The Nicholas Reaction of Indoles. Propargylation of Indoles with (Propargyl)dicobalt Hexacarbonyl Cations

Abstract
Indole reacted with (propargyl alcohol)Co2(CO)6 complex 1 to give 3-(1, 1-dimethylpropargyl)indole 3, whereas N''-methoxycarbonyltryptamine 7 gave the corresponding N-substituted derivative 11. The reaction of 7 with (propargyl acetate) Co2(CO)6 complex 23 provided 3a-(1,1-dimethylpropargyl)hexahydropyrroloindole cobalt complex 9. Oxidative demetalation of 3, 11, and 9 with Fe(NO3)3 gave 5, 13, and 27, respectively. Hydrogenation of 5 afforded the corresponding 3-(1,1-dimethylallyl)indole 6.
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