HFIP-Promoted Selective Hydroxyalkylation of Aniline Derivatives with Arylglyoxal Hydrates

Abstract

A HFIP-promoted highly selective hydroxyalkylation of aniline derivatives with arylglyoxal hydrates has been realized. The reaction produces various N,N-dialkylanilines and their derivatives with α-hydroxy carbonyl units in good to excellent yields under mild conditions. Furthermore, the synthetic potential of this method has been demonstrated by the facile synthesis of several structurally interesting molecules such as benzil, 1,2,4-triazine, quinoxaline, hydantoin, and 2-thiohydantoin with aromatic amine units.

Rhodium-Catalyzed Tandem C–H Annulation Enabled by Transient Directing Group Strategy and Sequential Nucleophilic Substitution

“…On the basis of the forementioned results and previous literature, − , a plausible mechanism was proposed (Scheme ). Initially, intermediate I is formed by anion exchange of [Cp*RhCl 2 ] 2 with AgSbF 6 and carboxylic acid via Cl – extraction.…”

“…An elaborate strategy is exploring the one-pot synthesis of 6H-benzo[c]-chromen-6-ol via tandem C−H activation, which could construct C−C bond via nucleophilic substitution to provide benzo[c]chromenes under mild conditions. 8 In 2017, the Cui group developed a rhodium-catalyzed tandem C−H activation of benzamides with diazonaphthalen-2(1H)-ones for the synthesis of lactones. 9 Recently, the Samanta group disclosed a similar methodology by using ruthenium as the catalyst (Scheme 1C).…”

“…Therefore, developing an efficient pathway to reach one-pot synthesis of benzo­[ c ]­chromenes via tandem C–H activation would attract extensive interest. An elaborate strategy is exploring the one-pot synthesis of 6 H -benzo­[ c ]­chromen-6-ol via tandem C–H activation, which could construct C–C bond via nucleophilic substitution to provide benzo­[ c ]­chromenes under mild conditions …”

1,1,1,3,3,3-Hexafluoro-2-Propanol-Promoted Friedel–Crafts Reaction: Metal-Free Synthesis of C3-Difluoromethyl Carbinol-Containing Imidazo[1,2-a]pyridines at Room Temperature

“…It has been reported that HFIP can be used to promote the generation of a C-C bond by cleavage of a C-O bond (the substrates of aromatic aldehyde hydrate, propar-gyl alcohol, difluoroacetaldehyde ethyl hemiacetal, etc.) via the Friedel-Crafts alkylation pathway [26][27][28][33][34][35]. Based on the properties of HFIP and the above-mentioned control experimental results, a plausible mechanism of HFIP-promoted Friedel-Crafts alkylation was put forward (Scheme 3).…”

Gold-Catalyzed “Back-to-Front” Synthesis of 4-Silyloxyindoles

“…To synthesize the required pyrrolyl diol derivatives 1 and 2 , we utilized the hydroxyalkylation of pyrroles with glyoxals. We followed the procedure described by Ren et al, involving the reaction of pyrroles with arylglyoxals in the presence of HFIP as a promoter . The readily obtained pyrrol-2-yl α-acyloins S1a-j were then treated with alkynyl organometallics to produce pyrrol-2-yl glycols 1 .…”