Architectural Spiroligomers Designed for Binuclear Metal Complex Templating

The first structurally, spectroscopically, and electronically characterized metal-spiroligomer complexes are reported. The binuclear [M₂L₂]⁴⁺ ions (M = Mn, Zn) are macrocyclic “squares” and are characterized by X-ray diffraction, ¹H and ¹³C NMR, electronic absorption, emission, and mass spectroscopies. The manganese complex contains two spin-independent Mn^II ions and is additionally characterized using EPR and CD spectroscopies and CV

Architectural Spiroligomers Designed for Binuclear Metal Complex Templating

The first structurally, spectroscopically, and electronically characterized metal-spiroligomer complexes are reported. The binuclear [M₂L₂]⁴⁺ ions (M = Mn, Zn) are macrocyclic “squares” and are characterized by X-ray diffraction, ¹H and ¹³C NMR, electronic absorption, emission, and mass spectroscopies. The manganese complex contains two spin-independent Mn^II ions and is additionally characterized using EPR and CD spectroscopies and CV

Hydrophobic Substituent Effects on Proline Catalysis of Aldol Reactions in Water

Derivatives of 4-hydroxyproline with a series of hydrophobic groups in well-defined orientations have been tested as catalysts for the aldol reactions. All of the modified proline catalysts carry out the intermolecular aldol reaction in water and provide high diastereoselectivity and enantioselectivity. Modified prolines with aromatic groups <i>syn</i> to the carboxylic acid are better catalysts than those with small hydrophobic groups (<b>1a</b> is 43.5 times faster than <b>1f</b>). Quantum mechanical calculations provide transition structures, TS-<b>1a</b>_water and TS-<b>1f</b>_water, that support the hypothesis that a stabilizing hydrophobic interaction occurs with <b>1a</b>