Bipyrimidines

The alkenylation protocol between styrene, ethyl acrylate or acrylonitrile, and 5-bromo- and 5-iodo-pyrimidine gives the coupling product (882) (79CPB193, 81H(16)965>. Formation of 4,4 -bipyrimidines (884) is a major pathway from 4-iodopyrimidines (883) under the relatively vigorous conditions... 

Naphthyndine complexes are mostly chelates but there are some bridged complexes. The 4,4 -bipyrimidine (9-XXI) has high 77-acceptor ability and can chelate N,N, or t)1 through the end N atoms. 

Substituted 4-chloropyrimidines are dimerized to 4,4 -bipyrimidines (397) by the same low-valent nickel protocol (93S478). 

The relatively vigorous reaction conditions required to effect vinyl substitution by heteroaryl halides under the influence of Pd-catalysis may lead to homo-coupling. The dominating reaction path in attempted alkenyl-ations of 4-iodopyrimidines was the formation of 4,4 -bipyrimidines (19) (Scheme 4 Section II.A.2). In reactions of 4-iodopyrimidines with a Pd-catalyst at 160°C, near-quantitative yields of the 4,4 -bipyrimidine were obtained (79CPB193). Also, in the reaction of 2-iodo-4-methylquinoline with Pd(OAc)2 as added catalyst, a major reaction path led to 4,4 -dimethyl-2,2 -biquinoline (Scheme 2 Section II.A.2.) (82CPB3647). 

Two of the classical bis-nitrogen ligands to assemble porphyrins (predominantly zinc metallated) are the bidentate l,4-diazabicyclo[2.2.2]octane (DABCO) and 4,4 -bipyridine (bipy). Other di-topic nitrogen-ligands studied include hydrazine, 4,4 -bipyrimidine, diaza-pyrene, 5,5 -dicyano-2,2 -bipyri-dine, perylene-bisimide, extended bipyridine units and non-covalently linked di-pyridyl ligands via bipy-metal interactions. The formation of various bis-porphyrin and multiporphyrin assemblies using these versatile ligands were studied in detail by Sanders, Anderson, Hunter, Branda and many others. The structures of the supramolecular multi-porphyrin architectures are schematically represented in Fig. 9. 

W chelate = substituted bipy or phen, 2,2 -bi(4H-5,6-dihydro-thiazine) biacetylbis (phenylimine) or 4,4 -bipyrimidine ]. ... 

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