title: One-pot multimolecular macrocyclization for the expedient synthesis of macrocyclic aromatic pentamers by a chain growth mechanism.
abstract: 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.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
authors.forename: Bo
authors.initials: B
authors.lastname: Qin
authors.forename: Sheng
authors.initials: S
authors.lastname: Shen
authors.forename: Chang
authors.initials: C
authors.lastname: Sun
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Du
authors.forename: Kun
authors.initials: K
authors.lastname: Zhang
authors.forename: Huaqiang
authors.initials: H
authors.lastname: Zeng
mesh_terms: D003500:Cyclization; D006860:Hydrogen Bonding; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D017553:Phosphorus Compounds / Q000737:chemistry
chemical_list: D047028:Macrocyclic Compounds; D017553:Phosphorus Compounds; C013196:phosphoryl chloride