A simple method for the formation of cyclopropylamines: The first synthesis of tricyclopropylamine

Article abstract of DOI:10.1016/0040-4039(95)01560-4

A mild, one-step method to cyclopropylate amines is described. Treatment of a variety of secondary and primary amines with [(1-ethoxycyclopropyl)oxy]trimethylsilane and sodium cyanoborohydride in methanol gave mono- and dicyclopropylamines in good yield. Sterically hindered di- and tricyclopropylamines, including the previously unreported tricyclopropylamine, were prepared using this method. The pKas of some mono-, di- and tricyclopropylamines were measured showing a reduction of ~1-2 pKa unit per added cyclopropyl group.