Cofactor-Controlled Chirality of Tropoisomeric Ligand

• A new tropos ligand with an integrated anion receptor receptor site has been prepared. Chiral carboxylate and phosphate anions that bind in the anion receptor unit proved capable of stabilizing chiral conformations of the achiral flexible bidentate biaryl phosphite ligand, as shown by variable temperature H-1 and P-31 NMR spectroscopical studies of palladium(0) olefin complexes. Palladium allyl complexes of the supramolecular ligand-chiral cofactor assemblies catalyzed asymmetric allylic substitutions of rac-(E)-1,3-diphenyl-2-propenyl carbonate and rac-3-cyclohexenyl carbonate with malonate and benzylamine as nucleophiles to provide nonracemic products. Although moderate enantioselectivities were observed, (ee:s up to 66%), the results confirm the ability of the anionic guests to affect the conformation of the ligand.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

Carboxylation

Conformations

Ions

Negative ions

Palladium compounds

Substitution reactions

Allylic substitution

Anion receptor

Benzylamines

Chiral conformations

Olefin complexes

Palladium allyl complexes

Phosphate anions

Phosphite ligands

Publication and Content Type

ref (subject category)

art (subject category)