title: Brønsted Acid-Mediated Annulation of α-Oxo Ketene Dithioacetals with Pyrroles: Efficient Synthesis of Structurally Diverse Cyclopenta[b]pyrroles.
abstract: 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.
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227.
authors.forename: Xiaoge
authors.initials: X
authors.lastname: Yang
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227.
authors.forename: Kaikai
authors.initials: K
authors.lastname: Wu
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227.
authors.forename: Jiping
authors.initials: J
authors.lastname: Chen
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Sun
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China), Fax: (+86) 411-8437-9227. zkyu@dicp.ac.cn.|State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032 (China). zkyu@dicp.ac.cn.
authors.forename: Zhengkun
authors.initials: Z
authors.lastname: Yu
keywords: Brønsted acids; annulation; pyrroles; synthetic methods; thioacetals