Synthesis of tetrahydrofuro[3,2-]pyridines via Pictet-Spengler reaction.

A semi-one-pot method for the synthesis of 4-substituted tetrahydrofuro[3,2-]pyridines by the Pictet-Spengler reaction was developed. The method is based on the condensation of easily accessibly 2-(5-methylfuran-2-yl)ethanamine with commercially available aromatic aldehydes followed by acid-catalyzed Pictet-Spengler cyclization. Using this approach, we synthesized a range of 4-substituted tetrahydrofuro[3,2-]pyridines in reasonable yields. The reactivity of some of the products was investigated and selected synthetic transformations of the obtained tetrahydrofuro[3,2-]pyridines were shown.