Enantiopure, Monodisperse Alleno-acetylenic Cyclooligomers: Effect of Symmetry and Conformational Flexibility on the Chiroptical Properties of Carbon-Rich Compounds
作者:Pablo Rivera-Fuentes、Belén Nieto-Ortega、W. Bernd Schweizer、Juan T. López Navarrete、Juan Casado、François Diederich
DOI:10.1002/chem.201100131
日期:2011.3.28
A series of enantiopure, monodisperse alleno‐acetylenic cyclooligomers were synthesized. The single‐crystal X‐ray structures of the cyclic trimer and hexamer were resolved, providing insights into the symmetry of these molecules. Electronic circular dichroism (ECD), optical rotatory dispersion (ORD), Raman spectroscopy, and vibrational circular dichroism (VCD) data were analyzed with the aid of theoretical
Amplification of Chirality in Monodisperse, Enantiopure Alleno-Acetylenic Oligomers
作者:Pablo Rivera-Fuentes、José Lorenzo Alonso-Gómez、Ana G. Petrovic、Fabrizio Santoro、Nobuyuki Harada、Nina Berova、François Diederich
DOI:10.1002/anie.200906191
日期:2010.3.15
Enantiomerically pure alleno‐acetylenic oligomers of defined lengths were synthesized by the palladium‐mediated oxidative homocoupling of optically pure 1,3‐diethynylallenes. The large amplification of their chiroptical properties strongly suggests the formation of helical secondary structures. This assignment is supported by time‐dependent quantum chemical calculations.