ISSN:
0899-0042
Schlagwort(e):
polycyclic aromatic hydrocarbons
;
arynes
;
cyclopentadienones
;
conformation
;
steric hindrance
;
rotational barriers
;
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Two exceptionally crowded derivatives of octaphenylnaphthalene bearing ortho-methyls on the phenyl substituents - 2,3,5,6,7,8-hexaphenyl-1,4-di(o-tolyl)naphthalene (2) and 2,3,6,7-tetraphenyl-1,4,5,8-tetra(o-tolyl)naphthalene (3) - were prepared by the addition of tetraarylbenzynes to tetraarylcyclopentadienones. Both compounds exist as a mixture of conformational isomers which do not interconvert at ordinary temperatures. The yield of 2 and its distribution of conformers is strongly influenced by the choice of precursors in the final cycloaddition; one method gives a high yield of a 55:45 trans-2:cis-2 mixture, while another gives a very low yield of a 15:85 trans-2:cis-2 mixture. Kinetic epimerization of the latter indicated that the barrier to rotation about the tolyl-naphthalene bonds is 33.1 kcal/mol. Chirality 10:154-158, 1998. © 1998 Wiley-Liss, Inc.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/chir.24
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