Selective Construction of Diverse Polycyclic Spirooxindoles via a Three-Component Reaction of Cyclic Mercapto-Substituted β-Enamino Esters, Isatins, and Cyclic 1,3-Diketones

Three-Component Reaction for the Synthesis of Spiro-Heterocycles from Isatins, Substituted Ureas, and Cyclic Ketones

We reported an efficient three-component reaction to access new spiro heterocycles through the annulation reactions of isatins, substituted ureas, and cyclic ketones under normal laboratory conditions, which is another example of isatins being used to build spiro compounds by the ring-opening and recyclization processes. The wide range of substrates, simple operation, normal experimental conditions, and high yields make the approach of high practical value.

Regioselective and Diastereoselective Construction of Diverse Dispiro-Indanone-Fluorenone-Oxindole Motifs

A convenient synthetic protocol for regioselective and diastereoselective construction of complex dispiro-indanone-fluorenone-oxindole motifs was developed by the base-promoted annulation reaction of bindone and MBH carbonates of isatins by adjusting reaction conditions. DABCO promoted the annulation reaction of bindone and MBH carbonates of isatins in DCM at room temperature, affording dispiro[indene-2,4'-fluorene-1',3″-indoline] derivatives in good yields and with high diastereoselectivity. Triethylamine promoted the annulation reaction of two molecular 1,3-indanediones and MBH esters of isatins in ethanol at elevated temperature and selectively gave dispiro[indene-2,4'-fluorene-3',3″-indolines] in moderate yields. However, triethylamine promoted the annulation reaction of excess 1,3-indanediones and MBH esters of isatins in refluxing ethanol, affording dispiro[indene-2,4'-fluorene-3',3″-indolines] with the Z-isomer as the major product and the E-isomer as the minor product.

Construction of Spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione Derivatives via Ring-Opening and Recyclization of Isatins and C-OH Cleavage of 2-Naphthol

An efficient three-component reaction to access spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione derivatives has been developed through the ring-opening and recyclization process of isatins and dehydroxylation of 2-naphthol, which is different from their conventional reaction modes. Experimental observations suggest that p-toluenesulfonic acid is the key factor that promotes the success of this synthetic strategy. The research provided a novel approach for the construction of spiro compounds from isatins and 2-naphthol in organic synthesis.

Synthesis of acyloxy-2H-azirine and sulfonyloxy-2H-azirine derivatives via a one-pot reaction of β-enamino esters, PIDA and carboxylic acid or sulfonic acid

PIDA mediated oxidative acyloxylation/azirination and sulfonyloxylation/azirination of β-enamino esters were investigated. A series of functionalized acyloxy-2H-azirine and sulfonyloxy-2H-azirine derivatives was synthesized in moderate to good yields. This represents the first oxidative sulfonyloxylation/azirination of β-enamino esters with PIDA and sulfonic acid for access to sulfonyloxy-2H-azirine. Hypervalent iodine reagents enable cascade C-O/C-N bond formation. Furthermore, a possible reaction pathway was proposed based on the experimental results.

Recent Progress in the Synthesis of Heterocycles Based on 1,3-Diketones

N,O-heterocycles containing the dicarbonyl ring play a significant role in heterocyclic and therapeutic chemistry. Since the discovery of 1,3-diketones, numerous research works have been achieved regarding the synthesis and its chemical reactivity. In this review, we have described the most relevant publications involving β-diketone compounds published during the period between 2018 to date. In addition, we include the 1,3-diketones-based heterocyclic compounds prepared by various synthetic methodologies.

Molecular diversity of the acid promoted domino reaction of 3-hydroxy-3-(indol-3-yl)indolin-2-ones and cyclic mercapto-substituted β-enamino esters

The acetic acid promoted reaction of 3-hydroxy-3-(indol-3-yl)indolin-2-ones and mercapto-substituted β-enamino esters showed very interesting molecular diversity.