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Updated: Oct 12, 2025

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
Published on: December 16, 2019
Hetero-Type Benzannulation Leading to Substituted Benzothio-Phenes
Taro Kono1, Ryosuke Sasaki1, Hideki Goto1
1Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.
Abstract:
TiCl4 (or SnCl4)-promoted hetero-type benzannulation reactions using various (2,2-dichlorocyclopropyl)(thiophen-2-yl)methanols proceeded smoothly to produce uniquely substituted 4-chlorobenzothiophenes (five examples). The present approach involves the first distinctive thiophene formation from thiophene cores, in contrast to traditional methods of thiophene formation from benzene cores. The stereocongested (less reactive) Cl position in the obtained 4-chlorobenzothiophenes functioned successfully as the partners of three cross-coupling reactions: (i) a Suzuki-Miyaura cross-couplings using Pd(OAc)2/SPhos/K3PO4 catalysis (seven examples; 63-91%), (ii) a hydroxylation using KOH/Pd(dba)2/tBu-XPhos catalysis (85%), and (iii) a borylation using a B2(pin)2/Pd(dba)2/XPhos/NaOAc catalysis-provided 4-(pin)B-benzothiophene (58%).
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