Heteroatom-substituted expanded radialenes: one-pot synthesis and characterization of expanded 1,3-dithiolane[n]radialenes.
The one-pot synthesis, crystal structure, and electronic absorption properties of expanded 1,3-dithiolan[5]radialene (6a), the first heteroatom-substituted expanded radialene molecule with dithiolanylidene groups as strongly donor termini, has been developed. Catalyzed by Ni(PPh3)2Cl2-PdCl2-CuI, radialene 6a was assembled by a highly efficient one-pot and protection-free oxidative coupling reaction of five alpha-enediyne units starting from the ready available alpha,alpha-diethynyl ketene dithioacetal (13) under mild conditions. The crystal of 6a, obtained by slow evaporation of DMSO and acetone solutions, shows that the inclusion complex of DMSO molecules in the cavity of radialene 6a molecule is formed. More importantly, owing to the introduction of the strong electron-donating alkylthio groups, per(alkylthiolated) expanded radialene 6a shows an extremely strong intramolecular push-pull interaction and enhanced macrocyclic cross-conjugation.
Zhao
Yu-Long
YL
Department of Chemistry, Northeast Normal University, Changchun 130024, China.
Liu
Qun
Q
Zhang
Jing-Ping
JP
Liu
Zhi-Qiang
ZQ