Synthesis of Tetrahydro-1H-indeno[1,2-b]pyridine via Cascade Cyclization and Friedel–Crafts Reaction

Abstract

A convenient protocol has been established for the synthesis of 1-tosyl-2,3,4,5-tetrahydro-1H-indeno[1,2-b]pyridine via cascade cyclization and Friedel-Crafts reaction of 4-methyl-N-(pent-4-yn-1-yl)benzenesulfonamides and aldehydes in good yields. The methodology has been used for the total synthesis of the antidepressant agent (±)-5-phenyl-2,3,4,4a,5,9b-hexahydro-1H-indeno[1,2-b]pyridine.

Synthesis of Nitrogen-Containing Heterocyclic Scaffolds through Sequential Reactions of Aminoalkynes with Carbonyls

“…Both electronwithdrawing and electron-donating groups in the aromatic ring of the aldehyde were tolerated. The methodology was applied to the total synthesis of the antidepressant agent (±)-5-phenyl-2,3,4,4a,5,9b-hexahydro-1H-indeno [1,2-b]pyridine 96 (Scheme 79) [94]. The sequential rhodium(III)-catalyzed intramolecular annulation/aromatization of o-alkynyl amino aromatic ketones 97 achieved a one-pot building up of the pyrrolo[1,2a]quinolines 98.…”

“…Both electron-withdrawing and electron-donating groups in the aromatic ring of the aldehyde were tolerated. The methodology was applied to the total synthesis of the antidepressant agent (±)-5-phenyl-2,3,4,4 a ,5,9 b -hexahydro- 1H -indeno [1,2- b ]pyridine 96 ( Scheme 79 ) [ 94 ].…”

Synthesis of Nitrogen Containing Heterocyclic Scaffolds through Sequential Reactions of Aminoalkynes with Carbonyls

“…Both electronwithdrawing and electron-donating groups in the aromatic ring of the aldehyde were tolerated. The methodology was applied to the total synthesis of the antidepressant agent (±)-5-phenyl-2,3,4,4a,5,9b-hexahydro-1H-indeno [1,2-b]pyridine 96 (Scheme 79) [94].…”

Synthesis of 3C-alkylated active methylene substituted 2H-indazole derivatives via sequential ring opening of donor–acceptor cyclopropanes and reductive cyclization reaction

“…To the best of our knowledge, 3 C -alkylated 2 H -indazoles have not yet been synthesized by utilizing DACs. In the pursuit of synthesizing nitrogen heterocycles as per our continuing interest, 8 we report a facile sequential protocol for the synthesis of 2 H -indazoles containing a 3 C -alkylated active methylene group via Ni(ClO 4 ) 2 ·6H 2 O catalyzed NRO reaction of o -nitro-containing DACs with arylamines followed by SnCl 2 ·2H 2 O-mediated reductive cyclisation reactions (Scheme 2). Moreover, alkylated active methylene side-chains could be further manipulated into other functionalities.…”