o-Cyanobenzoate: A Recyclable and Reusable Stereo-directing Group for β-O-Glycosylation via Pd(0)-catalyzed Ferrier
Pradip Das1, Mosidur Rahaman Molla1, Amit Kumar2
1Department of Chemistry, National Institute of Technology Patna, Patna, 800005, India.
Abstract:
Inner sphere Tsuji-Trost reaction has found recent application for β-selective Ferrier rearrangement of glycal substrates with alcohol nucleophiles. Herein, we report an efficient and stereoselective synthesis of 2,3-dideoxy-β-O-glycosides from C3-(o-cyanobenzoate) ester protected glycal donors via Ferrier rearrangement under Pd(0)-catalyzed Tsuji-Trost conditions. The synthesized donors indeed reacted with a variety of acceptors to afford the corresponding glycosides in good yields and excellent β-stereoselectivity. The stereochemical outcome of the reactions has been found to be independent of the nature of protecting groups or conformational flexibility of the glycal donors. Furthermore, regeneration of ortho-cyanobenzoic acid post rearrangement makes it a recyclable and reusable stereodirecting group. A preliminary mechanistic study demonstrates the importance of cyano-group for the observed rearrangement and stereoselectivity. Incorporation of the directing group on the benzoate ester has altered the reactivity of the ester group as a leaving group for Tsuji-Trost as well as Ferrier Rearrangement pathway.
Related Concept Videos
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
The carbonyl center is...
Hydroboration-Oxidation of Alkenes
Preparation of Diols and Pinacol Rearrangement
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration


