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Total Syntheses of (−)‐Secologanin, (−)‐5‐Carboxystrictosidine, and (−)‐Rubenine
Author(s) -
Rakumitsu Kenta,
Sakamoto Jukiya,
Ishikawa Hayato
Publication year - 2019
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.201902073
Subject(s) - chemistry , epoxide , stereoselectivity , enantioselective synthesis , dihydropyran , indole test , ring (chemistry) , total synthesis , stereochemistry , optically active , monoterpene , combinatorial chemistry , organic chemistry , catalysis
The first enantioselective total syntheses of (−)‐secologanin ( 1 ), (−)‐5‐carboxystrictosidine ( 2 ), and (−)‐rubenine ( 3 ) were accomplished in 10, 9, and 14 steps, respectively. The key transformation in the synthesis of 1 was a sequential anti ‐selective organocatalytic Michael reaction/Fukuyama reduction/spontaneous cyclization to form an optically active dihydropyran ring. In addition, the secologanin tetraacetate ( 16 ), which is a potential key intermediate for the bioinspired divergent syntheses of monoterpenoid indole alkaloids, was prepared in gram‐scale in seven steps. The total syntheses of 2 and 3 , which are classified as glycosylated monoterpenoid indole alkaloids, were achieved through bioinspired transformations such as a diastereoselective Pictet–Spengler reaction, a site‐ and stereoselective epoxidation, and a site‐selective epoxide ring‐opening followed by a lactonization reaction.