In:
Asian Journal of Organic Chemistry, Wiley, Vol. 4, No. 12 ( 2015-12), p. 1392-1398
Abstract:
Dynamic 1 H NMR experiments on monobridged tetraarylethenes (bistricyclic aromatic enes devoid of one bridge, BAE‐1s) revealed the conformational processes in 13 – 15 (BAE‐1 s, X=S, Se, and Te) and in their respective thiiranes. The experimental energy barriers Δ G ≠ c were found to be 59.0, 72.2, and 67.9 kJ mol −1 for 13 , 14 , and 15 , and 63.4, 64.4, and 61.3 kJ mol −1 for 26 , 27 , and 28 , respectively. In contrast to the bis(α‐naphthyl) derivatives 13 – 15 , no dynamic processes were detected for the bis(β‐naphthyl) derivatives 16 – 20 . These results are in agreement with the mechanisms of enantiomerization of 13 – 15 derived from DFT calculations. The folded‐twisted global minima conformers of 13 – 15 undergo enantiomerization via inversion of the central ring, accompanied by rotation of the α‐naphthyl substituents. The B3LYP/SDD free energy barriers, Δ G 298 , for the enantiomerizations of BAE‐1s 13 – 15 are 57.4, 66.6, and 80.2 kJ mol −1 , respectively. The minima and transition‐state conformations are chiral and the enantiomerization may proceed via chiral pathways.
Type of Medium:
Online Resource
ISSN:
2193-5807
,
2193-5815
DOI:
10.1002/ajoc.201500316
Language:
English
Publisher:
Wiley
Publication Date:
2015
detail.hit.zdb_id:
2679333-7
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