Reductive Radical Cascades Triggered by Alkoxyl Radicals in the β-Cyclodextrin Framework

Abstract

The generation and fate of 2,3,6-icosa- O-methyl-β-cyclomaltoheptaos-6- O-yl radical under reductive conditions is described. Two radical cascade reactions are involved: the main one is triggered by a 1,8-HAT of the hydrogen at 5C. The radical can reach the anomeric hydrogen at 1C three sugar units ahead using a six-step sequence. The different hydrogen donor ability of the group 14 hydrides permits one to selectively stop the cascade at 5C, 2C, and 4C to obtain β-CD with a β-l-Ido p unit, acyclic hepta-, and hexa-saccharide structures, respectively.

Radical Dehydroxymethylative Fluorination of Carbohydrates and Divergent Transformations of the Resulting Reverse Glycosyl Fluorides

“…Product 2 r might be an intriguing structure as modified trehaloses have proven to be attractive synthetic targets because of their potential in investigating trehalose metabolism in Mycobacterium tuberculosis . β‐CD‐derived primary alkoxyl radicals have been observed to exclusively undergo 1,8‐HAT with DIB/I 2 as the oxidant in structural modifications of β‐CDs . However, in our hands, this reactive species generated fluoride 2 z in 62 % yield by exclusive β‐scission of the primary alkoxyl radical.…”

Dynamic Control of the Self-Assembling Properties of Cyclodextrins by the Interplay of Aromatic and Host-Guest Interactions

“…Imposing distance restrictions in CDs through covalent bonds can lead to significant alterations in their primary structure, usually by provoking conformational changes in one or several of the monosaccharide building blocks, which may substantially perturb the inclusion capabilities (Fujita et al, 1988; Fukudome et al, 2007b; Álvarez-Dorta et al, 2015, 2016; Immel et al, 2001; Fukudome et al, 2007; León et al, 2018). Compounds 4 and 5 were purposely conceived to avoid this and keep the toroidal βCD cavity characteristic of βCD undistorted, so that any effect in their supramolecular properties can be ascribed to the presence of the naphthalene component, devoid from additional effects on the βCD macroring topology.…”

Nitrogenation and Oxygenation of an Unstrained C–C Bond Enabled by the Merger of Visible-Light and Cu-Catalysis

“…Recently, Stahl developed elegant examples on nitrogenation and oxygenation of benzylic C–H bonds using copper catalysis (Scheme c) . Moreover, methods focusing on nitrogen radical triggered 1,n-H atom abstraction have also been reported by Cook, Knowles, Rovis, and other groups. , However, the selective activation of remote and unstrained C–C bonds of amines remains less explored. Thus, the successful application of functional group migration for carbon skeletal modification of amine derivatives would accelerate analogue evaluation in medicinal chemistry.…”