Synthesis of Dye-Bridged Crown Ether-Cyclodextrin Dyads and Their "Class-Selective" Coloration for Amines

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Like the essential roles of tosylates in the CD chemistry, the corresponding permethylated tosylates and monoalcohols are, undoubtedly, of great value as starting materials for making various amphiphilic and lipophilic CD derivatives, such as amines, esters, ethers, halides, and sulfides. Therefore, a facile preparative method for such intermediates is desired. We were able to establish a new practical method based on a new 20 g-scale direct permethylation reaction for the preparation of versatile 6-O-monotosyl and 6-monohydroxy permethylated α-, β-, and γ-cyclodextrins in good yields The present permethylation technique with a NaH-MeI combination is applicable to other polyhydroxy compounds with NaI-susceptible substituents.The first [5] supercy clodextrin whose nano-sized cyclo-pentameric array is held only by a mechanical bond was syn-thesized by the pentakis-azo coupling of a new hermaphrodite monomer with 2-naphthol as a stopper, isolated by chroma-tography, and characterized by MS, 2D NMR, and Vis spectral methods with the help of computer simulation. The chemical architecture has the following characteristics : (1) it is the first example of [n]SCDs constructed with s-mode insertion ; (2) it enables the termination at a molecular hierarchy with α-D-glucopyranose as the bottom ; (3) it is a nano-sized, condensed and lipophilic pentagon with a diameter of 3.9 nm and a thickness of 1.9 nm.In order to judge whether the self-association to face-to-face or cyclic dimers is a general or special phenomenon, we have designed and synthesized new lipophihc monomers composed of a permethylated α-cyclodextrin as host, an azobenzene moiety as internal guest and aρ-xylylene spacer inserted between the two. The synthesis of the two monomers and their self-association to stable lipophilic face-to-face dimmers are described.