N.C.A. synthesis of asymmetric [^{73, 75}Se]selenoethers

A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit

“…Di- and trisubstituted selenoureas can be synthesized from isoselenocyanates, LiAlSeH, NaHSe, (Me 2 Al) 2 Se, N-heterocyclic carbenes, carbon diselenide, and Woollins’ Reagent ([PhP­(Se)­(μ-Se)] 2 ), but these approaches can be complicated because key reagents or intermediates are unstable or must be prepared in multiple steps. However, a few disubstituted selenoureas have been prepared in a single step from alkyl isocyanides, elemental selenium, and primary amines. − We have greatly expanded this approach to prepare a library of di- and trisubstituted selenoureas 1 – 31 in 60–98% yields (Scheme , Table ). Unlike thioureas, tri- and disubstituted selenoureas are air-sensitive, and in some cases slightly light-sensitive, eventually depositing elemental selenium over several months if stored under ambient conditions.…”