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

Indole reacted with (propargyl alcohol)Co 2 (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)Co 2 (CO) 6 complex 23 provided 3a-(1,1-dimethylpropargyl)hexahydropyrroloindole cobalt complex 9. Oxidative demetalation of 3, 11, and 9 with Fe(NO 3 ) 3 gave 5,13, and 27, respectively. Hydrogenation of 5 afforded the corresponding 3-(1,1-dimethylallyl)indole 6