RESUMEN
An enantioselective [4 + 1] cycloaddition reaction of ortho-quinone methides and bromomalonates using a quinine and BINOL derived phase-transfer catalyst is described. With high yields and enantioselectivities, the method provided a variety of optically active dihydrobenzofurans, which represent a valuable structural motif present in numerous naturally occurring and biologically active molecules.
Asunto(s)
Indolquinonas/química , Indolquinonas/síntesis química , Malonatos/química , Malonatos/síntesis química , Catálisis , Reacción de Cicloadición , EstereoisomerismoRESUMEN
Cooperation is key! Chiral Brønsted acid/rhodium(II) cooperative catalysis enabled an enantioselective three-component aldol-type reaction of 3-diazo oxindoles and anilines with glyoxylates to give highly functionalized and structurally diverse 3-amino oxindoles in high stereoselectivity (>20:1 d.r., 99 % ee; see scheme).
Asunto(s)
Aldehídos/química , Indoles/síntesis química , Rodio/química , Catálisis , Técnicas Químicas Combinatorias , Indoles/química , Estructura Molecular , Oxindoles , EstereoisomerismoRESUMEN
A highly enantioselective carbenoid-associated N-H functionalization/Michael addition cascade reaction is developed by virtue of Ru(II)/chiral organo bifunctional catalyst relay catalysis. In this way, a variety of optically pure 3-amino-3-alkyloxindoles can be easily achieved. Moreover, on the basis of this metal/organo relay catalytic three-component protocol, a key intermediate for the formal synthesis of (-)-psychotrimine could be obtained in six steps with 25% overall yield.
RESUMEN
An unprecedented gold-catalyzed synthetic method for the direct assembly of aryl-annulated carbazoles from 2-alkynyl arylazides and alkynes is described. The reaction is proposed to proceed via a sequential cyclopropenation and intramolecular metal carbene/arene Friedel-Crafts-type reaction, respectively, mediated by two gold carbene intermediates.