A diversity-oriented access to diastereoselective arylidene 2,5-diketopiperazines is elaborated via a sequential Ugi post-transformation involving catalytic cyclization and oxidative Heck reaction sequence. This sequence offers an interesting multicomponent entry to a library of 2,5-diketopiperazines and arylidene 2,5-diketopiperazines under mild reaction conditions in good to excellent yields.

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Gold­(I)-catalyzed reactions of electron-poor alkynes are still a challenging process. A straightforward synthesis of phosphorus-based heterocycles, namely, 2-phenyl 1H-isophosphinoline 2-oxides 1, is reported. The reaction used PPh3AuCl precatalyst in combination with triflic acid under microwave activation and afforded isophosphinoline 2-oxides 1 in moderate to quantitative yields through a fully regioselective 6-endo-dig hydroarylation cyclization, paving the way toward an effective synthesis of phosphorus heterocycles.

Five-component sequential Ugi/nucleophilic addition reaction of aromatic aldehydes, primary amines, propiolic acid, isocyanides, and hydrazides has been developed in order to access polyfunctional pseudopeptides. The reaction may proceed through formation of N-substituted 2-alkynamides as intermediates. This process is found to be mild and operationally simple with broad substrate scope.

An efficient approach for the synthesis of pyrazolopyridines containing the aminochromane motif through a base-catalyzed cyclization reaction is reported. The synthesis was carried out through a three-component reaction of (arylhydrazono)methyl-4H-chromen-4-one, malononitrile, primary amines in the presence of Et3N at room temperature. However, carrying out the reaction under the same conditions without base led to a fused chromanyl-cyanopyridine. High selectivity, high atom economy, and good to high yields in addition to mild reaction conditions are the advantages of this approach.