jo050993p_si_002.pdf (556.44 kB)
Heteroatom-Substituted Expanded Radialenes: One-Pot Synthesis and Characterization of Expanded 1,3-Dithiolane[n]radialenes
journal contribution
posted on 2005-08-19, 00:00 authored by Yu-Long Zhao, Qun Liu, Jing-Ping Zhang, Zhi-Qiang LiuThe 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 α-enediyne units starting from the ready available α,α-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.