Unexpected Formation of Thiophene in the Pyrrole Synthesis from Methoxyallene and Methyl Isothiocyanate

The sequential reaction of lithiated methoxyallene, methyl isothiocyanate, and 2-(bromomethyl)-1,3-dioxolane in the presence of CuBr yields a 2,3-disubstituted thiophene instead of the expected pyrrole. The process is accomplished in one preparative stage and involves intramolecular cyclization of t...

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Bibliographic Details
Published in:Russian journal of organic chemistry 2021-02, Vol.57 (2), p.287-291
Main Authors: Tarasova, O. A., Nedolya, N. А., Albanov, А. I., Trofimov, B. A.
Format: Article
Language:English
Subjects:
Alkylation
Chemistry
Chemistry and Materials Science
Lithium
Organic Chemistry
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Summary:The sequential reaction of lithiated methoxyallene, methyl isothiocyanate, and 2-(bromomethyl)-1,3-dioxolane in the presence of CuBr yields a 2,3-disubstituted thiophene instead of the expected pyrrole. The process is accomplished in one preparative stage and involves intramolecular cyclization of the in situ-generated lithium allenylimidothioate and N -alkylation of the resulting lithium thienylamide. Varying the reaction conditions does not affect its route: in all cases, the only product is N -(1,3-dioxolan-2-ylmethyl)-3-methoxy- N -methylthiophen-2-amine.
ISSN:1070-4280
1608-3393
DOI:10.1134/S1070428021020214