Indolylmethanols as Reactants in Catalytic Asymmetric Reactions

Abstract

Indolylmethanols have emerged as versatile reactants in catalytic asymmetric reactions because of the facile generation of reactive intermediates from these compounds. The most common indolylmethanols are 3-indolylmethanols and 2-indolylmethanols, and the reaction types applicable to these heterocycles mainly include catalytic enantioselective substitutions and cyclizations. Using indolylmethanols as reactants in catalytic asymmetric reactions enables the enantioselective construction of a variety of indole-containing frameworks.

Synergistic‐Catalysis‐Enabled Reaction of 2‐Indolymethanols with Oxonium Ylides for the Construction of 3‐Indolyl‐3‐Alkoxy Oxindole Frameworks

“…To further improve the reactiony ield, other parameters, such as reaction temperature, the addition of additives, the ratio of the reagents, andt he catalyst loading, were carefully modulated;h owever,n oi mprovement was obtained (for details, see the Supporting Information). We attributed this result to the generation of ab yproduct (5)i na ll of the reactions, which was formed throught he proton transfer of oxoniumylide C.…”

“…[4] In addition, these indole derivatives serve as versatile reactants and building blocksi no rganic synthesis. [5,6] Therefore, the construction of 3indolyl-3-alkoxy oxindole frameworks hasd rawn great attention from the chemistry community.…”

“…[10] Indolylmethanols are versatile reactants for the construction of indole-related frameworks. [5,6,11,12] Recently,w ef ound that the C3-position of 2-indolylmethanold isplayed unusual electrophilicity,b ecause it could transform into ad elocalized cation through dehydration in the presence of aB rønsted acid and be readily attacked by an ucleophile (Scheme 2). [13,14] However,a pplicable nucleophiles were limited to arenes (such as 2naphthol and indole) [14] and carbonyl compounds (such as pyrazol-5-one and enolizable anhydrides), [13] and the reactions between such nucleophilesa nd 2-indolylmethanols are already well-established [Eq.…”

Catalytic Asymmetric (4+3) Cyclizations of In Situ Generated ortho‐Quinone Methides with 2‐Indolylmethanols

“…In recent years,indolylmethanols have been identified as competent three-atom synthons in catalytic asymmetric reactions,e specially under chiral B-H catalysis. [9][10][11][12] Notably, our group has discovered that the C3-position of 2-indolylmethanols can display electrophilicity in the presence of chiral B-H compounds (Scheme 2), thereby undergoing enantioselective substitutions [Scheme 2, Eq. (4)], [13] as well as (3+ +2) and (3+ +3) cyclizations [Scheme 2, Eq.…”

Chiral Phosphoric Acid Catalyzed Asymmetric Synthesis of Hetero‐triarylmethanes from Racemic Indolyl Alcohols

“…[1] Therefore,t he development of efficient strategies for enantioenriched heterotriarylmethane derivatives is of great interest to the synthetic community.D iarylmethanols have emerged as versatile precursors for the construction of hetero-triarylmethane derivatives. [2] Ther acemic alcohols used can be easily converted into active intermediates,such as quinone methides (QMs) or carbocationic species,b ya na cid-catalyzed dehydration pathway.R ecently,g reat achievements have been made in the catalytic asymmetric 1,4-additions and formal S N 1 substitutions of diarylmethanols to deliver hetero-triarylmethanes.A sar esult, various activation patterns have been successfully documented, such as bifunctional modes, [3] coordination catalysis, [4] and dual ion-pairing modes. [5] However, the enantioselective transformations based on the more challenging monoactivation mode still remain unexplored.…”