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Short Paper | Regular issue | Vol 94, No. 7, 2017, pp.1351-1358
Published online, 6th June, 2017
DOI: 10.3987/COM-17-13734
■ Synthesis of Novel Tetracyclic Thieno[3’,2’:2,3]pyrido[4,5-d]pyrido[1,2-a]pyrimidinones via Pictet-Spengler Cyclization

Yi-Xin Tang, Dao-Lin Wang,* and Jian-Hua Qian

*Liaoning Key Laboratory of Synthesis & Application of Functional Compound, College of Chemistry & Chemical Engineering, Bohai University, Jinzhou 121001, China

Abstract

Synthesis of novel thieno[3’,2’:2,3]pyrido[4,5-d]pyrido[1,2-a]pyrimidin-5-one derivatives (5) via Pictet-Spengler cyclization is reported. The key intermediate, 2-(3-amino-4-cyano-5-phenylaminothieno-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (3), was readily prepared from 2-chloromethyl-4H-pyrido[1,2-a]pyrimidin-4-one (1) with potassium (2,2-dicyano-1-phenylaminoethen-1-yl)thiolate (2) by Thorpe-Ziegler isomerization. Reaction of the intermediate amine with aromatic aldehydes in the presence of p-TsOH gives tetracyclic thienopyridine-fused pyrido[1,2-a]pyrimidines 5 in good yields.