1,3-Dipolar cycloaddition reactions of azomethine ylides play an important role in the synthesis of highly substituted pyrollidines which are found in the structures of many important natural products and pharmaceuticals . Using this chemistry, four chiral centers can be created in a single step. The asymmetric version of this reaction has been tried both with achiral azomethine ylides and chir...

In this paper, we describe studies on the cyclopropanation of Michael acceptors with chiral sulfur ylides. It had previously been found that semi-stabilized sulfonium ylides (e.g., Ph-stabilized) reacted with cyclic and acyclic enones and substituted acrylates with high ee and that stabilized sulfonium ylides (e.g., ester-stabilized) reacted with cyclic enones again with high ee. The current st...

the kinetics of the reactions between triphenylphosphine 1 and dialkyl acetylenedicarboxylates 2, in the presence of a nh-acid such as 5-nitroindazole 3,were studied. corresponding kinetic parameters to all reactions were evaluated, with the second order rate constant (k) values calculated. effects of solvent, temperature, and reactants (dialkyl acetylenedicarboxylates) structure and concentrat...

We have identified an unusually stable helical coil allotrope of phosphorus. Our ab initio density functional theory calculations indicate that the uncoiled, isolated straight one-dimensional chain is equally stable as a monolayer of black phosphorus dubbed phosphorene. The coiling tendency and the attraction between adjacent coil segments add an extra stabilization energy of ∼12 meV/atom to th...

Highly soluble dimedone-derived o-alkoxyphenyliodonium ylides have been prepared and characterized by single crystal X-ray diffraction. These new iodonium ylides are useful reagents for the preparation of oxazole derivatives by reaction with carbodiimides.