This review summarizes the recent developments in MCRs, incorporating different strategies along with their mechanistic aspects.

No abstract

Microwave-assisted (MWA) multicomponent reactions (MCRs) have successfully emerged as one of the useful tools in the synthesis of biologically relevant heterocycles. These reactions are strategically employed for the generation of a variety of heterocycles along with multiple point diversifications. Over the last few decades classical MCRs such as Ugi, Biginelli, etc. have witnessed enhanced yield and efficiency with microwave assistance. The highlights of MWA-MCRs are high yields, reduced reaction time, selectivity, atom economy and simpler purification techniques, such an approach can accelerate the drug discovery process. The present review focuses on the recent advances in MWA-MCRs and their mechanistic insights over the past decade and shed light on its advantage over the conventional approach.

A series of bis- and tris(oxobenzimidazolyl)hydroborato compounds, namely, [Bo]Na and [To]-Na (R = Me, Bu, Ad), which feature uncommon sterically demanding LX [O] and LX [O] donor ligands, have been obtained via the reactions of NaBH with 1-R-1,3-dihydro-2H-benzimidazol-2-ones. Evidence that the alkyl substituents are suitably located to have a significant impact on the coordination environment is provided by the observation that the methyl derivative [To]Na(κ-diglyme) exhibits κ-coordination of the diglyme, whereas the t-butyl and adamantyl derivatives, [To]Na(κ-diglyme) and [To]Na(κ-diglyme), exhibit κ-coordination. The [Bo] and [To] ligands also allow for isolation of discrete mononuclear thallium compounds, [Bo]Tl and [To]Tl, for which the steric demands of the ligands have been quantified in terms of both cone angle and buried volume concepts.

There are few reports that describe crystal structures of compounds containing cobalt complexed to either dimethyl sulfoxide (Me 2 SO) or quinoline (C 9