Synthesis, Structures, and Properties of BN-Dinaphthothiophenes: Influence of B and N Placement on Photophysical Properties and Aromaticity

Substitution of the C═C functionality with the isosteric and isoelectronic B-N moiety has emerged as a powerful way to expand the family of polycyclic aromatic hydrocarbons. In this paper, two types of BN-dinaphthothiophene (BN-DNT) derivatives with different B and N substitution patterns were synthesized in short steps from commercially available materials. X-ray crystallographic analysis revealed that BN-DNT 1 and 2 had rigid and planar frameworks. Their photophysical properties and the aromaticity of the BN rings of the BN-DNTs were slightly dependent on the B and N substitution patterns. However, their response toward fluoride anions was greatly dependent on the B and N substitution patterns.

Palladium complexes of anionic N-heterocyclic carbenes derived from sydnones in catalysis

The anion of N-phenylsydnone, which can be generated on treatment of N-phenylsydnone with cyanomethyllithium without decomposition, can be represented as tripolar zwitterionic and as anionic N-heterocyclic carbene resonance forms. Its palladium complex was prepared from 4-bromo-3-phenylsydnone and tetrakis(triphenylphosphine)palladium and proved to be active as catalyst in Suzuki-Miyaura reactions. Thus, 2,5-dibromo-3,4-dinitrothiophene was effectively converted into 2,5-diaryl-3,4-dinitrothiophenes with 1-naphthyl, (4-trifluoromethoxy)phenyl, [4-(methylsulfanyl)phenyl], and biphenyl-4-yl boronic acid. 3-(Phenanthren-9-yl)quinoline was prepared by Suzuki-Miyaura reaction starting from 3-bromoquinoline. 1-Chloro-2,4-dinitrobenzene cross-coupled with phenyl boronic acid, 1-naphthyl boronic acid, 9-phenanthryl boronic acid. 4-Bromobenzylic alcohol gave (4-isopropylphenyl)methanol on sydnone-palladium complex-catalyzed reaction with isopropyl boronic acid.