Essential Multicomponent Reactions I

Construction of Covalent Organic Frameworks via Multicomponent Reactions

“…The Debus−Radziszewski reaction 19 is one of the oldest MCRs for the synthesis of imidazole derivatives via the condensation of an α-dicarbonyl compound (e.g., oxalaldehyde, benzil, and 2-oxopropanal), an aldehyde, and two equivalents of an ammonium salt under acidic conditions. 20 This reaction is an appealing choice for polymer synthesis because of the aromaticity of the obtained products and the high efficiency of the involved transformations. 21 In fact, the Debus−Radziszewski reaction was the first MCR used for COF synthesis.…”

“…Even though certain MCRs proceed quantitatively or almost quantitatively, the associated side reactions are more complex (and hence, more problematic) than those of two-component reactions. In the Debus–Radziszewski reaction, the generation of imidazoles as the main products by hydroxyl group expulsion can be accompanied by the formation of oxazoles by the undesired expulsion of amino groups . The occurrence of this side reaction results in the formation of COFs partially linked with benzoxazole blocks that are difficult to detect and distinguish by conventional characterization techniques such as FT-IR and ssNMR spectroscopies because of their low contents.…”

“…In the Debus− Radziszewski reaction, the generation of imidazoles as the main products by hydroxyl group expulsion can be accompanied by the formation of oxazoles by the undesired expulsion of amino groups. 20 The occurrence of this side reaction results in the formation of COFs partially linked with benzoxazole blocks that are difficult to detect and distinguish by conventional characterization techniques such as FT-IR and ssNMR spectroscopies because of their low contents. In addition, MCRs involving imine intermediates, e.g., Strecker, A 3 coupling, and Doebner reactions, may stagnate at the imine stage, especially when the third component is bulky or charged, which complicates access to the formed framework.…”

Synthesis of Novel (bis‐)1,5‐Disubstituted‐1H‐tetrazole‐Decorated Monomers and Their Respective Polymers via Thiol‐ene Polymerization

“…[19][20][21] Hence, due to the broad plethora of potential applications of aliphatic substituted tetrazole-containing polymers in the field of biomedical and energy-relevant materials research, there is an ever-increasing demand for the development of straightforward and efficient polymerization. On the one hand, multi-component reactions (MCRs, such as Passerini, [22] Biginelli, [23] or Ugi [24] ) and their relevant polymerization approaches have appeared as suitable methods, as those reactions enable the generation of a single product from three or more starting materials in a onepot manner. Indeed, MCRs and multi-component polymerizations (MCPs) are generally considered as sustainable synthesis tools as they provide operational simplicity under mild conditions with high efficiency and deliver a great diversity of product structures.…”

Synthesis of poly(pyrazolopyridine)s by Hantzsch multicomponent polymerization

“…Multicomponent reactions (MCRs) are considered for long time by organic chemists as efficient tools for the synthesis of complex structures [1][2][3][4][5]. Such reactions have been especially used for the development of new substances for drug application [6].…”