Macrocycle Contraction and Expansion of a Dihydrosapphyrin Isomer

作者:Xie, Yongshu*; Wei, Pingchun; Li, Xin; Hong, Tao; Zhang, Kai; Furuta, Hiroyuki
来源:Journal of the American Chemical Society, 2013, 135(51): 19119-19122.
DOI:10.1021/ja4112644

摘要

Cyclization of a pentapyrrane with two terminal beta-linked pyrroles afforded a dihydrosapphyrin isomer (1) with the pyrroles linked in a unique beta,alpha-alpha,beta mode, which was rather reactive, and thus it readily underwent a ring-contracted rearrangement to a pyrrolyl norrole (2), and succeeding ring expansion to a terpyrrole-containing isosmaragdyrin analogue (4). 1, 2, and 4 contain the internal ring pathways with a minimum of 17, 15, and 16 atoms, respectively. 1, 2, and 4 are almost nonfluorescent, whereas the complex of 2 with Zn2+ shows a distinct NIR emission peak at 741 nm. The unprecedented pyrrole transformation chemistry by confusion approach is illustrated.