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Concise Syntheses of bis‐ Strychnos Alkaloids (−)‐Sungucine, (−)‐Isosungucine, and (−)‐Strychnogucine B from (−)‐Strychnine
Author(s) -
Zhao Senzhi,
Teijaro Christia.,
Chen Heng,
Sirasani Gopal,
Vaddypally Shivaiah,
Zdilla Michael J.,
Dobereiner Graham E.,
Andrade Rodrigo B.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201602663
Subject(s) - strychnos , strychnine , chemistry , brucine , indole test , stereochemistry , monomer , indole alkaloid , combinatorial chemistry , alkaloid , organic chemistry , biochemistry , polymer
The first chemical syntheses of complex, bis‐ Strychnos alkaloids (−)‐sungucine ( 1 ), (−)‐isosungucine ( 2 ), and (−)‐strychnogucine B ( 3 ) from (−)‐strychnine ( 4 ) is reported. Key steps included (1) the Polonovski–Potier activation of strychnine N ‐oxide; (2) a biomimetic Mannich coupling to forge the signature C23−C5′ bond that joins two monoterpene indole monomers; and (3) a sequential HBr/NaBH 3 CN‐mediated reduction to fashion the ethylidene moieties in 1 – 3 . DFT calculations were employed to rationalize the regiochemical course of reactions involving strychnine congeners.