First Practical and Efficient Synthesis of 3‐Phosphorylated β‐Carboline Derivatives Using the Pictet–Spengler Reaction

We report here the first practical and efficient synthesis of the diethyl 1,2,3,4‐tetrahydro‐β‐carboline‐3‐phosphonates 3 and 4 as well as diethyl 9 H ‐β‐carboline‐3‐phosphonates 5 and 6 . The target compounds were prepared in good yields by application of the Pictet–Spengler reaction of easily obtainable phosphotryptophan diethyl ester 7 . The procedure is based on simple preparation of racemic 7 followed by a Pictet–Spengler reaction with several aldehydes and subsequent oxidation chemistry.