Mechanistic Studies for Synthesis of Bis(indolyl)methanes: Pd-Catalyzed C–H Activation of Indole–Carboxylic Acids with Benzyl Alcohols in Water

Abstract

Abstract:A method for synthesis without protecting groups of bis(indolyl)methanes by the (η 3

Radical‐Induced, Palladium‐Catalyzed C–H Activation: An Approach to Functionalize 4H‐Benzo[d][1,3]oxazin‐4‐one Derivatives by Using Toluenes, Aldehydes, and Benzyl Alcohols

“…In the past decade, remarkable progress has been made in the area of transition‐metal‐catalyzed direct oxidative carbon‐carbon and carbon‐heteroatom bond formation reactions by employing C–H activation strategies because of the atom economy of these transformations, their few reaction steps, and their use of readily available and inexpensive starting materials Among several substrates that have been explored to date, toluenes, aldehydes, and benzyl alcohols have gained considerable attention as elegant reaction partners in the direct functionalization of organic molecules because of their stability, low toxicity and commercial availability . Moreover, these substrates do not require any prefunctionalization when used as coupling partners and, thus, have changed the landscape of organic synthesis .…”

Direct Substitution of Alcohols in Pure Water by Brønsted Acid Catalysis

“…Based on the classification of Sharpless, the reactions are named as “on water” protocols when some of the reactants are insoluble in the aqueous medium [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. It is important to note that a few metal-catalyzed examples have been also developed “on water”, such as with gold(III) [ 36 , 37 ], In(III) [ 38 ] or Pd(0) [ 39 , 40 , 41 , 42 , 43 ]. However, high temperature or the use of a co-catalyst or an acid additive is necessary.…”

Transition Metal‐Catalyzed CH Activation of Indoles

“…[141] Indoles containing carboxylic acid moieties were coupled to benzylic alcohols in mostly good yields(Scheme 65), utilizing acatalytic system composed of Pd(OAc) 2 andaphosphinosulfonate,i nw atera sr eactionm edium. [142] Indoles Scheme 61. Cu-catalyzed, stereospesific Friedel-Crafts alkylation of indoles.…”

“…Reaction Couplingpartner/reagentC atalyst References 1a rylation aryl halides Pd [101,102,104,105] 2b enzoic acids Pd [107] 3a rylhydrazines Pd [108] 4c yclohexanones Pd [109] 5d iaryliodonium salts Cu [110] 6N -heterocyclic compounds Pd [111][112][113][114] 7a lkynylation alkynes Au [115] 8b enzylation benzylic alcohols Au [116] 9o lefination alkenes Pd [117,118] 10 acylation benzaldehydes Pd [119] 11 TMEDA Cu [120] 12 nitrilesP d [121] 13 CO and alcohols Rh [122] 14 a-amino carbonyl compounds Cu [123] 15 Pd [124] 16 synthesis of bisindoles alcohols Pd [141,142] 17 aldehydes Ag [143] 18 amines Pd [144] 19 annulation alkenes Pd 21 cyanation CuCN Pd [150] 22 K 4 [Fe(CN) 6 ]P d [151] 23 t-BuNC Pd [152] 24 NH 4 HCO 3 and DMSOP d [153] 25 amidation isocyanides Pd [154] Scheme 44. Pd-catalyzedarylation.…”