Synthesis and ring-expanding oligomerization of an extremely strained macrocyclic aromatic ether-sulfone.
[reaction: see text] An extremely strained, 5-ring, macrocyclic aromatic ether-sulfone, [-1,4-C(6)H(4)SO(2)-1,4-C(6)H(4)O-1,3-C(6)H(4)O-1,4-C(6)H(4)SO(2)-1,4-C(6)H(4)-], synthesized by nickel-catalyzed intramolecular coupling of a bis-chlorophenylene-terminated precursor, undergoes fluoride-promoted ring expansion in dilute solution, giving a series of higher macrocyclic oligomers including cyclic dimer, trimer, and tetramer. The latter contains 20 aromatic residues in a 92-atom ring and is one of the largest synthetic organic macrocycles to be crystallographically characterized. The synthesis, structure, and ring expansion of a related macrocyclic ether-ketone are also reported.
Colquhoun
H M
HM
Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK. h.m.colquhoun@rdg.ac.uk
Zhu
Z
Z
Williams
D J
DJ