Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Chem Asian J. 2011 Dec 2;6(12):3298-305. doi: 10.1002/asia.201100409. Epub 2011 Jul 20.
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.
POCl(3)介导的一锅法环化反应允许高度选择性地形成由内部氢键固定的五残基大环。通过使用定制的竞争实验和动力学模拟进行的机理研究提供了一个全面的模型，支持了一锅法形成芳香五聚体的链增长机制，其中双官能单体单元连续添加到另一个单体或生长的低聚物主链上的速度比涉及单体以上的长低聚物的其他类型的双分子缩合快。在 B3LYP/6-31G*水平下的密度泛函理论（DFT）计算表明，与其他四、六和七残基大环相比，五残基五聚体是最稳定的。这些新的机理见解可能有助于分析其他环化、齐聚和聚合反应。
