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.