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One‐Pot Multimolecular Macrocyclization for the Expedient Synthesis of Macrocyclic Aromatic Pentamers by a Chain Growth Mechanism
Author(s) -
Qin Bo,
Shen Sheng,
Sun Chang,
Du Zhiyun,
Zhang Kun,
Zeng Huaqiang
Publication year - 2011
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201100409
Subject(s) - pentamer , monomer , chemistry , bifunctional , intramolecular force , residue (chemistry) , hydrogen bond , side chain , oligomer , combinatorial chemistry , stereochemistry , polymer chemistry , polymer , molecule , organic chemistry , catalysis , biochemistry
POCl 3 ‐mediated one‐pot macrocyclization allows the highly selective formation of five‐residue macrocycles that are rigidified by internally placed intramolecular hydrogen bonds. Mechanistic investigation by using tailored competition experiments and kinetic simulation provides a comprehensive model, supporting a chain‐growth mechanism underlying the one‐pot formation of aromatic pentamers, whereby the successive addition of a bifunctional monomer unit onto either another monomer or the growing oligomeric backbone is faster than other types of bimolecular condensations involving oligomers longer than monomers. DFT calculations at the B3LYP/6‐31G* level reveal the five‐residue pentamer to be the most stable with respect to alternative four‐, six‐, and seven‐residue macrocycles. These novel mechanistic insights may become useful in analyzing other macrocyclization , oligomerization, and ploymerization reactions.