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Paper | Special issue | Vol 42, No. 1, 1996, pp.229-236
Published online, 1st January, 1970
DOI: 10.3987/COM-95-S10
Practical Total Syntheses of Physostigmines and of Phenserines: A Synopsis

Xue-Feng Pei, Qian-sheng Yu, Bao-yuan Lu, Nigel H. Greig, and Arnold Brossi

*Department of Chemistry, Georgetown University, Washington DC 20057, and Scientist Emeritus NIH, USA


(±)-1,3-Dimethyl-3-cyanomethyl-5-methoxyoxindole (8), or (3S)-enriched 8 obtained by asymmetric alkylation, separated into the optically pure enantiomers (8a) and (8b) when chromatographed on a microcrystalline cellulose triacetate (MCTA) column. Asymmetric alkylation of (±)-1,3-dimethyl-5-tetrahydropyranyloxyoxindole (6) gave the nitrile (9) ((3S) 66 % ee) which could not be separated on the MCTA column. Optically pure eseroline (17a) was obtained by recrystallization of the fumarate salt (66 % ee) obtained from 9 after reduction with Vitride, reductive N-methylation, and treatment with 2N HCl.