FACILE ACID-PROMOTED DECARBOXYLATION OF A MACROCYCLIC COMPLEX - CRYSTAL-STRUCTURE OF OPENTADECA-1(15),5,7,13-TETRAEN-2-OLATO]NICKEL(II)

A new chiral tetradentate compound has been prepared from (S)-2,3-diam inopropanoic acid and 3-ethoxymethylenepentane-2,4-dione and the corre sponding nickel(II) and palladium(II) complexes have been characterize d. The racemic form of the nickel(II) complex underwent template-contr olled ring closure with 1,3-diaminopropane to form a new 15-membered c arboxylato-substituted macrocycle. In the presence of acid, this speci es underwent an unusual and facile oxidative-decarboxylation reaction to produce a new hydroxy-substituted macrocycle, the crystal structure of which has been determined.