Corona[5]arenes Accessed by a Macrocycle‐to‐Macrocycle Transformation Route and a One‐Pot Three‐Component Reaction

Abstract

AbstractCorona[5]arenes, a novel type of macrocyclic compound that is composed of alternating heteroatoms and para‐arylenes, were synthesized efficiently by two distinct methods. In a macrocycle‐to‐macrocycle transformation approach, S6‐corona[3]arene[3]tetrazine underwent sequential SNAr reactions with HS‐C6H4‐X‐C6H4‐SH (X=S, CH2, CMe2, SO2, and O) to produce the corresponding corona[3]arene[2]tetrazines. Different corona[3]arene[2]tetrazine compounds were also constructed in a straightforward manner by a one‐pot three‐component reaction of HS‐C6H4‐X‐C6H4‐SH (X=S, CH2, CMe2, SO2, and O) with diethyl 2,5‐dimercaptoterephthalate and 2 equiv of 3,6‐dichlorotetrazine under very mild conditions. All corona[5]arenes adopted 1,2,4‐alternate conformational structures in the crystalline state yielding similar nearly regular pentagonal cavities. Both the cavity size and the electronic property of the acquired macrocycles were fine‐tuned by the nature of the bridging element X.