[Synthesis]
The general procedure for the synthesis of 6-methyl-7-azaindole from trimethylcyclotriboroxane and 6-chloro-1H-pyrrolo[2,3-B]pyridine is as follows:
1. 6-methyl-7-aza-indole (1.00 g, 6.55 mmol), 2,4,6-trimethyl-1,3,5,2,4,6-trioxa-triazine (1.0 ml, 7.2 mmol), and potassium carbonate (2.72 g, 19.7 mmol) were suspended in 13 ml of dimethoxyethane and degassed in a microwave reactor with three vacuum-argon cycles .
2. [1,1'-Bis(diphenylphosphino)ferrocene]-palladium(II) dichloride complex with dichloromethane (0.29 g, 0.33 mmol) was added and again degassed in three vacuum-argon cycles.
3. the reaction mixture was stirred at 120 °C for 2 h under microwave radiation.
4. After completion of the reaction, the mixture was cooled, filtered through diatomaceous earth and eluted with ethyl acetate.
5. The filtrate was concentrated under pressure and the residue was purified by an Isolera purification system (ethyl acetate-hexane gradient, 0:100 ascending to 50:50) to afford 0.57 g (4.31 mmol, 65% yield) of 6-methyl-7-azaindole as a beige solid with 98% purity.
Product characterization data:
1H NMR (300 MHz, chloroform-d) δ ppm: 10.87 (br.s., 1H), 7.86 (d, J = 7.63 Hz, 1H), 7.29 (dd, J = 3.52, 2.35 Hz, 1H), 6.97 (d, J = 7.63 Hz, 1H), 6.47 (dd, J = 3.52, 1.76 Hz, 1H) , 2.69 (s, 3H).
HPLC/MS (15 min) Retention time: 2.57 min.
LRMS: m/z 133 (M + 1). |