The earlier reported three-component Castagnoli–Cushman-type synthesis of 1,4,6-trisubstituted 1,6-dihydropyridin-2-(3H)-ones from 3-arylglutaconic acids, primary amines, and aromatic aldehydes has been further investigated. It was shown to proceed via 3-arylglutaconic anhydrides, which, in turn, were found to give superior results in the two-component reactions with imines. The initial formation of the Castagnoli–Cushman carboxylic acids was shown to be the case, and their decarboxylation was found to follow a complex, “forked” pathway, which was confirmed by deuterium incorporation experiments.

A convenient general approach towards 1,4-disubstituted αdiazo glutaconimides starting from β-substituted glutaconic acid anhydrides has been developed. It involves condensation with amines and subsequent diazo transfer reaction. This new class of diazocarbonyl heterocycles has been converted into a series of polysubstituted pyridine-2,6(1H,3H)-diones and oxazolo[5,4-b]pyridin-5(4H)-ones via a Rh 2 (esp) 2-catalyzed XH-insertion reaction and [3 + 2] cycloaddition with nitriles, respectively. Results and discussion Glutaconimides 5, precursors of the target diazo compounds 4, were obtained by analogy with the methods described in the literature [21] from synthetically available β-substituted glutaconic acid anhydrides 6. [18-19] Initial attempt at the Regitz diazo transfer using an equivalent amount of a base (DBU, TEA, DIPEA) resulted only in a negligible yield of 4. This was

A novel and efficient method for the synthesis of heteroannulated [1,4]benzodiazepines via an isocyanide-based multicomponent reaction is reported. The tetrazolo[1,5-a][1,4]benzodiazepines were obtained by a facile azide Ugi five-center four-component reaction (U-5C-4CR) using ketones, sodium azide, ammonium chloride, and corresponding isocyanide. The aforementioned tetrazolodiazepines represent a notable class of compounds with proven platelet aggregation inhibitory and cholecystokinin agonist activities.

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