Facile synthesis of functionalized spiro[indoline-3,2'-oxiran]-2-ones by Darzens reaction

• Qin Fu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 918–924, doi:10.3762/bjoc.9.105

• ; oxindole; oxirane; spiro-epoxyoxindole; spirooxindole; Introduction The spirooxindole unit is a privileged heterocyclic motif that forms the core structure of a large family of natural alkaloids and many pharmacological agents with important bioactivity and interesting structural properties [1][2][3][4][5

• . The main problem is that the N-alkylated spiro epoxyoxindole 4 is accompanied by the formation of spiro epoxyoxindole 3 even if equivalent reactants are used, which is consistent with the recently reported reactions of isatins with alkylating agents having an acidic methylene group by Blanco et al

• . [19]. To our delight, the spiro epoxyoxindole 3 could be selectively obtained in 85% yield when the reaction was carried out in the system of K2CO3/CHCl3 at about 50 °C for 10 h. On the other hand the N-alkylated spiro epoxyoxindole 4 was also successfully prepared in 90% yield in this system when