transition‐metal catalysis. Unlike all known helical phosphines used so far in catalysis, the phosphorus function of phosphahelicenes is embedded in the helical structure itself. This crucial structural feature originates unprecedented catalytic behaviors and efficiency. An appropriate design and fine tuning allowed both high catalytic activity and good enantiomeric excesses to be attained in the gold promoted
Switchable anthranyl receptors controlled by 1O2 show a different preorganization of the binding sites induced by two combined effects: the structural modification and the on/off mode for the host atropisomerism.
由1 O 2控制的可切换蒽酰基受体显示出由两种组合效应诱导的结合位点的不同预组织:结构修饰和宿主阻转异构现象的开/关模式。
Synthesis and resolution of a new helically chiral azahelicene
作者:Faouzi Aloui、Riadh El Abed、Angéla Marinetti、Béchir Ben Hassine
DOI:10.1016/j.tetlet.2008.04.135
日期:2008.6
Helically chiral azahexahelicene 3 was prepared in four steps using the Mizoroki-Heck coupling followed by classical oxidative photodehydrocyclisation. Resolution of this new chiral system was achieved through separation by HPLC providing (-)- and (+)-3 in high optical purity. The absolute configurations of (-)- and (+)-3 were assigned as M and P, respectively, by means of circular dichroism. Each of the hexa-cyclic systems (M)-(-)- and (P)-(+)-3 was reacted with boron tribromide to provide the corresponding helical pyridophenols in good yields. (C) 2008 Elsevier Ltd. All rights reserved.
Synthesis and characterization of new hexahelicene derivatives
作者:Faouzi Aloui、Riadh El Abed、Angéla Marinetti、Béchir Ben Hassine
DOI:10.1016/j.tetlet.2007.01.058
日期:2007.3
The synthesis and structural characterization of a new hexahelicene derivative 2 is reported. This compound features a new type of structure bearing a bromine atom and a methoxy group. Suitable crystals of the latter indicate that its conformation closely resembles that of the unsubstituted [6]helicene, whose idealized symmetry is C2. This 3-bromo-14-methoxyhexahelicene was subjected to lithiation/phosphinilation