8,14,30,36-Tetramethoxy[2.0.2.0](1,6)naphthalenophane-1,19-diyne: a double-helically twisted cyclophane by diastereoselective dimerization.
The title compound and its corresponding etheno- and ethano-bridged compounds were successfully synthesized in enantiomerically pure form by McMurry coupling of 2,2'-dimethoxy-(R)- or -(S)-1,1'-binaphthyl-6,6'-dicarbaldehydes as the key reaction. The reaction proceeded in a highly diastereoselective manner; the reaction of the racemic dialdehyde did not afford the meso coupling product but gave only the racemic one in poor yield. The diyne crystallized in the chiral monoclinic space group P2(1) from toluene/hexane. Structural analysis reveals that it has a considerably twisted double-helical structure in crystal form. The spectral properties (NMR, UV/Vis, and CD) clearly indicate the highly strained nature of the molecule. In particular, its UV/Vis and CD spectra exhibit a bathochromic shift of about 20 nm for the naphthyl pi-pi* transitions.
Kawase
Takeshi
T
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.
Nakamura
Takamitsu
T
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.
Utsumi
Keiichiro
K
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.
Matsumoto
Kouzou
K
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.
Kurata
Hiroyuki
H
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.
Oda
Masaji
M
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan, Fax: (+81) 6-6850-5387.