chapter  4
6 Pages

Metal-Free, Diamine-Mediated, Oxidative Monoamidation of Benzylated Carbohydrates

Some carbohydrates containing amide functional groups at the anomeric position (glyconamides) can be prepared1 as key intermediates for the synthesis of high value-added molecules, such as iminosugars and N-alkyliminosugars, which are lead compounds for the treatment of a variety of diseases.1-4

Experimental Methods .............................................................................................28 General Methods .................................................................................................28 N-(3-Aminopropyl)-2,3,4-tri-O-benzyl-d-xylonamide (1) .................................28 N-(3-Aminopropyl)-2,3,4,6-tetra-O-benzyl-d-gluconamide (2) .........................29

Acknowledgments ....................................................................................................29 References ................................................................................................................ 32

mary amines in order to form N-alkylated gluconamides in one step.1 The reaction, performed in t-BuOH at 90°C in the presence of molecular iodine, leads to modest to good yields depending on the nature of the starting materials (45%–74%). Being aware of the interest in such compounds and the difculties involved in the synthesis of glyconamides from benzylated carbohydrates, we optimized conditions for this oxidation.5 It consists of the direct conversion of aldose hemiacetals to amides, which can be directly performed using iodine as the oxidant. The main advantage of this metal-free reaction is that both aldehyde oxidation and C-N bond formation are performed in a single step.6,7 We found that at room temperature, using methanol (analytical grade) instead of t-BuOH at 90°C, the yields of glyconamides were improved (80%–98%). In the case of diamines, we found that a monoamidation is carried out, which leads to functionalized glyconamides.