Synthesis of 3-acetyl-6-(o-methyl benzoyl)-N-ethylcarbazole

Abstract

3-Acetyl-6-(o-methyl benzoyl)-N-ethylcarbazole was prepared through successive o-methyl benzoylation and acetylation of N-ethylcarbazole in one pot. The overall yield was 85.6% and the structure was confirmed by 1 H-NMR and 13 C-NMR. A preliminary investigation had also been carried out on the mechanism of the o-methyl benzoylation of N-ethylcarbazole.

Synthesis of 1-{6-(2-methylbenzoyl)-N-ethylcarbazole-3-yl}-ethane-1-one oxime O-acetate

“…In our previous study [13], the side reaction of diacylation at the 3-and 6-positions of N-ethylcarbazole is effectively inhibited by reaction-condition control. This study focuses on the steps of oximation and esterification.…”

“…Key intermediate 3-acetyl-6-(o-methylbenzoyl)-N-ethylcarbazole was synthesized from N-ethylcarbazole referring to our previous study [13].…”

“…Many typical synthetic methods for carbazole oxime ester photoinitiator [13,14] have been reported with the general process as shown in Scheme 1. In such a process, by-products with the symmetrical acyl group are easily produced during acylation, and they are very hard to separate from each other because of their similar structures.…”

“…) 13. C-NMR (100 MHz, CDCl 3 ): 13.85, 14.73, 19.87, 19.90, 38.09, 108.67, 109.04, 120.02, 122.63, 123.20, 124.43, 125.35, 125.51, 126.66, 127.97, 128.40, 129.58, 129.78, 130.91, 136.15, 139.67, 141.96, 143.31, 162.90, 168.97, 198.33.…”