Harnessing sulfur and nitrogen in the cobalt(iii)-catalyzed unsymmetrical double annulation of thioamides: probing the origin of chemo- and regio-selectivity |
| |
Authors: | Majji Shankar Arijit Saha Somratan Sau Arghadip Ghosh Vincent Gandon Akhila K Sahoo |
| |
Institution: | School of Chemistry, University of Hyderabad, Hyderabad India.; Institut de Chimie Moléculaire et des Matériaux d''Orsay, CNRS UMR 8182, Université Paris-Saclay, Bâtiment 420, 91405 Orsay cedex France ; Laboratoire de Chimie Moléculaire (LCM), CNRS UMR 9168, Ecole Polytechnique, Institut Polytechnique de Paris, route de Saclay, 91128 Palaiseau cedex France, |
| |
Abstract: | 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. |
| |
Keywords: | |
|
|