Adding a certain compound to certain chemical reactions, such as: 6478-79-1, name is 5,6-Dichloro-2-methylbenzimidazole, belongs to imidazoles-derivatives compound, can increase the reaction rate and produce products with better performance than those obtained under traditional synthetic methods. Here is a downstream synthesis route of the compound 6478-79-1, Application In Synthesis of 5,6-Dichloro-2-methylbenzimidazole
General procedure: To extend the scope of the 2-methyl-1H-benzimidazole substrates for our cascade reaction, we nextexamined the reaction of 2-fluorobenzonitrile (2a) with a variety of 2-methyl-1H-benzimidazolederivatives 1 under the conditions (Cs2CO3, DMSO, 120 C). The results are shown in Table 2. As shown in Table 2, almost all of the tested combinations successfully produced the desiredbenzimidazo[1,2-a]quinolines 8ba-8la with moderate to good isolated yields, though an undeniableamount of overreaction product 9 was isolated in most entries. Unsymmetrical 1H-benzo[d]imidazolessuch as 1b, 1e, 1f and 1g exist as an equilibrium mixture of their tautomers. Therefore, the SNAr sequenceof our cascade reaction with these substrates theoretically provides a regioisomeric mixture of thecorresponding adducts. Our survey revealed that the regiochemical outcome is highly controlled uponutilizing 1e, 1f and 1g having a substituent at the 4-position to give 8ea, 8fa and 8ga without detectingtheir regioisomers (entries 5-7). However, no reigioselectivity was observed with the cascade reactionwith 1b bearing methyl substituent at the 5-position (entry 2). These results suggest to us that the lesssterically congested nitrogen atom of 1H-benzo[d]imidazoles preferably reacted with 2-fluorobenzonitrile(2a) in the SNAr reaction. 2-Methyl-1H-benzimidazole derivatives 1h, 1i, and 1j, having an electrondonating group (-CH3, -OCH3,-SCH3), reacted with 2a to give 8ha, 8ia, and 8ja in modest yields underthe conditions, respectively (entries 8-10). When the benzimidazoles 1k and 1l possessing an electronwithdrawing group (-CN, -CO2Et) at the 2-methyl group were treated with 2a under the conditions, alarge amount of insoluble unidentified product was produced. In these reactions, the desired cascadeproduct 8la was not detected while the cascade product 8ka was isolated in a modest yield (entries 11 and12). The cascade products 8ka and 8la were obtained in good yields upon replacing Cs2CO3 with K2CO3.(entries 11 and 12). In our SNAr/Knoevenagel cascade reaction with 1k and 1l, we found the Knoevenagelcondensation between aldehydes and the active methylene of 1k and 1l occured preferably to the SNArreaction in the first step, and the desired cascade adducts could not be obtained.14 These comparativeresults indicate that the SNAr reaction occured preferably to the Dieckmann-Thorpe type reaction in thepresent cascade reaction upon fine-tuning the base used.
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Reference:
Article; Kato, Jun-Ya; Ito, Yutaro; Ijuin, Ryosuke; Aoyama, Hiroshi; Yokomatsu, Tsutomu; Heterocycles; vol. 93; 2; (2016); p. 613 – 627;,
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