title: Novel bis-betaines and betaines within [1(4)]meta-heterophane frameworks.
abstract: After prior selection of betaine building blocks for the construction of quadrupolar heterophane frameworks, a convergent "3+1" synthetic strategy is reported for the synthesis of the title macrocycles composed of heterocyclic betaine subunit(s). These typify the first example of simple cyclophanes constructed out of both highly pi-excessive and highly pi-deficient heteroaromatic moieties linked in a 1,3-alternating fashion. The chemical reactivity of the quadrupolar heterophanes 1a and 1c toward electrophiles under neutral conditions corroborated their bis-betaine structure. The structural features of the bis-betaines 1, betaines 2 x PF6 and 5 x X, and the corresponding dicationic [1(4)]heterophanes 3 x 2X and 4 x 2Cl were studied by 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry, and confirmed by single-crystal X-ray diffraction analysis of macrocycles 1a and 2a x PF6.
authors.affiliation: Laboratori de Química Orgànica, Facultat de Farmàcia, Universitat de Barcelona, Spain.
authors.forename: Ermitas
authors.initials: E
authors.lastname: Alcalde
authors.forename: Neus
authors.initials: N
authors.lastname: Mesquida
authors.forename: Lluïsa
authors.initials: L
authors.lastname: Pérez-García
authors.forename: Susana
authors.initials: S
authors.lastname: Ramos
authors.forename: Montserrat
authors.initials: M
authors.lastname: Alemany
authors.forename: Matías L
authors.initials: ML
authors.lastname: Rodríguez