Pd-Catalyzed Migratory Cycloisomerization of N-Allyl-o-allenylaniline Derivatives

Abstract

The Pd-catalyzed migratory cycloisomerization of N-allyl-o-allenyl aniline derivatives is first reported to give indoles having a substituent at the 2-position.

Formation of anti‐Bredt‐type azabicyclo[4.2.0]octene frameworks through photochemical intramolecular [2+2] cycloaddition between indole and a distal double bond of allene

“…Therefore, many efforts have been dedicated to the preparation of this particular molecular frameworks so far [8][9][10]. Whereas the preparative method for indolines fused with 5-or 6-membered ring has wide variety among these traditional processes [8], those for cyclobutane-fused indolines have been much less explored [11][12][13][14][15][16][17].…”

Oxidative Route to Indoles via Intramolecular Amino-Hydroxylation of o-Allenyl Anilines

“…Kanai has impressively developed a copper-catalyzed asymmetric protocol in which after cyclization to form the indole the resulting chiral allyl copper intermediate can be effectively intercepted with aldehyde and ketone electrophiles . Most recently, Arisawa has reported a palladium-mediated approach in which an N -allyl aniline substituent is first deprotected, and following cyclization of the nitrogen atom onto the allene facilitated by palladium activation, the resulting palladium species undergoes a reductive elimination to form a C–C bond to complete the butenyl side chain . We proposed that by using either hypervalent iodine or lead­(IV) carboxylate oxidants we should be able achieve a net amino-hydroxylation by cyclizing in an exo fashion onto the allene and capturing the intermediate with the oxidant’s carboxylate ligand.…”

Nickel-Catalyzed trans-Carboamination across Internal Alkynes to Access Multifunctionalized Indoles

“…Due to their physiological relevance and their scope in practical applications, various synthetic methodologies have been developed over the years to construct indole systems . Transition-metal-catalyzed annulation of 2-alkynyl aniline derivatives has gained significant attention due to the ease of substrate synthesis and high atom economy of the process. − The transformations involve the formation of alkenyl–metal (Pd, Pt, Rh, Ir, Au, Cu, Co, In) complex intermediates that undergo either electrophilic trapping or 1,3-migration of a broad range of functional groups including methyl, allyl, benzyl, propargyl, α-alkoxyalkyl, acyl, silyl, sulfonyl, and B­(OR) 2 groups to afford diverse indole structures (Scheme a). Despite the efficiency and broad applications of this reaction, it has certain drawbacks.…”