Total Synthesis of (+)‐(8S,13R)‐Cyclocelabenzine

An asymmetric synthesis of the spermidine alkaloid (+)‐cyclocelabenzine (1a) and its (−)‐(13S)‐epimer 1b is described using optically active (+)‐(3S)‐3‐amino‐3‐phenylpropionic acid as the chiral building block. The isoquinolin‐1‐one fragment 15 was synthesized by a modified Bischler‐Napieralski reaction. The relative configuration of the (−)‐isomer was determined by an X‐ray crystal‐structure analysis, which enabled us to determine the absolute configuration of natural (+)‐1a as (8S,13R).