US Patent 4,000,197
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
The synthesis of enantiomers of a series of methoxy- and alkyl- substituted phenylisopropylamines is described. The synthesis comprises reducing the imines, formed by the reaction of appropriate phenylacetones with either (+)- or (-)-α-methylbenzylamine, by low-pressure reduction techniques, and subsequently subjecting the optically active N-(α-phenethyl)phenylisopropylamine derivative to hydrogenolysis. The hydrogenolysis products are characterized by enantiomeric purities in the range of 96 - 99%. Yields of products are approximately 60%.
Barfknecht, Charles F. and Nichols, David E. Asymmetric synthesis of phenylisopropylamines. US Patent 4,000,197 filed July 23, 1973 and issued December 28, 1976. https://ir.uiowa.edu/patents/8