The present invention is a photochromic material formed of a biimidazole compound represented by general formula (1-1):
(where, R
4
and R
5
respectively and independently represent a halogen atom or alkyl group, R
1
to R
3
and R
6
to R
8
respectively and independently represent a hydrogen atom, halogen atom, alkyl group, fluoroalkyl group, hydroxyl group, alkoxyl group, amino group, alkylamino group, carbonyl group, alkylcarbonyl group, nitro group, cyano group or aryl group, Ar
1
to Ar
4
respectively and independently represent a substituted or unsubstituted aryl group, R
4
may form a condensed, substituted or unsubstituted aryl ring with R
3
, and R
5
may form a condensed, substituted or unsubstituted aryl ring with R
6
).
Synthesis of Higher Helicenes
via Olefin Metathesis and C-H Activation
作者:Shawn Collins、Julie Côté
DOI:10.1055/s-0028-1088165
日期:——
Functionalized heterohelicenes were prepared using sequential olefinmetathesis and direct arylation reactions. Functionalization via C-H activation always occurs at the least hindered position of the [5]helicene carbon skeleton. Attempts at blocking the least hindered positions to force arylation at the interior of the helicene skeleton result in decomposition of the starting material. Installation