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8337672 
Journal Article 
Quinolizidines. XVIII. Syntheses of (—)- and (+)-Ankorines through a Lactim Ether Route 
Fujii, T; Yoshifuji, S; Ohba, M; Yoneyama, K; Kizu, H 
1986 
Yes 
Chemical and Pharmaceutical Bulletin
ISSN: 0009-2363
EISSN: 1347-5223 
34 
2 
669-676 
English 
A formal chiral synthesis of the Alangium alkaloid (—)-ankorine [(—)-6] has been accomplished in the form of the synthesis of the lactam phenol (.+)-14 from the (+)-trans-lactim ether (+)-5 and 2-benzyloxy-3,4-dimethoxyphenacyl bromide through the intermediates (+)-10 and 11. A parallel sequence of conversions starting from the (—)-trans-lactim ether (—)-5 and proceeding through the intermediates (—)-10, 24, (—)-14, (—)-25, 26, (+)-27, and (+)-28 produced the enantiomer [(+)-6] of natural ankorine. For an alternative chiral synthesis of (—)-6, ethyl cincholoiponate [(+)-19] was acetylated and the resulting N-acetyl derivative (+)-20 was oxidized with Ru04 to give the 6-piperidone (+)-21 and 2-piperidone (-)-23 in 55% and 27% yields, respectively. The (—)-cis-lactim ether (—)-16, obtained by ethylation of (+)-21 with triethyloxonium fluoroborate, was then converted into (—)-13, a known precursor for the synthesis of (—)-ankorine [(—)-6], in good overall yield by a “lactim ether route,” which proceeded through (+)-15 and 12. © 1986, The Pharmaceutical Society of Japan. All rights reserved. 
Alangium alkaloid (—)-ankorine synthesis; ankorine (+)-antipode synthesis; benzyl ether hydrogenolysis; benzylic alcohol catalytic hydrogenolysis; lactim ether alkylation; lithium aluminum hydride ester reduction; N-acetylcincholoiponate ruthenium tetroxide oxidation; regioselective lactam formation Bischler-Napieralski cyclization; sodium borohydride phenacyl group reduction