Hetero-bifunctional γ-cyclodextrins having dansylcysteine and tosyl groups at two adjacent sugar units: synthesis and determination of regio-chemistry

Three-in-one: Miniature Models of Natural Acyl-transfer Systems Enable Vector-selective Reaction on the Primary Side of Cyclodextrins

Miniature models of acyl-transfer systems in cells, which were composed by replacing the protein, coenzyme and substrate with CD, functional group, and CD, respectively, and combining them all together in one, displayed definite role-sharing and exact cooperation of the functional groups and hydrophobic cavity, and thus enabled the regio-specific reaction.

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

The synthesis of batch-to-batch reproducible cyclodextrin (CD) derivatives often requires functionalization at specific positions of the CD skeleton. However, the regioselective preparation of this type of CD derivatives remains a challenge in synthetic chemistry. Thus, the present study aimed to prepare all positional regioisomers on the primary rim of homobifunctionalized diazido-α-CDs by selective substitution on the primary rim. Specifically, three positional regioisomers 6^A,6^B-, 6^A,6^C-, and 6^A,6^D-diazido-α-CDs were prepared via different intermediates (using sulfonylation with capping agents, bromination and tosylation). Furthermore, heterobifunctionalized 6^A-azido-6^X-mesitylenesulfonyl-α-CDs were also synthesized, and all regioisomers were successfully separated by HPLC. Moreover, the heterobifunctionalized α-CD regioisomers were isolated in gram-scale quantities, isomers AB and AC in the form of a pseudoenantiomeric mixture. The pseudoenantiomers AC/CA and AB/BA were resolved on an analytical scale by HPLC–MS at 10 °C. Thus, the presented synthetic and analytical methods for homo- and heterodisubstituted α-CDs are efficient and reproducible for the preparation of various pure regioisomeric CD derivatives. Accordingly, our findings indicate, (i) the versatility of selectively modified azido and mesitylene CD skeletons in preparing new types of α-CD derivatives and (ii) the potential of using resolved α-CD pseudoenantiomers in other research fields such as organocatalysis.

Synthesis and Characterization of Bradykinin Derivatives Based on a β-Cyclodextrin Core

Mono-6A-fluorenylmethyloxycarbonylamino-mono-6X-succinyl-β-cyclodextrin (1), an amino acid-based bi-functionalized derivative of β-cyclodextrin (β-CD), has been functionalized with the bioactive peptide, bradykinin and/or sulfonamides using fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS). The all-in-one molecule contains a carrier (cyclodextrin), targeting agent (bradykinin), and/or model drug (sulfonamide). Varying combinations of these bradykinin-focussed molecules have been synthesized using Fmoc SPPS on Rink amide resin. The positioning of the sulfonamide group, the bradykinin peptide and the cyclodextrin carrier are essential for biological activity. The inclusion of spacers is also important. Structure–activity studies performed on three cancer cell lines in vitro support these conclusions.

An "against the rules" double bank shot with diisobutylaluminum hydride to allow triple functionalization of α-cyclodextrin

Frustration leads to overreaction: when diametrically opposed regioselective debenzylation is frustrated, an unexpected double debenzylation reaction affords original tetrafunctionalized cyclodextrins in a controlled and efficient manner. A rationale of the reaction is proposed based on a kinetic study.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2007-2008

This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.