STEREOCHEMISTRY AND KINETICS OF ADDITION OF AMINES TO ACETYLENIC KETONES

The reactions of a series of 3‐(p‐substituted phenyl)‐1‐phenylprop‐2‐yn‐1‐ones with piperidine and morpholine in methanol were studied and their rates measured. The products were 3‐piperidino‐ and 3‐morpholino‐3‐(p‐substituted phenyl)‐1‐phenylprop‐2‐en‐1‐ones. 1H NMR spectra were used to determine the configurations of the obtained products. A good Hammett correlation was obtained with ρ values of 1·15–1·10 and 1·15–0·53 for piperidine and morpholine, respectively, which suggest a carbanionic character of the transition state. A two‐step mechanism is postulated for these nucleophilic additions. Copyright © 1990 John Wiley & Sons Ltd.