Palladium benzene macrocycles

Over the last decade, the chemistry of the carbon-carbon triple bond has experienced a vigorous resurgence [1]. Whereas construction of alkyne-con-taining systems had previously been a laborious process, the advent of new synthetic methodology based on organotransition metal complexes has revolutionized the field [2]. Specifically, palladium-catalyzed cross-coupling reactions between alkyne sp-carbon atoms and sp -carbon atoms of arenes and alkenes have allowed for rapid assembly of relatively complex structures [3]. In particular, the preparation of alkyne-rich macrocycles, the subject of this report, has benefited enormously from these recent advances. For the purpose of this review, we Emit the discussion to cychc systems which contain benzene and acetylene moieties only, henceforth referred to as phenylacetylene and phenyldiacetylene macrocycles (PAMs and PDMs, respectively). Not only have a wide... 

Other type of complexes have also been used for the oxidation of hydrocarbons. For instance, Fujiwara and coworkers employ a coordinated complex of palladium with o-phenanthroline as an efficient catalyst for the direct conversion of benzene into phenol. Moro-oka and coworkers use an oxo-binuclear iron complex, whereas Machida and Kimura work with macrocyclic polyamines. Sasaki and coworkers employ Pd-Cu composite catalysts, which are prepared by impregnating the respective metal salts on silica gel. 

The colourless conjugated macrocycle 666, which consists of twelve benzene rings and twelve acetylene units, has been obtained by palladium-catalysed intramolecular coupling of the iodo compound 665. ... 

All lation of palladium(II)-coordinated phosphane ligands with l,2-bis(chloro-methyl)benzene gives rise to new chelate rings and coincidentally to the macrocyclic complex [Pd(L1216)](HC03)2 (Eq. 5.5). 

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