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Issue 10, 2019
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On water: iodine-mediated direct construction of 1,3-benzothiazines from ortho-alkynylanilines by regioselective 6-exo-dig cyclization

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Abstract

Herein, we report the 6-exo-dig ring closure of ortho-alkynylanilines with readily available aroyl isothiocyanate. An environmentally benign, metal- and base-free, iodine promoted cascade synthesis of highly functionalized (benzo[1,3]thiazin-2-yl)benzimidic acids has been accomplished via in situ generated ortho-alkynylthiourea. The established methodology employs the abundant chemical feedstock of ortho-alkynylanilines and aroyl isothiocyanates and could be applied in the late-stage synthesis of pharmaceutically active 1,3-benzothiazine containing molecules. Furthermore, the discovered protocol exclusively delivers bis (benzo[1,3]thiazin-2-yl)dibenzimidic acid products and preserves the iodo-olefin substitution pattern which can be exploited by further derivatization.

Graphical abstract: On water: iodine-mediated direct construction of 1,3-benzothiazines from ortho-alkynylanilines by regioselective 6-exo-dig cyclization

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Publication details

The article was received on 17 Jan 2019, accepted on 07 Feb 2019 and first published on 07 Feb 2019


Article type: Paper
DOI: 10.1039/C9OB00128J
Citation: Org. Biomol. Chem., 2019,17, 2657-2662

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    On water: iodine-mediated direct construction of 1,3-benzothiazines from ortho-alkynylanilines by regioselective 6-exo-dig cyclization

    K. M. Saini, R. K. Saunthwal, S. Kumar and A. K. Verma, Org. Biomol. Chem., 2019, 17, 2657
    DOI: 10.1039/C9OB00128J

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