The Mild Cleavage of 2-Amino-2-deoxy-d-glucoside Methoxycarbonyl Derivatives

Abstract

The conversion of methyl carbamate to the corresponding free amine is described for a series of 2-amino-2-deoxy-D-glucosamine derivatives. Cleavage of methoxycarbonyl moiety with MeSiCl(3) and triethylamine in dry THF at 60 degrees C and subsequent aqueous hydrolysis yields the free amine in 54 to 93% yields. The selective cleavage of methyl carbamates with MeSiCl(3) in the presence of a 2,2,2-trichloroethoxycarbonyl group or 2-azido glycosides affords selectively, orthogonal N-deprotected carbohydrates.

α-N-Acetylmannosamine (ManNAc) Synthesis via Rhodium(II)-Catalyzed Oxidative Cyclization of Glucal 3-Carbamates

“…To complete the ManNAc arrays 3 and 4 , we applied acetyl migration after N-deprotection of substrates 23 and 29 (Scheme and Table ). Despite the thermodynamic tendency toward amide products and the proximity of the reacting groups in the intermediate β-acetoxy amines, acetyl transfer was sluggish upon hydrogenolysis of the N -Cbz compounds, even in the polar, protic (MeOH/EtOAc) reaction mixture . The crude material after hydrogenation of 23a was converted cleanly to acetamide 3a upon protracted stirring in the presence of pyridine (Table , entry 1).…”

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“…Methoxycarbonyl group has been introduced as an amino protecting group that may be removed in an orthogonal manner with Me 3 SiCl and Et 3 N in THF. 293…”

Synthesis of Fluorous Photolabile Aldehyde and Carbamate and Alkyl Carbamate Protecting Groups for Carbohydrate-Associated Amines

“…Because the new protecting group showed good stability under both acidic and basic conditions, work next turned to finding suitable conditions to remove the group. Several mild conditions known to remove alkyl carbamates were initially attempted (using trimethylsilyl iodide and methyl trichlorosilane respectively) to remove the FOC, but none were successful in removing the carbamate. After witnessing the stability of FOC under Zemplén conditions, we realized a stronger basic medium was needed for a nucleophile-mediated deprotection.…”