A Direct and an Efficient Regioselective Synthesis of 1,2-Benzothiazine 1,1-dioxides, β-Carbolinones, Indolo[2,3-c]pyran-1-ones, Indolo[3,2-c]pyran-1-ones, Thieno[2,3-c]pyran-7-ones and Pyrano[3’,4’:4,5]imidazo[1,2-a]pyridin-1-ones via Tandem Stille/Heterocyclization Reaction

Abstract

A general regioselective one-pot synthesis of 1,2-benzothiazine 1,1-dioxides from 2-iodo benzenesulfonamide moieties and allenylstannanes is described using a domino Stille-like/Azacyclization reaction. The conditions developed also opened a novel access to β-carbolinones, indolopyranones, thienopyranones and pyrano-imidazopyridines.

Synthesis of 3,6‐Disubstituted 4‐Ethoxycarbonylpyranoindol‐1‐ones Utilizing 3‐Amino‐2‐pyrone Synthesis

“…[2] There are several synthetic methods of pyranoindol-1-ones via pyrone moiety formation of indole derivatives, including formylation/lactonization of indole diester, [3] electrophilic cyclization of alkynyl ester, [4] oxidative coupling of heteroarene carboxylic acids with diphenylacetylene, [5] cycloisomerization of 3-ethynyl-indole-2-carboxylic acid, [1] tandem coupling oxacyclization reaction, [6] a one pot deprotection/lactonization of indole ester, [2] annulation of allenes with indole-2-carboxylic acid derivatives, [7] FeCl 3 -promoted regioselective annulation of o-(1alkynyl)heterocyclic carboxylates with disulfide, [8] triflic acid promoted hydrolysis/cyclization sequence of 2-(alkynyl)benzamides, [9] copper-catalyzed annulation of 1-methyl-3-iodo-indole-2-carboxylic acid with alkynes having alkoxycarbonyl groups, [10] Au/Pd cooperatively catalyzed cross-coupling reactions, [11] oxidative [4 + 2] annulation of substituted arenecarboxylic acid with alkyne, [12] gold(III) chloride-catalyzed cycloisomerization of alkyne-tethered indole carboxylic acids, [13] and tandem Stille/heterocyclization reaction. [14] On the other hand, in 2018, Shimizu and co-workers reported the synthesis of pyranoindol-1-one via indole moiety formation of 3-amino-2pyrone derivative using palladium-catalyzed intramolecular Heck reaction. [15] 3,6-Disubstituted 4-carbonyl pyranoindol-1ones have been interested because the effects of 3,6-disubstituents and a 4-carbonyl group on the biological activity are not known.…”