Preparation of Functionalized Amides Using Dicarbamoylzincs

Abstract

We report a new convenient preparation of dicarbamoylzincs of type (R¹ R² NCO)₂ Zn by the treatment of ZnCl₂ and formamides R¹ R² NCHO with LiTMP in THF (15 °C, 15 min) or by the reaction of formamides R¹ R² NCHO with TMP₂ Zn (25 °C, 16 h). This second method tolerates sensitive groups such as an ester, ketone or nitro function. Reaction of these dicarbamoylzincs with allylic, benzylic, aryl, alkenyl bromides, acid chlorides, aldehydes or enones provided various polyfunctional amides in 47-97 % yields. ¹³ C NMR characterization of these new carbamoylzinc derivatives is reported.

Keywords: Amides; Carbamoyl; Lithium; Metalation; Zinc.