing a new structural type of ylides. The influence of the electron-withdrawing substituents of various nature on the stability and physicochemical properties of phenoxaphosphonium ylides is discussed. Our findings reveal a progressive reduction in ylide stability as the carbonyl group is replaced first with a phosphonate group and then with a nitrile group. NMR data indicates that the presence of a cyclic phosphonium group results in a lowered energy barrier to rotation about the carbon-carbon bond, both in phosphonium and mixed phosphonium-iodonium ylides with alpha-carboxyl substituents when compared to triarylphosphonium ylides. These experimental results are further supported and analyzed in the context of density functional theory (DFT) calculations. A series of phosphonium ylides and mixed phosphonium-iodonium ylides, featuring a new structural type has been synthesized. This study highlights the correlation between the stability of the ylides and the nature of the electron-withdrawing groups. We delve into the impact of the structural variations within the phosphonium fragment on the rotational barrier of the C-C bond in carbonyl ylides.image

Automated summary

A series of phosphonium ylides and mixed phosphonium-iodonium ylides, representing a new structural type, have been synthesized. This study highlights the correlation between the stability of the ylides and the nature of the electron-withdrawing groups. We delve into the impact of the structural variations within the phosphonium fragment on the rotational barrier of the C-C bond in carbonyl ylides.