Magnetic Core-Shell Fe3O4@C-SO3H as an Efficient and Renewable ‘Green Catalyst’ for the Synthesis of O-2,3-Unsaturated Glycopyranosides

Abstract

A magnetic core-shell solid-acid catalyst Fe 3 O 4 @C-SO 3 H was studied for synthesis of O-2,3-unsaturated glycosides through Ferrier rearrangement. The donors include 3,4,6-tri-O-acetyl-D-glucal and 3,4di-O-acetyl-L-rhamnal. The acceptors consist of primary alcohols, secondary alcohols, tert-butanol, unsaturated alcohols, halogenated alcohol, sterol, sugars, and phenols. O-2,3-Unsaturated glycosides were obtained rapidly (<3 h) and efficiently (up to 98%) in good α selectivity (α/β >5:1 to 19:1). Moreover, the catalyst can be easily separated from the reaction with an external magnetic force and reused for a minimum of five times without any significant decrease in the yields of the products after every recycle, suggesting it a promising green catalyst in 2,3unsaturated glycosides syntheses.

Synthesis of 2-Nitro-2,3-Unsaturated Glycosides by a Nanomagnetic Catalyst Fe3O4@C@Fe(III)

“…In addition, we are introducing a nano-magnetic core-shell catalyst into a Ferrier rearrangement of glycals due to their extraordinary noncontact magnetic separation ( Wang et al, 2019 ; Zhang et al, 2021 ). Previously, Fe 3 O 4 @C-SO 3 H and Fe 3 O 4 @C@Fe(Ⅲ) have been studied for the synthesis of O -2,3-unsaturated glycosides ( Zhang et al, 2017 ; Dong et al, 2019 ; Jiang et al, 2020a ). The donors included 3,4,6-tri- O -acetyl-glucal, 3,4,6-tri- O -acetyl-2-haloglucals, and 3,4-di- O -acetyl-L-rhamnal.…”