Synthesis of indolo[2,3-c]coumarins and indolo[2,3-c]quinolinones via microwave-assisted base-free intramolecular cross dehydrogenative coupling
摘要:
A microwave-assisted base-free intramolecular cross dehydrogenative coupling (CDC) of 3-aniline substituted coumarins and quinolinones have been developed. A broad range of indolo[2,3-c]coumarins and indolo[2,3-c]quinolinones can be easily afforded in good to high yields (up to 93%) under palladium catalysis. The method is among the most straightforward and convenient ways to access these fused polyheterocycles. (C) 2018 Elsevier Ltd. All rights reserved.
A convenient protocol for the rapid and efficient synthesis of 3-(N-substituted) aminocoumarins is described. The synthetic route developed involves the Pd-catalyzed C–N coupling reaction from readily available 3-bromocoumarin derivatives in the presence of the catalytic system Pd(OAc)2/Xantphos. Under these conditions, a series of nucleophiles including amides, sulfonamides, carbamates and functionalized