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A novel synthesis of 2,3‐dihydro‐1 H ‐thieno[3,4‐ b ]pyrroles via ring transformation of cyclic sulfonium ylides by titanium(IV) chloride‐triethylamine system
Author(s) -
Maruoka Hiroshi,
Yamagata Kenji,
Okabe Fumi,
Tomioka Yukihiko
Publication year - 2005
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570420438
Subject(s) - sulfonium , chemistry , dimethylamine , triethylamine , ring (chemistry) , medicinal chemistry , chloride , amine gas treating , sodium hydride , titanium , hydrochloride , transformation (genetics) , salt (chemistry) , polymer chemistry , organic chemistry , biochemistry , gene
A series of cyclic sulfonium ylides 4a‐h reacted with titanium( IV ) chloride in the presence of triethyl‐amine to give the corresponding fused 2,3‐dihydro‐1 H ‐thieno[3,4‐ b ]pyrroles 5a‐h , via a ring opening and recyclization. In contrast, treatment of compounds 4a, 4b, 4e and 4f with titanium(IV) chloride, triethy‐lamine and dimethylamine hydrochloride gave the corresponding thiophenes 6a, 6b, 6e and 6f . Furthermore, compounds 6a and 6b easily underwent cyclization with sodium hydride to afford the corresponding 5a and 5b .