A Au(i)-catalyzed hydrogen bond-directed tandem strategy to synthesize indeno-chromen-4-one and indeno-quinolin-4-one derivatives

Abstract

A gold-catalyzed hydrogen bond-directed tandem cyclization strategy to synthesize indeno-chromen-4-one and indeno-quinolin-4-one derivatives has been developed. The hydrogen bond existing between the hydroxyl group (or the amide group) and the carbonyl group played an essential role in controlling the selectivity, which was confirmed by both experimental and theoretical evidence.

Reagent-free intramolecular hydrofunctionalization: a regioselective 6-endo-dig cyclization of o-alkynoylphenols

“…29 It is known that the acidity and nucleophilicity of the phenolic O-H group in substrate 1 are important for reaction rates. 22 Most reactions were completed within 3 h. A variety of halogen (F, Cl, and Br), alkyl, alkoxy, and nitro containing substrates were compatible under the optimized conditions, regardless of the ring and substitution positions, affording the desired regioselective 6-endo-dig product 2 in good yields (up to 100%).…”

“…The reactivity and regioselectivity of ynones such as those in o-alkynoylphenols rely on the presence of intramolecular hydrogen bonds (H-bonds) between the phenolic H atom and the carbonyl moiety. For instance, Jiang et al 22 utilized H-bonds to tactically prevent the Michael addition of the phenolic O-H group to the alkyne β-carbon in the initial step of synthesizing indeno-chromen-4-one and indeno-quinolin-4one derivatives. Similar roles of H-bonds have been discussed in earlier reports as well.…”

New and Scalable Access to Karrikin (KAR1) and Evaluation of Its Potential Application on Corn Germination

“…Acid‐ and base‐mediated 6‐ endo ‐dig cyclization of enol and in particular phenol to acetylene have often been reported in the literature for the synthesis of chromones, but the alkyne moiety from 7 is weakly activated, and the enol too sensitive for these conditions. Metal‐catalyzed activation of the acetylene was then considered and in particular, gold (I) complexes, as already been intensively studied and used . Gold triphenylphosphine triflimidate (10 mol‐%) was added to the mixture after completion of the hydrolysis and to our delight, 17% of 1 were isolated.…”

“…Metal-catalyzed activation of the acetylene was then considered and in particular, gold (I) complexes, as already been intensively studied and used. [29] [30] Gold triphenylphosphine triflimidate (10 mol-%) was added to the mixture after completion of the hydrolysis and to our delight, 17% of 1 were isolated. Introduction of the catalyst from the start of the hydrolysis led to a strong increase of the final yield (67%) which was further improved by replacing TsOH with MsOH (75%, Table 1, entries 5 and 6).…”

Tandem Reactions of Ynones: via Conjugate Addition of Nitrogen‐, Carbon‐, Oxygen‐, Boron‐, Silicon‐, Phosphorus‐, and Sulfur‐Containing Nucleophiles

“…As reported by Cheng and co‐workers in 2016, exposure of alkynoylphenols bearing an ether moiety to a gold/silver system enabled the synthesis of compounds 89.5 [Eq. (89‐1)] and 89.6 [Eq.…”