Microwave Assisted Synthesis of 2,3‐Dihydro‐4H‐ furo[2,3‐d]pyrido[1,2‐a]pyrimidin‐4‐ones and furo[2,3‐d]pyrido[1,2‐a]pyrimidin‐4‐one

Abstract

In this work, furo[2,3d]pyrido [1,2-a]pyrimidin-4-ones were obtained by microwave assisted radical cyclizations of 2-hydroxy-4H-pirido[1,2a]pirimidin-4-ones with conjugated alkenes and phenylacetylene via Mn(OAc) 3. Conventional heating and microwave irradiated reaction types were compared using parameters like temperature, time and molar ratios to determine best reaction condition. Obtained compounds were purified by chromatographic methods and characterized by spectroscopic techniques ( 1 H NMR, 13 C NMR, HRMS, FTIR). Also, to determine the exact configuration and regioselectivity of isolated compounds, XRD analysis were performed.

A “Neat” Synthesis of Substituted 2-Hydroxy-pyrido[1,2-a]pyrimidin-4-ones

“…When synthesizing the otherwise unsubstituted 2-hydroxy-PPD 2a, literature reports are consistent that using 2aminopyridine and a malonate derivative to effect two successive amidation reactions is an efficient method. 21,[24][25][26][27][28] However, in our hands we found inconsistent results when we applied these methods to access 2-hydroxy-PPDs beyond the scope explored in the original report. With a goal to establish conditions that could be broadly applied to a library of commercially available 2-aminopyridine building blocks, we began by evaluating three methods (A-C) to access five 2hydroxy-PPDs (2a-c, 2e, 2f; Figure 2).…”