Gold(III)‐Mediated Contraction of Benzene to Cyclopentadiene: From p‐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.

Benziporphyrins, a unique platform for exploring the aromatic characteristics of porphyrinoid systems

“…42 1,4-Naphthiporphyrin 51 reacted similarly to give palladium(II) benzocarbaporphyrins 60 (Scheme 25). 43 These underwent a reversible protonation of the inner carbon atom (Scheme 26) 43 in a similar fashion to results previously obtained for metalated N-confused porphyrins. 43 Treatment of 47a and 47b with Na[AuCl 4 ]·2H 2 O and potassium carbonate in dichloromethane gave the gold(III) complexes 61a and 61b in 10% and 14% yields, respectively.…”

“…40 Aromatic palladium complexes related to 58 have also been prepared from benzocarbaporphyrins 41 and a carbachlorin. 43 Treatment of 47a and 47b with Na[AuCl 4 ]·2H 2 O and potassium carbonate in dichloromethane gave the gold(III) complexes 61a and 61b in 10% and 14% yields, respectively. 39 An analogous tranfor-mation occurs when 47 or 51 were reacted with sodium tetrachloroaurate dihydrate (Scheme 26).…”

“…43 Treatment of 47a and 47b with Na[AuCl 4 ]·2H 2 O and potassium carbonate in dichloromethane gave the gold(III) complexes 61a and 61b in 10% and 14% yields, respectively. 43 Closely related chemistry had been observed when a carbaazuliporphyrin was reacted with silver(I) acetate in the presence of methanol. 44 When the reaction was performed in the presence of methanol, a dimethoxy derivative 62 was formed instead.…”

Pincerlike Cyclic Systems for Unraveling Fundamental Coinage Metal Redox Processes

“…Further, and in a related manner as mentioned above in the reactions described by Lash's group to yield 5-Ag III complexes, ligands 6i and 6j were reacted with Ag I OAc to yield the corresponding lactoneAg III complex 6k-Ag III regardless of the starting ligand (Scheme 8) [34]. , and 17c-Au III were isolated (Scheme 10) [36]. The reaction leads to the contraction of the benzene and naphthalene units into cyclopentadiene and benzocyclopentadiene, respectively, thus providing an alternative route toward the formation of the former ones out of the previously described [28].…”

Phenanthriporphyrin: An Antiaromatic Aceneporphyrinoid as a Ligand for a Hypervalent Organophosphorus(V) Moiety

“…[1][2][3][4][5][6][7][8][9][10] Such compounds can demonstrate peculiar electronic and molecular structures and create au nique macrocyclic environment for coordination forcing atypical intermolecular reactivity.F or instance,acontraction of p-phenylene to cyclopentadiene is triggered by insertion of palladium(II) or gold(III) into p-benziporphyrin. [6,11,12] Herein, we report the synthesis and properties of an ew member of the aceneporphyrinoid class,n amely phenanthriporphyrin 4-H 3 (Scheme 1). Formally, 4-H 3 can be classified as adicarbaporphyrinoid, [13,14] that is,asaporphyrinoid with two carbon atoms in the core {CCNN}, but also as ap rototypical system containing the rigid phenathrenylene unit.…”