Abstract
The 1H NMR spectrum of tetramesitylethylene (2) was analyzed, and the signals were assigned by means of a 2D NOESY spectrum. Attempts to observe anisochrony of the enantiotopic groups of a racemic mixture of 2 in a chiral solvent by 1H NMR were unsuccessful. Molecular mechanics and MNDO calculations satisfactorily reproduce the ground-state conformation. The calculated barrier for the enantiomerization process is 21.8 (MM2) and 28.2 (MNDO) kcal mol−1. 2 was chromatographically resolved on a (+)-poly(triphenylmethyl)methacrylate (PTrMA) column. Its specific rotation is [α]25 = −12100° at 365 nm and −2300° at 589 nm (d line). The activation parameters for the enantiomerization of 2 in perhydrofluorene are ΔG‡ = ΔH‡ = 39.6 kcal mol‒1 and ΔS‡ = 0 cal mol−1 K−1. The barrier for 2 is the highest determined experimentally for a correlated rotation.
Original language | English |
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Pages (from-to) | 3689-3693 |
Number of pages | 5 |
Journal | Journal of Organic Chemistry |
Volume | 57 |
Issue number | 13 |
DOIs | |
State | Published - 1 Jun 1992 |