Imidazole als Induktoren der Cyclo-Oligomerisation von N-Alkyl-maleinimiden und der cis-trans, Umlagerung von Maleinsäure-dimethylester

✍ Scribed by Th. Wagner-Jauregg; Q. Ahmed; E. Pretsch

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: German
• Weight: 445 KB
• Volume: 56
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19730560424

✦ Synopsis

Abstract

N‐Methylimidazole (N–M), in boiling acetonitrile, catalyzes the oligomerization of N‐alkyl maleimides (2) to tri‐, tetra‐, penta‐ and hexamers. In the presence of small amounts of hydroquinone the trimers of 2 are formed, which have the structure of N,N′,N″‐trialkyl‐cyclohexane‐1,2,3,4,5,6‐hexacarboxy‐1,2:3,4:5,6‐tri‐midies (6). A possible mechanism of this catalytic cyclo‐oligometization is discussed. Dependant from the chemical nature of the N‐alkyl substituent of the maleimides, imidazole or benzimidazole and some of its C‐substituted products also can function as oligomerization catalysts. However in this case the normal 1:1 addition is the main reaction, as observed also with pyrazoles plus 2. Maleic dimethylester was isomerized to fumaric dimethylester in the presence of N‐methylimidazol. These observations reveal additional catalytic functions to the well known hydrolysis catalyzing properties of imidazoles.