Mutual Cooperation in the Formal Allyl Alcohol Nucleophilic Substitution and Hydration of Alkynes for the Construction of γ‐Substituted Ketones

Abstract

Mutual cooperation in the formal allyl alcohol nucleophilic substitution reaction and hydration of an alkyne has been utilized in the presence of a gold catalyst to give a series of γ-functionalized ketones with high to excellent yields. This reaction actually involved an intramolecular O-H insertion cyclization of an alkyne to form the dihydrofuran intermediate, which was followed by the nucleophilic addition ring-opening of a dihydrofuran to give the target compound.

1,3-Bis(carboxymethyl)imidazolium Chloride as a Metal-Free and Recyclable Catalyst for the Synthesis of N-Allylanilines by Allylic Substitution of Alcohols

“…The allylic substitution of alcohols with anilines is a simple method to afford this type of compounds. Regarding this reaction, three products are expected depending on the substituents: 2-allylanilines, , 4-allylanilines, − and N -allylanilines, − ,,,− this product being the predominant one regardless of the catalytic system when transition-metal complexes are employed . Nevertheless, only a few examples of the allylic substitution of alcohols with anilines employing metal-free catalytic systems have been described.…”

Combination of Metal-Catalyzed Cycloisomerizations and Biocatalysis in Aqueous Media: Asymmetric Construction of Chiral Alcohols, Lactones, and γ-Hydroxy-Carbonyl Compounds

“…Although isomerization reactions always proceed with a total mass transfer from substrates to products (a very attractive point for green chemistry), they often lack practical applications, since an increase in structural complexity is not always achieved. As an alternative, the formal metal-catalyzed hydration of alkynes, through the initial intramolecular cyclization of a pendant nucleophile (NuH), facilitates the desired increase in the functionalization under the reaction conditions (aqueous media, mild temperature, absence of methanol as cocatalyst) compatible with a further biocatalytic step (Scheme ).…”

DES‐Type Interactions To Promote Solvent‐Free and Metal‐Free Reactions between Nitrogen‐Containing Heterocycles and Allylic Alcohols

“…Derivatives of 2-phenylindole are of particular interest, as this scaffold is present in several biologically significant molecules, which further cements the relevance of the procedure described. [2] Next, a variety of indoles bearing substitution on the benzo-condensed ring were submitted to the allylation reaction with alcohol 2 a, providing the expected 3-allylindoles (7)(8)(9)(10)(11)(12)(13) in almost quantitative yield independently of the electronic properties of the substituent. The position of the substituent seems to influence the rate of the reaction due to steric hindrance since a bromo substituent in the 4-position required a longer reaction time to produce 13, although it was isolated in quantitative yield (Scheme 2).…”

“…[3,4] Over the years, several methodologies have been developed for the allylation of indoles with allylic alcohols (Scheme 1a). Most approaches described in the literature employ metals to promote the reaction, including the Pd-catalysed Tsuji-Trost reaction, [4][5][6][7] or salts and complexes of several transition metals (such as gold, [8][9][10] aluminium, [11] zinc, [12,13] iron, [14][15][16] ytterbium, [17] ruthenium, [18] iridium, [19] molybdenum, [20] and indium [19,[21][22][23] ), and supported catalysts based on copper nanoparticles, [24] or phosphomolybdic acids. [25] Metal-free alternatives have also been reported, employing a variety of Brønsted acidic catalysts, mostly including sulfonic acids [14,[26][27][28][29][30][31][32][33] or fluorinated alcohols; [34] although the use of other catalytic systems, such as iodine [35] or frustrated Lewis pairs [36] have been described.…”