Carbon−Carbon Bond Formation and Cleavage in the Dimerization of a Nickelacycle

Abstract

Addition of 1,12-dilithiotriphenylenediyl to L2NiCl2 (L = PEt3) gives the nickelacycle L2Ni(1,12-triphenylenediyl), which decomposes to a dimer (L2Ni2C36H20) containing two coupled triphenylene moieties with a new C−C bond. Thermolysis of the dimer completes the coupling, yielding a chiral tetraphenylene, while alkyne addition leads to cleavage of the newly formed C−C bond of the dimer and cycloaddition of the alkyne to the triphenylene fragment.

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

“…Previously an incorporation of ap hosphorus(V) center into the {CNN} coordination core of carbaporphyrinoid has been reported for N-fused dihydrotelluraporphyrin. [27][28][29] Them ethoxide ligands at the phosphorus(V) center are readily exchangeable for hydroxides during chromatography on basic alumina or if traces of water are present in asolvent as documented by 1 HNMR spectroscopy ( Figure S25). [24,25] Nevertheless,t he binding component where the C(4) and C(5) carbon atoms of phenanthrene (where the numbers refer to "free" phenanthrene) are simultaneously bound has been recognized in silylated phenanthrenes [26] and metalated triphenylene derivatives.…”

Cyclobishelicenes: Shape‐Persistent Figure‐Eight Aromatic Molecules with Promising Chiroptical Properties

“…Robert mers embedded in the crystal and confirmed the assumptions of Thulin and Wennerstrçm on its geometry. [4] p-Extendeda nalogs of cyclobisphenanthrene (1a)w ere prepared more recently,n amely cyclobistriphenylene (1b) [5] and the functionalized cyclobisperylene 1c. [6] Significantly,t he enantiomers of 1c have been resolved by HPLC and found configurationally stable for three hours at 150 8Ca nd their absolute configurations were tentatively assigned without furtheri nvestigation.…”

“…The substituted cyclobis [4]helicenes 2a,b were reported by Isobe. [7] These molecules can adopt several moderately distorted conformationst hat interconvertr apidlya t2 08Cw ith barriers to enantiomerizationd etermined at 42.2 and5 3.9 kJ mol À1 , respectively.T heir time-averaged structures maya ctually be regarded as flatp lanes without peculiar topology.C yclobis [5]helicene (3a)w as synthesized, again,b yT hulin and Wennerstrçm in the early days of chiral polycyclic aromatich ydrocarbons chemistry andi ts fluorescencep roperties examined. [8] Recently, the synthesis of the substituted octaester analog 3b was reported by some of us.…”

“…[8] Recently, the synthesis of the substituted octaester analog 3b was reported by some of us. [9] Herein, we report the resolution of cyclobis [5]helicene 3b by HPLC techniques, and the full structural, chiroptical, and conformational analyses of its enantiomers. The computed enantiomerization processes and barriers to enantiomerization of all cyclobis[n]helicenes in Figure1are also reported.…”

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

“…[24,25] Nevertheless,t he binding component where the C(4) and C(5) carbon atoms of phenanthrene (where the numbers refer to "free" phenanthrene) are simultaneously bound has been recognized in silylated phenanthrenes [26] and metalated triphenylene derivatives. [27][28][29] Them ethoxide ligands at the phosphorus(V) center are readily exchangeable for hydroxides during chromatography on basic alumina or if traces of water are present in asolvent as documented by 1 HNMR spectroscopy ( Figure S25). Consequently,i tw as crucial for any characterization that the sample was recrystallized just before measurements and that all experiments were carried out in an inert atmosphere.…”