Activation of Primary Amines by Copper(I)-Based Lewis Acid Promoters in the Solventless Synthesis of Secondary Propargylamines

Primary amines are activated by copper(I)-based Lewis acid promoters in an A (3) -coupling one-pot solventless reaction with aldehydes and phenylacetylene for the synthesis of secondary propargylamines. The reaction is promoted by a CuSO (4) /NaI system, a practical precursor of the in situ generated effective CuI/I (2) system, that worked well, but only in a restricted number of examples. Substitution of I (2) with CeCl (3) 7H (2) O in a one-pot two-step reaction provided good yields and a wider applicability, with the added value given by a safer procedure.