Copper‐Catalyzed Domino Synthesis of Benzimidazo[2,1‐b]quin‐ azolin‐12(6H)‐ones Using Cyanamide as a Building Block

Abstract

A convenient copper-catalyzed domino method for the synthesis of benzimidazoA C H T U N G T R E N N U N G [2,1-b]quinazolin-12(6H)-ones has been developed via reactions of readily available substituted 2-bromo-N-(2-halophenyl)benzamides with cyanamide, in which cyanamide acts as a useful building block.

Carbonylation Chemistry Applied to the Synthesis of Benzimidazo[2,1‐b]quinazolin‐12‐ones

“…t, J =7.6 Hz, 1H), 7.04–6.88 (m, 2H); 13 C NMR (151 MHz, MeOH‐ d 4 +1 drop DCl and DMSO‐ d 6 (ratio 8 : 2, MeOH‐ d 4 : DMSO‐ d 6 )) δ=161.41, 155.36, 152.35, 145.44, 132.69, 128.85, 126.65, 124.76, 124.39, 117.59, 116.67, 114.72, 114.52, 113.23; IR (neat) (cm −1 ): 2972 & 2914 (aromatic C−H stretching), 1692 (C=O), 1630–1428 (ring breathing, C=N, aryl N−H deformations), 1268 (C−N stretch), 757 & 743 (aromatic C−H bending). These data are in agreement with literature data [7a,8a] …”

“…dd, J =8.39, 1.22 Hz, 1H [C‐8 isomer]), 7.86–7.77 (m, 2H), 7.59–7.46 (m, 3H), 7.40–7.30 (m, 2H), 3.90 (s, 3H), 3.89 (s, 3H); 13 C NMR (101 MHz, DMSO‐ d 6 ) δ=166.70, 166.68, 159.38, 159.27, 149.03 (br), 148.40 (br), 135.60 (br), 135.50 (br), 127.58 (br), 127.54, 127.43 (br), 127.39, 127.06, 123.10, 122.84, 122.76, 122.24, 116.17, 115.03, 52.70, 52.56; IR (neat) (cm −1 ): 2949 & 2850 (C−H stretches) 1712 (C=O, ester), 1659 (C=O, lactam), 1618–1432 (ring breathing, C=N, aryl N−H deformations), 1261 (C−N stretch), 753 (aromatic C−H bending); HRMS (ESI) m/z calcd for C 16 H 12 N 3 O 3 [M+CH 3 OH+H]+ 326,113519, found 326.1301. The data of the C‐9 isomer are in agreement with literature data [8a] …”

“…; 13 C NMR (151 MHz, MeOH‐ d 4 +1 drop DCl) δ=158.49 (C‐12 [C‐8 or C‐9 isomer], 158.32 (C‐12 [C‐8 or C‐9 isomer]), 145.59 (C‐5a [C‐8 or C‐9 isomer]), 145.56 (C‐5a [C‐8 or C‐9 isomer]), 139.80 (C‐8 [C‐8 isomer]), 138.92 (C‐12a [C‐8 or C‐9 isomer]), 138.90 (C‐12a [C‐8 or C‐9 isomer]), 137.72 (C‐2 [C‐8 or C‐9 isomer]), 137.67 (C‐2 [C‐8 or C‐9 isomer]), 136.82 (C‐9 [C‐9 isomer]), 130.89 (C‐6a [C‐8 isomer]), 129.74 (C‐8 [C‐9 isomer]), 129.02 (C‐4 [C‐8 or C‐9 isomer]), 128.97 (C‐4 [C‐8 or C‐9 isomer]), 128.55 (C‐6a [C‐9 isomer]), 127.68 (C‐10a [C‐9 isomer]), 127.11 (C‐9 [C‐8 isomer]), 126.98 (C‐3 [C‐8 or C‐9 isomer]), 126.94 (C‐3 [C‐8 or C‐9 isomer]), 125.41 (C‐10a [C‐8 isomer]), 118.74 (C‐1 [C‐8 or C‐9 isomer]), 118.70 (C‐1 [C‐8 or C‐9 isomer]), 117.19 (C‐10 [C‐9 isomer]), 116.73 (C‐10 [C‐8 isomer]), 116.35 (C‐4a [C‐8 or C‐9 isomer]), 116.33 (C‐4a [C‐8 or C‐9 isomer]), 113.63 (C‐7 [C‐8 isomer]), 113.23 (C‐7 [C‐9 isomer]), 21.78 (methyl [C‐9 isomer]), 21.74 (methyl [C‐8 isomer]); IR (neat) (cm −1 ): 2987 (aromatic C−H stretching), 2918 (symmetric C−H stretch), 1671 (C=O), 1633–1445 (ring breathing, C=N, aryl N−H deformations), 1237 (C−N stretch), 758 & 742 (aromatic C−H bending); HRMS (ESI) m/z calcd for C 15 H 12 N 3 O [M+H]+ 250.0972, found 250.0964. The data of the C‐8 isomer are in agreement with literature data [2b,8a] …”

Synthesis of Benzo[4,5]imidazo[1,2-c]pyrimidin-1-amines and Their Analogs via Copper-Catalyzed C–N Coupling and Cyclization

“…A similar pathway has already been proposed in copper-catalyzed coupling and cyclization reactions using cyanamide. 10,16…”

The synthesis ofN‐containing heterocyclic compounds catalyzed by copper/L‐proline

“…[ 65 ] In 2012, Fu's group developed a method for the preparation of benzimidazo[2,1‐ b ]quinazolin‐12‐(6 H )‐ones 173 through CuI‐catalyzed tandem reaction of 2‐bromo‐ N ‐(2‐bromophenyl)benzamides 171 and cyanamides 172 (Scheme 28). [ 66 ] The yield of 173a increased from 41% to 67% with L ‐proline as the ligand. From the reaction mechanism below, we could see that the ligand promoted two intramolecular N ‐arylation steps.…”