An Atropisomerism Study of Large Cycloarylenes: [n]Cyclo-4,10-Pyrenylenes' Case.
Chemistry
; 29(24): e202203848, 2023 Apr 25.
Article
in En
| MEDLINE
| ID: mdl-36740789
ABSTRACT
An atropisomerism of large cycloarylenes was studied using [n]cyclo-4,10-pyrenylenes (n=6-21) as an illustrative example with two simple assumptions (1) alternating configurations (R,S,R,S,
) are thermodynamically most stable, and (2) three consecutive identical configurations (R,R,R or S,S,S) are prevented. Ni-mediated coupling of a 5,9-diiodopyrene gave a series of directly-linked cyclic pyrene oligomers in one-pot reaction. As-synthesized cyclic hexamer was assigned as an (R,S,S,R,R,S) structure, converted into an (R,S,R,S,R,S)-form upon heating. Cyclic heptamer consists of two types of C2 symmetric structures predicted from assumption (2), one of which was convergent to one another by heating. Three atropisomers of cyclic octamer were analyzed from the possible five candidates by means of 1 H nuclear magnetic resonance (NMR) spectroscopy, and the conversion process to (R,S,R,S,R,S,R,S) configurations upon heating was investigated. In total, according to two simple rules, the analysis of atropisomerism could be performed smoothly.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Chemistry
Journal subject:
QUIMICA
Year:
2023
Type:
Article
Affiliation country:
Japan