84911-79-5Relevant articles and documents
A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
, p. 13798 - 13805 (2021/09/07)
The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
Boronic Acids as Phase-Transfer Reagents for Fischer Glycosidations in Low-Polarity Solvents
Manhas, Sanjay,Taylor, Mark S.
, p. 11406 - 11417 (2017/11/10)
Protocols employing phenylboronic acid as a phase-transfer reagent for Fischer glycosidations in low-polarity organic solvents are described. In addition to providing rate acceleration, the formation of a substrate-derived boronic ester alters the course of the reaction by selective promotion of a furanoside- or pyranoside-selective pathway. Computational modeling of the relative energies of the glycoside-derived boronic esters provides results that are qualitatively consistent with the observed distributions of furanoside versus pyranoside products. The boronic esters that are obtained as direct products of these reactions serve as protected intermediates for the synthesis of functionalized glycosides. Complexation of particular diol groups by the boronic acid also enables selective transformations of mixtures of carbohydrates.
Application of the Wharton rearrangement for the de novo synthesis of pyranosides with ido, manno, and colito stereochemistry
Cuccarese, Michael F.,Wang, Hua-Yu Leo,O'Doherty, George A.
, p. 3067 - 3075 (2013/06/27)
A de novo asymmetric synthesis of α-ido-pyranosides, as well as several deoxy and amino variants, has been achieved. The procedure involves a palladium(0)-catalyzed glycosylation in combination with a Wharton rearrangement/epoxide-opening reaction sequence to access sugars with ido, manno, and colito stereochemistry as well as several azido analogues. A de novo asymmetric synthesis of α-ido-pyranosides, as well as several deoxy and amino variants, has been achieved. The procedure involves a palladium(0)- catalyzed glycosylation in combination with a Wharton rearrangement/epoxide- opening reaction sequence to access sugars with ido, manno, and colito stereochemistry as well as several azido analogues. Copyright
