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. 2022 May 6;87(9):6312-6320.
doi: 10.1021/acs.joc.1c02606. Epub 2022 Apr 18.

Synthesis of Benzo[ b]thiophenes via Electrophilic Sulfur Mediated Cyclization of Alkynylthioanisoles

Zahra Alikhani  1 , Alyssa G Albertson  1 , Christopher A Walter  1 , Prerna J Masih  2 , Tanay Kesharwani  1
Affiliations

Synthesis of Benzo[ b]thiophenes via Electrophilic Sulfur Mediated Cyclization of Alkynylthioanisoles

Zahra Alikhani et al. J Org Chem. .

Abstract

A stable dimethyl(thiodimethyl)sulfonium tetrafluoroborate salt was employed for the electrophilic cyclization reaction of o-alkynyl thioanisoles for the synthesis of 2,3-disubstituted benzo[b]thiophenes. The reaction described herein works well with various substituted alkynes in excellent yields, and a valuable thiomethyl group was introduced with ease. The reaction utilizes moderate reaction conditions and ambient temperature while tolerating various functionalities. To elucidate the mechanism, electrophilic addition reactions using the dimethyl(thiodimethyl)sulfonium tetrafluoroborate salt with diphenylacetylene was demonstrated.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1.
Figure 1.
Scheme 1.
Scheme 1.
Synthetic Routes for the Construction of 3-Sulfenyl Benzo[b]thiophenes Derivatives from o-Alkynylthioanisole
Scheme 2.
Scheme 2.
Proposed Mechanism for Cyclization Reaction
Scheme 3.
Scheme 3.
Proposed Mechanism for the Addition Reaction
Scheme 4.
Scheme 4.
Electrophilic Addition Reactions of Diphenyl Alkyne
Scheme 5.
Scheme 5.
Proposed Mechanism for the Addition Reaction in the Presence and Absence of TBAB
Scheme 6.
Scheme 6.
Scale-up Reaction and Further Elaboration
See this image and copyright information in PMC

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