Colloid and nanosized catalysts in organic synthesis: XIII. Synthesis of 2-R-2-imidazolines catalyzed by copper and iron oxide nanoparticles

Electrophilically activated nitroalkanes in reaction with aliphatic diamines en route to imidazolines

“…We were surprised to nd that imidazolines 4fa and 4 were obtained in these reactions as sole isolable products (Scheme 6). The yields of these products were quite moderate, but still signicantly better than in attempted reactions involving electrophilically activated a-nitrotoluene (1f) (Scheme 3, entries 13,14). Such outcome can be explained as follows (Scheme 6).…”

“…Unexpectedly, we met a major challenge trying to employ anitrotoluene (1f) as an electrophilic component of the featured transformation. The reaction was very sluggish, did not proceed to completion, and afforded very poor yields (Scheme 3, entries [13][14]. An attempt to carry out this process under more forcing conditions did not lead to improvement, as the products notably decomposed at elevated temperatures.…”

“…11,12 Normally, preparation of 2-imidazolines 4 is very straightforward and involves acylation of 1,2-diamines 2 with carbonyl compounds 1 (acyl, thioacyl, carbamoyl halides, esters, carboxylic acids, or nitriles) and subsequent cyclocondensation of the formed b-aminocarboxamide intermediate 3 (Scheme 1). [13][14][15][16] For number of years we were interested in electrophilic activation of nitroalkanes and their reactions with different nucleophilic species. We pondered if this approach can be employed to access 2-imidazolines.…”