Traceless synthesis of diketopiperazine fused tetrahydro-β-carbolines on soluble polymer support.

Kaushik Chanda, Cheng-Ting Chou, Jin-Ji Lai, Shu-Fen Lin, Gorakh S Yellol, Chung-Ming Sun

Index: Mol. Divers. 15(2) , 569-81, (2011)

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Abstract

The Pictet-Spengler reaction, using polyethylene glycol immobilized tryptophan ester with a variety of ketones, was achieved by refluxing condition in acidic chloroform. The linear as well as cyclic ketones were employed. All the ketones were reacted within 6-8 h to furnish soluble polymer-supported tetrahydro-β-carboline in good yields. Further expansion at N-terminus of tetrahydro-β-carbolines was achieved through a reaction with chloroacetyl chloride. Finally, the 2,5-diketopiperazine skeleton was constructed over a β-carboline by amination of the resulting N-chloroacetamides and subsequent intramolecular cyclization leading to cleavage of the polymer; constitutes a traceless synthesis of tetracyclic molecular architecture. Significantly, this strategy affords a straightforward and efficient approach for the construction of biological promising molecules with high purity and good yields.