Probing Intramolecular CH−π Interactions in o-Quinodimethane Adducts of [60]Fullerene Using Variable Temperature NMR
摘要:
Several o-quinodimethane adducts of [60]fullerene were synthesized and their intramolecular aryl CH-fullerene pi interactions were studied using variable temperature-NMR (VT-NMR). Evaluation of the rate constants associated with the first-order transition states for cyclohexene boat-to-boat inversions enables quantification of Delta G(double dagger) values for each inversion. A comparison between two constitutional isomers, only one of which is capable of intramolecular CH-pi interactions, provides a lower limit of 0.95 kcal/mol for each aryl CH-fullerene pi interaction.
Probing Intramolecular CH−π Interactions in <i>o</i>-Quinodimethane Adducts of [60]Fullerene Using Variable Temperature NMR
作者:Ryan P. Kopreski、Jonathan B. Briggs、Weimin Lin、Mikaël Jazdzyk、Glen P. Miller
DOI:10.1021/jo201921h
日期:2012.2.3
Several o-quinodimethane adducts of [60]fullerene were synthesized and their intramolecular aryl CH-fullerene pi interactions were studied using variable temperature-NMR (VT-NMR). Evaluation of the rate constants associated with the first-order transition states for cyclohexene boat-to-boat inversions enables quantification of Delta G(double dagger) values for each inversion. A comparison between two constitutional isomers, only one of which is capable of intramolecular CH-pi interactions, provides a lower limit of 0.95 kcal/mol for each aryl CH-fullerene pi interaction.
Syntheses of 3-Aryl Tetrahydroisoquinolines via an Intermolecular [4 + 2] Cycloaddition of Sultines with Imines
The development of an intermolecular aza-Diels–Alder (DA) cycloaddition of sultines and imines is reported. By exploiting sultines as o-quinodimethane precursors and aryl imines as dienophiles in the presence of Cu(OTf)2, an aza-DA reaction proceeds to provide a wide variety of 3-aryl tetrahydroisoquionlines in moderate to excellent yield (up to 89%). The synthetic utility of these products was demonstrated