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Synthesis of Enantiomerically Pure Tetrahydro‐2‐methylharman
Author(s) -
Shiqi Peng,
Min Guo,
Winterfeldt Ekkehard
Publication year - 1993
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199319930125
Subject(s) - chemistry , acetaldehyde , dehydration , reagent , condensation , pictet–spengler reaction , diastereomer , stereochemistry , medicinal chemistry , organic chemistry , ethanol , biochemistry , physics , thermodynamics
L ‐Tryptophan methyl ester reacts with acetaldehyde in a Pictet‐Spengler condensation to give a 2.5:1 mixture of the stereoisomers (1 S ,3 S )‐ 2 and (1 R ,3 S )‐ 2 . These were converted by ammonolysis into the corresponding amides (1 S ,3 S )‐ 3 or (1 R ,3 S )‐ 3 . On methylation of (1 S ,3 S )‐ 3 or (1 R ,3 S )‐ 3 the corresponding 2‐methylcarbolineamide (1 S ,3 S )‐ 4 or (1 R ,3 S )‐ 4 were obtained. Dehydration of (1 S ,3 S )‐ 4 or (1 R ,3 S )‐ 4 affords 2‐methylcarbolinenitrile (1 S ,3 S )‐ 5 or (1 R ,3 S )‐ 5 . After reduction with NaBH 4 (1 S ,3 S )‐ 5 or (1 R ,3 S )‐ 5 was decyanated and the title compound (1 S )‐ 6 or (1 R )‐ 6 was obtained. With NOE experiments their stereochemistry were determined and their optical purities were confirmed by measurements using a chiral shift reagent.