Harnessing sulfur and nitrogen in the cobalt(iii )-catalyzed unsymmetrical double annulation of thioamides: probing the origin of chemo- and regio-selectivity
| Autor: | Somratan Sau, Arghadip Ghosh, Akhila K. Sahoo, Vincent Gandon, Majji Shankar, Arijit Saha |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Chemical Science |
| ISSN: | 2041-6539 2041-6520 |
| DOI: | 10.1039/d1sc00765c |
| Popis: | An unconventional cobalt(iii)-catalyzed one-pot domino double annulation of aryl thioamides with unactivated alkynes is presented. Sulfur (S), nitrogen (N), and o,o′-C–H bonds of aryl thioamides are involved in this reaction, enabling access to rare 6,6-fused thiopyrano-isoquinoline derivatives. A reverse ‘S’ coordination over a more conventional ‘N’ coordination of thioamides to the Co-catalyst specifically regulates the formation of four [C–C and C–S at first and then C–N and C–C] bonds in a single operation, a concept which is uncovered for the first time. The power of the N-masked methyl phenyl sulfoximine (MPS) directing group in this annulation sequence is established. The transformation is successfully developed, building a novel chemical space of structural diversity (56 examples). In addition, the late-stage annulation of biologically relevant motifs and drug candidates is disclosed (17 examples). The preliminary photophysical properties of thiopyrano-isoquinoline derivatives are discussed. Density functional theory (DFT) studies authenticate the participation of a unique 6π-electrocyclization of a 7-membered S-chelated cobaltacycle in the annulation process. A Co-catalyzed one-pot double annulation of sulfoximine bearing thioamides with alkynes for the synthesis of [6,6]-fused thiopyrano-isoquinolines is disclosed. The annulation involves a 6π-electrocyclization of 7-membered S-chelated cobaltacycle. |
| Databáze: | OpenAIRE |
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