Synthesis Route for 109690-46-2

123-38-6
propanal
73-22-3
L-tryptophan
~71%
109690-46-2
1-ethyl-2,3,4,9-...

Reference:

Xinjiang Huashidan Pharmaceutical Research Co., Ltd. Patent: EP1634881 A1, 2006 ; Location in patent: Page/Page column 14; 15; 95 ;