Blog

Synthesis, Structures and Properties of π-Extended Double Helicene: A Combination of Planar and Nonplanar π-Systems

Takao Fujikawa , Yasutomo Segawa , and Kenichiro Itami

J. Am. Chem. Soc., 2015, DOI: 10.1021/jacs.5b03118

The synthesis, structures, and properties of a π-extended double helicene 1 are described. This double helicene 1 was synthesized by a four-fold oxidative C–H biphenylation of naphthalene followed by the Scholl reaction or via five steps including the Suzuki–Miyaura cross-coupling reaction and the Scholl reaction. Due to the two helical substructures, 1 has three isomers, i.e., two enantiomers in a twisted form [(P,P) and (M,M)] and one diastereoisomer in a meso form. X-ray crystallographic analysis of the twisted isomers (twisted-1) revealed a tightly offset packing pattern of (P,P)- and (M,M)-twisted isomers, affording a three-dimensional lamellar stacking structure. A high isomerization barrier (43.5 kcal mol–1) and the relative thermal stability of twisted-1 isomer over meso-1 by 0.9 kcal mol–1 were estimated by DFT calculations. The three isomers were successfully separated by chiral HPLC and characterized by circular dichroism spectroscopy as well as by TD-DFT studies. Electronic state variation resulting from the molecular geometry difference between the two diastereoisomers (twisted-1 and meso-1) was observed by UV–vis absorption and fluorescence spectra.

Related post

  1. Electro-Activated Conductivity a…
  2. Molecular Catalysis for Fulleren…
  3. Initiation of carbon nanotube gr…
  4. C-H Arylation of Phenanthrene wi…
  5. Stereodivergent Synthesis of Ary…
  6. Nickel-Catalyzed Biaryl Coupling…
  7. Palladium-Catalyzed C–H and C–N …
  8. Oxidative C–H/C–H Coupling of Az…

Twitter@Itami Lab

Itami Lab Facebook

Instagram@Itami Lab

最近の記事

Flickr@Itamilab

天池先輩からコーヒースープ伴夫妻からのお歳暮です!潤さん、宮村さん、ありがとうございます!!武藤さん、ビールありがとうございます!平賀大都わーいやなさん、あつしさん、ありがとうございます!!だいぶ前だけど、Stripes look #ootdHalloween lookラインを洗う時ですら格好良く。戸谷先生教育実習!imageけいしゅう、誕生日おめでとう!誕生日は英吉家!!3年生に名古屋ぼろ勝ちアピール中!!アリシア卒業おめでとう女子会!
PAGE TOP