Total Synthesis of (+)‐(8<i>S</i>,13<i>R</i>)‐Cyclocelabenzine

Abstract

Abstract An asymmetric synthesis of the spermidine alkaloid (+)‐cyclocelabenzine ( 1a ) and its (−)‐(13 S )‐epimer 1b is described using optically active (+)‐(3 S )‐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 (8 S ,13 R ).