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A radical promoted approach for the selective synthesis of furo[3,2‐b]quinolines and benzylidene‐1,3‐dihydrofuro[3,4‐b]quinolines have been achieved from 2‐alkynyl quinoline‐3‐carbaldehydes by fine‐tuning of base and oxidant in good yields. In the presence of an oxidant, the reaction afforded the 5‐endo‐dig cyclized furoquinolines by decarbonylative intramolecular cyclization via a Dakin‐type reaction; however, in the absence of oxidant, 5‐exo‐dig cyclized products were obtained selectively through reductive intramolecular cyclization. The formation of furoquinolines was further supported by X‐ray crystallographic studies. The proposed mechanism was well supported by the control experiments. [ABSTRACT FROM AUTHOR]

An effective base‐induced selective approach for the synthesis of linear and branched N‐alkylated heterocycles by hydroamination of olefins has been described. The designed C–N bond formation method was directed through the olefin, as with styrenes only linear N‐alkylated product was obtained, and acrylates gave linear as well as branched alkylated heterocycles. This protocol provided the synthesis of exclusive N‐alkylated product instead of the C‐3 Michael addition product. The reaction was also compatible with phenyl vinyl sulfone, thus leading to the formation of sulfone substituted heterocycles in good yield. Further, the method was utilized for the synthesis of medicinally important analogs of CB1 Cannabinoid receptor and Dimebon analogue in short reaction sequence. [ABSTRACT FROM AUTHOR]

Transition‐metal‐free regioselective synthesis of functionalized amino‐indenones by the reaction of ortho‐alkynylaldehydes with a broad range of primary amines by intramolecular cyclization has been described. The designed reaction proceeds through KOH‐mediated Prins‐type cyclization and DMSO‐promoted oxidation of the cyclopent‐2‐en‐1‐one system. The proposed mechanism and role of solvent were well supported by control experiments. For the first time, we have disclosed the reverse reactivity of (2‐alkynyl)‐arylaldimines in a super basic system. [ABSTRACT FROM AUTHOR]