Isoxazole derivatives R 0240 1,3-Dipolar Cycloadditions. Part 14. Highly Selective Cycloadditions of C,N-Diaryl Nitrones to Diethyl Aryl Methylene Malonates. -1,3-Dipolar cycloaddition of nitrones (I) to arylmethylenemalonates (II) occurs with complete regio-and diastereoselectivity to furnish trans-3,5-diarylisoxazolidines (III). This is in contrast to nitrone cycloaddition reactions with cinnamic acid derivatives, which provide two diastereomeric cycloadducts. -(BANERJI*, A.; SENGUPTA, S.; NAYAK, A.; BISWAS, P. K.; BHATTACHARYA, B.; DASGUPTA, S.; SAHA, R.; PRANGE, T.; NEUMAN, A.; Indian J.

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Europium(III)triflate has been proved to be an effective catalyst for intramolecular cyclization of aryl-substituted carboxylic acid to afford arylated γ-butyrolactone. Various attractive features, such as broad substrate scope, a wide range of functional group tolerance, operational simplicity, complete atom economy, and good-to-excellent yields have made this new protocol more appealing. Moreover, this method provides a practical alternative to the existing catalysts.

3,6-diaryl-2,3,3a,4-tetrahydropentalene-1,5-dione, a new class of compounds have been synthesized via Pauson-Khand carbonylative cyclization of enyne moiety followed by DMP oxidation. Straight forward nature, good yield, and wide substrate scope are the attractive features of this reaction. Additionally, this class of compounds may be further elaborated to triquinane natural product-like molecules.