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Brønsted Acid‐Mediated Annulation of α‐Oxo Ketene Dithioacetals with Pyrroles: Efficient Synthesis of Structurally Diverse Cyclopenta[ b ]pyrroles
Author(s) -
Yang Xiaoge,
Wu Kaikai,
Wu Ping,
Chen Jiping,
Sun Chenglin,
Yu Zhengkun
Publication year - 2015
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.201501022
Subject(s) - annulation , ketene , chemistry , brønsted–lowry acid–base theory , trifluoroacetic acid , pyrrole , cycloaddition , organic chemistry , allene , intramolecular force , olefin fiber , medicinal chemistry , catalysis
Brønsted acid‐mediated annulation of internal olefins α‐oxo ketene dithioacetals to pyrroles was efficiently achieved to afford cyclopenta[ b ]pyrroles. A pair of Brønsted acids with acid strengths, that is, trifluoroacetic acid, and para ‐toluenesulfonic acid hydrate, were applied to promote the annulation reactions. The resultant products were readily oxidized to sulfones by meta ‐chloroperoxybenzoic acid. Subsequent treatment with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene gave desulfurized terminal olefins or [2+2] cycloaddition products from the desulfurized olefin intermediates. The present protocol provides facile access to structurally diverse cyclopenta[ b ]pyrrole derivatives under mild conditions.