Polar [3 + 2] cycloaddition of ketones with electrophilically activated carbonyl ylides. Synthesis of spirocyclic dioxolane indolinones

Ghenia Bentabed-Ababsa, Aicha Derdour, Thierry Roisnel, Jose A. Sáez, Luis R. Domingo, Florence Mongin
2008 Organic and biomolecular chemistry  
The [3+2] cycloaddition reaction between carbonyl ylides generated from epoxides and ketones (ethyl pyruvate, ethyl phenylglyoxylate, isatin, N-methylisatin and 5-chloroisatin) to give substituted dioxolanes and spirocyclic dioxolane indolinones was investigated. The effect of 10 microwave irradiation on the outcome of the reaction was studied. The thermal reaction between 2,2-dicyano-3-phenyloxirane and N-methylisatin was theoretically studied using DFT methods. This reaction is a domino
more » ... n is a domino process that comprises two steps. The first is the thermal ring opening of the epoxide to yield a carbonyl ylide intermediate, whereas the second step is a polar [3+2] cycloaddition to yield the final spiro cycloadducts. The cycloaddition presents a low 15 stereoselectivy and a large regio-and chemoselectivity. Analysis of the electrophilicity values and the Fukui functions at the reagents involved in the cycloaddition step allowed to explain the chemical outcome. 65 13 C NMR signals. In addition, the NOESY experiment clearly showed the relationship between H2 (see Table 1 , a) at 6.27 ppm and the methyl group at C4 at 1.96 ppm. Cis 4a was then identified unequivocally by X-ray structure analysis. Suitable
doi:10.1039/b804856h pmid:18698474 fatcat:4mcoddm6abbnffv534inkbqiyu