Short synthesis of tryptophane and β‐carboline derivatives by reaction of indoles with N‐(diphenylmethylene)‐α,β‐didehydroamino acid esters

The ethylaluminum dichloride catalyzed Michael‐type addition of indoles 1a‐h to the N‐(diphenylmethylene)‐α,β‐didehydroamino acid esters 2a‐c allows a new synthesis of β‐methyltryptophanes 41,m and a new route for 1,1‐diphenyl‐3‐carbalkoxy‐1,2,3,4‐tetrahydro‐β‐carbolines 5a‐m.