Synthesis 2025; 57(01): 209-217
DOI: 10.1055/a-2373-0255
paper
Special Topic Dedicated to Prof. H. Ila

A Formal [3+3] Annulation of Morita–Baylis–Hillman Ketones to Construct Pyrimidobenzothiazoles

Rajkiran Kumari
,
Suman Kumawat
,
Ministry of Education, India, (Grant/Award Number: MoE-STARS/ STARS-2/2023-1017) and Science and Engineering Research Board, (Grant / Award Number: CRG/2022/008471).


Dedicated to Prof. H. Ila on the occasion of her 80th birthday

Abstract

A calcium triflate-promoted reaction of Morita–Baylis–Hillman (MBH) ketones, derived by the oxidation of MBH adducts, with 2-aminobenzothiazoles resulted in the formation of 4H-pyrimido[2,1-b]benzothiazoles. Formally, the transformation represents a [3+3] annulation and presumably proceeds via an aza-Michael addition followed by an intramolecular condensation. The reaction is completely regioselective and tolerates a wide range of substrates to afford a variety of analogues of the fused heterocycle in good yields.

Supporting Information



Publication History

Received: 31 May 2024

Accepted after revision: 23 July 2024

Accepted Manuscript online:
25 July 2024

Article published online:
21 August 2024

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