Double isocyanide cyclization: a synthetic strategy for two-carbon-tethered pyrrole/oxazole pairs.

A new strategy for the construction of the compounds with two different heterocycles, linked by a C(2)-tether via a domino process involving [5 + 1] annulation, ring-opening, and subsequent double isocyanide cyclization, from the reaction of ethyl isocyanoacetate with divinyl ketones (DVKs) has been developed. The chemoselective fragmentation of the cyclohexanone intermediate is the key for the formation of not only the C(2)-tether but also the two different heterocycles.