Gold(III)‐Mediated Contraction of Benzene to Cyclopentadiene: From <i>p</i>‐Benziporphyrin to Gold(III) True Tetraarylcarbaporphyrin

Abstract

The reaction of p-benziporphyrin, sodium tetrachloroaurate(III) dihydrate, and potassium carbonate in dichloromethane yielded gold(III) 5,10,15,20-tetraaryl-21-carbaporphyrin owing to the contraction of p-phenylene to cyclopentadiene. This molecule is the very first representative of a true 5,10,15,20-tetraaryl-21-carbaporphyrin complex where four trigonal donor atoms are involved in equatorial coordination. The contraction adds an unprecedented route to numerous organic transformations of aromatic compounds catalyzed by simple gold(III) compounds. p-Benziporphyrin provided the unique environment to alter the fundamental reactivity of the benzene unit facilitating its contraction to cyclopentadiene.