Synthesis of Potentially Bioactive Heterocycles: Thermal [3,3]Sigmatropic Rearrangement of 4‐(4′‐Aryloxybut‐2′‐ynyloxy)‐6‐methyl‐2‐pyridone

Synthesis of a number of hitherto unreported 4‐aryloxymethylene‐7‐methyl‐2,3‐dihydropyrano[3,2‐c]pyridine‐5‐ones 4a–h have been achieved in moderate yields by the thermal [3,3]sigmatropic rearrangement of 4‐(4′‐aryloxybut‐2′‐ynyloxy)‐6‐methyl‐2‐pyridone.     

7‐Step Flow Synthesis of the HIV Integrase Inhibitor Dolutegravir

Dolutegravir (DTG), an important active pharmaceutical ingredient (API) used in combination therapy for the treatment of HIV, has been synthesized in continuous flow. By adapting the reported GlaxoSmithKline process chemistry batch route for Cabotegravir, DTG was produced in 4.5 h in sequential flow operations from commercially available materials. Key features of the synthesis include rapid manufacturing time for pyridone formation, one‐step direct amidation of a functionalized pyridone, and telescoping of multiple steps to avoid isolation of intermediates and enable for greater throughput.     

Synthesis and insecticidal bioactivities of 2,3-dihydroimidazo[1,2-a]pyridin-5(1H)-one derivatives

A novel synthesis of 2,3-dihydroimidazo[1,2-a]pyridin-5(1H)-one, and insecticidal derivatives were described.     

Synthesis of 2,3‐Disubstituted 4‐Pyridone From a β‐Aminocarboxylate Derivative and Acetoacetate

The reaction of diethyl aminomethylenemalonate with ethyl acetoacetate proceeded, when catalyzed by anhydrous hydrogen chloride, toward a respectively substituted α‐ instead of γ‐pyridone derivative formation, contrary to the literature report. Additionally, it was found that the amine used as a starting component in this reaction showed a great tendency to autocondensation under the influence of anhydrous hydrogen chloride to yield 5‐ethoxycarbonyl‐2‐pyridone. The most convenient method to prepare 4‐pyridone 2,3‐disubstituted derivative appeared to be a three‐step synthesis, starting from a chain enamine formation, which was subjected to cyclization, followed by oxidation of the last intermediate. The usefulness of the stepwise synthesis was demonstrated on the 3‐ethoxycarbonyl‐2‐methyl‐4‐pyridone preparation as an example.