1<i>H-</i>Phosphindoles as Structural Units in the Synthesis of Chiral Helicenes
作者:Keihann Yavari、Souad Moussa、Béchir Ben Hassine、Pascal Retailleau、Arnaud Voituriez、Angela Marinetti
DOI:10.1002/anie.201202024
日期:2012.7.2
Building helicenes: A photochemical cyclization approach affords helicenes in which the fused ring sequence ends with a phosphole unit (see scheme). The stereogenic phosphorus centers of the substrates control the screw sense of helical chirality. The terminal phosphole units undergo photochemical [2+2] annulations to give dimeric helical structures.
A Ni(0) promoted intramolecular [2+2+2] cyclotrimerization of triynes provides suitable access to a new series of phosphorus embeddinghelicenes. [6]Oxahelicenes in which the helical sequence terminates with a phosphole oxide unit have been prepared in both racemic and enantiopure forms and characterized by X-ray diffraction studies.