‘Click Synthesis’ of Some Novel Benzimidazol Oxime Ethers Containing Heterocycle Residues as Potential ß‐Adrenergic Blocking Agents

Abstract

The 'click synthesis' of some novel O-substituted oximes, 5a-5j, which contain heterocycle residues, as new analogs of b-adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)-2-(1H-benzo[d]imidazol-1-yl)-1-phenylethanone oxime, followed by their reaction with 2-(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4, which by a subsequent tetra-n-butylammonium bromide (TBAB)-catalyzed reaction with N-H heterocycle compounds (Scheme 1), led to the target compounds 5a-5j in good yields.

N-Phenacyldibromobenzimidazoles—Synthesis Optimization and Evaluation of Their Cytotoxic Activity

“…The literature data indicate efficient methods for the alkylation of benzimidazole with monohalogenophenacyl halides, but there is little information on the corresponding reactions with di- or trihalogenophenacyl chlorides. For instance, the reaction of benzimidazole with phenacyl bromide is efficiently carried out (yield up to 92%) using NEt 3 as a base in acetone [ 30 ] or MeCN [ 31 , 32 ] at reflux, in some cases with the addition of a catalytic amount of tetrabutylammonium bromide (TBAB) [ 33 , 34 ] or tetrabutylammonium hydrogen sulfate (TBAHSO 4 ) [ 35 ]. The reactions carried out without the addition of an external base reached only 53–60% yield [ 36 , 37 ].…”