Synlett 2023; 34(04): 337-342
DOI: 10.1055/a-1988-1916
letter

l-Proline-Catalyzed Three-Component Reaction of 4-Chloro-3-formylcoumarin, Sodium Sulfide, and α-Halo Ketones: A Direct Approach to Thieno[3,2-c]coumarins

Vandana Thotathil
a   Department of Chemistry and Earth Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
,
Raed M. Al-Zoubi
b   Surgical Research Section, Department of Surgery, Hamad Medical Corporation, Doha, Qatar
c   Department of Biomedical Sciences, College of Health Sciences, QU-Health, Qatar University, P.O. Box 2713, Doha, Qatar
d   Department of Chemistry, Jordan University of Science and Technology, P.O. Box 3030, Irbid, 22110, Jordan
,
Mona Sawali
a   Department of Chemistry and Earth Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
,
Haw-Lih Su
e   Central Laboratories Unit, Qatar University, P.O. Box 2713, Doha, Qatar
,
a   Department of Chemistry and Earth Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
› Author Affiliations
This work was supported by a Qatar University Student Grant [QUST-2-CAS-2020-8] and the Medical Research Center (MRC)/Academic Health System (AHS) (Grant No. MRC-01-22-414).


Dedicated to Professor Hala S. Al-Easa of Qatar university on the occasion of her retirement.

Abstract

A new protocol for the synthesis of thieno[3,2-c]coumarins is disclosed. In this method, a 3-formyl-2-oxo-2H-chromene-4-thiolate anion is generated in situ by treatment of 4-chloro-3-formylcoumarin with sodium sulfide. This chromene-4-thiolate undergoes an l-proline-catalyzed substitution/Knoevenagel cascade with various α-halo ketones to afford the desired thienocoumarins in moderate to good isolated yields. This protocol eliminates the need for stoichiometric amounts of inorganic bases and the use of foul-smelling thiols. The reaction conditions tolerate a variety of α-halo ketones.

Supporting Information



Publication History

Received: 13 October 2022

Accepted after revision: 27 November 2022

Accepted Manuscript online:
27 November 2022

Article published online:
10 January 2023

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