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Total Synthesis of the Proposed Structure of Turkiyenine
Author(s) -
Kobayashi Hisataka,
Sasano Yusuke,
Kanoh Naoki,
Kwon Eunsang,
Iwabuchi Yoshiharu
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201501365
Subject(s) - benzazepine , chemistry , benzofuran , stereochemistry , total synthesis , isoquinoline , annulation , amide , alkylation , ketone , organic chemistry , catalysis
The secondary metabolite, turkiyenine, is a probable bioactive component of the medicinal plant, Hypecoum procumbens L. Structurally, it is an isoquinoline‐derived alkaloid composed of dihydrobenzofuran and 3‐benzazepine‐1‐one moieties arranged in a unique spirocyclic structure. Yet despite the intriguing structure and medicinal relevance of benzofuran and benzazepine motifs, neither a synthetic study nor a biological evaluation of turkiyenine have been reported to date. Herein we communicate the first total synthesis of the proposed structure of turkiyenine, and on the basis of X‐ray crystallography show that the proposed structure is incorrect. The key steps of our synthesis include an aza‐spiro annulation onto a benzofuran using a rhodium–nitrenoid to construct a 3‐alkyl‐3‐amino‐2,3‐dihydrobenzofuran, an acyl‐alkylation of an aryne onto a β‐ketolactam to form a 3‐benzazepine‐1‐one, and chemoselective reduction of an amide in the presence of a ketone.