[Structure: see text] A new mechanism involving a diimine intermediate is proposed for vicinal diamine-catalyzed synthesis of warfarin. Decreasing the NCCN dihedral angle by varying the diamine results in an increase in the enantioselectivity of warfarin synthesis.

Sixteen diphenylethylenediamine analogues including those with electron donating, electron withdrawing, and sterically bulky substituents have been prepared in good overall yields (70-90%) and in enantiomerically pure form (>99% ee) by diaza-Cope rearrangement reaction. A single chiral mother diamine, ((R,R)-1,2-bis-(2-hydroxyphenyl)-1,2-diaminoethane), is reacted with appropriate aldehydes to form the initial diimines that rearrange to give all the product diimines in the (S,S) form. The daughter diamines are obtained by hydrolysis of the product diimines. Density functional theory computation shows that resonance-assisted hydrogen-bond is the main driving force behind all the rearrangement reactions. Chiral high performance liquid chromatography and circular dichroism spectroscopy show that the highly stereospecific rearrangement reactions take place with apparent inversion of stereochemistry.

Helical chirality can be imprinted onto a 2,2′‐dihydroxybenzophenone derivative (see picture) in a highly stereospecific manner. A single amino acid combines with the receptor to form an imine with two internal hydrogen bonds. The azo group allows sensing of amino acid enantiopurity by circular dichroism spectroscopy.

Helizität kann einem 2,2′‐Dihydroxybenzophenon‐Derivat hoch stereospezifisch übertragen werden (siehe Bild). Eine einzige Aminosäure bindet an den Rezeptor, sodass ein Imin mit zwei internen Wasserstoffbrücken entsteht. Dank der Azogruppen lässt sich die Enantiomerenreinheit der Aminosäure CD‐spektroskopisch bestimmen.