Efficient preparations of novel ynamides and allenamides

Practical syntheses of a series of novel ynamides and allenamides are described here. While a base-induced isomerization protocol of propargyl amides leads to an array of chiral and achiral allenamides, ynamides are prepared from enamides via bromination followed by base-induced elimination of the Z-bromoenamides. These ynamides and allenamides possess improved thermal stability compared to ynamines and allenamines. They can be isolated, purified, and handled with ease, and thus, should be synthetically more useful than traditional ynamines and allenamines. (C) 2001 Elsevier Science Ltd. All rights reserved.