Sulfur-capped cyclodextrins: a new class of cavitands with extroverted as well as introverted donor functionalities

Abstract

Ansa-cyclodextrins were obtained in high yields by reaction of sodium sulfide with A,B-di- or A,B,D,E-tetramesylated alpha-CD precursors; the resulting thiocavitands are suitable for forming nanotubular molecules, as well as for hosting metal-organic fragments.

Synthesis and NMR characterization of β‐alanine‐bridged hemispherodextrin, a very efficient chiral selector in EKC

“…Analogously, on the 13 C spectra each methylene appears as a different signal with respect to the other. As expected, the A and D rings of CD of the b-CD are not equivalent after the functionalization and thus the 6-methylenes of these glucopyranosinic rings give rise to four separate signals on the 1 H spectra and as two separate signals on the 13 C spectra. This trend is generally observed in the case of the bis derivatives of CDs [23,37].…”

“…In the anomeric region, three groups of signals can be seen: they are due to the H-1 of the trehalose and the H-1 of the functionalized rings and to the other glucopyranosinic rings of CD. Also on the 13 C spectra the C-1 of the CD unit appears as six different signals. The symmetry of the CD is lost after the functionalization and this is observed not only in the number of signals of the protons and of the carbon atoms of the CD but also in that of the protons of the ethylenic chain of the b-alanines.…”

“…In the literature several different moieties were used as capping units such as aromatic chains [9][10][11], polar chains [12][13][14][15], peptidic chains [16], often with the aim to conjugate the properties of CDs with the different properties of the substituted chain. In our laboratory, our approach was directed to reinforce the peculiar characteristics of the CDs by including a saccharidic unit in the substituted chain.…”

Regioselective Double Capping of Cyclodextrin Scaffolds

“…Double capping strategy based on the use of the bulky reagent 1. E -tetramesylated a-CD 5 with small phenylphosphide, [23,24] or very small sulfide dianions, [25,26] showed that these cyclisation processes are highly regioselective, even regiospecific (because only adjacent glucose units were being bridged) in the case of the more sterically crowded phenylphosphide, towards 6 A ,6…”

Cyclodextrin and phosphorus(iii): a versatile combination for coordination chemistry and catalysis

“…In this respect, the length of the capping unit as well as its rigidity are crucial. [68][69][70][81][82][83][84][85] In the case of phosphine ligands, Armspach and Matt achieved this goal by bridging two CD glucose units with a single P(III) atom. The first derivatives with a phosphorus lone pair pointing towards the cavity interior (31)(32)(33)(34), were obtained by reaction of dilithium phenylphosphide (Li 2 PPh) in THF with dimesylates 27-30, respectively (Scheme 15).…”