Regioselective Syntheses of 3-Benzyl-Substituted 7H-Thiazolo[3,2-<i>a</i>]pyrimidine-7-ones through Palladium-Catalyzed Heteroannulation of Acetylenic Compounds

<table>Proposed mechanism for the formation of either 3-aryl-substituted <i>7</i>H-thiazolo[3,2-<i>a</i>]pyrimidine-7-ones 4 or 3-aryl-substituted 5H-thiazolo[3,2-<i>a</i>]pyrimidine-5-ones 5 at room temperature. Reagents and conditions: (a) reduction of Pd(II) to Pd(0) with alkyne and Et3N; (b) CuI, Et3N; (c) nucleophilic attack on the triple band (V) catalyzed by CuI, Et3N to generate the product 4 or 5.</table>

Organic Chemistry International

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Scheme 2

Scheme 2: Regioselective Syntheses of 3-Benzyl-Substituted 7H-Thiazolo[3,2-<i>a</i>]pyrimidine-7-ones through Palladium-Catalyzed Heteroannulation of Acetylenic Compounds 

Scheme 2 | Regioselective Syntheses of 3-Benzyl-Substituted 7H-Thiazolo[3,2-a]pyrimidine-7-ones through Palladium-Catalyzed Heteroannulation of Acetylenic Compounds 