Synthesis of Spiro Indole-2-Ones Using Three Component Reaction of N-Alkylisatins and Triphenylphosphonium Intermediates.

OBJECTIVE: A simple and efficient procedure is achieved for the synthesis of indole-2-one derivatives via three-component reaction of N-alkylisatin, activated acetylenic compounds and alkyl bromide in the presence of triphenylphosphine in water under two conditions; room temperature and microwave irradiation.

MATERIALS AND METHODS: All chemicals used in this work were prepared from Fluka (Buchs, Switzerland) and were used without further purification. N-alkylisatin were synthesized in the laboratory in the procedure that is reported in the literature. Electrothermal 9100 apparatus is employed for measuring of melting points of products. Elemental analyses for C, H, and N were performed with Heraeus CHN-O-Rapid analyzer. Mass spectra were recorded on a FINNIGAN-MAT 8430 spectrometer operating at an ionization potential of 70 eV. Measurement of IR spectra was performed by Shimadzu IR-460 spectrometer. 1H, and 13C NMR spectra were evaluated with a BRUKER DRX- 500 AVANCE spectrometer at 500.1 and 125.8 MHz, respectively.

RESULTS: The results were demonstrated that simple mixing of N-alkylisatin, dialkyl acetylenedicarboxylate and alkyl bromides in the presence of triphenylphosphine by using of microwave condition is the efficient method for preparation of indole derivatives in good yields. In the optimized reaction conditions, water is solvent and temperature of the mixture of reaction is 80 oC.

CONCLUSION: In this study, the reaction of activated acetylenic compounds with N-alkylisatin and alkyl bromide in the presence of triphenylphosphine is investigated which is led to a facile synthesis of some functionalized indoles.