In this study, a two-step methodology was developed for the synthesis of chiral pyrroles from 2-nitroglycals via Ferrier rearrangement and Barton-Zard reaction under mild conditions without transition metal catalysts. The Ferrier rearrangement reaction of 2-nitro-glycals and a series of O-nucleophiles proceeded smoothly in the presence of N-heterocyclic carbene (NHC) catalyst and K 2 CO 3 which allowed the highly stereoselective synthesis of the diverse 2-nitro-2,3-unsaturated glyco-sides in excellent yields. Subsequently, the rearrangement products were conveniently transformed into the desired chiral pyrroles by [3 + 2] cycloaddition (Barton-Zard reaction) with isocyanoacetate in the presence of Cs 2 CO 3 . One-pot strategy was also successfully demonstrated for the gram-scale synthesis of one chiral pyrrole. This is the first report of stereoselective conversion from 2-nitroglycals to chiral pyrrole.

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A novel and highly efficient magnetic Fe3O4@C@Fe(III) core–shell catalyst, in which the carbon shell was prepared from lotus leaf, was fabricated. This nanocatalyst was successfully applied in the synthesis of a series of 2,3-unsaturated O-glycosides in excellent yields and with high selectivity, especially in the case of 2-halo O-glycosides, which differ in reactivity from nonsubstituted O-glycosides, but which have scarcely been explored before. Moreover, the catalyst could be easily separated from the reaction by the application of an external magnetic force and reused a minimum of five times without any significant decrease in the yields of the products. In addition, the reaction proceeded readily on a gram scale, which provides a bright prospect for future applications.

A sustainable magnetic core-shell nanocatalyst Fe3O4@C@Fe(III) was successfully applied in the synthesis of a series of 2-nitro-2,3-unsaturated O-glycosides with excellent yields (up to 89%) and high stereoselectivity (α:β > 19:1). The substrate ranges are widely applicable, including different kinds of alcohols and even structurally complex acceptors. In addition, phenols could be applied in good yields. Moreover, the catalyst could be easily separated from the reaction by the application of an external magnetic force and reused a minimum of five times without any significant decrease in catalytic performance.

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.