Facile stereoslective synthesis of spiro[indole-oxiranes] by combination of phase transfer catalyst and ultrasound irradiation and their bioassay

An alternative and environmentally benign pathway for diastereoslective synthesis of fluorinated spiro[indole-3,2'-oxirane]-3'-benzoyl-2(1H)-ones (2a-g) is reported. The spiro[indole-3,2'-oxiranes] derivatives were obtained in 90-97% yield exclusively via the epoxidation of 3-aroylmethylene indole-2-ones with 30% aqueous hydrogen peroxide using cetyltrimethyl ammonium bromide as a phase transfer catalyst under ultrasound irradiation. The lead compounds have been tested for their antimicrobial activity and antioxidant properties.

Straightforward Stereoselective Synthesis of Spiro-epoxyoxindoles

[reaction: see text] The in situ preparation of a sulfonium ylide reagent achieved the highly diastereoselective epoxidation of isatins, so that a new and straightforward access to biologically significant spiro-epoxyoxindoles is provided. The first investigations of an asymmetric version are reported with enantiopure sulfides.