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Metal‐Free C sp −C sp and C sp −C sp 3 Bond Cleavages of N,S ‐Enynes toward Thiophene‐Fused N ‐Heterocycles
Author(s) -
Liu Zhuqing,
Gao Runli,
Lou Jiang,
He Yuan,
Yu Zhengkun
Publication year - 2018
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201800599
Subject(s) - thiophene , chemistry , quinoline , sulfur , ring (chemistry) , tetracene , indole test , stereochemistry , medicinal chemistry , combinatorial chemistry , anthracene , organic chemistry
Alkylthio‐functionalized, o‐ anilide‐embedded enynes, that is, N,S ‐1,6‐enynes, were efficiently reacted with elemental sulfur to afford thiophene‐fused N ‐heterocycles. The one‐pot sulfur incorporation/cascade cyclization strategy offers a straightforward route to 4 H ‐thieno[3,2‐ b ]indoles and thieno[3,4‐ c ]quinoline‐4(5 H )‐thiones through the tunable C sp −C sp and C sp −C sp 3 bond cleavages of the N,S ‐1,6‐enynes, forming both a N ‐heterocycle and a fused thiophene ring. The five‐ring π systems azacyclopenta[ f,g ]tetracene scaffolds were also obtained from the cascade cyclization of 2‐halogen‐functionalized thieno[3,4‐ c ]quinoline‐4(5 H )‐thiones. The present synthetic protocol avoids use of prefunctionalized indole and thiophene derivatives as the building blocks for the construction of thiophene‐fused N ‐heterocycles under metal‐free conditions.