«Push‐Pull»‐Acetylene als Hilfsmittel zur Synthese von Amiden

Abstract

Amide Synthesis by Means of 'Push-Pull'-AcetylenesSummary 'Push-pull'-acetylenes react easily with carbon acids. Addition of amines to the crude reaction mixture gives amides in an excellent yield by a simple one-pot procedure. Because of the high selectivity of the acetylenes 1 towards carboxylic functions and of the high selectivity of the enol esters 4 towards amine functions, 'pushpull'-acetylenes could be excellent reagents for peptide synthesis.

Highly Site-Selective Metal-Free C–H Acyloxylation of Stable Enamines

“…On the other hand, if – OAc attacks the α-site of the enamine, intermediate C is probably obtained (path b) and consequently undergoes elimination to give D . Finally, the amide product 4 can be obtained by rearrangement of α-acyloxylation intermediate D through protonation intermediate E …”

“…Cation intermediate B then is pronated to afford the β-acyloxylation product 3. On the other hand, if − OAc attacks the α-site of the enamine, intermediate C is probably obtained (path b) and consequently undergoes elimination to give D. Finally, the amide product 4 can be obtained by rearrangement of α-acyloxylation intermediate D through protonation intermediate E. 16 To better understand the mechanism, several control and isotopic labeling experiments were investigated (Scheme 5). First, we carried out the reaction using 18 O-labeled water (Scheme 5a).…”

The Aminopropenal‐ and Aminopentadienal Rearrangement

“…Compared with isoxazolium salts 4 [39][40] [41] and ynamines 12 [12] [14], PPacetylenes 1 could offers everal advantages as peptide reagents: Comparedw ith ynamines, their characteristicsa re al owerb asicity,a sw ell as ah igher selectivity. First experiments showed that carboxylic amidesc oulde asily be prepared in as imple one-potr eaction by adding carboxylic acids to the new PP-acetylenesinafirst step,followed by adding the amine to the same solution in asecond step [35]. 7.…”