Azides, cycloaddition with DMAD

Herein, the author reports Lewis acid-catalyzed diverse cycloaddition reactions of NSBVs 6-1 with a wide variety of isocyanides, azides, and diazo compounds. These reactions afforded 5,8-diaza- and 2,5,9-triaza-brexadiene derivatives as highly fused A -containing polycyclic frameworks, which are structurally and chemically interesting cage-shaped compounds, but not readily accessible by other means. Unique and unprecedented rearrangement-cycloaddition patterns are revealed. These reaction patterns are not only different from our previously reported reaction with DMAD or RNCO, but most notably, very different from the reactions... 

In another paper, the same authors investigated the 1,3-dipolar cycloaddition on 2-(lH)-pyrazine scaffolds 72 and electron-rich azides, using Cu(0) and CUSO4 as pre-catalysts. To demonstrate the versatility of this approach, they reported the generation of different templates (73 in Scheme 25) as an application of cUck chemistry . They also investigated the Diels-Alder reaction of the so obtained triazoles with dimethyl acetylenedicarboxylate (DMAD), under microwave irradiation. The latter reaction allowed obtaining various pyridinones in good yields (74 and 75 in Scheme 25) [57]. 

Hassner et al. (15) explored the synthetic utility of the polymeric azidation reagent 63 to prepare di- and tri-azidomethanes 64 and 66 at ambient temperature. They also studied the intermolecular cycloaddition of these azides with dimethyl acetylenedicarboxylate (DMAD) to yield the corresponding cycloadducts... 

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