Efficient preparations of novel ynamides and allenamides

Practical syntheses of a series of novel ynamides and allenamides are descr ibed 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 sta bility 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 r ights reserved.