Direct copper(II)-mediated regioselective α-halogenation of N-aryl enaminones

A Study of the Reactions of 3‐Bromopropenals with Anilines for the Synthesis of α‐Bromo Enaminones

“…Further, the use of TsOH • H 2 O in the reaction at 25 °C resulted in the enaminone being formed in only 34% yield (entry 10). The reactions were then performed at elevated temperatures (entries [11][12][13][14][15]. The desired product was formed in 76% yield when the reaction was carried out for 2 h at 60 °C (entry 13).…”

“…The solvent was removed under reduced pressure using a rotatory evaporator and the crude product was purified by silica-gel column chromatography using ethyl acetate/hexane mixture as the eluent. 9, 167.8, 142.3, 142.2, 139.0, 134.9, 132.2, 131.2, 128.8, 128.6, 122.2, 115.4, 114.0, 104.1, 61.9, 14.4 8, 167.6, 158.6, 141.1, 132.9, 131.9, 131.6, 131.0, 130.6, 129.3, 122.7, 121.8, 118.9, 106.6, 62.0, 14.5 9, 168.3, 142.3, 142.1, 139.0, 135.1, 132.3, 131.3, 128.9, 128.7, 122.2, 115.2, 114.1, 104.3, 52.8 8, 168.1, 158.5, 141.2, 133.1, 131.9, 131.7, 131.0, 130.6, 129.3, 122.8, 121.8, 118.5, 106.7, 52.9 9, 167.3, 142.3, 139.1, 134.8, 132.2, 131.1, 128.8, 128.6, 122.2, 115.9, 114.0, 104.1, 69.6, 22 8, 167.2, 158.6, 141.1, 132.8, 132.0, 131.6, 131.0, 130.6, 129.3, 122.7, 121.8, 119.3, 106.5, 69.6, 22.2 167.9, 142.4, 142.2, 139.1, 134.9, 132.2, 131.3, 128.8, 128.7, 122.2, 115.6, 114.1, 104.2, 65.8, 30.8, 19.5, 13.9 8, 167.7, 158.5, 141.2, 132.9, 131.9, 131.6, 131.0, 130.6, 129.3, 122.7, 121.8, 118.8, 106.6, 65.8, 30.8, 19.5, 13.9 9, 166.8, 141.5, 141.4, 138.9, 137.7, 134.7, 131.4, 128.9, 128.7, 116.8, 115.8, 114.4, 104.8, 62.4, 14.5 8, 166.5, 157.9, 140.4, 135.7, 134.2, 131.6, 131.2, 130.5, 129.5, 122.9, 120.0, 115.1, 107.3, 62.4, 14.5 .39 (dd, J = 8.9, 2.5 Hz, 1H), 6.87 (d, J = 9.0 Hz, 1H), 4.63 (q, J = 7.1 Hz, 2H), 1.46 (t, J = 7.1, 3H); 13 C-NMR (100 MHz, CDCl 3 ) δ 188. 9, 166.8, 141.6, 141.0, 138.9, 134.8, 131.8, 131.4, 128.9, 128.7, 127.3, 116.4, 115.5, 104.7, 62.4, 14.4 8, 166.6, 158.0, 139.9, 132.9, 131.6, 131.2, 130.6, 129.5, 127.9, 122.8, 119.8, 107.1, 62.4, 14.5 3, 141.8, 140.7, 138.1, 134.6, 133.3, 131.5, 128.7, 128.6, 123.5, 115.7, 114.9, 105.1, 101. 1, 136.44, 136.41, 135.7, 131.6, 128.7, 128.6, 127.0, 122.3, 115.9, 106.6 6, 140.7, 138.2, 137.4, 135.5, 134.1, 132.8, 131.5, 128.7, 128.6, 126.7, 115.9, 105.9, 20.4 5,154.6,141.0,138.3,135.9,131.5,130.3,128.6,128.5,125.0,…”

“…5, 139.34, 139.30, 139.1, 137.9, 135.8, 135.6, 131.8, 129.5, 128.7, 128.6, 117.45, 117.43, 114.0, 107.2 5,139.5,137.9,136.4,135.5,135.2,131.8,128.7,128.6,127.4,126.5,117.2,107.1;HRMS (ESI) 3, 149.3, 141.5, 140.5, 138.1, 131.5, 130.9, 128.6, 121.7, 118.3, 111. 158.5,148.4,139.4,131.2,130.3,130.0,129.8,129.3,128.2,119.3,117.4,105.1;HRMS (ESI) 7.6 Hz,1H),2H),4H),1H),6.96 (d,J = 8.4 Hz,1H); 13 C-NMR (100 MHz, CDCl 3 ): δ 194. 5, 188.8, 141.6, 141.1, 138.6, 136.7, 136.0, 131.3, 128.7, 128.5, 122.3, 121.5, 113.2, 104.9 (d,J = 13.2 Hz,1H),2H),1H),2H),7.32 (dd,J = 1.2,8.0 Hz,1H),1H),1H),6.80 (d,J = 8.4 Hz,1H); 13 C-NMR (100 MHz, CDCl 3 ) δ 188.2, 141. 8,…”

“…[12] It is also noteworthy that the αfunctionalization of enaminones starting from enaminones, but under different reaction conditions compared to this study was reported. [13] In 2014, Murakami and co-workers [14] reported on a method for the synthesis of α-amino enaminones via the rhodiumcatalyzed reaction of N-sulfonyl-1,2,3-triazoles with formamides. However, there are only limited reports of the direct synthesis of α-functionalized compounds.…”

Selectfluor-triggered fluorination/cyclization of o-hydroxyarylenaminones: A facile access to 3-fluoro-chromones

“…In addition, the groups of Kandula 71 and Zhao 72 also reported a Selectfluor-triggered tandem cyclization strategy for constructing 3-fluoro-chromones via direct elimination of 3,3-difluorinated 2-amino chromanones at room temperature in a short time ago. As our ongoing interest in enaminone chemistry, [73][74][75][76][77][78][79][80][81][82] herein, we report a fast and efficient Selectfluor-triggered fluorination/cyclization reaction of o-hydroxyarylenaminones for the construction of 3-fluoro-chromones promoted by potassium carbonate (Scheme 1(c)). Interestingly, this reaction is mechanistically different compared to the previously reported methods 71,72 where 2-(dimethylamino)-3,3difluorochroman-4-one.…”