A. T. K. is highly indebted to the Department of Science and Technology, Ministry of Science and Technology (SERB), New Delhi for the financial support (research project Grant No.: CRG/2018/002120/OC). Ms. Santa Mondal is grateful to Indian Institute of Technology Guwahati (IIT Guwahati) for her research fellowship. The authors are also thankful to Ministry of Human Resource Development for 500 MHz NMR facility in the department (MHRD, Grant No. F. No. 5-5/2014-TS-VII). We duly acknowledge the Department of Science and Technology, Ministry of Science and Technology, New Delhi for providing 500 MHz NMR facility under the DST-FIST program (Sanction No. SR/FST/CS-II/2017/23C), and North East Centre for Biological Sciences and Healthcare Engineering, IIT Guwahati (Sanction No. BT/COE/34/SP28408/2018) for 400 MHz NMR facility.
An efficient synthetic protocol for the α-sulfenylation of 1,3-dicarbonyl compounds is reported through a cross dehydrogenative coupling reaction with 4-hydroxydithiocoumarins in the presence of 10 mol% KI and 1 equiv. TBHP in toluene under reflux conditions. Some of the products are utilized for the synthesis of substituted new pyrazole derivatives on reaction with phenylhydrazine in ethanol at room temperature. In addition, α-benzylation is also achieved on treatment with benzyl bromide using K2CO3/CH3CN under mild conditions. The salient features of the present protocol are good yields, mild reaction conditions, shorter reaction time, no byproducts were formed (sulfoxide/sulfone), and no deacylation occurs during the process. In the present protocol, 4-hydroxydithiocoumarin is converted into a suitable electrophile through a radical substitution pathway, which undergoes ultimately C–S bond formation with 1,3-dicarbonyl compounds by a nucleophilic substitution reaction.
2b
Sorlozano-Puerto A,
Albertuz-Crespo M,
Lopez-Machado I,
Gil-Martinez L,
Ariza-Romero JJ,
Maroto-Tello A,
Baños-Arjona A,
Gutierrez-Fernandez J.
Pharmaceuticals 2021; 14 (21) 1
