In:
European Journal of Inorganic Chemistry, Wiley, Vol. 26, No. 6 ( 2023-02-17)
Abstract:
Functionalization of the phenolic rim of p‐tert‐ butylcalix[8]arene with phenanthroline to create a cavity leads to formation of two regioisomers. Substitution of positions 1 and 5 produces the known C 2v ‐symmetric regioisomer 1,5‐(2,9‐dimethyl‐1,10‐phenanthroyl)‐ p ‐ tert ‐butylcalix[8]arene ( L 1,5 ), while substitution of positions 1 and 4 produces the C s ‐symmetric regioisomer 1,4‐(2,9‐dimethyl‐1,10‐phenanthroyl)‐ p ‐ tert ‐butylcalix[8]arene ( L 1,4 ) described herein. [ Cu(L 1,4 )I ] was synthesized from L 1,4 and CuI in good yield and characterized spectroscopically. To evaluate the effect of its cavity on catalysis, Ullmann‐type C−S coupling was chosen as proof‐of‐concept. Selected aryl halides were used, and the results compared with the previously reported Cu(I)/ L 1,5 system. Only highly activated aryl halides generate the C−S coupling product in moderate yields with the Cu(I)/ L 1,4 system. To shed light on these observations, detailed computational investigations were carried out, revealing the influence of the calix[8]arene macrocyclic morphology on the accessible conformations. The L 1,4 regioisomer undergoes a deformation that does not occur with L 1,5 , resulting in an exposed catalytic center, presumably the cause of the low activity of the former system. The 1,4‐connectivity was confirmed in the solid‐state structure of the byproduct [ Cu(L 1,4 − H) (CH 3 CN) 2 ] that features Cu(I) coordinated inside a cleft defined by the macrocyclic framework.
Type of Medium:
Online Resource
ISSN:
1434-1948
,
1099-0682
DOI:
10.1002/ejic.202200596
Language:
English
Publisher:
Wiley
Publication Date:
2023
detail.hit.zdb_id:
1475009-0
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