Synthesis of C3-functionalized indole derivatives via Brønsted acid-catalyzed regioselective arylation of 2-indolylmethanols with guaiazulene

Abstract

The first Brønsted acid catalyzed method for the construction of guaiazulenyl C3-functionalized indole derivatives was established. The reactions proceeded smoothly at ambient temperature by used (±)-10-camphorsulfonic acid (CSA) as catalyst,...

An update on chiral phosphoric acid organocatalyzed stereoselective reactions

“…90 The electrophilicity of 2-indolylmethanols at the C3 position is commonly exploited in many reactions. 91–94 However, this report shows one of the few examples where the electronic nature of C3 is contrary, 95 the result of a cooperative effect between a CPA and hexafluoroisopropanol (HFIP).…”

Selective construction of polycyclic cyclohepta[b]indoles and cyclopenta[b]indoles via cycloaddition reaction of 3-(indol-3-yl)maleimides and (indol-2-yl)methanols

“…In recent years, 2-indolylmethanols have been demonstrated as versatile platform molecules for the synthesis of indole-based heterocycles through substitution reactions and annulation reactions. 8,9 It is well-known that 2-indolylmethanols can easily be converted into delocalized cation intermediates with carbocation resonance structures by the use of Brønsted or Lewis acids that act as a catalyst. 10 Therefore, 2-indolylmethanols displayed unusual umpolung reactivity and dual reactivity (C3-nucleophilic and C3-electrophilic).…”

Regioselective Reaction of 2-Indolylmethanols with Enamides

“…On the other hand, 2-indolylmethanols can also transform into carbocations, vinyliminium and delocalized cations in the presence of a Lewis or Brønsted acid to participate in various substitution reactions. In this context, various nucleophiles include indoles and electron-rich heterocycles [29][30][31][32], naphthol [33], phosphines [34,35], thiophenols [36], tryptamines and tryptophols [37], sodium sulfinates [38], aldehydes [39], vinyl silyl ethers [40], 2-alkyazaarenes [41], azlactones [42], prazol-5ones [43], anhydrides and cyclic enaminoes [44,45] and guaiazulenes [46] and have been applied in the substitution of 2-indolylmethanols either at the C3 position or benzyl position. Nevertheless, the design and development of efficient, atom-economical and practical approaches are still needed to generate biologically important indole-containing compounds.…”