DABCO-Catalyzed DMSO-Promoted Sulfurative 1,2-Diamination of Phenylacetylenes with Elemental Sulfur and o-Phenylenediamines: Access to Quinoxaline-2-thiones
Thi Minh Chau Tran, Nang Duy Lai, Thai Thanh Thu Bui, Dinh Hung Mac*, Thi Thu Tram Nguyen, Pascal Retailleau and Thanh Binh Nguyen*
*Vietnam National University, Hanoi, 19 Le Thanh Tong, Hanoi, Vietnam;
Université Paris-Saclay, 91198 Gif-sur-Yvette, France,
Email: macdinhhung
hus.edu.vn, thanh-binh.nguyencnrs.fr
T. M. C. Tran, N. D. Lai, T. T. T. Bui, D. H. Mac, T. T. T. Nguyen, P. Retailleau, T. B. Nguyen, Org. Lett., 2023, 25, 7186-7191.
DOI: 10.1021/acs.orglett.3c02835
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Abstract
DABCO serves as a sulfur-activating catalyst to achieve the sulfurative 1,2-diamination of phenylacetylenes with elemental sulfur and o-phenylenediamines in the presence of DMSO as terminal oxidant. This cascade three-component reaction is triggered by the addition of active sulfur species to the triple bond of phenylacetylenes.
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proposed mechanism
Representative protocol for the synthesis of 3-phenylquinoxaline-2(1H)-thione
A mixture of o-phenylenediamine (1.2 mmol, 130 mg), sulfur (1.5 mmol, 48 mg), phenylacetylene (1.0 mmol, 102 mg), DABCO (0.2 mmol, 22 mg) and DMSO (3 mmol, 234 mg, 0.2 mL) was heated at 80 ºC with a heating block for 16 h in a 7-mL test tube closed with a rubber septum. The mixture cooled to room temperature was treated with MeOH (2 mL) with vigorous stirring to promote the separation of a yellow precipitate. The product was filtered, washed with a 1:9 mixture of MeOH:CH2Cl2 and dried in vacuo to give pure desired product (Yellow solid, 181 mg, 76%).
Key Words
benzo-fused N-heterocycles, quinoxalinones, multicomponent reactions, DMSO
ID: J54-Y2023
