Synthesis of amino allenes via reaction of α-aminoalkylcuprates with propargyl substrates

alpha-Aminoalkylcuprates prepared from carbamates via sequential deprotonation and treatment with CuCN . 2LiCl react with propargyl bromides, mesylates, tosylates, acetates, and epoxides to afford amino allenes via a S(N)2' substitution process. Propargyl bromides and sulfonates give good yields of amino allenes while the acetates afford low yields. Substrates undergo regiospecific S(N)2' substitution and the use Sc(OTf)(3) affords improved yields of amino allenes from propargyl epoxides. The Boc protected alpha-amino allenes can be cyclized to oxazolidones or deprotected to afford the free amines. (C) 1999 Elsevier Science Ltd. All rights reserved.