Double elimination protocol for the synthesis of arylene ethynylenes containing heteroaromatic rings
The double elimination reaction of β-substituted sulfones offers a versatile strategy for synthesis of arylene ethynylene kits containing heteroaromatic rings. A sequence of aldol reaction between α-sulfonyl carbanion and aldehyde, trapping the resulting aldolate to give β-substituted sulfone, and double elimination of this intermediate can be integrated in one pot. This protocol allows thiophene, pyridine, and ferrocene units to be accommodated in phenylene ethynylene arrays.
Metal-assisted assembly of pyridine-containing arylene ethynylene strands to enantiopure double helicates
Pyridine-containing arylene ethynylene strands were connected to the 2- and 2′-positions of (R)- and (S)-1,1′-binaphthyl templates. The arylene ethynylene moieties underwent intramolecular coordination with Ag(I) or Cu(I) ion to afford enantiopure double helicates. The double-helical structure was elucidated on the basis of circular dichroic (CD) spectra. The importance of intramolecular complexation of the double strands for the helicate formation was confirmed by comparison with a ligand bearing a single strand. Connection of the strands through an ether linkage enabled a sorting out of the Cotton effect induced by double-helical arylene ethynylene moieties. The CD exciton chirality method unambiguously proved that the termini of the strands approach each other upon complexation and that the sense of the induced helicity is the same as predicted by molecular modeling.
Orita, Akihiro,Nakano, Takehiro,An, De Lie,Tanikawa, Kazumi,Wakamatsu, Kan,Otera, Junzo
p. 10389 - 10396
(2007/10/03)
Double elimination protocol for access to pyridine-containing arylene-ethynylenes
The arylene-ethynylene arrays involving pyridine were constructed successfully by taking advantage of double elimination reaction of β-substituted sulfones (sulfoximines) which are easily accessible from arylmethyl sulfones (sulfoximines) and aromatic aldehydes. This protocol was utilized for synthesis of an enantiopure arylene-ethynylene framework bearing a binaphthyl stereogenic core.