One-pot sequential Heck reduction-cyclization (HRC) reactions leading to the synthesis of substituted 2-quinolones have been developed by using a heterogeneous or mixed homogeneous/heterogeneous multitask palladium catalyst with charcoal as a support. The whole sequence occurs under very mild conditions without the need for additives (ligand or base) by taking advantage of the high reactivity of aryldiazonium salts as "super electrophiles". Recycling experiments showed that the reused heterogeneous Pd(0)/C catalyst was not able to promote another HRC sequence but was, however, still highly active for hydrogenation, hydrodehalogenation, as well as hydrogenolysis reactions.

Fischer indole cyclization has recently been described as an efficient approach to the synthesis of azaindoles bearing electron‐donating groups. We now show that this cascade reaction can be very efficient for the formation of a wider range of 4‐ and 6‐azaindoles by using microwave irradiation.

Extending the Scope of the Aza-Fischer Synthesis of 4-and 6-Azaindoles. -The cascade reaction of the Fischer synthesis can be efficiently applied to the formation of 4-and 6-azaindoles using microwave irradiation. Blocking of the C-2 position in starting pyridine (XII) prevents any cyclization at C-2, albeit it does not efficiently direct to position C-4. This results in a low yield of cyclization product (XIII). The unsatisfying yield for 7-azaindole (XV) is consistent with similar related syntheses of these type of heterocycles. -(THOMAE, D.; JEANTY, M.; COSTE, J.; GUILLAUMET, G.; SUZENET*, F.; Eur.