Biphenylphosphine-Palladium(II) Complexes-Catalyzed Friedel-Crafts Reaction for the Synthesis of α-Amino and α-Hydroxy Indolylacetates and Diindolylacetates

Abstract

Biphenylphosphine-palladium(II) complexes-catalyzed Friedel-Crafts reaction of N-methylindol with imino and carbonyl compounds afforded a-amino and a-hydroxy substituted indolylacetates and diindolylacetates in good yields.

Asymmetric Friedel–Crafts Alkylations of Indoles with Ethyl Glyoxylate Catalyzed by (S)‐BINOL‐Titanium(IV) Complex: Direct Access to Enantiomerically Enriched 3‐Indolyl(hydroxy)acetates

“…Nevertheless, Mikami and co-workers reported in 2001 that biphenylphosphine-palladium(II) could successfully catalyze Friedel-Crafts reaction of indoles with glyoxylate to generate indolylacetates or bisindolylacetates as the main product, depending on the reaction conditions. [17] In 2002, Jørgensens group demonstrated that heteroaromatic compounds, including indoles, reacted with ethyl glyoxylate to give Friedel-Crafts addition adducts in good yields in various aqueous media. [18] During the preparation of this manuscript, Deng and co-workers reported enantioselective Friedel-Crafts reactions of indoles with carbonyl compounds catalyzed by bifunctional Cinchona alkaloids.…”

“…In the following steps, intermediate 11 may follow pathway I [17] to give the undesired bisindole product (3a') or follow pathway II to provide the expected product (3a) and release the chiral catalyst for the catalytic cycles. Under our conditions, the pathway I may be suppressed at lower temperature.…”

Catalytic Functionalization of Indoles in a New Dimension

“…α‐(3‐Indolyl)glycines ( 86 ; R 1 : H, R 2 : CO 2 R) are an important family of synthetic intermediates for the preparation of nonproteinogenic amino acids 97c,d,f. Indolylglycines can be conveniently obtained as a racemic mixture by spontaneous98, 99a,b or catalyzed99c Friedel–Crafts alkylation of indoles with preformed or in situ prepared glyoxylate imines. Good levels of diastereoselectivity can be achieved when preformed alkylating agents are used by introducing a chiral auxiliary on the imine 98a.…”

Active Pd(II) Complexes as Either Lewis Acid Catalysts or Transition Metal Catalysts

“…The Friedel-Crafts-type reactions of N-methylindole with ethyl glyoxylate 51 are catalyzed by the Lewis acidity of Pd(II) complexes [183]. Unprecedentedly,…”