Versatile Dehydrating Agents

DMC (1) has been reported by T. Isobe and T. Ishikawa as a powerful dehydrating equivalent to DCC. The dehydrating reagent 1 is applied to the esterification of hindered alcohols¹⁾, conversion of aromatic oximes and carboxamides into nitriles¹⁾ and construction of heterocycles²⁾ under nearly neutral conditions. Moreover, it is applicable to chlorination, oxidation, reduction and rearrangement under nearly neutral conditions³⁾. The resulting cyclic urea 3 byproduct can be removed easily by washing with water.

The reagent 1 gradually decomposes with moisture in the air so that extra care in handling is needed. However, DMC in dichloromethane 1b is easy handled using a syringe. In addition, CIP (2) can be used like 1 and it is more stable than 1 against moisture.